WO2014047918A1

WO2014047918A1 - Methods and apparatus for contention-based transmission

Info

Publication number: WO2014047918A1
Application number: PCT/CN2012/082425
Authority: WO
Inventors: Lili Zhang; Wei Bai; Xinying Gao; Haiming Wang; Pengfei Sun; Jing HAN
Original assignee: Broadcom Corporation
Priority date: 2012-09-29
Filing date: 2012-09-29
Publication date: 2014-04-03

Abstract

Systems and techniques for contention-based transmission are described. Each of a plurality of user devices transmits conditions information to a base station. The base station configures a contention-based resource for each of the user devices. A user device having data to transmit transmits a scheduling request identifying a contention-based resource being requested and also transmits the data. If the base station decodes the data, it sends an acknowledgement to the user device, and if no collision occurs but the base station fails to decode the data, it sends a normal acknowledgement to the user device. If a collision occurs, the base station sends feedback to the user device indicating that a collision occurred, and depending on the nature of the feedback, the user device performs retransmission with a random backoff or performs contention-free retransmission.

Description

METHODS AND APPARATUS FOR

CONTENTION-BASED TRANSMISSION

TECHNICAL FIELD:

The present invention relates generally to telecommunications. More particularly, the invention relates to systems and techniques for contention based transmission

BACKGROUND:

Modem cellular communication networks typically support numerous user devices, and network operators are constantly struggling to manage their bandwidth so as to serve the increasing demands presented by customers. One approach that is receiving increasing attention is the use of smaller cell sizes. Advantages presented by smaller cell sizes include shorter channel delay profile, a smaller number of user devices to be served by each cell, and lower mobility requirements. Numerous additional advantages can be expected. As network systems, such as third generation preferred partnership (3 GPP) and 3 GPP Long Term Evolution and Long Term Evolution Advanced (LTE and LTE-A) turn more and more toward smaller cell sizes, changes from current systems concentrated around macro cells can be expected.

SUMMARY:

In one embodiment of the invention, an apparatus comprises at least one processor and memory storing computer program code. The memory storing the computer program code is configured to, with the at least one processor, cause the apparatus to at least configure, for transmission by a user device, a scheduling request for a contention-based resource to be used for transmission by the user device to a base station, wherein transmission of the scheduling request provides indicia identifying the contention-based resource being requested, and configure data for transmission to the base station using the contention-based resource. In another embodiment of the invention, an apparatus comprises at least one processor and memory storing computer program code. The memory storing the computer program code is configured to, with the at least one processor, cause the apparatus to at least determine a configuration of a contention-based resource for use by a user equipment based on conditions information received from the user equipment and configure, for transmission, to the user equipment, a signal indicating the configuration of the contention-based resource.

In another embodiment of the invention, a method comprises configuring, for transmission by a user device, a scheduling request for a contention-based resource to be used for transmission by the user device to a base station, wherein transmission of the scheduling request provides indicia identifying the contention-based resource being requested, and configuring data for transmission to the base station using the contention-based resource.

In another embodiment of the invention, a computer readable medium stores computer program code. Execution of the computer program code by a processor configures an apparatus to at least configure, for transmission by a user device, a scheduling request for a contention-based resource to be used for transmission by the user device to a base station, wherein transmission of the scheduling request provides indicia identifying the contention-based resource being requested, and configure data for transmission to the base station using the contention-based resource.

In another embodiment of the invention, a computer readable medium stores computer program code. Execution of the computer program code by a processor configures an apparatus to at least determine a configuration of a contention-based resource for use by a user equipment based on conditions information received from the user equipment and configure, for transmission, to the user equipment, a signal indicating the configuration of the contention-based resource. BRIEF DESCRIPTION OF THE DRAWINGS:

Fig. 1 illustrates a wireless network and several user devices according to an embodiment of the present invention;

Fig. 2 illustrates a process according to an embodiment of the present invention;

Fig. 3 illustrates a signaling sequence according to an embodiment of the present invention; and

Fig. 4 illustrates devices according to an embodiment of the present invention.

