CN102256301A

CN102256301A - User selection method for simultaneously meeting unicast and multicast services

Info

Publication number: CN102256301A
Application number: CN2011101976493A
Authority: CN
Inventors: 任品毅; 贾毅; 杜清河; 陈志刚; 王熠晨; 吴广恩
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2011-07-15
Filing date: 2011-07-15
Publication date: 2011-11-23
Anticipated expiration: 2031-07-15
Also published as: CN102256301B

Abstract

The present invention provides a user selection method that satisfies both unicast and multicast services, including: 1) superimposing unicast on the carrier originally assigned to multicast to establish a user selection model; 2) through block diagonalization and power control Ensure that the multicast service rate on the carrier will not be reduced; 3) Select unicast and the unicast user set with the highest rate. The method of the present invention, when multicast service is transmitted, considers that users also need unicast service when they need multicast service, and proposes that in the OFDM system, on the subcarriers allocated to multicast, BD is used to guarantee Under the premise that the reception performance of the worst multicast users is not affected, superimpose unicast, and ensure the maximum rate and no new worst link users by selecting the optimal unicast user set and the corresponding power control scheme .

Description

A user selection method satisfying both unicast and multicast services

技术领域 technical field

本发明属于无线通信技术领域，尤其是一种同时满足单播及多播业务的用户选择方法。The invention belongs to the technical field of wireless communication, in particular to a user selection method satisfying both unicast and multicast services.

背景技术 Background technique

随着无线网络的发展，用户对业务的质量要求越来越高，有限的频谱资源越来越满足不了用户的要求。因此提出了对多个用户传输相同数据的多播技术，可以很好的利用频谱，提高资源的利用效率。然而由于多播业务的多个用户信道链路情况不一，为了满足所有用户的业务需求，多播的数据速率往往受限于链路最差的用户，这样链路较好用户的资源没有充分利用。同时，当多个用户接收例如视频和电视节目这种多播业务的同时，他们也会有相应的例如电话、短信等单播业务的需求。为了解决这个问题，同时考虑到用户需求多播的同时也需求单播的情况，研究在一个子载波上同时传输单播和多播业务具有实际价值。With the development of wireless networks, users have higher and higher requirements for service quality, and limited spectrum resources cannot meet the requirements of users more and more. Therefore, a multicast technology for transmitting the same data to multiple users is proposed, which can make good use of frequency spectrum and improve resource utilization efficiency. However, due to the different channel links of multiple users in the multicast service, in order to meet the service needs of all users, the data rate of multicast is often limited to the user with the worst link, so the resources of users with better links are not sufficient. use. At the same time, when multiple users receive multicast services such as video and TV programs, they also have corresponding demands for unicast services such as telephone calls and short messages. In order to solve this problem, and considering the fact that users require both multicast and unicast, it is of practical value to study the simultaneous transmission of unicast and multicast services on one subcarrier.

发明内容 Contents of the invention

本发明的目的是为了克服现有的多播系统受限于链路最差用户，而好的用户的资源没有充分得到利用的问题；提出一种同时满足单播及多播业务的用户选择方法，该方法在保证多播速率没有减小的同时，最大化单播的速率，有效的提高了频谱的利用率，从而提高整个系统的性能。The purpose of the present invention is to overcome the problem that the existing multicast system is limited to users with the worst links, and the resources of good users are not fully utilized; to propose a user selection method that satisfies both unicast and multicast services , this method maximizes the unicast rate while ensuring that the multicast rate does not decrease, effectively improving the utilization rate of the spectrum, thereby improving the performance of the entire system.

本发明的目的是通过以下技术方案来实现的：The purpose of the present invention is achieved through the following technical solutions:

本发明是一种同时满足单播及多播业务的用户选择方法，起特殊之处在于以下步骤中：The present invention is a user selection method that satisfies unicast and multicast services at the same time, and is special in the following steps:

1)在原有分配给多播的载波上叠加单播；1) Superimpose unicast on the carrier originally assigned to multicast;

2)通过BD和功率控制保证不会减小该载波上的多播业务速率；2) Ensure that the multicast service rate on the carrier will not be reduced through BD and power control;

3)通过单播用户选择保证单播速率最大。3) Ensure the maximum unicast rate through unicast user selection.

