WO2014043892A1

WO2014043892A1 - Collision handling for contention based uplink transmission

Info

Publication number: WO2014043892A1
Application number: PCT/CN2012/081751
Authority: WO
Inventors: Zhi Zhang; Jianchi Zhu
Original assignee: Nokia Corporation
Priority date: 2012-09-21
Filing date: 2012-09-21
Publication date: 2014-03-27

Abstract

In accordance with an example embodiment of the present invention, an apparatus comprises processor and memory including computer program code, wherein the memory and the computer program code, with the processor, configured what the processor to cause the apparatus transmit a message on at least one physical resource block to a network node, receive a resource utilization map and a user equipment specific signaling that indicates availability status of at least one group of physical resource blocks and perform contention based uplink transmission on the at least one physical resource block that also belongs to the at least one group of physical resource block.

Description

COLLISION HANDLING FOR CONTENTION BASED UPLINK

TRANSMISSION

TECHNICAL FIELD

[0001] The exemplary and non-limiting embodiments relate generally to wireless communication systems, methods, devices and computer programs and, more specifically, to data transmission in local area networks.

BACKGROUND

[0002] Cellular communication may comprise that mobiles roam in cell coverage areas of cells comprised in cellular communication systems. A mobile may communicate with at least one base station at a time, wherein each base station may control at least one cell in the cellular commumcations system. Cellular communication systems may operate in accordance with industry standards, whereby interoperability may be achieved. In an interoperable functioning system, a mobile manufactured by a first manufacturer may successfully communicate with a base station manufactured by a second manufacturer, for example. Base stations comprised in a radio access network of the cellular coimnunication system may in turn communicate with core network nodes manufactured by further manufacturers.

[0003] One modern cellular network system is known as evolved universal mobile telecommunications system, UMTS, terrestrial radio access network, E-UTRAN, also referred to as UTRAN-LTE or as E-UTRA. The long term evolution, LTE, based local area network, LTE- LAN, solution aims to provide high speed data transmission for local area coverage, such as indoor, residential, enterprise scenarios, etc. SUMMARY

[0004] The below summary section is intended to be merely exemplary and non- limiting.

[0005] Various aspects of examples of the invention are set out in the claims.

[0006] In a first aspect thereof an exemplary embodiment provides an apparatus comprises at least one processor and at least one memory including computer program code, wherein the at least one memoiy and the computer program code configured, with the at least one processor, to cause said apparatus to receive at least one signal in uplink transmission, detect a collision in one of the at least one received signal, identify at least one physical resource block in which the collision is detected, update a resource utilization map and transmit it to at least one user equipment and transmit a signal to the at least one user equipment, wherein the signal indicates availability status of at least one group of physical resource blocks.

[0007] In another aspect thereof an exemplary embodiment provides an apparatus comprises at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code configured, with the at least one processor, to cause said apparatus to transmit a message on at least one physical resource block to a network node, receive a resource utilization map and a user equipment specific signaling that indicates availability status of at least one group of physical resource blocks, and perform contention based uplink transmission on the at least one physical resource block that also belongs to the at least one group of physical resource block.

[0008] In a further aspect thereof an exemplary embodiment provides an apparatus comprises at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code configured, with the at least one processor, to cause said apparatus to transmit a message on at least one physical resource block to a network node, receive a resource utilization map without receiving a user equipment specific signaling, and perform contention based uplink transmission on physical resource blocks on the resource utilization map but not on the one of the at least one physical resource block in which the collision is detected.

[0009] In another aspect thereof an exemplary embodiment provides an apparatus comprises at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code configured, with the at least one processor, to cause said apparatus to transmit a message on at least one physical resource block to a network node, receive a user equipment specific signaling, which indicates availability status of at least one group of physical resource blocks, without receiving a resource utilization map, and perfonn contention based uplink transmission on at least one of the at least one physical resource block that belongs to the at least one group of physical resource block, any physical resource block of the at least one group of physical resource block, and physical resource blocks other than the at least one group of physical resource block. [0010] In another aspect thereof an exemplary embodiment provides a method comprising receiving, at a network node, at least one signal in uplink transmission, detecting a collision in the at least one received signal, identifying at least one physical resource block in which the collision is detected, updating a resource utilization map and transmitting it to at least one user equipment and transmitting a signal to the at least one user equipment, wherein the signal indicates availability status of at least one group of physical resource blocks.

[0011] In a further aspect thereof an exemplary embodiment provides a method comprising transmitting a message on at least one physical resource block to a network node, receiving a resource utilization map and a user equipment specific signaling that indicates availability status of at least one group of physical resource blocks, and performing contention based uplink transmission on the at least one physical resource block that also belongs to the at least one group of physical resource block.

[0012] In another aspect thereof an exemplary embodiment provides a method comprising transmitting a message on at least one physical resource block to a network node, receiving a resource utilization map without receiving a user equipment specific signaling, and performing contention based uplink transmission on physical resource blocks on the resource utilization map but not on the one of the at least one physical resource block in which the collision is detected.

[0013] In another aspect thereof an exemplary embodiment provides a method comprising transmitting a message on at least one physical resource block to a network node, receiving a user equipment specific signaling, which indicates availability status of at least one group of physical resource blocks, without receiving a resource utilization map, and performing contention based uplink transmission on at least one of the at least one physical resource block that belongs to the at least one group of physical resource block, any physical resource block of the at least one group of physical resource block, and physical resource blocks other than the at least one group of physical resource block.

[0014] In another aspect thereof an exemplary embodiment provides a computer readable medium tangibly encoded with a computer program executable by a processor to perform actions comprising receiving, at a network node, at least one signal in uplink transmission, detecting a collision in the at least one received signal, identifying at least one physical resource block in which the collision is detected, updating a resource utilization map and transmitting it to at least one user equipment, and transmitting a signal to the at least one user equipment, wherein the signal indicates availability status of at least one group of physical resource blocks.

[0015] In another aspect thereof an exemplary embodiment provides a computer readable medium tangibly encoded with a computer program executable by a processor to perform actions comprising transmitting a message on at least one physical resource block to a network node, receiving a resource utilization map and a user equipment specific signaling that indicates availability status of at least one group of physical resource blocks, and performing contention based uplink transmission on at least one of physical resource blocks other than the at least one group of physical resource block and the at least one physical resource block that also belongs to the at least one group of physical resource block.

[0016] In another aspect thereof an exemplary embodiment provides an apparatus comprising means for receiving, at a network node, at least one signal in uplink transmission, means for detecting a collision in the at least one received signal, means for identifying at least one physical resource block in which the collision is detected, means for updating a resource utilization map and transmitting it to at least one user equipment and means for transmitting a signal to the at least one user equipment, wherein the signal indicates availability status of at least one group of physical resource blocks.

[0017] In another aspect thereof an exemplary embodiment provides an apparatus comprising means for transmitting a message on at least one physical resource block to a network node, means for receiving a resource utilization map and a user equipment specific signaling that indicates availability status of at least one group of physical resource blocks and means for performing contention based uplink transmission on the at least one physical resource block that also belongs to the at least one group of physical resource block.

