Method and system for coordinated multipoint transmission coordination

Abstract

A priority resource limited CoMP scheme based on a user coordination priority index is proposed for coordination set selection and resource allocation in small cell networks. A coordination priority index is configured and then sent by a CoMP control unit (CCU) to a donor (serving) transmission / reception point (TRP), which is determined as a function of the required bit rate and the SINR or CQI for that particular user equipment (UE). Then, the donor transmission / reception point (TRP) sends the coordination priority index sent by the CCU to the corresponding user equipment (UE). The configuration of the coordination priority index allows the user equipment (UE) to select the amount of channel state information (CSI) or subset of channel state information (CSI) reports to be reported such that a threshold index of the coordination priority is met.

Description

Technical Field

[0001] This invention relates to multi-point coordinated transmission schemes and to optimizing the selection of cooperative sets and resource allocation in small cell networks. Background Technology

[0002] The upcoming mobile communication systems are expected to provide ubiquitous connectivity and seamless service delivery in all situations. The anticipated large number of devices, along with the coexistence of human-centric and machine-type applications, will lead to a great diversity of communication scenarios and characteristics. Against this backdrop, many advanced communication technologies are being researched. Each of these technologies is typically optimized for a subset of foreseeable communication scenarios.

[0003] More recent LTE-A and 5G NR-based cellular network designs envision coordinated multipoint (CoMP) transmissions to achieve near-universal frequency reuse that can be deployed in both intra-cell and inter-cell scenarios. From this perspective, networks can utilize multiple transmit / receive point (TRP) transmission schemes, such as incoherent joint transmission and dynamic point selection or blanking, to gain diversity gain and avoid congestion. 5G NR Rel-16 supports both single-PDCCH and multi-PDCCH-based TRPs. Single-PDCCH or single-DCI TRPs assume good backhaul conditions, where different layers, frequency resources, or transmissions of the PDSCH are mapped to different TRPs or panels. Multi-PDCCH / M-DCI-based TRPs can be used with both ideal and non-ideal backhaul and assume minimal information exchange between TRPs. In the latter case, PDSCH transmissions through individual TRPs can be independent.

[0004] Figure 1 A small cell network with CoMP transmission is shown.

[0005] Figure 1 A typical small cell network configuration is presented, where CoMP transmissions can occur. The envisioned small cells and users are covered by macro transmit / receive points (TRPs) 110 equipped with CoMP control units (CCUs) 100 to provide clustering decisions. Small cells 111, 112, 113, 114, 115, 116, 117, 118, 119, and 120 are uniformly deployed within macro cell 110, and user equipment elements 130 are randomly distributed throughout the cells. Rayleigh fading can be considered for channel modeling between the transmit / receive points and users.

[0006] Several downlink CoMP schemes have been developed in 3GPP. We can note examples such as Joint Transport (JT), Dynamic Point Selection / Duplicate Blanking (DPS / DPB), and Coordinated Scheduling / Beamforming (CS / CB). The baseline Rel-15 NR scheme uses DPS, where a User Equipment (UE) can be dynamically served by one of several Transmitter / Receiver Points (TRPs) temporarily providing the best channel conditions to the UE in the coordinated cluster. Typically, DPS works in conjunction with the DPB CoMP scheme, where dynamic decisions are made to avoid scheduling any UE from one or more TRPs. This has the advantage of reducing interference to UEs served by the remaining TRPs.

[0007] In DPS / DPB, the User Equipment (UE) receives transmissions from only one Transmit / Receive Point (TRP) at any given time. In joint transmission, the UE is served by multiple TRPs simultaneously. Two groups of joint transmission techniques are defined: Coherent Joint Transmission (CJT) and Incoherent Joint Transmission (NCJT). CJT performs joint beamforming from all coordinated TRPs and can be considered a large-scale distributed MIMO system. In NCJT, a single codeword is transmitted to the target UE at layers from different TRPs, which makes the requirements for synchronization and channel state information (CSI) accuracy lower than in CJT.

[0008] In all the multiple transmit / receive point (TRP) schemes mentioned, channel state information (CSI) is crucial. The network needs to obtain the amount of CSI for each transmission / interference assumption. Each transmission / interference assumption can be characterized by a given combination of QCL assumptions of CMR and / or IMR. Only then can the network make optimal scheduling decisions, which in a TRP architecture include determining the number of layers to receive from each transmit / receive point (TRP).

[0009] As the number of cooperating transmit / receive points and the number of beams per transmit / receive point (TRP) increases, obtaining full channel state information (CSI) for all possible interference assumptions becomes cumbersome, especially in terms of uplink reporting resources. This prompted the 3GPP RAN1 project to work on CSI enhancements for multiple transmit / receive points (TRPs) in Rel-17. Following the study in 3GPP RAN1#102-e, various high-level classifications of proposals resulted in two main types of schemes for CSI enhancements for multiple transmit / receive points (TRPs), published as “R1-2007268 Technical Categorization for Channel State Information (CSI) enhancements for Transmission / Reception Point” and “FR1 FDD reciprocity Huawei”. The first type typically considers a single CSI reporting configuration, where one or more CSI reporting amounts based on predefined / indicated / configured / UE-selected channel and interference assumptions are associated with different transmit / receive points. The second category considers multiple Channel State Information (CSI) reports to report multiple CSI report volumes based on predefined / indication / configuration / user equipment (UE) selected channel and interference assumptions.

[0010] The achievable performance of a multiple transmit / receive point (TRP) scheme depends on the channel state information (CSI) reported at the scheduler. It goes without saying that full CSI feedback with information about each transmission / interference assumption will enable the network to better select transmission schemes for each user equipment (UE). This will allow the network to achieve near-optimal performance based on scheduling algorithms. However, this requires:

[0011] i) A significant amount of information needs to be exchanged on the network backhaul.

[0012] ii) Large uplink reporting overhead due to Channel State Information (CSI) reporting.

[0013] iii) The additional complexity required by the scheduling algorithm.

[0014] Therefore, enhanced Channel State Information (CSI) is desired for multiple transmit / receive points (TRPs).

