JP6763842B2 - Control of modulation and coding schemes for transmission between base station and user equipment - Google Patents

Description

The present invention relates to the field of cellular networks, in particular to the evolution of LTE networks, and more specifically to networks including LTE networks and evolved LTE networks.

Further development has been made for LTE, such as the Beyond 4G (B4G) radio system, which is assumed to be commercially available in 2020. However, LTE evolution may be introduced some day within the new release.

LTE delivers a peak bit rate of 30 bps / Hz using 64QAM modulation and 8x8 MIMO transmission. As a result, B4G requires modulations higher than 64QAM, such as 256QAM, to meet future requirements. Higher-order modulations are suitable, for example, for relay backhaul because of their excellent channel quality and excellent radio frequency (RF) characteristics, which are more relay than user equipment (UE) or isolated indoor cells. Easily feasible for, in which case the UE is in close proximity to the access point and thus has a good link to the access point, and interference from other access points is attenuated by the wall. Because of little or no.

Determining the modulation order for LTE Release 10 is described in TS36.213 V10.3, Chapter 7.1.7 and CQI Definition, Chapter 7.2.3. In LTE (and LTE-Advanced), theoretical spectral efficiency is limited by 64QAM modulation. Extensions to 256QAM provide improved spectral efficiency.

The LTE standard defines MCS (modulation and coding scheme) indexes and modulation tables, as well as CQI (channel quality indicator) tables. They are used to determine and select the appropriate modulation and coding scheme. Currently the table supports up to 64QAM. The question is how to introduce 256QAM extensions, or other higher-order modulation extensions for LTE, while maintaining upward compatibility and avoiding significant complexity.

There is a need for improved and flexible systems and methods adapted to allow extensions to higher order modulations while maintaining upward compatibility for LTE. In particular, it is desired to maintain the signaling format and, more specifically, to use different encoding schemes and potentially use the same number of bits as when so-called blind decoding should be applied.

The request is satisfied by the gist based on the independent claims. Effective embodiments of the present invention are described in the dependent claims.

According to a first aspect of the present invention, there is a method of controlling a modulation and coding scheme for transmission between a base station and a user device, wherein the modulation and coding scheme has a first maximum modulation order. Can be selected based on a first modulation and coding scheme table that includes entries corresponding to multiple modulation and coding schemes with, or supports multiple modulation and coding schemes with a second maximum modulation order. A method is provided that can be selected based on a second modulation and coding scheme table that includes the entry to be made. This method selects a first modulation and coding scheme table or a second modulation and coding scheme table by the base station and sets the modulation and coding scheme for transmission between the base station and the user equipment. Includes control by the base station based on the selected modulation and coding scheme table.

This aspect of the invention is based on the idea of extending the modulation and coding scheme table to higher order modulations while maintaining upward compatibility. The first table supports, for example, up to 64QAM (quadrature amplitude modulation), and the second table supports, for example, 256QAM, or other higher order modulation extensions. Although 256QAM is articulated here, other modulations of higher order than those used in the first table, such as 128QAM, can also be used, or generally by modulation order and / or coding scheme. Note that the characterized higher order modulation and coding schemes (MCS) can also be used.

The idea of this method is to introduce higher order modulations while still supporting the modulation and coding scheme (MCS) tables introduced for lower modulation orders.

In this document, the term "modulation order" is determined by the number of different symbols that can be transmitted using it. In general, the MCS also considers different code rates and therefore indicates the average number of payload bits that can be transmitted per symbol. The first maximum modulation order and the second maximum modulation order may be the same or different.

The term "modulation and coding scheme table" refers to the MCS table defined in LTE and is used to determine and select the appropriate modulation and coding scheme. The second table is an extended MCS table based on MCS defined in LTE, but contains entries corresponding to higher order modulation. For example, upward compatibility is guaranteed by making the first table as strict as currently defined in the LTE standard.

The first and second tables may differ in some respects. For example, one table may be biased towards a lower MCS and a second table may be biased towards a higher MCS value. For example, one table may have more MCS values lower than some threshold MCS. Further, the density of MCS values in low MCS may be high in one table, or the center of gravity or average of MCS values may be low in one table. In one embodiment, one table is a mirror image of the other, eg, mirrored at the central MCS.

As used herein, the term "base station" refers to any kind of physical entity that can communicate with a user device or other network device by selecting a modulation and coding scheme from such an MCS table. The base station in this document may be any type of network device that provides the required functionality for the method, or it may be a transceiver node that communicates with a central entity. The base station is, for example, NodeB or eNB.

The base station explicitly notifies the UE of changes to the MCS table to be used, or notifies it as part of the capability query procedure and implicitly selects the MCS table.

According to one embodiment of the present invention, the second maximum modulation order is higher than the first maximum modulation order. In particular, the first maximum modulation order corresponds to 64QAM and the second maximum modulation order corresponds to 256QAM.