在上述技术方案中，步骤1)的具体操作如下：In above-mentioned technical scheme, the concrete operation of step 1) is as follows:

1-1)、根据无线场景布置的结果，在所有载波上调度多播业务和单播业务；1-1), according to the result of wireless scene deployment, schedule multicast services and unicast services on all carriers;

1-2)、在调度多播的载波中，根据链路最差用户性能，计算多播的速率；1-2), in the carrier for scheduling multicast, calculate the rate of multicast according to the worst user performance of the link;

1-3)、在调度多播的载波中，给多播数据叠加单播数据流，根据此时多播链路最差用户性能，计算多播的速率：1-3), in the carrier for scheduling multicast, superimpose the unicast data flow to the multicast data, and calculate the multicast rate according to the worst user performance of the multicast link at this time:

在上述技术方案中，只是将单播流通过叠加编码与多播一同发送。In the above technical solution, only the unicast stream is sent together with the multicast through superposition coding.

在上述技术方案中，叠加单播前，用户i多播信号的SNR为：In the above technical solution, before superimposing unicast, the SNR of user i's multicast signal is:

${SNR SNR}_{m m,, i i}^{((k k))} = = \frac{{P P}_{m m} {| | {w w}_{m m,, k k}^{H h} {h h}_{i i}^{((k k))} | |}^{22}}{{N N}_{00}} - - - - - - ((11))$

叠加后，用户i多播信号的SINR为：After superposition, the SINR of user i multicast signal is:

${SINR SINR}_{m m,, i i} = = \frac{{P P}_{m m} {| | {w w}_{m m,, k k}^{H h} {h h}_{i i}^{((k k))} | |}^{22}}{{P P}_{u u} \underset{j j &Element; &Element; {U u}_{k k}}{Σ Σ} {| | {w w}_{j j,, k k}^{H h} {h h}_{i i}^{((k k))} | |}^{22} + + {N N}_{00}} - - - - - - ((22))$

用户j，j∈U_k，单播信号SINR为：For user j, j∈U _k , the SINR of the unicast signal is:

${SINR SINR}_{u u,, j j}^{((k k))} = = \frac{{| | {w w}_{j j,, k k}^{H h} {h h}_{j j}^{((k k))} | |}^{22}}{\underset{n no &Element; &Element; {U u}_{k k},, n no &NotEqual; &NotEqual; j j}{Σ Σ} {| | {w w}_{n no,, k k}^{H h} {h h}_{i i}^{((k k))} | |}^{22} + + {N N}_{00}} - - - - - - ((33))$

在上述的技术方案中，步骤2)包括如下操作：In above-mentioned technical scheme, step 2) comprises following operations:

2-1)、在调度多播的载波中，根据块对角化，令单播数据流都在最差链路用户的正交子空间发送；2-1), in the carrier of the scheduled multicast, according to the block diagonalization, the unicast data flow is sent in the orthogonal subspace of the worst link user;

2-2)、为了防止因为单播干扰出现链路更差用户，对单播流进行功率控制。2-2). In order to prevent users with worse links due to unicast interference, power control is performed on unicast streams.

在上述技术方案中，先通过BD达到多播链路最差用户速率不变的目的，然后通过功率控制保证不会产生其他更差用户，这样就可以保证多播速率不变，同时可以叠加单播数据流。In the above technical solution, BD is used to achieve the purpose of keeping the rate of the worst user of the multicast link unchanged, and then power control is used to ensure that no other worse users will be generated. broadcast data stream.

在上述技术方案中，步骤3)包括如下操作：In the above-mentioned technical scheme, step 3) comprises the following operations:

3-1)、遍历所有可能的单播用户集，根据步骤2)计算各种单播用户集下的单播速率，选择单播和速率最大的单播集；3-1), traverse all possible unicast user sets, calculate the unicast rate under various unicast user sets according to step 2), and select the unicast set with the largest unicast and rate;

3-2)、次优的用户集选择策略，根据步骤2)首先选择一个速率最大用户，然后在这个用户已选择基础上，选择下一个用户，如果速率增加则继续选择，否则用户选择结束。3-2), the suboptimal user set selection strategy, according to step 2), first select a user with the highest rate, and then select the next user on the basis of this user's selection, if the rate increases, continue to select, otherwise the user selection ends.

本发明具有以下有益效果：本发明首先通过块对角化来解决了单播数据流对原多播最差用户的性能不会产生影响，然后通过功率控制保证了不会产生比原多播最差用户性能更差的用户，最后进行用户选择保证了在不减小多播数据速率的前提下，最大化单播数据速率；同时提出了复杂度更低的次优用户选择方法。The present invention has the following beneficial effects: firstly, the present invention solves the problem that the unicast data flow will not affect the performance of the original multicast worst user through block diagonalization, and then ensures that the worst user performance of the original multicast will not be generated by power control. For users with worse performance, user selection is finally performed to ensure the maximum unicast data rate without reducing the multicast data rate; meanwhile, a suboptimal user selection method with lower complexity is proposed.