DETAILED DESCRIPTION:

Embodiments of the present invention recognize that as the vision of wireless networking evolves, and particularly as interest in and use of smaller cell sizes grows, careful consideration of the opportunities presented by these changes can lead to more efficient service to the many users of wireless communications. Embodiments of the invention recognize that the smaller number of devices served by a smaller cell, and the lower accompanying data load, presents opportunities for changes to access mechanisms that can allow for reduced access delay. Current scheduling mechanisms used in macro cells contemplate large numbers of user devices and large data loads, but embodiments of the invention recognize that proper selection and design of alternative scheduling or access mechanisms can achieve benefits such as reduced control channel signaling and lower latency. Embodiments of the invention recognize that contention based uplink can allow for reduced signaling by allowing for transmission without a need for an uplink grant in response to a scheduling request, as well as latency caused by waiting for an uplink grant before transmitting. Embodiments of the invention further recognize, however, that collisions degrade transmission efficiency, and therefore provide enhanced mechanisms to allow for use of a shared resource and the simultaneous transmission of a scheduling request and a transmission block. Embodiments of the present invention therefore associate scheduling requests with shared resources to which access is sought, and further provide the association of different resources with different scheduling requests, so that a scheduling request can include indicia identifying a resource to which access is sought.

In 3 GPP and 3 GPP LTE and LTE-A systems, uplink data is transmitted by user devices, also known as user equipments or UEs to a base station, typically implemented as an eNodeB (eNB) over a physical uplink shared channel (PUSCH). Contention-based PUSCH primarily focuses on allowing uplink-synchronized UEs to transmit uplink data without sending a scheduling request (SR) and buffer status report (BSR) and waiting for a response from an eNB. Many contention-based techniques reduce the probability of contention by making the UE or the eNB aware of the likelihood of collision, and also presume that the eNB does an effective and fast resource allocation between contention-based and contention-free (CF) transmission. Embodiments of the present invention, as noted above, provide for a flexible linkage between a scheduling request and a required resource, as well as configuration by an eNB of resources for a UE based on information received by the eNB from the UE.

Fig. 1 illustrates a system 100 comprising a base station implemented as an eNB 102 serving a cell 104. The eNB 102 supports UEs 106A-106E. The eNB receives information from each UE to be used to configure shared resources for the UE, and each UE, when it has data to transmit, transmits a prompt-scheduling request (prompt-SR, or P-SR) and the data. The P-SR identifies a configured resource which the UE is seeking to use for its transmission. If the eNB successfully decodes the data, it sends an acknowledgement (ACK), and if the eNB fails to decode the data it sends either a normal negative acknowledgement (NACK), in cases in which the data was not decoded but no collision occurred, or a response associated with a collision. The response associated with a collision may be an enhanced NACK or a retransmission order with characteristics described in greater detail below. When the UE receives a response indicating a decoding failure, it proceeds in one of the ways indicated below.

Fig. 2 illustrates details of the communication between an eNB and the eNBs to achieve configuration of resources for the UEs and to manage transmission by the UEs. At step 202, a UE transmits conditions information that may be used by the eNB to determine a desired configuration for use of a resource or resources, such as a physical uplink shared channel (PUSCH) by the UE. The conditions information may be transmitted over a physical uplink control channel and may be performed periodically, or may be triggered by predefined events, such as a need for transmission by the UE using a contention-based PUSCH transmission, or a change in traffic profile.

The conditions information may include, for example, arrival moment, packet length per arrival, traffic information such as traffic type and preferred traffic priority, and default modulation coding scheme (MCS). In one or more embodiments of the invention, such as in a system configured to use time division duplex (TDD), the UE and eNB use a modulation coding scheme based on channel reciprocity.