Note that other modulation orders, such as 128QAM, can also be used.

In addition, the first table contains a small number of high MCS so that it can react quickly if the channel suddenly improves.

According to yet another embodiment of the invention, the maximum modulation order corresponds to the highest modulation and coding scheme (MCS). Moreover, its highest modulation and coding scheme is the same for both tables.

According to yet another embodiment of the invention, the method further determines and determines the actual channel state of the radio transmission channel used for transmission between the base station and the user device by the base station. The base station determines the maximum supported modulation order based on the actual channel state, and compares the maximum supported modulation order with the first maximum modulation order and the second maximum modulation order. Includes selecting the first modulation and coding scheme table or the second modulation and coding scheme table by the base station based on.

If the actual channel state does not support higher order modulation or the user equipment (UE) cannot support higher order modulation, the base station modulates and encodes for transmission based on the first table. To carry out. If the actual channel state is good enough for higher order modulation and the UE supports higher order modulation, then the base station is a second table that supports higher order modulation up to, for example, 256QAM. Modulation and coding are performed based on.

According to yet another embodiment of the invention, the method further comprises transmitting information representing the selected modulation and coding scheme table to the user equipment.

The base station gives the UE a signal containing information about the MCS table selected and used. The UE then takes further action, such as a CQI report, based on that information.

According to yet another embodiment of the present invention, the transmission of information to the user device is based on radio resource control signaling.

By using a common signal link, the UE is easily notified about the selected MCS table. This information is also included in any information signal consisting of UE information in view of other resource controls.

According to yet another embodiment of the invention, the transmission of information to the user device is based on implicit signaling.

This refers to the case where the UE receives information from the base station and determines the selected MCS table based on that information. This is the case, for example, as part of a capability query procedure that also makes capabilities available to the eNB. During this type of configuration procedure in which the eNB determines the capabilities of the UE, the tables are switched and the UE is implicitly notified without any specific signaling.

According to yet another embodiment of the invention, the method comprises receiving confirmation information from a user apparatus representing the changes made to the selected modulation and coding scheme table.

The base station makes changes from one table to the selected MCS table after receiving the confirmation signal from the UE. Therefore, the confirmation signal represents the final modification of the MCS table performed by the base station.

According to yet another embodiment of the invention, the first modulation and coding scheme table and the second modulation and coding scheme table are the first modulation and coding scheme table and the second modulation and coding scheme table, respectively. Contains a common subset of equal entries co-located in the coding scheme table. In particular, this method comprises the selected modulation and coding scheme table after transmitting information representing the selected modulation and coding scheme table to the user device and before receiving confirmation information from the user device. Includes controlling modulation and coding schemes for transmission between the base station and user equipment based on a common subset of entries.

By using a common entry in both MCS tables, the base station uses the common entry unless there is a confirmation signal from the UE. This has the effect of eliminating misunderstandings and mismodulations and coding as both parts (base station and UE) use the same modulation and coding scheme (although they probably use different tables).

According to yet another embodiment of the invention, controlling the initial transmission between the base station and the user equipment is based on the first modulation and coding scheme table.

The base station and UE use the MCS table with the lowest maximum modulation order at the beginning of each communication. This has the effect that each communication starts at the same table and then the base station decides whether to change the MCS table. Then, if the UE can support an MCS table that supports higher order modulation, the changes are made based on the actual channel state.

According to yet another embodiment of the invention, the bits carrying the modulation and coding scheme index are the same for the first modulation and coding scheme table and the second modulation and coding scheme table.

Therefore, there is no need to modify the existing form of the MCS table or the coding and transmission mechanism used to carry the selections from that table, ensuring upward compatibility. In a more specific embodiment, the tables have the same size. In particular, a portion of the first MCS table and the second MCS table are equal, giving the common entry described above. The entries in the first MCS table associated with a very low modulation order are exchanged (redefined) with respect to the second MCS table to include higher order modulation.

According to yet another embodiment of the invention, the actual channel state is based on a first channel quality indicator table that supports a first maximum modulation order or a second that supports a second maximum modulation order. Determined based on the channel quality specifiers that can be selected based on the channel quality specifiers table, this method receives the channel quality specifiers from the user equipment by the base station and to the received channel quality specifiers. It involves determining by the base station the actual channel state of the radio transmission channel used for transmission between the base station and the user device based on it.

Like the MCS table, the CQI table is selected based on the selection of the MCS table. If there is a switch or change from the first MCS table to the second MCS table, there is also a change from the first CQI table to the second CQI table. Therefore, the UE determines the CQI based on the table corresponding to the selected MCS table.

According to yet another embodiment of the invention, the method selects a first channel quality indicator table or a second channel quality indicator table by the base station based on the selected modulation and coding scheme table. And include sending information representing the selected channel quality indicator table to the user equipment.