[0015] JT CoMP technology is difficult to apply in practice due to bottlenecks in backhaul capacity and radio resources at each transmit / receive point (TRP). Different methods for selecting transmit / receive points (TRPs) have been covered in the literature.

[0016] The traditional approach is to select the N highest values ​​of the reference signal received power (RSRP) for transmission / reception, known as the N-best way, as described, for example, in the following article: S. Chen, T. Zhao, H. C. Chen, Z. Lu, and W. Meng. Entitled “Performance analysis of downlink coordinated multipoint joint transmission in ultra-dense networks.” Published in IEEE Netw., vol. 31, no. 5, pp. 106–114, 2017. This approach suffers from poor fairness to users, especially in resource-constrained networks. The initial deployment goal is coverage, which later becomes spectral efficiency enhancement. Cell-edge user equipment (UEs) are first identified, and then joint transmission is performed for these UEs. In traditional macro-cell-only networks, cell-edge UEs can be easily identified based on their distance from the central macro transmission / reception point (TRP). However, in small cell networks, the distance between transmit / receive points can be short, and even user equipment located at the cell boundary can be close to the central transmit / receive point (TRP). The non-uniform distribution of transmit / receive points (TRPs) makes identifying cell-edge users more difficult because the distance between adjacent TRPs varies significantly and a universally applicable threshold cannot be found. Therefore, it is extremely difficult to determine which user equipment (UE) needs to perform joint transmissions in small cell networks. Another drawback of choosing N as the optimal transmit / receive point (TRP) is that the number of cooperating transmit / receive points (TRPs) is a fixed value N. Clearly, if N equals the number of primary interference sources, increasing the value of N does not significantly improve SINR performance.

[0017] Another approach to selecting a cooperating transmit / receive point (TRP) is to associate a user equipment (UE) with a TRP whose received power exceeds a given threshold. Therefore, the number of serving TRPs is not a fixed value N. A UE is more likely to have a higher density of serving TRPs. The advantage of this approach is that inter-cell interference can be effectively transformed into the desired signal, thus significantly improving SINR. However, when selecting a cooperating TRP, only the distance between the UE and the TRP is considered. In other words, it does not consider whether the UE is near the cell boundary. Cell-edge UEs have poorer SINR and therefore have higher priority for JT. UEs near TRPs, on the other hand, rarely need JT, as it could waste TRP resources. Furthermore, determining an appropriate threshold is another challenge, as radio channel conditions are constantly changing. If the threshold is set too high, some UEs may not have a serving TRP. If the threshold is set too low, user equipment is more likely to be associated with multiple transmit / receive points, and therefore each transmit / receive point (TRP) tends to serve more user equipment, which can overload the transmit / receive points.

[0018] The 3GPP project RAN1#102-e studied different aspects of enhancing channel state information (CSI) for multiple transmit / receive points, taking into account trade-offs between user equipment (UE) complexity, performance, and reporting / RS overhead.

[0019] The prior art solutions are known from the publication "R1-2005281 Channel State Information (CSI) feedback enhancements for URLLC". This document recommends that User Equipment (UE) report Cooperative Channel State Information (CSI) corresponding to network cooperative transmissions. When the network adopts cooperative transmissions corresponding to the Cooperative Channel State Information (CSI), this CSI can help to more accurately set the Modulation and Coding Scheme (MCS). For example, to avoid the UE only reporting the most "selfish" CSI, resulting in all NZPs used for Channel Measurement (CM), the network can configure specific reporting criteria / requirements (e.g., the top three CQIs, or one CQI in the 25-30 dB range and another in the 20-25 dB range), and the UE reports the obtained CSI and the determination in the CSI report. The network can then select the Cooperative Transmit / Receive Point (TRP) accordingly based on the reported CQIs and some specific URLLC requirements.

[0020] The goal is to improve the Channel State Information (CSI) reporting mechanism by reducing one or more of the following: reducing the amount of information exchanged on the network backhaul, reducing uplink reporting overhead, and reducing scheduling algorithm complexity. Summary of the Invention

[0021] According to the present invention, in a first aspect, a method is provided for transmitting channel state information in a cellular communication system comprising multiple transmitting / receiving points, wherein a user equipment (UE) can simultaneously communicate with multiple transmitting / receiving points, the communication being coordinated based on the channel state information transmitted by the UE. The method of this aspect includes: receiving from the UE a channel quality indicator representing a signal-to-interference-plus-noise ratio (SINR) of a communication, wherein the channel quality indicator is a channel quality indicator associated with a preferred channel, the preferred channel being a communication with the highest channel quality among the communications; determining a coordination priority index, the coordination priority index being proportional to a bit rate requirement associated with the UE and inversely proportional to the SINR, rounded to an integer; transmitting the coordination priority index to the UE; and the UE transmitting channel state information associated with a corresponding communication, the transmitted channel state information corresponding to a communication having the highest channel state information value, and wherein the number of communication channels to which the transmitted channel state information corresponds is equal to or less than the coordination priority index.

[0022] In the development of the first aspect, the method further includes the steps of: sending a selection criterion to the user equipment, and the user equipment applying the criterion to define the transmitted channel state information as a selected subset of the channel state information quantity and / or channel state information report.

[0023] In the development of the first aspect, the system is also configured to: assign the communication of the user equipment to multiple transmitting / receiving points based on the channel state information reported by the user equipment and the coordination priority index of the user equipment.

[0024] In the development of the first aspect, the step of assigning communication of a user equipment to multiple transmitting / receiving points includes: prioritizing the allocation of multiple transmitting / receiving points to user equipment with a higher coordination priority index compared to user equipment with a lower coordination priority index.