At step 204, the eNB makes an optimized decision on contention based grants. In one or more embodiments, the decision identifies UE contention groups and allocates resources among the groups, with the the goal of the optimization being minimization of the UE collision probability during CB-PUSCH transmission. In one or more embodiments of the invention, the optimization is based on the principles of UE contention. If diversity between UEs is accomplished over the time domain, UEs with different arrival moments may be in a group, so as to reduce overhead required for the contention-based grant in the physical downlink control channel (PDCCH). Overhead reduction is achieved by the ability to use one contention-based grant for several subframe transmissions. If diversity is accomplished in the frequency domain, contention based resource reservation may be accomplished based on packet length and previous scheduling resource partitioning, in order to guarantee resource mapping and accomplish frequency diversity.

The eNB may make a contention based resource grant for a group of UEs. The eNB may define which UEs are members of a group sharing a particular grant using a radio network temporary identifier (RNTI) which is shared by UEs within the same group and which may be configured using radio resource signaling (RRC) when an eNB initiates enabling of contention based uplink (UL) transmission.

In one or more embodiments of the invention, the eNB may configure a granularity of selection to be used in distinguishing between UEs, with different granularities being configured according to different traffic types. The eNB may distinguish between UEs using the same granularity, and the UEs may select the fineness of the distinction based on demand.

In one or more embodiments of the invention, transmissions by a UE are carried out in association with hybrid automatic repeat request (HARQ) processes. A HARQ process uses a new data indicator (NDI) to distinguish between a new transmission and a retransmission. A UE may store data for transmission in each of one or more HARQ buffers, with a HARQ buffer being associated with a particular HARQ process. Once contention-based uplink transmission is activated for a UE, then for a given HARQ process for which contention-based transmission is configured, then if the UE has stored data in the corresponding HARQ buffer and the initial transmission of the buffered data is initiated by the UE itself, then for the physical downlink control channel (PDCCH) of a received uplink grant, the UE is configured to recognize one NDI value, such as 1, as indicating retransmission, and another NDI value, such as 0, as indicating a new transmission. In a typical configuration, a UE will also have configured, or have access to, specifications defined by a media access control (MAC) protocol to interpret an NDI value, and for transmissions that are not initiated by the UE, the UE will interpret the NDI value based on a current MAC specified solution.

At step 206, a UE performs contention-based transmission. Transmission is accomplished by sending information over the configured contention-based PUSCH granted to the UE together with a prompt-SR, providing for identification of the UE and allowing reduction of further contention upon collision. The prompt-SR is distinguished from normal SR transmission, and can be initialized in any subframe in which it is needed and can have any of a number of flexible states, with each state being identified with a particular contention-based resource. The UE performing a transmission transmits the prompt-SR associated with its configured resource. In one or more embodiments of the invention, availability of particular P-SR resources may be dynamically triggered by media access control (MAC) signaling upon a collision, and may remain effective through a duration of a collision-free period, with the end of the period coming when a timer expires without a collision during the running of the timer. In one or more embodiments, different PUCCH formats can be used to relate each P-SR to a corresponding contention-based resource. For example, bits included in a PUCCH format can be used to indicate a mapped contention-based resource. In one or more embodiments of the invention, the P-SR resource and the contention-based resource may be explicitly mapped during the configuration performed at step 204 and described above, and in alternative or additional embodiments of the invention, bits defined in a PUCCH format being used, such as bits defined in format lb/3, may be used to indicate a P-SR/PUCCH resource link to a particular resource. At step 208, the eNB receives and evaluates the transmission from the UE. If no collision occurs, and the data packet is correctly received, the process proceeds to step 210 and the eNB feeds back an ACK to the UE. If no collision occurs and the data packet is incorrectly received, the process proceeds to step 220 and the eNB feeds back a normal negative acknowledgement (NAC ) to the UE, suitably using the physical downlink control channel (PDCCH). The process then proceeds to step 222 and the UE performs adaptive or non-adaptive retransmission based on eNB scheduling. If a data collision occurs and a packet is incorrectly received, the process proceeds to step 230 and the eNB perfomis feedback indicating that a retransmission is needed due to a collision. In one or more embodiments, the feedback is an enhanced NACK, which is expressed in a hybrid automatic repeat request (HARQ) format that differs from the normal ACK/NAC format, and indicates a data packet in collision. If a UE receives the enhanced NACK, the process proceeds to step 232 and the UE performs a random backoff in the next retransmission in order to avoid the collision, hi one or more alternative or additional embodiments, the eNB feeds back a retransmission indicator, suitably using the PDCCH. The retransmission indicator is related to time and frequency resource indication for a UE in collision, and the indicated time and frequency resource is limited within the contention based resources. The retransmission order is issued through a PDCCH order, which is sent with a corresponding contention-based degrant command to deactivate the corresponding time and frequency resource. If a UE receives the retransmission indicator, the process proceeds to step 234 and the UE retransmits the packet in assigned contention-free resources.