The information of the selected CQI table is given to the UE from the base station. The information may also be implicitly given by notifying the user device of the selected MCS table.

According to yet another embodiment of the present invention, the first channel quality indicator table and the second channel quality indicator table are the first channel quality indicator table and the second channel quality indicator table, respectively. Contains a common subset of equal entries placed in the same position within.

Like the MCS table, the CQI table contains a common subset. Therefore, it is guaranteed that there is no misunderstanding between the UE and the base station during the switch.

According to the second aspect of the present invention, the base station for controlling the modulation and coding scheme for transmission between the base station and the user apparatus, the modulation and coding scheme of which is the first maximum. Multiple modulations and encodings that can be selected based on a first modulation and coding scheme table that includes entries corresponding to multiple modulation and coding schemes with modulation order, or have a second maximum modulation order. A base station is provided that can be selected based on a second modulation and coding scheme table that includes entries corresponding to the scheme. This base station provides a selection unit for selecting a first modulation and coding scheme table or a second modulation and coding scheme table, and a modulation and coding scheme for transmission between the base station and the user equipment. , A control unit for controlling based on its selected modulation and coding scheme table.

A base station is any form of access point or attachment point that can provide wireless access to a cellular network system. Therefore, wireless access is made to a user device or other network device that can communicate wirelessly. The base station is a NodeB, eNB, home NodeB or HeNB, or other type of access point or multi-hop node or relay. Base stations are used specifically for B4G, LTE or 3GPP cells and communications.

The base station includes a receiving unit, for example, a receiver known to those of skill in the art. The base station also includes a transmitter or transmission unit, such as a transmitter. The receiver and transmitter may be implemented as a single unit, eg, a transceiver. The transceiver, or the receiving unit / transmitting unit, communicates with the user device via the antenna.

The base station also includes a selection unit and a control unit. The selection unit and control unit may be implemented as a single unit or as part of a standard control unit such as a CPU or microcontroller.

In one embodiment, the base station further determines the actual channel state of the radio transmit channel used for transmission between the base station and the user device, and is based on that determined actual channel state. It also has a decision unit to determine the maximum supported modulation order. The selection unit may be a first modulation and coding scheme table or a second modulation and coding scheme table based on a comparison of the maximum supported modulation order with the first maximum modulation order and the second maximum modulation order. Select.

The decision unit may be implemented as a single unit or as part of a standard control unit such as a CPU or microcontroller.

A user device (UE) is any form of communication end device that can be connected to the base station described herein. UEs are, in particular, cellular mobile phones, personal digital assistants (PDAs), notebook computers, printers, and / or any other mobile communication device.

The user device includes a receiving unit or receiver for receiving a signal from the base station. The user device includes a transmission unit for transmitting a signal. The transmitter unit is a transmitter known to those skilled in the art. The receiver and transmitter unit may be implemented as a single unit, eg, a transceiver. The transceiver, or receiver and transmitter unit, is made to communicate with the base station via an antenna.

The user apparatus further comprises a control unit for controlling and configuring transmissions based on information received from a base station representing the selected MCS table. The control unit may be implemented as a single unit or as part of a standard control unit such as a CPU or microcontroller.

According to a third aspect of the present invention, a cellular network system is provided. The cellular network system includes the base station described above.

Here, in general, the method and embodiment of the method according to the first aspect comprises performing one or more of the functions described with respect to the second or third aspect or the embodiment thereof. And vice versa, the base station or cellular network system according to the second and third aspects and embodiments thereof is a unit or unit for performing one or more functions described with respect to the first embodiment or embodiment thereof. Includes equipment.

According to a fourth aspect of the gist disclosed herein, a computer program for controlling a modulation and coding scheme for transmission between a base station and a user device is provided, which computer program is provided by a data processor assembly. When implemented, it is intended to control the method described in the first aspect or embodiment thereof.

The term computer program as used herein is equivalent to the term program element and / or computer-readable medium that contains instructions that control the computer system to align the execution of the methods described above.

The computer program is implemented as computer-readable instruction code using a suitable programming language such as JAVA®, C ++, and computer-readable media (removable disc, volatile or non-volatile). Stored in memory, embedded memory / processor, etc.). The instruction code acts to program a computer or other programmable device to perform its intended function. Computer programs are available from networks such as the World Wide Web where they are downloaded.

The gist disclosed herein can be realized by software for each computer program. However, the gist disclosed herein may be implemented by hardware for each of one or more specific electronic circuits. Furthermore, the gist disclosed herein may be realized in a hybrid form, i.e. a combination of software modules and hardware modules.