[0018] In another aspect thereof an exemplary embodiment provides an apparatus comprising means for transmitting a message on at least one physical resource block to a network node, means for receiving a resource utilization map without receiving a user equipment specific signaling, and means for performing contention based uplink transmission on physical resource blocks on the resource utilization map but not on the one of the at least one physical resource block in which the collision is detected. [0019] In another aspect thereof an exemplary embodiment provides an apparatus comprising means for transmitting a message on at least one physical resource block to a network node, means for receiving a user equipment specific signaling, which indicates availability status of at least one group of physical resource blocks, without receiving a resource utilization map and means for performing contention based uplink transmission on at least one of the at least one physical resource block that belongs to the at least one group of physical resource block, any physical resource block of the at least one group of physical resource block, and physical resource blocks other than the at least one group of physical resource block.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The foregoing and other aspects of exemplary embodiments are made more evident in the following Detailed Description, when read in conjunction with the attached Drawing Figures, wherein:

[0021] FIGURE 1 illustrates an example of an LTE based local area network, LTE- LAN;

[0022] FIGURE 2 illustrates an example of current LTE uplink scheduling procedure;

[0023] FIGURE 3 illustrates an example of a contention based uplink transmission in LTE-LAN;

[0024] FIGURE 4A illustrates an example of a collision handling contention based uplink transmission in LTE-LAN;

[0025] FIGURE 4B illustrates an example of a bitmap of a user equipment, UE, specific signaling from access point.

[0026] FIGURE 5 illustrates a flow chart of a collision handling contention based uplink transmission in LTE-LAN in accordance with at least one embodiment of the invention;

[0027] FIGURE 6 illustrates an example of a cell specific signaling and a UE specific signaling between an access point or a network node and UEs;

[0028] FIGURE 7 illustrates another example of a cell specific signaling and a UE specific signaling between an access point or a network node and UEs; [0029] FIGURE 8 illustrates an example of a simplified block diagram of exemplary electronic devices that are suitable for use in practicing various exemplary embodiments of this invention.

DETAILED DESCRIPTON

[0030] Different scenarios can be considered as local area in wireless communication.

The indoor hotspot scenario, for example as introduced in 3^rd generation partnership project, 3 GPP, document TR 36.814 v.9.0.0, consists of single floor of a building with 6- meter-high floor, 16 rooms of 15 meter by 15 meter and a long hall of 120 meter by 20 meter. Office enterprise scenario is another example, of which the area is a large work space. More indoor, residential and enterprise scenarios can be listed as examples of local area scenarios.

[0031] LTE-based local area network, LTE-LAN, aims to provide very high speed data transmission for local area wireless communication. FIGURE 1 illustrates an example of an LTE-LAN 100. The LTE-LAN 100 comprises an access point, AP, 1 10, which may also be a network node, a base station, BS, or an E-UTRAN Node B, evolved Node B or eNB, and one or more than one user equipment, UE. The LTE-LAN access point, AP, 110 provides LTE-based wireless connections to the local area devices, user equipments, mobile terminals or UEs 120, 130 and 140. The uplink data transmission of LTE-LAN 100 may be configured as contention-based uplink transmission, CBUT, according to one or more embodiment of the invention.

[0032] In the current LTE network, single-earner frequency division multiple access, SC-FDMA, has been adopted as the uplink multiple access scheme, mainly because of its lower peak-to-average power ratio, PAPR, which may benefit the mobile terminal or the UE in terms of transmit power efficiency compared to orthogonal frequency division multiple access, OFDMA, schemes.

[0033] OFDMA may be utilized in uplink transmission of local area networks for at least one of the following reasons, for example:

• Uplink PAPR is not an important issue in local area network, LAN, because transmit power of a UE may be almost equal to that of eNB . Uplink signal to interference plus noise ratio, SIN , distribution may be very close to downlink SINR distribution.

OFDMA for uplink in LAN has certain benefits comparing to SC-FDMA, such as more flexible resource allocation, uplink or downlink similarity for device to device, D2D, communication, similar uplink or downlink structure for intereference-aware cancellation design especially for dynamic time division duplex, TDD, uplink or downlink configuration switching and a same radio chip being applicable for both UE and LAN AP. [0034] In order to use OFDMA in uplink transmission in LAN such as, for example,

LTE_LAN, an uplink control channel as well as uplink scheduling procedures need to be redesigned. A UE may need to be configured with a new uplink control channel or uplink signaling procedure, which may be more appropriate for LAN.

[0035] Contention-free uplink transmission and contention-based uplink transmission are two commonly applied uplink transmission methods. Contention- free uplink transmission is currently used in data transmission in LTE as shown in FIGURE 2.

[0036] FIGURE 2 illustrates an example of a prior-art LTE uplink scheduling procedure 200. When UE 210 has uplink data stored in a UE logic buffer, it requests uplink resources for data transmission. Such a request can be triggered by an event or a periodic trigger 212, for example. The UE 210 sends a scheduling request, SR, 214 in a physical uplink control channel, PUCCH, format for contention- free uplink transmission, or alternatively the UE sends a SR on a physical random access channel, PRACH, 214 as a contention based uplink resource request. Based on scheduling policy, eNB 230 may allocate some physical uplink shared channel, PUSCH, resources for sending buffer status report, BSR, by means of sending uplink, UL, grant for BSR transmission 216 to the UE 210. After receiving the UL grant for BSR transmission, the UE 210 will transmit BSR, which indicates the amount of data available in the logic buffer, on scheduled PUSCH to eNB 230 for uplink scheduling 218. Then, eNB 230 may perform the uplink scheduling, UL scheduling, 220, which may include allocating corresponding uplink resources. And, eNB 230 may send UE 210 an uplink grant for UL data transmission 222, with the condition of the uplink radio connection between UE and eNB taken into account. Finally, the UE 210 may be configured to transmit uplink data 224 to the eNB 230,

[0037] The signaling between the UE and the eNB according to the current LTE standard is complicated, which adds to delay of data transmission. Since TDD is the major duplexing technology used in the LAN, the current uplink transmission procedure sometimes will generate undesired latency. For example, if a heavy TDD frame configuration in downlink is configured as a TDD configuration, the procedure in FIGURE 2 as described above may take at least 20ms to obtain uplink grant for requested uplink transmission.

[0038] It has been proposed and/or suggested in PCT/CN2012/078125 that in some embodiments, contention based uplink transmission, CBUT, may be employed in LAN, such as LTE-LAN, as shown in FIGURE 3, to reduce latency, because the CBUT mechanism does not require a scheduling request. In FIGURE 3, when a UE 310 triggers a contention based uplink transmission on PUSCH 314, it simultaneously indicates to the LTE-LAN AP 330, which may be a network node, an eNB or a base station, the contention based PUSCH decoding information. The PUSCH decoding information may comprise at least one of resource allocation and modulation and coding scheme, MCS. The PUSCH decoding information may be transmitted from the UE on PUCCH 312, for example, for the same subframe 320 or a temporally adjacent subframe. When multiple UEs allocated in the same LTE-LAN, the CBUT mechanism may incur collisions on the PUSCHs from different UEs. Collisions may cause failure of PUSCH decoding at the LTE-LAN AP 330. Therefore, embodiments of the present invention provide mechanisms for collision handling contention based uplink transmission. Such mechanisms may improve resource utilization efficiency of the CBUT mechanism.