[0025] According to a second aspect of the present invention, a method is provided for transmitting channel state information in a cellular communication system comprising multiple transmitting / receiving points, wherein a user equipment (UE) can simultaneously communicate with multiple transmitting / receiving points, the communication being coordinated based on the channel state information transmitted by the UE. The method in this aspect includes: the UE transmitting a channel quality indicator representing the signal-to-interference-plus-noise ratio (SINR) of the communication, wherein the channel quality indicator is a channel quality indicator associated with a preferred channel, the preferred channel being the communication with the highest channel quality; receiving a coordination priority index at the UE, the coordination priority index being proportional to a bit rate requirement associated with the UE and inversely proportional to the SINR, and rounded to an integer; and the UE transmitting channel state information associated with the corresponding communication, the transmitted channel state information corresponding to a communication having the highest channel state information value, and wherein the number of communication channels to which the transmitted channel state information corresponds is equal to or less than the coordination priority index.

[0026] In the second aspect of the development, the method further includes the steps of: receiving a selection criterion at the user equipment, and the user equipment applying the criterion to define the transmitted channel state information as a selected subset of the channel state information quantity and / or the channel state information report.

[0027] In the second aspect of development, the signal-to-interference-plus-noise ratio (SINR) is determined based on a predetermined mapping from channel quality indicator values ​​to SINR values.

[0028] In either the first or second aspect of the development, the signal-to-interference-plus-noise ratio (SIR) is determined by calculation corresponding to the type of user equipment.

[0029] In a further development of the first or second aspect, the coordination priority index is equal to the bit rate requirement associated with the user equipment divided by the sum rate of the preferred channel, rounded to an integer.

[0030] According to a third aspect of the present invention, a computer program comprising instructions is provided, which, when executed by a computer, cause the computer to perform the method according to the first or second aspect.

[0031] According to a fourth aspect of the present invention, a cellular communication system comprising multiple transmitting / receiving points is provided, wherein a user equipment (UE) can simultaneously communicate with each of the multiple transmitting / receiving points, the communication being coordinated based on channel state information transmitted by the UE. The system of this aspect is adapted to: receive from the UE a channel quality indicator representing a signal-to-interference-plus-noise ratio (SINR) of a communication, wherein the channel quality indicator is a channel quality indicator associated with a preferred channel, the preferred channel being the communication with the highest channel quality; determine a coordination priority index proportional to a bit rate requirement associated with the UE and inversely proportional to the SINR, rounded to an integer; transmit the coordination priority index to the UE; and wherein the UE is configured to transmit channel state information associated with a corresponding communication, wherein the transmitted channel state information pertains to a communication corresponding to a communication with the highest channel state information value, and wherein the number of communication channels pertaining to the transmitted channel state information is equal to or less than the coordination priority index.

[0032] According to a fifth aspect of the present invention, a user equipment is provided for use in a cellular communication system comprising multiple transmitting / receiving points, wherein the user equipment can simultaneously communicate with each of the multiple transmitting / receiving points, the communication being coordinated based on channel state information transmitted by the user equipment. The user equipment of this aspect is adapted to transmit a channel quality indicator representing the signal-to-interference-plus-noise ratio (SINR) of a communication, wherein the channel quality indicator is associated with a preferred channel, the preferred channel being the communication with the highest channel quality among the communications. The user equipment is also adapted to receive a coordination priority index proportional to a bit rate requirement associated with the user equipment and inversely proportional to the SINR, rounded to an integer. The user equipment is further adapted to transmit channel state information associated with a corresponding communication, the transmitted channel state information corresponding to a communication having the highest channel state information value, and wherein the number of communication channels to which the transmitted channel state information corresponds is equal to or less than the coordination priority index. Attached Figure Description

[0033] The above and other advantages of the present invention will now be described with reference to the accompanying drawings, wherein:

[0034] Figure 1 A small cell network with COMP transmission is shown;

[0035] Figure 2 A method for transmitting channel state information in a cellular communication system according to an embodiment is shown;

[0036] Figure 3 A method for transmitting channel state information in a cellular communication system according to an embodiment is shown from the perspective of a user equipment.

[0037] Figure 4 Illustrative examples based on certain implementation methods are presented.

[0038] Figure 5 Presented according to Figure 4 An example is the signaling of the coordination priority index from the CCU to the user equipment;

[0039] Figure 6 The achievable sum rate is shown in a set of simulations based on several different reporting strategies for the number of users in a macro cell.

[0040] Figure 7 It shows the basis Figure 6 A set of simulated network backhaul traffic data with different reporting strategies, which increases relative to the number of users in the macro cell;

[0041] Figure 8 It shows the basis Figure 6 Different reporting strategies, as functions of network backhaul traffic flows, and their implementability and rate; and

[0042] Figure 9 It shows the basis Figure 6 The fairness of different reporting strategies, which is a function of the number of unsatisfied users compared to the total number of users. Detailed Implementation

[0043] The implementation provides a priority-resource-constrained CoMP scheme that streamlines reporting in small cell networks based on a user's coordination priority index.

[0044] Figure 2 A method for transmitting channel state information in a cellular communication system according to an embodiment is shown.

[0045] like Figure 2 As shown, this is provided in, for example, the above reference. Figure 1The method described is for transmitting channel state information in a cellular communication system including multiple transmitting / receiving points, wherein a user equipment can simultaneously communicate with multiple transmitting / receiving points, and the communication is coordinated based on the channel state information transmitted by the user equipment.

[0046] like Figure 2 As shown, the method begins at step 200, followed by step 205 where the user equipment receives a channel quality indicator representing the signal-to-interference-plus-noise ratio (SINR) of a communication, wherein the channel quality indicator is associated with a preferred channel, which is the communication with the highest channel quality among the communications in which the UE participates. The method then proceeds to step 210, in which a coordination priority index is determined, which is proportional to the bit rate requirement associated with the user equipment and inversely proportional to the SINR, and is rounded to an integer.

[0047] As discussed above, the proposed scheme utilizes a parameter configured on the network side (e.g., on the CoMP control unit (CCU) side), which can be referred to as the user's coordination priority index. Considering that each user associates itself with the donor transmit / receive point (TRP) that provides it with the strongest reference signal received power (RSRP), this parameter is configured as a function of each user's desired bit rate and its SINR in the absence of coordination.