Although the normative embodiments of the gist disclosed herein have been described above, the methods for controlling the cellular network system, the base station, and the modulation and coding scheme for transmission between the base station and the user device are described below. Will be described in detail. Of course, it should be pointed out that a combination of features relating to different aspects of the gist disclosed herein is also conceivable. In particular, some embodiments will be described with reference to device-type embodiments, while other embodiments will be described with reference to method-type embodiments. However, those skilled in the art will appreciate the combination of features belonging to one aspect, as well as combinations of features relating to different aspects or embodiments, eg, device type, unless otherwise indicated. Combinations between the features of the form and the features of the embodiment of the method form will be disclosed with this application.

The above-described embodiments and embodiments and still another aspects and embodiments of the present invention will be apparent from the examples described below and will be described with reference to the drawings, but the present invention is not limited thereto. Note that in different drawings, the same or similar elements are indicated by the same reference character.

A cellular network system according to a normative embodiment of the present invention is shown. Simulations of spectral efficiency for 64QAM and 256QAM are shown. Simulations of 4x4 MIMO and 2x2 MIMO spectral efficiencies are shown for 64QAM and 256QAM, respectively. A base station and a user device in a cellular network system according to a normative embodiment of the present invention are shown.

Hereinafter, embodiments of the gist disclosed herein will be described with reference to the accompanying drawings and with reference to the viewpoints of current standards such as LTE and their further development. However, reference to the current standard is merely an example and does not limit the scope of claims.

FIG. 1 shows a cellular network system 100. The user device 102 receives the service of the first cell 103 of the cellular network system. The first cell is designated as the base station 101.

Transmission and communication between the base station and the user equipment is controlled based on the modulation and coding scheme. The modulation and coding scheme can be selected based on a first modulation and coding scheme table containing entries corresponding to multiple modulation and coding schemes with the first maximum modulation order, or a second. It can be selected based on a second modulation and coding scheme table that contains entries corresponding to multiple modulation and coding schemes with the maximum modulation order of. In one embodiment, the second maximum modulation order is higher than the first maximum modulation order (eg, up to 64QAM) (eg, up to 256QAM).

The base station determines the actual channel state of the radio transmit channel used for transmission between the base station and the user equipment. The base station then has the maximum supported modulation based on its determined actual channel state and, ultimately, on the information from the user equipment which modulation order the user equipment can support. Determine the order. The base station then bases the first modulation and coding scheme table or the second modulation based on a comparison of its maximum supported modulation order with its first maximum modulation order and second maximum modulation order. And select the coding scheme table. Therefore, the modulation and coding scheme (MCS) for transmission between the base station and the user equipment is controlled based on the selected modulation and coding scheme table.

The base station may also select tables based on other information, such as predetermined selection criteria.

In LTE (and LTE-Advanced), theoretical spectral efficiency is limited by 64QAM modulation. FIG. 2 shows LTE-advanced throughput (reference number 201) (code rate 8/9) simulated with modulation limited to 8 × 8 MIMO and 64 QAM in a spatially uncorrelated 1-tap Rayleigh channel. FIG. 2 also plots the spectral efficiency obtained by the extension to 256QAM for comparison (reference number 202). It is clear that the extension to 256QAM begins to act in the SNR range of approximately 25 dB. In this figure, the average SINR is plotted against throughput. Even if the average is lower than that region, the channel condition remains good for some time, regardless of whether 256QAM provides gain for fading.

LTE throughput is limited by the MCS even in more practical scenarios (eg, relay backhaul cases) where high spatial channel correlations that limit the use of large ranks occur. This is shown in FIG. 3, where spectral efficiency for 2x2 and 4x4 MIMO schemes with adaptive rank and MCS selection is plotted as a function of mean signal-to-noise ratio in high spectral correlation scenarios. .. Both the 2x2 and 4x4 schemes show two curves, one of which limits the MCS to 64QAM (2x2: 304, 4x4: 302), and the other the MCS It is extended to 256QAM (2x2: 303, 4x4: 301). It is clear that the extension to 256QAM already increases throughput from the SNR range of approximately 10 dB in these scenarios. This means that it is already feared that the throughput will be significantly lower than the maximum throughput possible with 64QAM.

The question is how to implement 256QAM for LTE to maintain upward compatibility and avoid significant complexity. The addition of 256QAM should be performed on both the MCS index and modulation tables defined in the LTE standard and the CQI table.

In Release 10, a new DCI format 2c was added to support closed-loop MIMO up to 8 layers. One simple solution is to define a new DCI format for 256QAM (and use more than 6 bits for the DCI modulation and coding scheme fields). This is not the desired solution. This is because it doubles the number of DCI formats and adds significant complexity. UMTS also extends from 16QAM to 64QAM by adding one special signaling bit [R1-070635 R1-070570]. That special bit can be provided by defining a new DCI format at the expense of poor decoding performance and more blind decoding, or by defining at least more arbitrary DCI sizes. Alternatively, the possibility of a bit being "stolen" from some other signaling and being stolen from a code assignment table that supports only half of its entries when 64QAM is enabled is limited, for example, in HSDPA.