[0039] In accordance with at least some embodiments of the invention, when a radio resource, for example, a PRB is simultaneously used by more than one UE for carrying a message and/or data, a collision occurs. For example, more than one UE may transmit PUSCH on the same PRB simultaneously, which causes collision. The UE may send its PUSCH decoding information on PUCCH. The AP may know the radio resource utilization status through the infonnation on PUCCH. If the AP identifies a radio resource, for example, the PRB is simultaneously used by more than one UE, the AP may determine that collision happens on this radio resource. The AP may be configured to identify the PRB as being simultaneously used by more than one UE by determining that more than one UE indicates on PUCCH that they have used the PRB. Identifying a PRB as being simultaneously used by more than one UE is an example of detecting that a collision has occurred.

[0040] Since the LTE-LAN AP, or more generally LAN AP, is aware of the resource allocation from the decoding information earned on the PUCCH, it can precisely know the resource and the UE(s) that the collision involves. With the knowledge of the collision, the LTE-LAN AP can broadcast a resource utilization map to the UEs and inform them of the assigned resources for transmission between the AP and the UEs and/or how to use certain resources, which will be discussed in more detail below by referring to FIGURE 4A.

[0041] FIGURE 4A shows an example of a procedure of collision handling for contention based uplink transmission in a LAN such as, for example, LTE-LAN, with the illustration of signaling flow 402 coordinated with broadcasting resource utilization map

404. AP 110 can be an access node, a network node, an eNB or a base station in an LTE- LAN. A resource allocation map is initially generated by AP 110 or stored in AP 110. The AP 110 broadcasts the resource utilization map 420 to UEs, which are UE1 120 and UE2 130 in FIGURE 4A, through a cell specific signaling, for example. The cell specific signaling can be carried on a physical downlink control channel, PDCCH, for example.

[0042] The AP 110 may send the resource utilization map on downlink subframe 0 and subframe 5, according to LTE Release 8, so that the UEs 120 and 130 can avoid potential collision once they obtain this map. The resource utilization map is not limited to be sent on subframes 0 and 5. In other words, AP 110 can send the resource utilization map additionally on other downlink subframes, for example when the resource utilization status changes a lot.

[0043] The resource utilization map may comprise a bitmap in which bit fields of length 2 bits are used to indicate one out of four types of statuses of each of the assigned PRBs for UE's uplink transmission. The four types PRBs in different statuses are defined in the following. • Vacant PRBs: The PRBs are not occupied for uplink transmission such as

CBUT. UE can perform uplink transmission such as CBUT on this PRB and the resources are free for UEs to compete on uplink transmission such as CBUT.

· Normal PRBs: The PRBs are currently occupied for uplink transmission such as CBUT without collision detected. UE can still perform uplink transmission such as CBUT on the PRBs in the next transmission.

• Constrained PRB: The PRBs are currently occupied for uplink transmission such as CBUT with collision detected. UE follows instruction, which may be carried on a UE specific signaling, to determine whether it can use this PRB for next transmission or not.

• Reserved PRB: The PRBs are reserved by AP or network. They are reserved mainly for UEs with initial uplink transmission such as CBUT, particularly when there is no Vacant PRBs for the UEs. Each UE will be assigned reserved PRBs so that this UE can always transmit data and/or messages on these PRBs. And, a UE cannot use the PRBs reserved for other UEs. Reserved PRBs may be indicated in random access channel (RACH) grant.

[0044] The resource utilization map can be transmitted on a common PDSCH, for example. A common PDCCH scrambled by a new cell radio network temporary identifier, C-RNTI, may be defined as contention based C-RNTI, CB-C-RNTI, to indicate one common PDSCH. Thus, all the UEs can read the common PDCCH and find the resource utilization map on the associated common PDSCH.

[0045] The common PDCCH can contain the information of the resource allocation and MCS adopted by the associated common PDSCH. The AP can insert a synchronization flag to the common PDCCH. This synchronization flag can consist of several bits, for example, 4 bits. The puipose of inserting a synchronization flag in the cell specific signaling on common PDCCH will be discussed more in detail later. [0046] At the time that the AP 110 broadcasts, or more generally transmits, the resource utilization map 420, the map indicates all the PRBs as Vacant PRBs 460, assuming there was no transmission between AP 110 and the UEs made prior to the AP 110 transmitting or broadcasting the resource utilization map 420 via a cell specific signal. The UEl 120 and UE2 130 may access the AP 110 by sending PRACH access requests 422 and 424. Responsive to receiving the PRACH access requests from the UEs, the AP 110 may reserve some PRBs for UEl 120 and UE2 130. And then, it may transmit, for example broadcast, resource utilization map 426 to indicate part of PRBs as Reserved PRBs, 464 and 468, particularly PRBs 464 reserved for UEl 120 and PRBs 468 reserved for UE2 130. The rest PRBs are indicated as Vacant PRBs, 462 and 466 in the resource utilization map.

[0047] Accordingly, UEl 120 and UE2 130 will perform uplink transmission such as CBUT 428 and 430 at the same time by using Reserved PRBs, 464 and 468 respectively, and, optionally, any physical resource blocks of the Vacant PRBs, 462 and 466. In the illustrated case, UEl 120 and UE2 130 both use at least part of the Vacant PRBs 466 for CBUT. The CBUT procedure has been discussed previously. From the received PUCCH indication from UEl 120 and UE2 130 during the CBUT, 428 and 430, the AP 110 detects collision 432. AP 110 further detects in which part of the PRBs, in this case PRBs 476, of the previous Vacant PRBs 466 the collision has occurred based at least in part on the CBUT from UEl 120 and UE2 130.

[0048] Since the status of at least some part of the PRBs has been changed, AP 110 will update the resource utilization map based on the current status of the assigned physical resource blocks, which includes the identified physical resource block in which the collision is detected. The status change of the PRBs may also be made based upon at least one of the received signal. The PRBs where collision occurs will be indicated as Constrained PRBs 476, and PRBs which have been used without collision as Normal PRBs, 474 and 478. Reserved PRBs 472 remains the same status as PRBs 464, same as Reserved PRBs 480 remains the same status as PRBs 468. Since nothing has been transmitted on Vacant PRBs 462, it continues to be indicated as Vacant PRBs 470 in the broadcasted resource utilization map 434. In the meantime, the AP 110 sends UE specific signalings 436 and 438 to UEs 120 and 130 respectively, to further inform the UEs how to utilize the resources for uplink transmission such CBUT.

[0049] FIGURE 4B illustrates an example of a bitmap of the UE specific signaling from AP, for example comprised in phase 436 of FIGURE 4A. The example UE specific signaling 405 comprises three parts, namely the first part 406, the second part 407 and the third part 408.

[0050] The first part 406 is in the form of a bitmap, which indicates the configuration of the groups of N PRBs. N contiguous or noncontiguous PRBs are grouped into a group of N PRBs. In other words, the group of N PRBs becomes a unit. The N is related to the bandwidth, for example, N may be 4 for a bandwidth of 20 MHz. The first part 406 has each bit indicating two statuses, Available status or Unavailable status, of a group of N PRBs, for example a group of N PRBs 409. The Unavailable status of a group of N PRBs 409, for example, indicates that this group of N PRBs 409 cannot be used for uplink transmission or CBUT. When a group of N PRBs 409 is in the status of Available, a UE may further have two options in terms of which Available group of N PRBs may be used and how to use it in the uplink transmission.