[0048] Those skilled in the art will understand that various definitions of a coordination priority index, rounded to an integer and proportional to the bit rate requirement associated with the user equipment and inversely proportional to the signal-to-interference-plus-noise ratio (SINNR), can be conceived. These can be chosen as a function of a particular desired behavior of the system, particularly regarding the relative importance of the bit rate requirement associated with the user equipment and the SINNR. As an example, the coordination priority index for each k-th user can be configured as follows:

[0049]

[0050] in Let γ be the SINR of the k-th user in the absence of collaboration, for example, denoted by watts, which can be estimated as a function of the reported CQI, and γ k It is the required bit rate for the k-th user, which determines the minimum traffic flow required to satisfy that particular user.

[0051] Those skilled in the art will understand that alternative definitions of the coordination priority index can be conceived. As an example of an alternative definition, the following could be used: in It is the achievable rate for the k-th user without collaboration.

[0052] Those skilled in the art will understand that, given Shannon's capacity formula Rk=B log2(1+SINR) k 0 ), where B is the bandwidth, this alternative definition still constitutes the definition of a coordination priority index that is proportional to the bit rate requirement associated with the user equipment and inversely proportional to the signal-to-interference-plus-noise ratio.

[0053] Therefore, the network can indicate to the user equipment (UE) a coordination priority index calculated by the network as a function of the following:

[0054] - Bit rate requirements derived from QoS

[0055] -SINR derived from CQI

[0056] QoS requirements

[0057] During the evolution of QoS management mechanisms in 3GPP (GSM / UMTS / LTE) networks, there was a migration from User Equipment (UE) level QoS management to network level QoS management. This QoS management approach will also be maintained in 5G networks. QoS management mechanisms in 5G networks should prioritize video and VoIP traffic for web search services and other quality-tolerant applications.

[0058] Typically, the quality of voice or data transmission can be evaluated and controlled in various ways. However, the availability of transmission under a given coverage condition is the primary indicator of its quality. End-to-end transmission quality can be managed by different IP QoS paradigms.

[0059] QoS itself can be defined as a set of parameters that indicate the degree to which a service is fulfilled. QoS management in communication networks is based on the fact that users of different services require different application types and different performance levels. The fundamental parameters are reliability (transmission link errors) and throughput / latency requirements. Services with strict latency and reliability requirements are considered real-time services, while services with high reliability and lenient latency requirements are classified as non-real-time services. Real-time service flows can require guaranteed bit rates to ensure the desired service performance, while non-real-time service flows cannot.

[0060] 5G uses QoS streams, and each QoS stream is identified by a QoS Stream Identifier (QFI). http: / / 5gblogs.com / 5G-quality-of-services-qos / Examples of 5G QoS stream characteristics (resource type, priority, packet delay budget, packet error rate, average window, maximum data burst size) are shown.

[0061] In particular, QoS defines the required or guaranteed bit rate, and it is this element of QoS that can be used as the basis for CPI calculation according to the implementation method presented herein.

[0062] SINR derived from CQI

[0063] As described above, the Channel Quality Indicator (CQI) represents the signal-to-interference-plus-noise ratio (SIR) of the channel with the highest channel quality as seen by the user equipment (UE). Strictly speaking, the method by which the CQI is calculated at a given UE is determined by the equipment configuration, such as settings provided by the equipment manufacturer. Based on this, in some implementations, the SIR can be determined at the network side through reverse calculation corresponding to the type of UE. This can be referenced to a database of CQI calculations based on equipment type.

[0064] Alternatively, the signal-to-interference-plus-noise ratio (SINR) can be determined based on a predetermined mapping from channel quality indicator (CQI) values ​​to SINR values. For example, Table 1 below is extracted from the following article: A. Chiumento, M. Bennis, C. Desset, L. Van der Perre, and S. Pollin, entitled “Adaptive Channel State Information (CSI) and feedback estimation in LTE and beyond: a Gaussian process regression approach.”, published in EURASIP Journal on Wireless Communications and Networking, vol. 2015, no. 1, pp. 168, 2015, which shows an example of effective SINR quantized as channel quality indicator (CQI) values, representing the highest modulation and code rates that the transmit / receive point (TRP) can use while maintaining a packet error rate (PER) below 10%.

[0065] Table 1 Mapping of SINR and CQI to Modulation and Code Rate

[0066] SINR(w) CQI modulation Bitrate Efficiency (information bits per symbol) 0.202 1 QPSK 78 0.1523 0.305 2 QPSK 120 0.2344 0.4808 3 QPSK 193 0.3770 0.7493 4 QPSK 308 0.6016 1.1915 5 QPSK 449 0.8770 1.8616 6 QPSK 602 1.1758 2.9471 7 16QAM 378 1.4766 4.4926 8 16QAM 490 1.9141 7.1994 9 16QAM 616 2.4063 10.8792 10 64QAM 466 2.7305 16.9394 11 64QAM 567 3.3223 26.1396 12 64QAM 666 3.9023 38.7971 13 64QAM 772 4.5234 60.4505 14 64QAM 873 5.1152 96.1390 15 64QAM 948 5.5547

[0067] In either case, defining the coordination priority index as proportional to the required bit rate and inversely proportional to SINR means that user equipment with low bit rate requirements will tend to report fewer Channel State Information (CSI) reports, while user equipment with high bit rate requirements will tend to report more CSI reports, and user equipment with low SINR will tend to report more CSI reports, while user equipment with high SINR will tend to report fewer CSI reports.

[0068] Then, the method proceeds to step 215, in which a coordination priority index is sent to the user equipment, and then proceeds to step 220, in which the user equipment sends channel state information related to each communication, wherein the communication to which the sent channel state information is directed corresponds to the communication with the highest channel state information value, and the number of communication channels to which the sent channel state information is directed is equal to or less than the coordination priority index.

[0069] Therefore, the coordination priority index configured for each user is then sent to the user equipment (UE) in downlink signaling by the transmit / receive point (TRP) so that the UE can select the amount of channel state information to be reported and / or a subset of channel state information reports that meet the threshold index of coordination priority.