Another possible solution is to take the existing MCS / CQI index table as a basis and switch its use to currently use only a subset of the MCS values, for example dropping every third, with an additional 256QAM. Try to make room for the value. This is a rough adaptation of the channel state and is not desirable. Hereinafter, this method is referred to as sub-sampling.

The idea of the method described here is to define a new procedure that allows the use of 256QAM in good channel conditions using the existing DCI format. For this purpose, additional new MCS and CQI index tables are created with extensions to 256QAM (Q _m = 8). This new table is the same size as the regular one. The determination of whether the original index table or the table with the extension of 256QAM is used is determined by the base station (or eNB), and the switch is directed to the UE in a signaling message or Or it is judged in an implicit way.

In one embodiment, both the original table and the table with 256QAM extension have a common index area, where the MCS / CQI index, modulation order and TBS index are the same and in the same position in both tables. It is in. Only this common MCS index area is used while switching tables to avoid ambiguity.

In one embodiment, an MCS / CQI index table with 256QAM expansion is formed so that room for TB (transport block) size associated with 256QAM is taken from the originally low TB size. In addition, there is some common modulation / TB size in the common MCS index area from the low range modulation set for situations where the extended 256QAM table is used and the channel state drops rapidly. These indexes can be subsampled from the lower TBS area.

A two-step switching procedure is provided for CQI index table switching to ensure that the UE knows the switch and does not use ambiguous table entries during the switch. The MCS table is pre-switched to the 256QAM version.

Also, for example, a high range set for situations where 256QAM must be used quickly before a clear selection is made during the initial call setup, or to allow a quick reaction towards good quality. There is also some common modulation / TB size in the common MCS index area from the modulation of.

The second table described here with respect to the MCS and CQI index tables is generated corresponding to 36.213 table 7.1.7-1, but with an extension to 256QAM (Q _m = 8). One option is to switch the original table 7.1.7-1 and the table with the 256QAM extension with an RRC message by the eNB (or MAC or control signaling messages can also be considered). In this case, the algorithm that plays the role of this switch is specific to the eNB vendor, but clearly considers the CQI report from the UE. The UE is responsible for switching the MCS index table based on the RRC message and sending a confirmation to the eNB for the received RRC message (confirmation is not important, but UEs that do not support switching do not confirm the command, so Helps avoid upward compatibility issues).

It takes about 100-200ms for RRC messages to take effect in the UE (upper layer processing delays are not standardized and depend on how often they are retransmitted in case of detection errors). Both tables allow data scheduling even during the time of uncertainty, as there is uncertainty associated with the start time when (1) RRC messages are lost and (2) new configurations are used by the UE. Must have a common MCS index area. This ensures that the MCS from that area is correctly understood, regardless of whether the switch has already been made. This common area is continuous, i.e. has continuous MCS entries, allowing fine adaptation during switching. The MCS index, modulation order and TBS index are the same in both MCS index tables in this area. For example, during the table switching RRC procedure, only this common MCS index area can be used before the eNB receives confirmation from the UE that it has received an MCS index table switching RRC message. This common index area is also used when implicit table switching is used, in which case only the common area can be used during the implicit switching procedure.

In addition, there is some common low modulation / TB size in the common MCS index area for situations where the extended 256QAM table is used and the channel state drops rapidly. The TB size required to send the switch command is obtained in the common MCS index area.

The new TB size will be introduced into the MCS / CQI index table with 256QAM extension to increase spectral efficiency at 256QAM.
● Room for these new TB sizes can be taken from the current low TB sizes (QPSK and possibly low 16QAM).
● The reserved TBS size for QAM is also in the common MCS area with low modulation. This MCS is used for retransmissions in poor channel conditions, especially if the previous initial transmission was done with a high MCS, especially with a high modulation order or a different number of specified resources. However, it is not necessary to reserve an entry for the included 256QAM.
● Also, in situations such as call settings where it is useful to use 256QAM quickly, there are several 256QAM entries in a common area (loss of upward compatibility and less input in the "normal" range. At the expense of). Such a default "compromise" MCS table, in which sub-sampling is used to obtain high dynamic range, can be used as soon as the eNB becomes aware of the UE's capabilities. Switching from a legacy table, that is, one with a low maximum modulation order, to that compromise table, that is, one with a high maximum modulation order, is implied as part of the ability query procedure that makes the ability available to the eNB. Can be done. There is then a clear switch to a table focused on low or high MCS, but if the channel state changes rapidly and a clear switch cannot be achieved, then a clear switch to the sub-sampled table. Switching is also done.

An example of a modulation table with MCS index and 256QAM extension is shown in Table 1. MCS indexes 12 to 31 refer to a continuous common MCS index area. MCS indexes 0, 5 and 10 refer to the sub-sampled low modulation common MCS index area, and MCS indexes 1 to 4, 6 to 9 and 1 refer to the 256QAM extension.