Fig. 3 illustrates signaling 300 between a UE 302 and an eNB 304 according to one or more embodiments of the present invention. The UE 302 sends a signal 306 to the eNB 304 to provide conditions information to be used to configure contention-based resources for the UE. The eNB 304 perfomis signaling 308 to the UE 302 to configured optimized contention based grants to the UE. When the UE 302 has data to transmit, it performs signaling 310 to transmit a P-SR and data to the eNB 304. The eNB 304 responds by signaling 312 to return either an ACK, a normal NACK, an enhanced NACK, or a retransmission indicator to the UE 302. If the UE's data transmission was not successfully decoded, the UE 302 perfomis a retransmission 314, with the specific retransmission being based on the return from the eNB 304.

Reference is now made to Figure 4 for illustrating a simplified block diagram of a base station, such an eNB 400 and a user device, such as a UE 450, suitable for use in practicing the exemplary embodiments of this invention. In Figure 4 an apparatus, such as the eNB 400, is adapted for communication with other apparatuses having wireless communication capability, such as the UE 450.

The eNB 400 includes processing means such as at least one data processor (DP) 404, storing means such as at least one computer-readable memory (MEM) 406 storing data 408 and at least one computer program (PROG) 410 or other set of executable instructions, communicating means such as a transmitter TX 412 and a receiver RX 414 for bidirectional wireless communications with the UE 450 via an antenna 416.

The UE 450 includes processing means such as at least one data processor (DP) 454, storing means such as at least one computer-readable memory (MEM) 456 storing data 458 and at least one computer program (PROG) 460 or other set of executable instructions, communicating means such as a transmitter TX 462 and a receiver RX 464 for bidirectional wireless communications with the eNB 400 via one or more antennas 466.

At least one of the PROGs 410 in the eNB 400 is assumed to include a set of program instructions that, when executed by the associated DP 404, enable the device to operate in accordance with the exemplary embodiments of this invention, as detailed above. In these regards the exemplary embodiments of this invention may be implemented at least in part by computer software stored on the MEM 406, which is executable by the DP 404 of the eNB 400, or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware). Similarly, at least one of the PROGs 460 in the UE 450 is assumed to include a set of program instructions that, when executed by the associated DP 454, enable the device to operate in accordance with the exemplary embodiments of this invention, as detailed above. In these regards the exemplary embodiments of this invention may be implemented at least in part by computer software stored on the MEM 456, which is executable by the DP 454 of the UE 450, or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware). Electronic devices implementing these aspects of the invention need not be the entire devices as depicted at Figure 1 or Fig. 4 or may be one or more components of same such as the above described tangibly stored software, hardware, firmware and DP, or a system on a chip SOC or an application specific integrated circuit ASIC.

In general, the various embodiments of the UE 450 can include, but are not limited to personal portable digital devices having wireless communication capabilities, including but not limited to cellular telephones, navigation devices, laptop/palmtop/tablet computers, digital cameras and music devices, and Internet appliances.

Various embodiments of the computer readable MEM 406 and 456 include any data storage technology type which is suitable to the local technical environment, including 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 DP 404 and 456 include but are not limited to general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and multi-core processors.

While various exemplary embodiments have been described above it should be appreciated that the practice of the invention is not limited to the exemplary embodiments shown and discussed here. Various modifications and adaptations to the foregoing exemplary embodiments of this invention may become apparent to those skilled in the relevant arts in view of the foregoing description.