[0051] The two options are controlled by the second part 407 of the UE specific signaling 405, which may be a 1-bit indication. The two options of Available status include the first option, or option 1, which means a UE can use the Available group of N PRBs 409 again if it has been used for the most recent uplink transmission and the second option, or option 2, which means a UE can use all the Available groups of N PRBs. Indicated by the 1-bit indication of second part 407, it can be bit "0" for the first option and bit "1" for the second option, or vice versa.

[0052] If a UE receives a resource utilization map through the cell specific signaling as well as the UE specific signaling, it may be configured to use the group of N PRBs that it used for the most recent uplink transmission, or the previously used PRBs regardless of the availability status, except the Unavailable Constrained PRBs. The UE may know its previous transmission parameters including PRB allocation and modulation and coding schemes, MCS. Thus, the UE may know or have the memory of which PRBs it used for uplink transmission previously. [0053] If a UE does not receive a resource utilization map through the cell specific signaling but receives the UE specific signaling, by checking the configuration of the groups of N PRBs and the availability status of each group in the first part 406, the UE may be configured to follow whichever option indicated by the 1-bit indication in the second part 407 of the UE specific signaling. As mentioned earlier, the UE can perform uplink transmission such as CBUT on either previously used PRBs that are in Available status or any of the N PRBs configured in the UE specific signaling that are in Available status.

[0054] In some embodiments, if a UE receives an indication of Constrained PRBs from a cell specific signaling, without receiving UE specific signaling, the UE will assume that it may perform uplink transmission on any PRBs contained in the resource utilization map except the Constrained PRBs or the Reserved PRBs reserved for other UEs.

[0055] In case a UE receives neither a cell specific signaling nor a UE specific signaling, the UE may assume that no collision has occurred and it may transmit data on uplink on any PRBs, except the Reserved PRBs that are not reserved for it.

[0056] The third part 408 in FIGURE 4B is a synchronization flag inserted in the UE specific signaling. The sequence of the first, second and third part of UE specific signaling 405 can be different from the one shown in FIGURE 4B. For example, the synchronization flag may be inserted in the first part of the UE specific signaling 405, the second part may contain the configuration of the groups of N PRBs and their availability status and the third part may be the 1-bit indication of the two options. Thus, the information contained in the three parts of the bitmap can be arranged or configured in a different order from the one given in the example in FIGURE 4B. Earlier a synchronization flag inserted in the cell specific signaling on common PDCCH was discussed. Having synchronization flags included in both the cell specific signaling and the UE specific signaling may serve two puiposes.

[0057] The first purpose is to assist UEs to realize which signaling is missed when the UEs do not receive a cell specific signaling, although the signaling has been transmitted to them. Reference made to FIGURE 4A, the synchronization flag in the cell specific signaling is used to synchronize the cell specific signaling 434 and the UE specific signaling, 436 and/or 438. The synchronization flag inserted in the cell-specific signaling 434 for the resource utilization map 434 may be the same as the synchronization flag inserted in the UE-specific signaling 436 and/or 438 for UEl 120 and/or to UE2 130. In case that a UE receives a UE specific signaling, 436 and/or 438, but missed the resource utilization map 434, when it receives the UE specific signaling, it will compare the inserted synchronization flag to the one in the cell specific signaling 434. If the comparison result shows a mismatch between the two synchronization flags, the UE, UEl 120 or UE2 130, will know that it misses the most recently updated resource utilization map 434.

[0058] The second purpose is that AP 110 can use the synchronization flag to indicate if the resource utilization map is updated. If the resource utilization map is not changed, the AP 110 may set or retain the same synchronization flag on a corresponding common PDCCH. When a UE, UEl 120 or UE2 130, reads the synchronization flag of the received cell specific signaling 434, and finds it being identical to the synchronization flag associated to its most updated cell specific signaling 434, for example synchronization flag in subframe 0 could be identical to synchronization flag in subframe 5, the UE knows there is no update on the resource utilization map. Therefore, the UE will not decode the corresponding common PDSCH in order to avoid unnecessary decoding procedure.

[0059] Reference made back to FIGURE 4A. In the illustrated example, the UEl 120 receives not only the cell specific signaling 434 but also the UE specific signaling 436 from AP 110. The cell specific signaling informs UEl 120 of Vacant PRBs 470, Reserved PRBs 472 and 480, Normal PRBs 474 and 478 and Constrained PRBs 476. The UE specific signaling 436 for UEl 120 indicates the Unavailable status 416 of the PRBs 476, in which collisions were detected. Thus, UEl 120 will not use the Constrained PRBs 476 for the next uplink transmission, CBUT 440, if UEl 120 receives both the cell specific signaling 434 and the UE specific signaling 436.

[00601 On the other hand, the AP 110 indicates the status of the PRBs 476 with collision detected as Available status 418 to UE2 130 via the UE specific signaling 438. Since UE2 130 received the resource utilization map through the cell specific signaling 434, combining the information from the cell and the UE specific signalings, UE2 130 shall continue using the previously used Constrained PRBs 476 for uplink transmission such as CBUT 442.

[0061] The uplink transmission from UEl and UE2, such as CBUT 440 and CBUT 442, is free of collision at this stage. After the collision handling CBUTs 440 and 442 are completed, the AP 1 10 will update the resource utilization map and transmit or broadcast the updated resource utilization map 444 to the UEs. The status of the Constrained PRBs 476 in the previous AP broadcasting 434 is changed to be Normal PRBs, like the Normal PRBs 474 and 478 in the previous AP broadcasting 434, which is part of the Normal PRBs 486 at this stage. The Vacant PRBs 462 remains to be Vacant PRBs 470 after CBUTs 420 and 430, and are still Vacant PRBs 482 after CBUTs 440 and 442, because the Vacant PRBs 462 has not been used for uplink transmission or CBUT so far. Once the PRBs become Reserved PRBs 464 for UEl 120 and Reserved PRBs 468 for UE2 130, they stay as Reserved PRBs till the link between the AP 1 10 and the UEs that those PRBs are reserved for is released. Thus, at the time of the AP broadcasting resource utilization map 444, the PRBs in the resource utilization map are divided into Normal PRBs 486, Vacant PRBs 482 and Reserved PRBs, 484 and 488.

[0062] There is no need for AP 1 10 to transmit a UE specific signaling at this stage simply because no collision is detected after CBUTs 440 and 442. The mechanism of collision handling for contention based uplink transmission brings the benefit of collision free of the uplink transmission such as CBUTs 440 and 442.