Similar to the MCS index table, a new CQI index table with 256QAM extensions and a common index area will be used. The CQI table is switched with the same RRC message that serves to switch the MCS index table. In another case, the CQI table is implicitly switched. The eNB is responsible for handling possible error situations caused by the UE not knowing which table to use during the exact time between this RRC procedure. The eNB, for example, simply ignores the non-common CQI indexes, rounds them to the closest common index or takes the risk, and determines which table is most likely to be associated with it based on discoverable techniques. can do. Such an error case occurs because in CQI the UE is unaware of the imminent switch, as opposed to MCS selection, where the eNB initiates the change and therefore can avoid ambiguous entries during the switch. , Because it cannot be avoided (unless it is uselessly always avoided). In order to increase the likelihood that the eNB will choose the correct decision in the case of ambiguous table entries, the minimum difference in TBS with respect to the MCS index must be maximized. This is the case of table 1. This is because the entries are arranged to increase TBS for both 256 and QAM cases. If the cases of 256QAM are in reverse order, then for MCS index 9, the TBS is 26 (for 256QAM) or 8 (for QPSK), i.e. the difference is 26-8 = 18. On the other hand, in Table 1, the difference is 33-8 = 25. The greater this difference, the less likely the eNB will be unable to use the discovery method (eg, if the channel is actually changed by that amount in 25 steps). For the same reason, it is useful to place the reserved 256QAM entries at the highest MCS index, i.e. with respect to the MCS index 11 in table 1. The reserved entry is only concerned with the downlink, not the uplink. Therefore, in the uplink table, it can be easily dropped and replaced with the normal entry of QAM (TBS10 in Table 1).

A two-step switching procedure can be used to avoid ambiguous CQI reports during the switching time, with the first command causing the eNB to notify the switching. Only CQI reports from the common MCS area are then used for the UE. In the second command, the eNB commands the execution of switching. The UE then fully uses the high MCS table. Here, despite the fact that there are two ambiguous cycles, there is no risk of misunderstanding. That is, during both ambiguous cycles, the UE either uses a well-defined MCS table (the original in the first ambiguous cycle and the final in the second cycle). Alternatively, only MCS from the common MCS area is used, and there is no risk of misunderstanding in this common area. This is because entries from a common MCS area are coded the same in both tables. This makes the order of entries in the high MCS area discontinuous, but this is less complicated and can be solved, for example, by implementing a lookup table.

The flow of messages according to this embodiment is as follows.
1) RRC message to switch from eNB to UE: MCS table and limit CQI reporting to a common index area. The eNB uses only the index area common to the MCS.
2) UE to eNB: Confirmation (and implied message), the eNB here uses the full index area of the new MCS table, and the eNB is the UE's new CQI table (initially only the common index area). ) To know to use.
3) From eNB to UE: Confirmation, the UE now uses the full index area of the new CQI table.

Despite the fact that there are two handshakes, there are only two, not four messages. This is because the intermediate message has two meanings in both the CQI and MCS tables.

Another solution to avoid ambiguous CQI reporting is to allow the UE to initiate a table switch to CQI and the eNB to initiate a switch to MCS. Therefore, the originator of a message can always switch to the corresponding table and therefore limit its use to a common index area during an ambiguous cycle.

A new UE category containing 256QAM is needed to indicate the capabilities of the UE to support 256QAM. If the UE does not support 256QAM, then the process and the MCS / CQI index table with 256QAM extensions are not used. Alternatively, the eNB can send a switch command and determine the response regardless of whether the UE supports 256QAM. At the initial access stage, the eNB does not yet know the capabilities of the UE, so 256QAM and thus higher modulation order MCS tables should not be used.

The process described above can be used to extend to higher MCS. The process can also be extended to cover three or more tables and switch between them. The common MCS represented in more than one table must always be in the same position. There are differences in the size and form of the common index area between the tables, for example, different tables can have different levels of subsampling. For example, there are three tables: low, medium and high. The intermediate table can contain every other MCS entry in the low modulation area, while the high table uses only every three entries (similar to Table 1), and those entries are the intermediate table. It is selected from those that also exist. This is possible because 2 is a divisor of 4, and therefore high table subsampling must not select every other or every four entries that do not fit. It may also be used for table 1 which covers a wide range of CQI values.

The solution proposed here has many effects. The existing DCI format design is immutable. This allows 256QAM to be supported for each DL DCI format while preserving the existing DCI blind decoding burden on the UE. The scheme proposed here provides a means for the eNB to easily avoid the case of complex errors due to signaling errors. The design proposed here allows the basic functions of the existing DL resource allocation (CQI / MCS index table) to be retained unchanged. Therefore, the effect on the DL scheduler operation is minimal.