[0070] This implementation provides a priority-restricted CoMP scheme based on a user's coordination priority index (CPI), which can also be used to perform cooperative set selection and resource allocation in small cell networks. Coordination clustering among all Transmitter / Receiver Points (TRPs) is determined by the CoMP Control Unit (CCU). According to some implementations, in addition to the reported Channel State Information (CSI), clustering may also consider a new CPI parameter reflecting the coordination priority of each user. For example, users with a lower CPI (lower priority) should be given priority at the CoMP Control Unit (CCU) to reduce the number of coordinated Transmitter / Receiver Points.

[0071] A two-layer heterogeneous network downlink scheme can be considered, where small base stations (SBSs) and users are covered by macro base stations (MBSs). SBSs are uniformly deployed in macro cells, and users are randomly distributed across the cells, as shown in the reference above. Figure 1 As described, macro base stations handle control signaling, while small base stations provide the necessary data services to users. Each MBS is equipped with a CoMP control unit (CCU) to provide clustering decisions regarding the behavior of SBSs connected to the CCU via backhaul links.

[0072] The coordinated clustering among all Transmitting Points (TRPs) can therefore be determined by the aforementioned or individual CCUs according to the following algorithm.

[0073] Multiple Service Base Stations (SBSs) can be selected to form a cooperative set and serve users. The non-overloaded SBS with the strongest received power should be allocated. At the CCU, users with lower priority values ​​should be considered first to reduce the number of serving SBSs. In this way, users with better channel conditions are served by fewer SBSs, while more SBSs serve users with poorer channel conditions. This has the advantage of reducing backhaul traffic to SBSs. An exemplary pseudocode of the proposed priority-resource-constrained CoMP scheme is detailed below:

[0074] Algorithm 1.

[0075]

[0076]

[0077] in

[0078] m is the index of the small base station under consideration.

[0079] k is the index of the user devices under consideration.

[0080] B k It is a cooperative set of small base stations serving the k-th user.

[0081] C is a matrix Where the coefficient C km In small base station SBS m Belongs to B k It has a value of 1 in SBS m Not belonging to B k It has a value of 0.

[0082] ω k It is the coordination priority index of the k-th user (determined, for example, as described above). It can be remembered that in some cases, the CPI can optionally be determined at the user equipment and sent to the CCU.

[0083] It represents the number of users simultaneously served by the m-th SBS at a specific time.

[0084] Based on this, it should be understood that small base station SMS m The return trip flow can be represented as Where R k It is the rate of user k.

[0085] Therefore, a method can be provided for allocating individual user equipments (User Equipments) among a plurality of User Equipments (User Equipments) to one or more transmit / receive points in a cellular communication system comprising a plurality of transmit / receive points. The method includes: determining a coordination priority index for each User Equipment, the coordination priority index reflecting the ratio between bit rate requirements associated with that User Equipment and inversely proportional to the signal-to-interference-plus-noise ratio (SIR), rounded to an integer; considering each User Equipment in order of coordination priority index, starting with the User Equipment having the lowest coordination priority index; and selecting for each User Equipment the smallest set of transmit / receive points that can satisfy the User Equipment's requirements when operating at full physical block capacity, such that a larger number of transmit / receive points are preferentially allocated to User Equipments with poor SIR conditions.

[0086] Therefore, in some implementations, an additional step, performed, for example at the CCU, may be provided to allocate the communication of a user equipment (UE) to multiple transmit / receive points based on the reported channel state information of the respective UE and the coordination priority index of the respective UE. Furthermore, the step of allocating the communication of a UE to multiple transmit / receive points may include: preferentially allocating multiple transmit / receive points to UEs with lower coordination priority indices compared to UEs with higher coordination priority indices. Additionally, the step of allocating the communication of a UE to multiple transmit / receive points may include considering the UEs in order of coordination priority index, starting with the UE with the lowest coordination priority index, and selecting the minimum set of transmit / receive points that can satisfy the UE's requirements when operating at full physical block capacity. This results in a larger number of transmit / receive points being preferentially allocated to UEs with poor signal-to-interference-plus-noise ratio (SNR) conditions.

[0087] For example, if a user equipment (UE) is triggered by multiple channel state information (CSI) reports along with a coordination priority index of 3, the UE will only respond with reports that consider the 3 best CQI indices.

[0088] It should be understood that Figure 2 The approach is presented from the system's perspective, and the equivalent approach can be presented from the user's device's perspective.

[0089] Figure 3 A method for transmitting channel state information in a cellular communication system according to an embodiment is shown from the perspective of a user equipment. This method is implemented in a system comprising multiple transmitting / receiving points, wherein the user equipment can simultaneously communicate with each of the multiple transmitting / receiving points, and the communication is coordinated based on the channel state information transmitted by the user equipment.

[0090] As shown, the method begins at step 300 before proceeding to step 305. In step 305, the user equipment sends a channel quality indicator representing the signal-to-interference-plus-noise ratio (SINR) of the communication, wherein the channel quality indicator is associated with a preferred channel, which is the communication with the highest channel quality (e.g., as described above). The method then proceeds to step 310, in which a coordination priority index is received at the user equipment. This coordination priority index is proportional to the bit rate requirement associated with the user equipment and inversely proportional to the SINR, and is rounded to an integer (e.g., as described above). The method then proceeds to step 320, in which the user equipment sends channel state information associated with each communication. The channel state information sent corresponds to the communication with the highest channel state information value, and the number of communication channels for which the channel state information is sent is equal to or less than the coordination priority index. The method then ends at step 325.

[0091] According to certain implementations, such as those described above, a standard is provided for user equipment (UE) to select channel state information (CSI) reporting in a multiple transmit / receive point (TRP) scenario. This selection can be performed when a coordination priority index, configured by the network and reported to the UE, is introduced. This new parameter has the advantage of reducing CSI reporting overhead in TRP systems and is also used by the CoMP control unit (CCU) to minimize backhaul network overhead.