附图说明 Description of drawings

图1为本发明的系统模型图；Fig. 1 is a system model diagram of the present invention;

图2为单播和多播叠加时的发射机框图；Figure 2 is a block diagram of the transmitter when unicast and multicast are superimposed;

图3为单播和多播叠加时的接收机框图；Figure 3 is a receiver block diagram when unicast and multicast are superimposed;

图4为本发明方法的流程图。Fig. 4 is a flowchart of the method of the present invention.

具体实施方式 Detailed ways

下面结合附图和具体实施实例对本发明做进一步的详细说明。The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation examples.

本发明的核心思想是在分配给多播的载波中，由于多播受限于链路最差用户，链路好的用户的资源没有得到充分的利用，因此提出在保证不影响多播速率的前提下，通过叠加编码将多播和单播叠加发送。为了达到不影响多播速率的目的，首先通过块对角化(BD，BlockDiagonalization)来解决单播数据流对原多播最差用户的性能不会产生影响，然后通过功率控制保证了不会产生比原多播最差用户性能更差的用户，最后通过用户选择策略保证了在不减小多播数据速率的前提下，最大化单播数据速率。同时提出了复杂度更低的次优用户选择策略。The core idea of the present invention is that among the carriers assigned to multicast, since multicast is limited to users with the worst links, the resources of users with good links are not fully utilized. Under the premise, multicast and unicast are superimposed and transmitted through superposition coding. In order to achieve the purpose of not affecting the multicast rate, block diagonalization (BD, BlockDiagonalization) is firstly used to solve the problem that the unicast data flow will not affect the performance of the original multicast worst user, and then the power control is used to ensure that no The user whose performance is worse than the worst user of the original multicast, finally ensures the maximum unicast data rate without reducing the multicast data rate through the user selection strategy. At the same time, a suboptimal user selection strategy with lower complexity is proposed.

本发明是一种同时满足单播及多播业务的用户选择方法，其包括：The present invention is a user selection method satisfying both unicast and multicast services, which includes:

1)在原有的分配给多播的载波上叠加单播，具体步骤如下：1) Superimpose unicast on the original carrier allocated to multicast, the specific steps are as follows:

1-1)、本发明中的OFDM系统是在一个蜂窝小区场景下，该蜂窝小区的基站(BS，Base Station)有N个天线，小区中具有M个单天线的移动台(MS，Mobile Station)，且M＞N，共有K个载波可用来传输数据。每个MS需求单播业务的同时也需求多播业务。因此，共有M个单播流和一个多播流可用来传输。但是单播流不能都用来发送，因此需要选择用来传输的用户，如图1所示。一共有K个子载波可用来传输数据，当所有用户在第k个载波上的最小SNR大于门限值SNR_th时，1≤k≤K，第k个子载波用来传输多播业务，否则传输单播业务，如图4所示。且在每个传输多播的子载波上，多播的传输功率为P_m，单播的传输功率为P_u。令h_i表示用户i的下行信道向量，h_i中每个元素都是独立同分布，且服从均值为0方差为1的复高斯分布。我们假设BS已知所有用户的信道状态信息，且在一个帧长时间内，信道不发生变化。1-1), the OFDM system among the present invention is under a cell scene, the base station (BS, Base Station) of this cell has N antennas, has the mobile station (MS, Mobile Station) of M single antenna in the cell ), and M>N, a total of K carriers can be used to transmit data. Each MS requires unicast services and multicast services at the same time. Therefore, a total of M unicast streams and one multicast stream are available for transmission. However, all unicast streams cannot be sent, so users need to be selected for transmission, as shown in Figure 1. A total of K sub-carriers can be used to transmit data. When the minimum SNR of all users on the k-th carrier is greater than the threshold value SNR _th , 1≤k≤K, the k-th sub-carrier is used to transmit multicast services, otherwise the transmission of single broadcast services, as shown in Figure 4. And on each subcarrier for multicast transmission, the multicast transmission power is P _m , and the unicast transmission power is P _u . Let h _i represent the downlink channel vector of user i, and each element in h _i is independent and identically distributed, and obeys a complex Gaussian distribution with a mean of 0 and a variance of 1. We assume that the BS knows the channel state information of all users, and the channel does not change within a long time frame.