[0063] As the AP 1 10 informs the UEl 120 of the connection release 446, any resources used or reserved for the communication between UEl 120 and AP 1 10 may be released as Vacant PRBs, which may be freely used by other UEs. It is shown in FIGURE 4A that the status of the previously Reserved PRBs 484 and part of the Normal PRBs used for CBUTs, 428 and 440, between UEl 120 and the AP 110 will be changed to be Vacant PRBs. Again, the AP 1 10 will update the resource utilization map due to the status change of part of the assigned PRBs. At the time when the AP 110 transmits or broadcasts the updated resource utilization map 448, with the connection between AP 1 10 and UE2 130 remained, the bitmap indicates the PRBs as Vacant PRBs 490, Normal PRBs 492 which were used by UE2 130 in the past CBUTs, 430 and 442, and Reserved PRBs 494 for UE2 130. [0064] FIGURE 5 illustrates a process 500 according to an embodiment of the present invention of a collision handling contention based uplink transmission in LTE-LAN. At step 502, an AP, which can be an access node, a network node, an eNB or a BS, detects collision from the uplink transmission from different UEs and identifies the PRBs in which the collision detected as Constrained PRBs. The AP shall update the existing resource utilization map as the status of the PRBs has been changed, for example the status of PRBs changed from Vacant PRBs to Reserved PRBs or from Normal PRBs to Constrained PRBs. The existing resource utilization map may include all the assigned PRBs for the UEs and the status of each PRB included in the map. The resource utilization map at AP can be created by the AP itself initially, or stored at the AP prior to the AP receiving of the uplink transmission.

[0065] The AP need to determine how to assign the PRBs with collision detected for the next uplink transmission. In other words, the AP will determine the availability of the Constrained PRBs to certain UEs, such as the UEs whose transmissions caused the collision, in order to avoid further collision on the same PRBs in the next transmission.

The Constrained PRBs can be used for the next uplink transmission. The AP may assign the Constrained PRBs to one of the UEs as well as inform the other UEs not to use it in the next uplink transmission. Afterwards, the AP will transmit or broadcast the updated resource utilization map, which comprises all the PRBs assigned for the UEs for their uplink transmission and the status of each of the assigned PRBs, to the UEs via the cell specific signaling.

[0066] The AP, as shown in step 504, will group N PRBs as a group of PRBs, which may be a group of contiguous or noncontiguous PRBs, wherein the group of N PRBs becomes a unit. The AP will further determine the availability status of each of the group of N PRBs to each of the UEs that it is connected with. There is a 1-bit indication of each group of N PRBs in the bitmap of a UE specific signaling to indicate if each group of N PRBs to a specific UE is either Available or Unavailable. The bitmap contained in the UE specific signaling has been discussed earlier in connection with FIGURE 4B.

[0067] In the next step 506, the AP will transmit the resource utilization map through the cell specific signaling, wherein the transmission may be in the form of broadcasting on PDCCH or evolved physical downlink control channel (ePDCCH). In the meantime, the AP transmits the UE specific signaling that indicates the configuration of the groups of N PRBs and the availability status of each group of N PRBs to the UEs. In some embodiments, the AP is configured to transmit UE specific signaling responsive to a determination that at least one collision has occurred, and the AP is configured to not transmit UE specific signaling responsive to a determination that no collisions have occurred.

[0068] At step 508, a UE determines if both the cell specific signaling and the UE specific signaling are received. If that is the case, the UE will check the UE specific signaling, particularly for the configuration of the groups of N PRBs and the availability status of each group 510. The group of N PRBs can be consisted of N contiguous PRBs or N noncontiguous PRBs. Knowing its previously used PRBs, the UE may perform uplink transmission such as CBUT on its previously used PRBs no matter they are Available or Unavailable, except the group(s) of Unavailable Constrained N PRBs 512. In other words, the UE cannot transmit message or data on Constrained PRBs, if the specific signaling it received indicates that those PRBs are Unavailable to it. Otherwise, the UE can transmit on any group(s) of N PRBs it used in its previous uplink transmission in this case.

[0069] If the UE received neither the cell specific signaling nor the UE specific signaling at step 518, it will assume there is no collision detected in the previous uplink transmission such as CBUT. Therefore, it can transmit data or message on any PRBs 520, except the Reserved PRBs reserved for other UEs according to the previous resource utilization map.

[0070] In case a UE received the broadcasted resource utilization map but not the UE specific signaling, as in step 522, the UE is aware that the status of each PRB is one of the four statuses, Normal, Vacant, Constrained and Reserved. The UE will, at step 524, make the next uplink transmission such as CBUT, on any PRBs except the Constrained PRBs or the Reserved PRBs reserved for other UEs.

[0071] If a UE received the UE specific signaling but not the cell specific signaling, it will check the UE specific signaling at step 525. The UE will detect or determine the configuration of the groups of N PRBs, which may be N contiguous PRBs or noncontiguous PRBs, from the UE specific signaling. The configuration of the PRB groups can be contained in a bitmap as discussed earlier with FIGURE 4B. The UE will also, at step 526, determine the availability status of each group of the groups of N PRBs from the UE specific signaling. The availability status of each group of N PRBs may be indicated by a 1-bit indication, which may be the first part of the bitmap in FIGURE 4B. If the bitmap shows a particular group of the N PRBs is Unavailable, the UE shall, at step 528, perform uplink transmission such as CBUT on PRBs other than the Unavailable group of PRBs. However, if a group of the N PRBs is in Available status, the UE shall further check or determine, at step 530, another 1-bit indication in the second part of the UE specific signaling in FIGURE 4B. This 1-bit indication may indicate two options, a first option, option 1, or a second option, option 2. If the first option is indicated, the UE may, at step 534, transmit uplink data, such as CBUT, on previously used and currently Available PRBs. If the second option is indicated instead, the UE may use any of the Available PRBs of the N PRBs at step 536 for data transmission such as CBUT.

[0072] FIGURE 6 illustrates an example of a cell specific signaling and a UE specific signaling between AP, or more generally an access node or a network node, and UEs. The AP can be an access node, a network node, an eNB or a BS. Assuming one of the two statuses, Normal and Constrained, were indicated with each PRBs ranged from PRBl to PRB8, 610-617, in a resource utilization map through a cell specific signaling 602. In the figure "N" stands for Normal and "C" for Constrained. According to the definition of Normal status of a PRB, the UEs will understand or determine that PRB 1 610, PRB2 611, PRB7 616 and PRB8 617 have been used for a previous uplink transmission such as CBUT without collision detected on them. The UEs will also understand or determine that PRB3 612, PRB4 613, PRB 5 614 and PRB6 615 were previously used by the UEs for uplink transmission and collisions on those PRBs were detected by the AP, because the status of these four PRBs are indicated as Constrained PRBs in cell specific signaling 602.

[0073] Meanwhile, the UE that received the UE specific signaling 604 will determine that PRBl 610, PRB2 611, PRB 3 612 and PRB4 613 are configured as a group 630 of 4 contiguous PRBs, as well as PRB5 614, PRB6 615, PRB7 616 and PRBS 617 are configured as another group 632 of 4 contiguous PRBs, wherein N is 4 in this case. The UE specific signaling further shows the UE, which received the UE specific signaling 604, that the availability status of group 630, including PRBl 610 through PRB4 613, is Available, while the group 632 with PRBS 614 through PRB8 617 is in Unavailable status.

[0074] If that UE receives both signalings, 602 and 604, it can use the group of PRBs 630, which is consisted of PRBl 610 through PRB4 13, for the next uplink transmission such as CBUT. For the group of PRBs 632, which is composed of PRB5 614 through PRB8 617, that UE may use PRB7 and PRB8 because they were previously used for transmission by the UE (Normal PRBs) without detected collision. But, that UE cannot use PRB5 or PRB 6 because those two PRBs are Constrained PRBs and indicated as Unavailable in the UE specific signaling 604. If the UE receives the UE specific signaling 604 only but not the cell specific signaling 602, that UE need further look up the 1-bit indication for the particular option it is given, either to use its previously used PRBs, which is PRB l 610 through PRB4 613, that are Available or to use any of the Available PRBs, which is still PRBl 610 through PRB4 613 in this case, for uplink transmission, such as CBUT.