[0092] According to certain implementations, such as those described above, in addition to defining the number of channels for which a user equipment (UE) should send CSI information, the method may further include the steps of: sending a selection criterion to the UE, and the UE applying the criterion to define the transmitted channel state information as a selected subset of the channel state information quantity and / or channel state information reports. For example, the network may rely on a range of preferred modulation and coding schemes (MCS) that the network wishes to use to serve the UE to constrain the UE's CSI reporting. From the network's perspective, the preferred MCS will depend on the UE's traffic flow type (QoS requirements, target block error rate (BLER), throughput requirements). The criterion indication may be performed in RRC configuration / reconfiguration, DCI triggering CSI reporting, or MAC CE. In this way, the network maintains control over the selection criterion.

[0093] When triggered / configured by Channel State Information (CSI) reports for multiple transmit / receive points (TRPs), the User Equipment (UE) can calculate the amount of Channel State Information (CSI) in a single or multiple Channel State Information (CSI) reports, and as described above, can select a Channel State Information (CSI) report or a subset of Channel State Information (CSI) amounts that meet the criteria.

[0094] The proposed scheme is useful for many applications such as MU-MIMO communication and multiple transmitter / receiver point (TRP) scenarios. This could be of great interest in NR 5G systems.

[0095] As described above, one advantage of certain implementations is the reduction of overhead in configuring the Channel State Information (CSI) report for the User Equipment (UE). An illustrative example will now be considered, in which a User Equipment (UE) Channel State Information (CSI) report configuration with reduced overhead is presented.

[0096] Figure 4 Illustrative examples based on certain implementation methods are presented.

[0097] like Figure 4 As shown, a communication system as generally described above is provided, comprising a CoMP control unit (CCU) 200. The cell network consists of three transmit / receive points 421, 422, and 423. As illustrated, there are five user equipment units 431, 432, 433, 434, and 435 in the cell.

[0098] Figure 5 Presented according to Figure 4 An example is the signaling from the CCU to the user equipment to coordinate the priority index.

[0099] As generally described above, the CoMP control unit (CCU) 221 can be configured to send a coordination priority index to the donor (serving) transmit / receive points (TRPs) 421, 322, and 423. This coordination priority index is determined as a function of the desired bit rate and SINR or CQI for that particular user equipment (UE). The donor transmit / receive point (TRP) then sends the coordination priority index sent by the CCU to the corresponding user equipment (UE). The configuration of the coordination priority index allows the user equipment (UE) to select the amount of Channel State Information (CSI) to be reported or a subset of Channel State Information (CSI) reports that satisfy a threshold index for the coordination priority.

[0100] like Figure 5 As shown, the CCU first configures the user's coordination priority index ω k , and then as Figure 5 The image shows a message sent to the corresponding user equipment, similar to the element. Figure 4 They are similarly numbered. In this setting, the coordination priority index ω k It can have values ​​1, 2, or 3. However, in general, it can have other values ​​in other settings, up to N. max As the boundary, N max Configured by the CCU and representing the maximum size of the cooperative set for each user equipment (UE) in the network.

[0101] Advantageously, configuring and reporting the coordination priority index in this manner allows the user equipment (UE) to select the amount of Channel State Information (CSI) to be reported or a subset of Channel State Information (CSI) reports that meet the threshold index for coordination priority.

[0102] For example, consider the configuration of coordination priority for user equipment 434.

[0103] First, user equipment 434 reports the best CQI associated with the Transmit / Receive Point (TRP) C to the network. For this example, this CQI has an exponent of 7. Based on this CQI, the network estimates the SINR of user equipment 434 (using Table 1 above in this example, although other mechanisms can be employed as described).

[0104] CQI 7 → SINR = 4.694 dB.

[0105] User equipment 434 is considered satisfied if its available throughput is higher than the Guaranteed Bit Rate (GBR) used for its service (the bit rate expected to be provided by the GBR bearer). This Guaranteed Bit Rate is included in the individual QoS flow descriptions.

[0106] Assume this guaranteed bit rate is equal to 4 bits / s / Hz.

[0107] The network calculates the coordination priority index as follows:

[0108] w4 = GBR4 / log2(1+SINR) = 4 / log2(1+2.947) = 2.02, rounded to 2.

[0109] Take the upper limit value, w4=2 is the coordination priority index to be sent to user equipment 434.

[0110] User equipment 434 receives the index / threshold w4 = 2. This means that user equipment 434 will be served by a maximum of 2 cooperating send / receive points simultaneously.

[0111] Since User Equipment 434 can measure the average received power from all transmit / receive points in the cell, and since User Equipment 4 is notified that it is served by at most two cooperating transmit / receive points (because exponent / threshold = 2), User Equipment 434 is expected to submit a channel state information report corresponding to the joint transmission scenario (i.e., the two transmit / receive points exhibiting optimal channel characteristics as seen by UE 434), referencing Figure 4 It will indicate that the cooperative set of the sending / receiving points is {TRP421, TR423}.

[0112] Therefore, by allowing the user equipment (UE) to select one or more Channel State Information (CSI) reports from the configured transmission / interference assumptions, the Channel State Information (CSI) reporting overhead is reduced.

[0113] Based on Figure 2 or Figure 3 The simulation results were obtained through the implementation method. Figure 2 or Figure 3 The implementation involves implementing and utilizing user coordination priorities at the CCU to provide clustering decisions. For the proposed algorithm utilizing user coordination priorities, backhaul traffic and network traffic were evaluated, and compared with existing N-optimal schemes and optimal power coordination. In the N-optimal scheme, users are associated with N strongest transmit / receive points (TRPs), while in optimal power coordination, users are associated with RSRPs exceeding a threshold P. th It is associated with the Transmit / Receive Point (TRP).

[0114] exist Figure 1 The performance of the system presented can be simulated based on appropriate parameters (such as those shown in Table 2 below), for example, based on Monte Carlo simulations, where the locations of small cells and users are generated for each simulation.

[0115] Table 2: Simulation Parameters

[0116]

[0117] Figure 6 The achievable sum rate is shown in a set of simulations based on several different reporting strategies for the number of users in a macro cell.

[0118] As shown, the sum and rate are plotted on the y-axis in bits / s / Hz relative to the total number of users on the x-axis. Six different reporting schemes were considered, as summarized in Table 3 below:

[0119] Table 3.