Further, some of the various features of the above non-limiting embodiments may be used to advantage without the corresponding use of other described features.

The foregoing description should therefore be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.

Claims

WHAT IS CLAIMED IS:

1. An apparatus comprising:

at least one processor;

memory storing computer program code;

wherein the memory storing the computer program code is configured to, with the at least one processor, cause the apparatus to at least:

configure, for transmission by a user device, a scheduling request for a contention-based resource to be used for transmission by the user device to a base station, wherein transmission of the scheduling request provides indicia identifying the contention-based resource being requested; and

configure data for transmission to the base station using the contention-based resource.

2. The apparatus of claim 1, wherein configuration of the scheduling request for transmission comprises configuring the scheduling request in one of two or more states, wherein the at least two states are associated with different contention-based resources.

3. The apparatus of claim 1, wherein each of the contention-based resources is associated with a physical uplink shared channel.

4. The apparatus of claim 1, wherein the memory storing the computer program code is further configured to, with the at least one processor, cause the apparatus to respond to a negative acknowledgement from the base station indicating a collision by configuring random backoff and retransmission by the user device, and respond to a retransmission indicator from the base station by configuring contention-free transmission by the user device.

5. The apparatus of claim 1 , wherein the scheduling request is transmitted over a physical uplink control channel, and wherein at least one characteristic of a format of the physical uplink control channel indicates the contention-based resource being requested.

6. The apparatus of claim 1, wherein availability of at least one contention-based resource associated with a scheduling request is triggered by media access control signaling occurring upon a collision.

7. The apparatus of claim 6, wherein the media access control signaling initiates a timer, and wherein the end of availability of the at least one contention-based resource occurs at an expiration of the timer without a collision.

8. The apparatus of claim 1, wherein the memory storing the computer program code is further configured to, with the at least one processor, cause the apparatus to determine if the user device has stored data in a hybrid automatic repeat request buffer corresponding to a hybrid automatic repeat request process for which contention-based transmission is configured and initial transmission of the buffered data is initiated by the user device and, if so, configure the user device to interpret a new data indicator taking on two different values so that a first value for the new data indicator is interpreted as directing retransmission and a second value for the new data indicator is interpreted as directing a new transmission.

9. The apparatus of claim 8, wherein, if initial transmission of buffered data is not initiated by the user device, the user device is configured to interpret a new data indicator based on media access control specifications.

10. An apparatus comprising:

at least one processor;

memory storing computer program code;

determine a configuration of a contention-based resource for use by a user equipment based on conditions information received from the user equipment; and configure, for transmission, to the user equipment, a signal indicating the configuration of the contention-based resource.

1 1. The apparatus of claim 10, wherein determination of the configuration of the contention-based resource for the user equipment comprises associating each of a plurality of a contention-based resource with a group of user equipments assigned to the resource and identifying the group to which the user equipment belongs.

12. The apparatus of claim 10, wherein the memory storing the computer program code is further configured to, with the at least one processor, cause the apparatus to, upon detection of a collision in a transmission by a user equipment to the base station, configure, for transmission to the user equipment, feedback indicating that a collision occurred.

13. The apparatus of claim 10, wherein the feedback is a negative acknowledgement including indicia indicating that a collision occurred.

14. The apparatus of claim 10, wherein the feedback is a retransmission indicator directing contention-free retransmission.

15. The apparatus of claim 10, wherein configuration of the feedback for transmission to the user equipment comprises configuration for transmission using a physical downlink control channel.

16. The apparatus of claim 10, wherein configuration of the contention based resource comprises defining triggering of availability of at least one contention-based resource associated with a scheduling request is by media access control signaling occurring upon a collision.

17. The apparatus of claim 16, wherein the media access control signaling initiates a timer, and wherein the end of availability of the at least one contention-based resource occurs at an expiration of the timer without a collision.