[0075] Another example of a cell specific signaling and a UE specific signaling between AP and UEs is illustrated in FIGURE 7, wherein the AP can be an access node, a network node, an eNB or a BS, for example. It is assumed that both UE1 and UE2 receive the cell specific signaling and the UE specific signaling for each of them. In the cell specific signaling, 702, PRB l 710, PRB2 71 1, PRB 7 716 and PRB 8 717 are identified as Normal PRBs as well as PRB 3 712, PRB4 713, PRB5 714 and PRB6 715 are identified as Constrained PRBs. Meanwhile, in the UE specific signaling for UE1 704, the group of N PRBs 730, where N equals to 4, comprises PRBl through PRB4, 710, 711, 712 and 713, and is identified in Available status. Another group of 4 PRBs 732, composed of PRB5 through PRB8, 714, 715, 716 and 717, is in Unavailable status. UE2 will identify or determine 706 that the group of 4 PRBs 740, which is the same group of PRBs 730, is consisted of PRBl through PRB4, 710, 711, 712 and 713, are identified as Unavailable to UE2, based on the UE specific signaling for UE2. And, the other group of PRBs 742, the same group of PRBs 732, composed of PRB5 through PRB8, 714, 715, 716 and 717, will be identified in Available status for UE2. [0076] In the cell specific signaling 702, the Constrained PRB3 712 through PRB6 715 indicates that UEl and UE2 both transmitted data and/or message on those PRBs in previous uplink transmissions and the AP has detected collision on those PRBs. Assuming that UEl knows that it used PRB1 710 through PRB6 715 for transmission previously and UE2 knows that it used PRB3 712 and PRB8 717 previously, the AP notifies UEl that it may use the PRB group 730, PRB1 710 through PRB4 713, for the next uplink transmission, because PRBl 710 and PRB2 711 are Normal and Available, and PRB3 712 and PRB 4 713 are identified Available from the UE specific signaling 704 although they are Constrained PRBs. However, UEl cannot transmit on PRB group 732, PRBS 714 through PRB 8 717, because PRB 5 714 and PRB 6 715 are in the status of Unavailable to UEl and UEl did not previously use PRB7 and PRB8 for its uplink transmission. Similarly, AP informs UE2 via UE specific signaling 706 to UE2 that it may use the group of PRBs 742, which comprises PRB 5 714 through PRB 8 717, for uplink transmission such as CBUT, because PRB5 714 and PRB6 715 are Available Constrained PRBs and the PRB7 and PRBS are Normal and Available. But, UE2 cannot transmit data and/or message on the group of PRBs 740, which is PRBl 710 through PRB 4 713, because PRB3 712 and PRB 4 713 are Unavailable and UE2 did not previously use PRBl 710 and PRB2 711. By executing mechanism of the collision handling contention based uplink transmission, there will be no collision on PRBl 710 through PRB 8 717 between UEl and UE2 in the next uplink transmission such as CBUT.

[0077] Reference is made to FIGURE 8, which illustrates an example of a simplified block diagram of example electronic devices that are suitable for use in practicing various example embodiments of this invention. In FIGURE 8, AP 802 is adapted for communication over a wireless link 804 with an apparatus, such as a mobile device or mobile terminal or a UE 805. The AP 802 may be an access point, an access node, a base station or an eNB similar to AP 110 of FIGURE 1 , AP 420 of FIGURE 4A, and the APs discussed with FIGURE 6 and FIGURE 7, wherein an eNB may comprise a frequency selective repeater, of any wireless network such as LTE, LTE-A, GSM, GERAN, WCDMA, CDMA, Wireless LAN, and the like. It is commonly found that one or more than one UE are under the control of an AP such as AP 802. For simplicity, one UE 805 is shown in FIGURE 8. The UE 805 may be a user device similar to the devices 120, 130 and 140 in FIGURE 1, UE 210 in FIGURE 2, UEs 120 and 130 in FIGURE 4A and the UEs discussed with FIGURE 6 and FIGURE 7. The reason that a UE and an AP are both illustrated here is that one convenient mechanism for carrying out embodiments of the present invention usually involves communication using a communication network.

[0078] The UE 805 includes processing means such as at least one data processor, DP

806, storing means such as at least one computer-readable memory, MEM 808, for storing data 810, at least one computer program, PROB 811, or other set of executable instructions, communication means such as a transmitter, TX 812, and a receiver, RX 814, for bidirectional wireless communications with the AP 802 via at least one antenna 816.

[0079] The AP 802 also includes processing means such as at least one data processor,

DP 820, storing means such as at least one computer-readable memory, MEM 822, for storing data 824 and at least one computer program, PROG 826, or other set of executable instructions. The AP 802 may also include communication means such as a transmitter, TX 828, and a receiver, RX 830, for bidirectional wireless communications with the at least one UE 805 via at least one antenna 832.

[0080] The at least one of PROG 826 in the AP 802 includes a set of program instructions which, when executed by the associated DP 820, enable the device to operate in accordance with the exemplary embodiments of the present invention, as detailed above. The UE 805 also stores software 81 1 in its MEM 808 to implement certain exemplary embodiments of this invention. Thus, the exemplary embodiments of this invention may be implemented at least in part by computer software stored on MEM 808 and 822, which is executed by the DP 806 of the UE 805 and/or by the DP 820 of the AP 802, or by hardware, or by a combination of stored software and hardware and/or firmware. Electronic devices implementing these aspects of the invention need not be the entire devices as depicted in FIGURE 4A or FIGURE 5. Instead, they may be one or more components of same such as the above described stored software, hardware, firmware and DP, or a system on a chip, SoC, or an application specific integrated circuit, ASCI.

[0081] Data processor 820, 806 may comprise, for example, at least one of a microprocessor, application-specific integrated chip, ASIC, field-programmable gate array, FPGA, and a microcontroller. Data processor 820, 806 may comprise at least one, and in some embodiments more than one, processing core. Memory 822, 808 may comprise, for example, at least one of magnetic, optical and holographic or other kind or kinds of memory. At least part of memory 822, 808 may be comprised in data processor 820 and/or 806. At least part of memory 822, 808 may be comprised externally to data processor 820 and/or 806.

[0082] The various embodiment of the UE 805 can include, but are not limited to personal portable digital devices having wireless communication capabilities, including but not limited to wireless handsets, cellular telephones, navigation devices, laptop/palmtop/tablet computers, digital cameras and music devices, and Internet appliances.

[0083] Various embodiments of the computer readable MEMs 808 and 822 include any data storage technology type which is suitable to the local technical environment, which includes but not limited to semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, removable memory, disc memory, flash memory, DRAM, SRAM, EEPROM and the like. Various embodiments of the DPs 806 and 820 include but are not limited to general purpose computers, special purpose computers, microprocessors, digital signal processors, DSPs, and multi-core processors.