FIG. 4 shows a cellular network system 400 according to a normative embodiment of the present invention. The cellular network system includes a base station 101 and a user device 102 that receives services from the base station.

Hereinafter, the base station will be described together with the determination unit. However, note that the decision unit is optional.

The base station determines the actual channel state of the radio transmit channel used for transmission between the base station 101 and the user equipment 102, and the maximum supported modulation based on the determined actual channel state. A determination unit 402 for determining the order is provided. The base station further has a first modulation and code based on a predetermined criterion or a comparison of the maximum supported modulation order with the first maximum modulation order and the second maximum modulation order. It comprises a selection unit 403 for selecting a conversion scheme table or a second modulation and coding scheme table. Further, the base station includes a control unit 404 for controlling the modulation and coding scheme for transmission between the base station and the user equipment based on the selected modulation and coding scheme table.

A base station is any form of access point or attachment point that can provide wireless access to a cellular network system. Therefore, wireless access is made to a user device or other network device that can communicate wirelessly. A base station is a NodeB, eNB, home NodeB or HeNB, or other type of access point.

The base station includes a receiving unit, for example, a receiver known to those of skill in the art. The base station also includes a transmitter or transmission unit, such as a transmitter. The receiver and transmitter may be implemented as a single unit, eg, transceiver 401. The transceiver, or the receiving unit / transmitting unit, communicates with the user device via the antenna.

The decision unit 402, selection unit 403 and control unit 404 may be implemented as a single unit or as part of a standard control unit such as a CPU or microcontroller.

A user device (UE) is any form of communication end device that can be connected to the base station described herein. UEs are, in particular, cellular mobile phones, personal digital assistants (PDAs), notebook computers, printers, and / or any other mobile communication device.

The user device includes a receiving unit or receiver for receiving a signal from the base station. The user device includes a transmission unit for transmitting a signal. The transmitter unit is a transmitter known to those skilled in the art. The receiver and transmitter unit may be implemented as a single unit, eg, transceiver 405. The transceiver, or receiver and transmitter unit, is made to communicate with the base station via an antenna.

The user apparatus further comprises a control unit 406 for controlling and configuring transmissions based on information received from a base station representing the selected MCS table. The control unit may be implemented as a single unit or as part of a standard control unit such as a CPU or microcontroller.

With respect to the gist disclosed herein, some embodiments refer to "base station", "eNB", etc., each of which refers to the general term "network component" or in other embodiments the term "network access node". Please understand that it is considered to be implicitly disclosed. It is also believed that other terms relating to a particular standard or particular communication technology implicitly disclose each general term with the desired function.

Furthermore, it should be noted that the base stations disclosed herein are not limited to the dedicated entities described in some embodiments. Rather, the gist described herein can be implemented in different ways at different locations in the communication network while performing the desired function.

According to embodiments of the present invention, the appropriate entities disclosed herein (eg, components, units and devices), eg, decision units, allow the processor device to perform the functionality of each entity disclosed herein. It may be provided, at least in part, in the form of a computer program. According to other embodiments, the suitable entities disclosed herein may be provided in hardware. According to other hybrid embodiments, some entities are provided in software, while other entities are provided in hardware.

It should be noted that the entities disclosed herein (eg, components, units and devices) are not limited to the dedicated entities described in some embodiments. Rather, the gist disclosed herein can be implemented in different ways and at different particle sizes at the device level, while performing the desired function. Further note that according to embodiments, individual entities (eg, software modules, hardware modules or hybrid modules) may be provided for each feature disclosed herein. According to other embodiments, entities (eg, software modules, hardware modules, or hybrid modules (software / hardware composite modules)) are configured to provide the two or more features disclosed herein.

Note that the word "prepare" does not exclude other elements or stages. Also, in the further refinement of the present invention, features from the different embodiments described above can be combined. It should also be noted that the reference code in the claims should not be construed as limiting the scope of the claims.

100: Cellular network system 101: Base station 102: User device 103: Cell 201: 64QAM 8x8 MIMO
202: 256QAM 8x8 MIMO
301: 256QAM 4x4 MIMO
302: 64QAM 4x4 MIMO
303: 256QAM 2x2 MIMO
304: 64QAM 2x2 MIMO
400: Cellular network system 401: Base station transceiver 402: Base station determination unit 403: Base station selection unit 404: Base station control unit 405: User device transceiver 406: User device control unit

Claims (11)