18. The apparatus of claim 10, wherein configuration of the contention-based resource for the user device comprises configuring the user device to determine if it has stored data in a hybrid automatic repeat request buffer corresponding to a hybrid automatic repeat request process for which contention-based transmission is configured and initial transmission of the buffered data is initiated by the user device and, if so, to interpret a new data indicator taking on two different values so that a first value for the new data indicator is interpreted as directing retransmission and a second value for the new data indicator is interpreted as directing a new transmission.

19. The apparatus of claim 18, wherein the user device is configured, if initial transmission of buffered data is not initiated by the user device, to interpret a new data indicator based on media access control specifications.

20. A method comprising:

configuring, for transmission by a user device, a scheduling request for a contention-based resource to be used for transmission by the user device to a base station, wherein transmission of the scheduling request provides indicia identifying the contention-based resource being requested; and

configuring data for transmission to the base station using the contention-based resource.

21. The method of claim 20, wherein configuration of the scheduling request for transmission comprises configuring the scheduling request in one of two or more states, wherein the at least two states are associated with different contention-based resources.

22. The method of claim 20, wherein each of the contention-based resources is associated with a physical uplink shared channel.

23. The method of claim 20, further comprising responding to a negative acknowledgement from the base station indicating a collision by random backoff and retransmission, and responding to a retransmission indicator from the base station with contention- free transmission.

24. The method of claim 20, wherein the scheduling request is transmitted over a physical uplink control channel, and wherein at least one characteristic of a format of the physical uplink control channel indicates the contention-based resource being requested.

25. The method of claim 20, wherein availability of at least one contention-based resource associated with a scheduling request is triggered by media access control signaling occurring upon a collision.

26. The method of claim 25, wherein the media access control signaling initiates a timer, and wherein the end of availability of the at least one contention-based resource occurs at an expiration of the timer without a collision.

27. The method of claim 20, further comprising determining if the user device has stored data in a hybrid automatic repeat request buffer corresponding to a hybrid automatic repeat request process for which contention-based transmission is configured and initial transmission of the buffered data is initiated by the user device and, if so, configuring the user device to interpret a new data indicator taking on two different values so that a first value for the new data indicator is interpreted as directing retransmission and a second value for the new data indicator is interpreted as directing a new transmission.

28. The method of claim 27, wherein, if initial transmission of buffered data is not initiated by the user device, the user device is configured to interpret a new data indicator based on media access control specifications.

29. A method comprising:

determining a configuration of a contention-based resource for use by a user equipment based on conditions information received from the user equipment; and configuring, for transmission, to the user equipment, a signal indicating the configuration of the contention-based resource.

30. The method of claim 29, wherein determination of the configuration of the contention-based resource for the user equipment comprises associating each of a plurality of a contention-based resource with a group of user equipments assigned to the resource and identifying the group to which the user equipment belongs.

31. The method of claim 29, further comprising, upon detection of a collision in a transmission by a user equipment to the base station, configuring, for transmission to the user equipment, feedback indicating that a collision occurred.

32. The method of claim 31, wherein the feedback is a negative acknowledgement including indicia indicating that a collision occurred.

33. The method of claim 31, wherein the feedback is a retransmission indicator directing contention- free retransmission.

34. The method of claim 31, wherein configuration of the feedback for transmission to the user equipment comprises configuration for transmission using a physical downlink control channel.

35. The method of claim 29, wherein configuration of the contention based resource comprises defining triggering of availability of at least one contention-based resource associated with a scheduling request by media access control signaling occurring upon a collision.

36. The method of claim 31, wherein the media access control signaling initiates a timer, and wherein the end of availability of the at least one contention-based resource occurs at an expiration of the timer without a collision.

37. The method of claim 29, wherein configuration of the contention-based resource for the user device comprises configuring the user device to determine if it has stored data in a hybrid automatic repeat request buffer corresponding to a hybrid automatic repeat request process for which contention-based transmission is configured and initial transmission of the buffered data is initiated by the user device and, if so, to interpret a new data indicator taking on two different values so that a first value for the new data indicator is interpreted as directing retransmission and a second value for the new data indicator is interpreted as directing a new transmission.