[0120] Reporting Plan Figure 6 The curve in <![CDATA[1. Embodiment, N max = 2]]> Continuous line, triangle marker <![CDATA[2. Embodiment, N max = 3]]> Dotted lines, triangle markings 3. The best approach is N = 2 Continuous lines, circular markers 4. The best approach is N = 3 Dotted lines, circular markers 5. Optimal power coordination scheme: Pth = -70dBm Continuous lines, positive markings 6. Optimal power coordination scheme: Pth = -80dBm Dotted lines, square markers

[0121] Scheme 1 and Scheme 2 are embodiments of the present invention that further implement clustering based on CPI values ​​as described above.

[0122] N max This represents the maximum number of transmit / receive points associated with a user in the simulation based on the above implementation. The results were compared with those of the optimal N approach, where N is a fixed number of transmit / receive points (TRPs) serving a user, and also with the optimal power cooperation scheme, where P... th It is the power threshold.

[0123] exist Figure 6 As can be seen from the data, the achievable sum and rate of the proposed scheme increase linearly with the number of users in the network. However, in other schemes, a ceiling effect can be easily observed. In fact, for a large number of users, the sum and rate plateau and do not improve. This behavior is expected due to the limitations of radio resources in the network.

[0124] Figure 7 This paper presents a set of simulated network backhaul service flow data, which is based on... Figure 6 Different reporting strategies increase relative to the number of users in the macrocell.

[0125] As shown, the backhaul traffic flow is plotted on the y-axis in bits / s / Hz relative to the total number of users on the x-axis. Consider six different reporting schemes, as outlined in Table 3 above:

[0126] As shown, the network backhaul traffic of the N-optimal scheme and the optimal power cooperation scheme is far greater than that of the proposed scheme. In fact, the priority-resource-constrained CoMP algorithm changes the number of transmit / receive points (TRPs) associated with each user, and therefore only provides the necessary resource blocks.

[0127] Figure 8 It shows the basis Figure 6 Different reporting strategies, as functions of network backhaul services, are achievable and have varying rates.

[0128] As shown, the backhaul traffic flow is plotted on the y-axis in bits / s / Hz relative to the backhaul traffic flow on the x-axis. Six different reporting schemes were considered, as outlined in Table 3 above:

[0129] It is readily observed that, compared to other schemes, the proposed algorithm achieves the requested sum rate with less backhaul traffic. This confirms that user coordination prioritization begins to take effect, conserving more radio resources in the network.

[0130] Figure 9 It shows the basis Figure 6 The fairness of different reporting strategies, which is a function of the number of unsatisfied users compared to the total number of users.

[0131] As shown, the number of unmet users is plotted on the y-axis relative to the total number of users on the x-axis. Six different reporting schemes were considered, as outlined in Table 3 above:

[0132] As shown, the number of unmet users in the simulation based on the above-discussed implementation is lower for all values ​​of the total number of users compared to any other reporting scheme.

[0133] The above describes implementation methods. Those skilled in the art will recognize that all the features described above are applicable to implementation in suitably configured hardware. Aspects of the disclosed methods may take the form of a completely hardware implementation (e.g., an FPGA), a completely software implementation (e.g., for controlling a system according to the invention), or an implementation including both hardware and software elements. Software implementations include, but are not limited to, firmware, resident software, microcode, etc. The invention may take the form of a computer program product accessible from a computer-usable or computer-readable medium that provides program code used by or in conjunction with a computer or instruction execution system. Computer-usable or computer-readable can be any means capable of containing, storing, transmitting, propagating, or transmitting a program used by or in conjunction with an instruction execution system, apparatus, or device. The medium may be an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. In this context, a user equipment can be considered as a computer. Similarly, a CCU can be considered as a computer, and a CCU cooperating with other components of the system described herein is considered as a distributed computer system.

[0134] Specifically, a cellular communication system comprising multiple transmitting / receiving points can be provided, wherein a user equipment (UE) can simultaneously communicate with multiple transmitting / receiving points, the communication being coordinated based on channel state information transmitted by the UE. Such a system can be adapted to receive from the UE a channel quality indicator representing the signal-to-interference-plus-noise ratio (SINR) of a communication, wherein the channel quality indicator is associated with a preferred channel, which is the communication with the highest channel quality, to determine a coordination priority index that is proportional to the bit rate requirement associated with the UE and inversely proportional to the SINR, and rounded to an integer. The system can also be adapted to transmit the coordination priority index to the UE, wherein the UE is configured to transmit channel state information related to the corresponding communication, wherein the transmitted channel state information pertains to a communication corresponding to the communication with the highest channel state information value, and wherein the number of communication channels pertaining to the transmitted channel state information is equal to or less than the coordination priority index.

[0135] Similarly, the user equipment (UE) may be adapted to transmit a channel quality indicator representing the signal-to-interference-plus-noise ratio (SINR) of a communication, wherein the channel quality indicator is associated with a preferred channel as the communication with the highest channel quality. The UE may also be adapted (e.g., from the CCU) to receive a coordination priority index, which is proportional to the bit rate requirement associated with the UE and inversely proportional to the SINR, rounded to an integer, and the UE may also be adapted (e.g., to the CCU) to transmit channel state information associated with the corresponding communication. The transmitted channel state information pertains to a communication corresponding to the communication with the highest channel state information value, and the number of communication channels pertaining to the transmitted channel state information is equal to or less than the coordination priority index.

[0136] Therefore, a priority-based resource-constrained CoMP scheme based on a user coordination priority index is provided for performing coordination set selection and resource allocation in small cell networks. The CoMP control unit (CCU) configures and subsequently sends a coordination priority index to the donor (serving) transmit / receive point (TRP), which is determined as a function of the desired bit rate and SINR or CQI for that particular user equipment (UE). The donor transmit / receive point (TRP) then sends the coordination priority index sent by the CCU to the corresponding UE. The configuration of the coordination priority index allows the user equipment (UE) to select the amount of Channel State Information (CSI) to be reported or a subset of Channel State Information (CSI) reports that satisfy a threshold index for the coordination priority.