A method of controlling a modulation and coding scheme for transmission between a base station (101) and a user apparatus (102), the modulation and coding scheme being a plurality of modulations and coding schemes having a first maximum modulation order. A first modulation and coding scheme table containing an entry corresponding to a coding scheme, or a second including an entry corresponding to a plurality of modulation and coding schemes having a second maximum modulation order. In a method that can be selected based on the modulation and coding scheme table of 2, the first maximum modulation order and the second maximum modulation order are different.
The first modulation and coding scheme table or the second modulation and coding scheme table is selected by the base station (101).
A radio resource control (RRC) message containing information representing the selected modulation and coding scheme table is transmitted to the user apparatus (102) by the base station (101), and the base station (101) and the user. The modulation and coding scheme for transmission to and from device (102) is controlled by the base station (101) based on the selected modulation and coding scheme table.
Including that
The second maximum modulation order is higher than the first maximum modulation order, and in particular, the first maximum modulation order corresponds to 64QAM and the second maximum modulation order corresponds to 256QAM and is modulated. And the number of bits carrying the coding scheme index is the same for the first modulation and coding scheme table and the second modulation and coding scheme table, the method. The method further
The base station (101) determines the actual channel state of the radio transmission channel used for transmission between the base station (101) and the user equipment (102).
The base station (101) determines the maximum supported modulation order based on the determined actual channel state, and the maximum supported modulation order and the first maximum modulation order and the first. Claim 1 comprising selecting the first modulation and coding scheme table or the second modulation and coding scheme table by the base station (101) based on a comparison with the maximum modulation order of 2. The method described in. The method further includes receiving a confirmation information indicating the changes made were of the selected modulation and coding scheme table from said user device (102), The method of claim 2. The first modulation and coding scheme table and the second modulation and coding scheme table are in the same position within the first modulation and coding scheme table and the second modulation and coding scheme table, respectively. Contains a common subset of equal entries placed in
In particular, the method further
After transmitting the radio resource control (RRC) message representing the selected modulation and coding scheme table to the user equipment (102) and before receiving the confirmation information from the user equipment (102). , The modulation and coding scheme for transmission between the base station (101) and the user equipment (102) based on the selected modulation and coding scheme table, based on a common subset of the entries. Control,
The method according to claim 3 , which includes the above. Controlling the initial transmission between the base station (101) and the user apparatus (102) is in any one of claims 1 to 4 , based on the first modulation and coding scheme table. The method described. The actual channel state is based on a first channel quality specifier table that supports the first maximum modulation order or a second channel quality specifier table that supports the second maximum modulation order. Determined based on selectable channel quality indicators, said method
The channel quality indicator from the user apparatus (102) is received by the base station (101), and based on the received channel quality indicator, between the base station (101) and the user apparatus (102). The base station (101) determines the actual channel state of the radio transmission channel used for transmission.
The method according to claim 2, which includes the above. The method further
Based on the selected modulation and coding scheme table, the first channel quality indicator table or the second channel quality indicator table is selected by the base station (101), and the selected channel. Information representing the quality indicator table is transmitted to the user apparatus (102).
The method according to claim 6 , which includes the above. The first channel quality indicator table and the second channel quality indicator table are arranged at the same positions in the first channel quality indicator table and the second channel quality indicator table, respectively. The method of any one of claims 6 or 7 , comprising a common subset of equal entries. A base station (101) for controlling a modulation and coding scheme for transmission between a base station (101) and a user apparatus (102), wherein the modulation and coding scheme is the first maximum modulation order. Can be selected based on a first modulation and coding scheme table containing entries corresponding to multiple modulation and coding schemes with, or to multiple modulation and coding schemes with a second maximum modulation order. In a base station that can be selected based on a second modulation and coding scheme table that includes the corresponding entry, the first maximum modulation order and the second maximum modulation order are different.
A selection unit (403) for selecting the first modulation and coding scheme table or the second modulation and coding scheme table, and
A transceiver (401) configured to transmit a radio resource control (RRC) message containing information representing the selected modulation and coding scheme table to the user equipment (102).
A control unit (404) for controlling a modulation and coding scheme for transmission between the base station (101) and the user equipment (102) based on the selected modulation and coding scheme table.
With
The second maximum modulation order is higher than the first maximum modulation order, and in particular, the first maximum modulation order corresponds to 64QAM and the second maximum modulation order corresponds to 256QAM and is modulated. And the number of bits carrying the coding scheme index is the same for the first modulation and coding scheme table and the second modulation and coding scheme table, base station (101). A cellular network system (100) comprising the base station (101) of claim 9 . In the user equipment (102) for controlling the modulation and coding scheme for transmission between the base station (101) and the user equipment (102).
A transceiver unit for receiving a radio resource control (RRC) message from a base station (101) containing information representing a modulation and coding scheme table selected from two modulation and coding scheme tables with different maximum modulation orders. 405) and
A control unit (406) for controlling and configuring transmission based on the received information, and
With
One maximum modulation order is higher than the other maximum modulation order, in particular the other maximum modulation order corresponds to 64QAM, the one maximum modulation order corresponds to 256QAM, and the modulation and coding scheme index. The number of bits carried is the same in the two modulation and coding scheme tables, user equipment.

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