38. The method of claim 37, wherein the user device is configured, if initial transmission of buffered data is not initiated by the user device, to interpret a new data indicator based on media access control specifications.

39. A computer readable medium storing a program of instructions, execution of which by a processor configures an apparatus to at least:

40. The computer readable medium of claim 39, wherein configuration of the scheduling request for transmission comprises configuring the scheduling request in one of two or more states, wherein the at least two states are associated with different contention-based resources.

41. The computer readable medium of claim 39, wherein each of the contention-based resources is associated with a physical uplink shared channel.

42. The computer readable medium of claim 39, wherein execution of the computer program code by a processor further configures the apparatus to respond to a negative acknowledgement from the base station indicating a collision by random backoff and retransmission, and respond to a retransmission indicator from the base station with contention-free transmission.

43. The computer readable medium of claim 39, wherein the scheduling request is transmitted over a physical uplink control channel, and wherein at least one characteristic of a format of the physical uplink control channel indicates the contention-based resource being requested.

44. The computer readable medium of claim 39, wherein availability of at least one contention-based resource associated with a scheduling request is triggered by media access control signaling occurring upon a collision.

45. The computer readable medium of claim 44, wherein the media access control signaling initiates a timer, and wherein the end of availability of the at least one contention-based resource occurs at an expiration of the timer without a collision.

46. The computer readable medium of claim 39, wherein execution of the computer program code by a processor further configures the apparatus to determine if the user device has stored data in a hybrid automatic repeat request buffer corresponding to a hybrid automatic repeat request process for which contention-based transmission is configured and initial transmission of the buffered data is initiated by the user device and, if so, configure the user device to interpret a new data indicator taking on two different values so that a first value for the new data indicator is interpreted as directing retransmission and a second value for the new data indicator is interpreted as directing a new transmission.

47. The computer readable medium of claim 46, wherein, if initial transmission of buffered data is not initiated by the user device, the user device is configured to interpret a new data indicator based on media access control specifications.

48. A computer readable medium storing a program of instructions, execution of which by a processor configures an apparatus to at least:

49. The computer readable medium of claim 48, wherein determination of the configuration of the contention-based resource for the user equipment comprises associating each of a plurality of a contention-based resource with a group of user equipments assigned to the resource and identifying the group to which the user equipment belongs.

50. The computer readable medium of claim 48, execution of the computer program code by a processor further configures the apparatus to, upon detection of a collision in a transmission by a user equipment to the base station, configure, for transmission to the user equipment, feedback indicating that a collision occurred.

51. The computer readable medium of claim 50, wherein the feedback is a negative acknowledgement including indicia indicating that a collision occurred.

52. The computer readable medium of claim 50, wherein the feedback is a retransmission indicator directing contention- free retransmission.

53. The computer readable medium of claim 50, wherein configuration of the feedback for transmission to the user equipment comprises configuration for transmission using a physical downlink control channel.

54. The computer readable medium of claim 39, wherein configuration of the contention based resource comprises defining triggering of availability of at least one contention-based resource associated with a scheduling request by media access control signaling occurring upon a collision.

55. The computer readable medium of claim 54, wherein the media access control signaling initiates a timer, and wherein the end of availability of the at least one contention-based resource occurs at an expiration of the timer without a collision.

56. The computer readable medium of claim 39, wherein configuration of the contention-based resource for the user device comprises configuring the user device to detemiine if it has stored data in a hybrid automatic repeat request buffer corresponding to a hybrid automatic repeat request process for which contention-based transmission is configured and initial transmission of the buffered data is initiated by the user device and, if so, to interpret a new data indicator taking on two different values so that a first value for the new data indicator is interpreted as directing retransmission and a second value for the new data indicator is interpreted as directing a new transmission.

57. The computer readable medium of claim 56, wherein the user device is configured, if initial transmission of buffered data is not initiated by the user device, to interpret a new data indicator based on media access control specifications.