[0084] An exemplary embodiment provides a computer readable medium tangibly encoded with a computer program executable by a processor to perform actions comprising receiving, at a network node, at least one signal in uplink transmission, detecting a collision in the at least one received signal, identifying at least one physical resource block in which the collision is detected, updating a resource utilization map and transmitting it to at least one user equipment, and transmitting a signal to the at least one user equipment, wherein the signal indicates availability status of at least one group of physical resource blocks.

[0085] In a further exemplary embodiment of the computer readable medium above, the uplink transmission is a contention based uplink transmission.

[0086] Another exemplary embodiment provides an apparatus comprising means for receiving, at a network node, at least one signal in uplink transmission, means for detecting a collision in the at least one received signal, means for identifying at least one physical resource block in which the collision is detected, means for updating a resource utilization map and transmitting it to at least one user equipment, and means for transmitting a signal to the at least one user equipment, wherein the signal indicates availability status of at least one group of physical resource blocks.

[0087] In a further exemplary embodiment of the apparatus above, the uplink transmission is a contention based uplink transmission.

[0088] In a further exemplary embodiment of any one of the apparatus above, the resource utilization map comprises physical resource blocks assigned for the transmission between the network node and the at least one user equipment.

[0089] In a further exemplary embodiment of the apparatus above, the resource utilization map further comprises at least one statuses of an assigned physical resource block.

[0090] In a further exemplary embodiment of the apparatus above, the at least one status of the assigned physical resource block indicates that at least one of: the assigned physical resource block has not been used in previous transmission, the assigned physical resource block was used for transmission in previous transmission without collision detected, the assigned physical resource block is reserved for a user equipment, and the assigned physical resource block was used for transmission in the previous transmission with collision detected.

[0091] In a further exemplary embodiment of the apparatus above, the updating the resource utilization map is based on at least one of the received signal, the at least one status of the assigned physical resource block and the identified at least one physical resource block in which the collision is detected.

[0092] In a further exemplary embodiment of any one of the apparatus above further comprises means for determining the availability status of the at least one group of physical resource blocks.

[0093] In a further exemplary embodiment of any one of the apparatus above, the availability status of the at least one group of physical resource blocks is indicated as available or unavailable.

[0094] In a further exemplary embodiment of any one of the apparatus above, the resource utilization map is transmitted via a cell specific signaling. [0095] In a further exemplary embodiment of the apparatus above further comprises means for inserting a synchronization flag or at least one synchronization bit in the cell specific signaling.

[0096] In a further exemplary embodiment of any one of the apparatus above, the signal comprising a bitmap and the availability status of at least one group of physical resource blocks is indicated by the bitmap.

[0097] In a further exemplary embodiment of any one of the apparatus above, the means for transmitting the resource utilization map to at least one user equipment comprising means for broadcasting the resource utilization map to the at least one user equipment.

[0098] In a further exemplary embodiment of any one of the apparatus above, the signal to the at least one user equipment is transmitted via a user equipment specific signaling.

[0099] In a further exemplary embodiment of the apparatus above further comprises means for inserting another synchronization flag or another at least one synchronization bit in the user equipment specific signaling, whereas the another synchronization flag is identical to the synchronization flag or the another at least one synchronization bit is identical to the at least one synchronization bit.

[00100] In a further exemplary embodiment of any one of the apparatus above, the at least one group of physical resource blocks comprising N physical resource blocks.

[00101] In a further exemplary embodiment of the apparatus above the N physical resource blocks are contiguous physical resource blocks.

[00102] It should be appreciated that the practice of the invention is not limited to the exemplary embodiments discussed here. Various modifications and adaptations to the foregoing exemplary embodiments of this invention may become apparent to those skilled in the arts in view of the foregoing description. Furthermore, some of the various features of the above non-limiting embodiments may be used to advantage without the corresponding use of other described features.

[00103] The foregoing description should therefore be considered as merely illustrative of the principles, teaching and exemplary embodiments of the present invention, and not in limitation thereof.

Claims

WHAT IS CLAIMED IS

1. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

said at least one memory and said computer program code configured, with said at least one processor, to cause said apparatus to perform at least the following:

receive at least one signal in uplink transmission;

detect a collision in one of the at least one received signal;

identify at least one physical resource block in which the collision is detected;

update a resource utilization map and transmit the resource utilization map to at least one user equipment; and

transmit a signal to the at least one user equipment, wherein the signal indicates availability status of at least one group of physical resource blocks.

2. The apparatus as in claim 1, wherein the uplink transmission is a contention based uplink transmission.

3. The apparatus as in claim 1 or claim 2, wherein the resource utilization map comprises information on physical resource blocks assigned for transmission between the apparatus and the at least one user equipment.

4. The apparatus as in claim 3, wherein the resource utilization map further comprises at least one status of an assigned physical resource block.

5. The apparatus as in claim 4, wherein the at least one status of the assigned physical resource block indicates that at least one of: the assigned physical resource block has not been used in previous transmission, the assigned physical resource block was used for transmission in previous transmission without collision detected, the assigned physical resource block is reserved for a user equipment, and the assigned physical resource block was used for transmission in the previous transmission with collision detected.

6. The apparatus as in claim 4 or claim 5, wherein said memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to update the resource utilization map based on at least one of the received signal, the at least one status of the assigned physical resource block and the identified at least one physical resource block in which the collision is detected.

7. The apparatus as in any one of claims 1 through 6, wherein said memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to determine the availability status of the at least one group of physical resource blocks for the at least one user equipment.

8. The apparatus as in any one of claims 1 through 7, wherein the availability status of the at least one group of physical resource blocks is indicated as available or unavailable.

9. The apparatus as in any one of claims 1 through 8, wherein said memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to transmit the resource utilization map via a cell specific signaling.

10. The apparatus as in claim 9, wherein said memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to insert a synchronization flag or at least one synchronization bit in the cell specific signaling.

1 1. The apparatus as in any one of claims 1 through 10, wherein the signal comprising a bitmap and the availability status of at least one group of physical resource blocks is indicated by the bitmap.

12. The apparatus as in any one of claims 1 through 11, wherein said memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to transmit the resource utilization map to the at least one user equipment comprising to broadcast the resource utilization map to the at least one user equipment.

13. The apparatus as in any one of claims 1 through 12, wherein said memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to transmit the signal to the at least one user equipment via user equipment specific signaling.

14. The apparatus as in claim 13, wherein said memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to insert another synchronization flag or another at least one synchronization bit in the user equipment specific signaling, whereas the another synchronization flag is identical to the synchronization flag or the another at least one synchronization bit is identical to the at least one synchronization bit.

15. The apparatus as in any one of claims 1 through 14, wherein the at least one group of physical resource blocks comprising N physical resource blocks.

16. The apparatus as in claim 15, wherein the N physical resource blocks are contiguous physical resource blocks.

17. A method comprising:

receiving, at a network node, at least one signal in uplink transmission;

detecting a collision in the at least one received signal;

identifying at least one physical resource block in which the collision is detected; updating a resource utilization map and transmitting it to at least one user equipment; and

transmitting a signal to the at least one user equipment, wherein the signal indicates availability status of at least one group of physical resource blocks.

18. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

transmit a message on at least one physical resource block to a network node;

receive a resource utilization map and a user equipment specific signaling that indicates availability status of at least one group of physical resource blocks; and

perform contention based uplink transmission on the at least one physical resource block that also belongs to the at least one group of physical resource block.