[0137] It should be understood that the configurations and / or methods described herein are exemplary in nature, and these particular implementations or examples should not be considered limiting, as many variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. Therefore, the various actions shown and / or described may be performed in the shown and / or described order, in other orders, in parallel, or omitted. Similarly, the order of the above processes may be changed.

[0138] The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various processes, systems and configurations disclosed herein, as well as any and all equivalents thereof.

Claims

1. A method for transmitting channel state information in a cellular communication system comprising multiple transmitting / receiving points, wherein, The user equipment is capable of simultaneously communicating with multiple transmitting / receiving points, the communication being coordinated based on channel state information transmitted by the user equipment, the method comprising: The user equipment receives a channel quality indicator representing the signal-to-interference-plus-noise ratio (SINR) of the communication, wherein the channel quality indicator is associated with a preferred channel, which is the communication with the highest channel quality. A coordination priority index is determined, which is proportional to the bit rate requirement associated with the user equipment and inversely proportional to the signal-to-interference-plus-noise ratio (SINR), and is rounded to an integer. Send the coordination priority index to the user equipment, and The user equipment sends channel state information related to the corresponding communication, the channel state information being sent being for a communication that corresponds to the communication with the highest channel state information value, and wherein the number of communication channels for which the channel state information being sent is equal to or less than the coordination priority index.

2. The method according to claim 1, further comprising the following steps: The user equipment sends a selection criterion, and the user equipment applies the criterion to define the transmitted channel state information as a selected subset of the channel state information quantity and / or channel state information report.

3. The method according to claim 1 or 2, wherein, The system is also configured to assign the communication of the user equipment to multiple transmitting / receiving points based on the channel state information reported by the user equipment and the coordination priority index of the user equipment.

4. The method according to claim 3, wherein the step of assigning communication of the user equipment to multiple sending / receiving points includes: Multiple transmit / receive points are preferentially assigned to user equipment with higher coordination priority indices compared to user equipment with lower coordination priority indices.

5. The method according to claim 1 or 2, wherein, The signal-to-interference-plus-noise ratio (SINR) is determined based on a predetermined mapping from channel quality indicator values ​​to SINR values.

6. The method according to claim 1 or 2, wherein, The signal-to-interference-plus-noise ratio (SIR) is determined by calculation corresponding to the type of user equipment.

7. The method according to claim 1 or 2, wherein, The coordination priority index is equal to the bit rate requirement associated with the user equipment divided by the sum rate of the preferred channel, rounded to an integer.

8. A method for transmitting channel state information in a cellular communication system comprising multiple transmitting / receiving points, wherein, The user equipment is capable of simultaneously communicating with multiple transmitting / receiving points, the communication being coordinated based on channel state information transmitted by the user equipment, the method comprising: The user equipment transmits a channel quality indicator representing the signal-to-interference-plus-noise ratio (SINR) of the communication, wherein the channel quality indicator is associated with a preferred channel, which is the communication with the highest channel quality among the communications. A coordination priority index is received at the user equipment. This coordination priority index is proportional to the bit rate requirement associated with the user equipment and inversely proportional to the signal-to-interference-plus-noise ratio (SINR), and is rounded to an integer. as well as The user equipment sends channel state information related to the corresponding communication, the channel state information being sent being for a communication that corresponds to the communication with the highest channel state information value, and wherein the number of communication channels for which the channel state information being sent is equal to or less than the coordination priority index.

9. The method according to claim 8, further comprising the following step: The user equipment receives a selection criterion and applies the criterion to define the transmitted channel state information as a selected subset of the channel state information quantity and / or channel state information report.

10. The method according to claim 8 or 9, wherein, The signal-to-interference-plus-noise ratio (SINR) is determined based on a predetermined mapping from channel quality indicator values ​​to SINR values.

11. The method according to claim 8 or 9, wherein, The signal-to-interference-plus-noise ratio (SIR) is determined by calculation corresponding to the type of user equipment.

12. The method according to claim 8 or 9, wherein, The coordination priority index is equal to the bit rate requirement associated with the user equipment divided by the sum rate of the preferred channel, rounded to an integer.

13. A computer program product comprising instructions that, when executed by a computer, cause the computer to perform the method according to any one of claims 1 to 12.

14. A cellular communication system comprising multiple transmitting / receiving points, wherein, The user equipment is capable of simultaneously communicating with multiple transmitting / receiving points, the communication being coordinated based on channel state information transmitted by the user equipment. The system is suitable for: The user equipment receives a channel quality indicator representing the signal-to-interference-plus-noise ratio (SINR) of the communication, wherein the channel quality indicator is associated with a preferred channel, which is the communication with the highest channel quality. A coordination priority index is determined, which is proportional to the bit rate requirement associated with the user equipment and inversely proportional to the signal-to-interference-plus-noise ratio (SINR), and is rounded to an integer. Send the coordination priority index to the user equipment, and The user equipment is configured to send channel state information related to the corresponding communication, wherein the communication to which the sent channel state information is directed corresponds to the communication with the highest channel state information value, and wherein the number of communication channels to which the sent channel state information is directed is equal to or less than the coordination priority index.

15. A user equipment used in a cellular communication system comprising multiple transmitting / receiving points, wherein, The user equipment is capable of simultaneously communicating with multiple transmitting / receiving points, the communication being coordinated based on channel state information transmitted by the user equipment, wherein: The user equipment is adapted to transmit a channel quality indicator representing the signal-to-interference-plus-noise ratio (SINR) of the communication, wherein the channel quality indicator is a channel quality indicator associated with a preferred channel, which is the communication with the highest channel quality in the communication. The user equipment is also adapted to receive coordination priorities, the coordination priority index being proportional to the bit rate requirement associated with the user equipment and inversely proportional to the signal-to-interference-plus-noise ratio, and rounded to an integer. as well as The user equipment is also adapted to send channel state information related to the corresponding communication, wherein the channel state information is sent for a communication corresponding to the communication with the highest channel state information value, and wherein the number of communication channels for which the channel state information is sent is equal to or less than the coordination priority index.

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