19. An apparatus comprising:

means for transmitting a message on at least one physical resource block to a network node;

means for receiving a resource utilization map and a user equipment specific signaling that indicates availability status of at least one group of physical resource blocks; and

means for performing contention based uplink transmission on the at least one physical resource block that also belongs to the at least one group of physical resource block.

20. The apparatus as in claim 18 or claim 19, wherein a collision is detected in one of the at least one physical resource block.

21. The apparatus as in any one of claims 18 through 20, wherein the user equipment specific signaling comprises a bitmap.

22. The apparatus as in claim 21, wherein the availability status of at least one group of physical resource blocks is indicated in the bitmap.

23. The apparatus as in any one of claims 18 through 22, wherein the message is transmitted via a contention based uplink transmission.

24. The apparatus as in any one of claims 18 through 23, wherein the resource utilization map comprising physical resource blocks assigned for the transmission between the apparatus and the network node.

25. The apparatus as in claim 24, wherein the resource utilization map further comprises at least one status of an assigned physical resource block.

26. The apparatus as in claim 25, wherein the at least one status of the assigned physical resource block indicates that at least one of: the assigned physical resource block has not been used in a previous transmission, the assigned physical resource block was used for transmission in the previous transmission without collision detected, the assigned physical resource block is reserved for a user equipment, and the assigned physical resource block was used for transmission in the previous transmission with collision detected.

27. The apparatus as in claim 25 or claim 26, wherein the resource utilization map is updated by the network node based on at least one of the transmitted message received at the network node, the at least one status of the assigned physical resource blocks and the at least one physical resource block in which the collision is detected.

28. The apparatus as in any one of claims 18 through 27, wherein the availability status of the at least one group of physical resource blocks is indicated as available or unavailable.

29. The apparatus as in claim 28, wherein the contention based uplink transmission is performed on the at least one physical resource block with the status of the assigned physical resource blocks indicated as used for transmission in the previous transmission without collision detected, or is performed on the at least one physical resource block with the status of the assigned physical resource blocks as having collision detected and the availability status indicated as available.

30. The apparatus as in any one of claims 18 through 29, wherein the resource utilization map is received in a cell specific signaling.

31. The apparatus as in claim 30, wherein the cell specific signaling comprising a synchronization flag or at least one synchronization bit.

32. The apparatus as in claim 31, wherein the user equipment specific signaling comprising another synchronization flag or another at least one synchronization bit, whereas the another synchronization flag is identical to the synchronization flag or the another at least one synchronization bit is identical to the at least one synchronization bit.

33. The apparatus as in any one of claims 18 through 32, wherein the resource utilization map is received in a broadcasted signaling.

34. The apparatus as in any one of claims 18 through 33, wherein the at least one group of physical resource block comprising N physical resource blocks.

35. The apparatus as in claim 34, wherein the N physical resource blocks are contiguous physical resource blocks.

36. A method comprising:

transmitting a message on at least one physical resource block to a network node; receiving a resource utilization map and a user equipment specific signaling that indicates availability status of at least one group of physical resource blocks; and performing contention based uplink transmission on the at least one physical resource block that also belongs to the at least one group of physical resource block.

37. The method as in claim 36, wherein a collision is detected in one of the at least one physical resource block.

38. The method as in claim 36 or claim 37, wherein the user equipment specific signaling comprising a bitmap.

39. The method as in claim 38, wherein the availability status of at least one group of physical resource blocks is indicated in the bitmap.

40. The method as in any one of claims 36 through 39, wherein the message is transmitted via a contention based uplink transmission.

41. The method as in any one of claims 36 through 40, wherein the resource utilization map comprises physical resource blocks assigned for the transmission between a user equipment and the network node.

42. The method as in claim 41, wherein the resource utilization map further comprises at least one status of the assigned physical resource blocks.

43. The method as in claim 42, wherein the at least one status of the assigned physical resource blocks indicates that the at least one of: the assigned physical resource block is not used for transmission in a previous transmission, the assigned physical resource block was used for transmission in the previous transmission without collision detected, the assigned physical resource block is reserved for a user equipment, and the assigned physical resource block was used for transmission in the previous transmission with collision detected.

44. The method as in claim 42 or claim 43, wherein the resource utilization map is updated by the network node based on at least one of the transmitted message received at the network node, the at least one status of the assigned physical resource blocks and the at least one physical resource block in which the collision is detected.

45. A computer readable medium tangibly encoded with a computer program executable by a processor to perform actions comprising:

transmitting a message on at least one physical resource block to a network node; receiving a resource utilization map and a user equipment specific signaling that indicates availability status of at least one group of physical resource blocks; and

performing contention based uplink transmission on at least one of physical resource blocks other than the at least one group of physical resource block and the at least one physical resource block that also belongs to the at least one group of physical resource block.

46. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

transmit a message on at least one physical resource block to a network node;

receive a resource utilization map without receiving a user equipment specific signaling; and

perform contention based uplink transmission on physical resource blocks on the resource utilization map but not on the one of the at least one physical resource block in which the collision is detected.

47. A method comprising:

transmitting a message on at least one physical resource block to a network node; receiving a resource utilization map without receiving a user equipment specific signaling; and

performing contention based uplink transmission on physical resource blocks on the resource utilization map but not on the one of the at least one physical resource block in which the collision is detected.

48. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

transmit a message on at least one physical resource block to a network node;

receive a user equipment specific signaling, which indicates availability status of at least one group of physical resource blocks, without receiving a resource utilization map; and

perform contention based uplink transmission on at least one of the at least one physical resource block that belongs to the at least one group of physical resource block, any physical resource block of the at least one group of physical resource block, and physical resource blocks other than the at least one group of physical resource block.

49. The apparatus as in claim 48, wherein a collision is detected in one of the at least one physical resource block.

50. The apparatus as in claim 48 or claim 49, wherein the availability status of the at least one group of physical resource blocks is indicated as available or unavailable.

51. The apparatus as in claim 50, wherein the contention based uplink transmission is performed on physical resource blocks other than the at least one group of physical resource block conditioned on the availability status of the at least one group of physical resource blocks indicated as unavailable.

52. The apparatus as in claim 50, wherein said memory and said computer program code are further configured, with said at least one processor, to cause said apparatus to check a one-bit option indication, which indicates one of a first option one and a second option, if the availability status of the at least one group of physical resource blocks is indicated as available.

53. The apparatus as in claim 52, wherein the contention based uplink transmission is performed on the at least one physical resource block that belongs to the at least one group of physical resource block with availability status indicated as available, if the first option is indicated by the one-bit option indication.

54. The apparatus as in claim 52, wherein the contention based uplink transmission is performed on any physical resource block of the at least one group of physical resource block with availability status indicated as available, if the second option is indicated by the one-bit option indication.

55. A method comprising:

transmitting a message on at least one physical resource block to a network node; receiving a user equipment specific signaling, which indicates availability status of at least one group of physical resource blocks, without receiving a resource utilization map; and

performing contention based uplink transmission on at least one of the at least one physical resource block that belongs to the at least one group of physical resource block, any physical resource block of the at least one group of physical resource block, and physical resource blocks other than the at least one group of physical resource block.