假设第k个子载波分配给了多播，在第k个子载波上，用户i的信道向量为

首先选择单播用户集U_k，满足1≤|U_k|≤M，其中|U_k|表示用户集合中用户的个数。设多播的信号为x，U_k用户单播的信号为y_j，j∈U_k，且有E[|x|²]＝E[|y_j|²]＝1，j∈U_k。对多播业务，每个天线发送相同的信号，即多播发射向量为

对第j个用户的单播信号的波束赋形向量为w_j，k，j∈U_k，所有的w_j，k构成了单播的波束赋形向量w_u，k。如图2所示，将多播和波束赋形后的单播信号叠加起来发射，于是第i个用户的接收为Suppose the kth subcarrier is assigned to multicast, on the kth subcarrier, the channel vector of user i is

Firstly, the unicast user set U _k is selected, satisfying 1≤|U _k |≤M, where |U _k | represents the number of users in the user set. Let the multicast signal be x, the unicast signal of U _{k user} be y _j , j∈U _k , and E[|x| ² ]=E[|y _j | ² ]=1, j∈U _k . For multicast services, each antenna sends the same signal, that is, the multicast transmission vector is

The beamforming vector for the unicast signal of the jth user is w _{j, k} , j∈U _k , and all w _{j, k} constitute the unicast beamforming vector w _{u, k} . As shown in Figure 2, the multicast and beamformed unicast signals are superimposed and transmitted, so the reception of the i-th user is

${r r}_{i i,, k k} = = \sqrt{{P P}_{m m}} {w w}_{m m,, k k}^{H h} {h h}_{i i}^{((k k))} x x + + \sqrt{{P P}_{u u}} \underset{j j &Element; &Element; {U u}_{k k}}{Σ Σ} {w w}_{j j,, k k}^{H h} {h h}_{i i}^{((k k))} {y the y}_{i i} + + {n no}_{i i,, k k},, {n no}_{i i,, k k} &Element; &Element; CN CN ((00,, {N N}_{00})) . .$

其中，n_i，k表示第i个用户在第k个子载波上的高斯白噪声，N₀指噪声的功率谱密度。Among them, n _{i, k} represent the white Gaussian noise of the i-th user on the k-th subcarrier, and N ₀ refers to the power spectral density of the noise.

在接收端，所有的用户直接译出多播数据，而用户j∈U_k还需要用接收数据r_j，k减去多播数据后，再译出单播数据，如图3所示。At the receiving end, all users directly translate the multicast data, and the user j∈U _k needs to subtract the multicast data from the received data r _j,k , and then decode the unicast data, as shown in Figure 3.

1-2)、叠加单播前，用户i多播信号在第k个子载波上的SNR为：1-2), before superimposing unicast, the SNR of user i multicast signal on the kth subcarrier is:

1-3)、叠加后，用户i多播信号在第k个子载波上的SINR为：1-3), after superimposition, the SINR of the user i multicast signal on the k subcarrier is:

${SINR SINR}_{m m,, i i}^{((k k))} = = \frac{{P P}_{m m} {| | {w w}_{m m,, k k}^{H h} {h h}_{i i}^{((k k))} | |}^{22}}{{P P}_{u u} \underset{j j &Element; &Element; {U u}_{k k}}{Σ Σ} {| | {w w}_{j j,, k k}^{H h} {h h}_{i i}^{((k k))} | |}^{22} + + {N N}_{00}} - - - - - - ((22))$

用户j，j∈U_k，单播信号在第k个子载波上的SINR为：For user j, j∈U _k , the SINR of the unicast signal on the kth subcarrier is:

本发明的目标是在保证多播速率不减小的基础上提升单播性能，而在第k个子载波上多播的速率为 $R_{m}^{(k)} = \log (1 + \min_{i} {{SNR}_{m, i}^{(k)}}), i = 1,2, . . ., M,$ 即多播的速率只和链路最差的用户有关，因此只要保证链路最差用户的SNR在叠加单播之后不变，就可以保证多播业务不受影响。The object of the present invention is to improve unicast performance on the basis of ensuring that the multicast rate does not decrease, and the rate of multicast on the k subcarrier is $R_{m}^{(k)} = \log (1 + \min_{i} {{SNR}_{m, i}^{(k)}}), i = 1,2, . . ., m,$ That is, the multicast rate is only related to the user with the worst link. Therefore, as long as the SNR of the user with the worst link remains unchanged after superimposing unicast, the multicast service can be guaranteed not to be affected.

综上所述，提出下面的优化模型：通过用户选择，功率控制，以及波束赋形设计，在保证多播速率不变的前提下，最大化单播数据的速率和。To sum up, the following optimization model is proposed: Through user selection, power control, and beamforming design, the rate sum of unicast data is maximized under the premise of keeping the multicast rate constant.

$\underset{{U u}_{k k},, {P P}_{u u},, {w w}_{j j,, k k}}{max max} {R R}_{u u}^{((k k))}$

$s . t . : \min_{i} {SINR}_{m, i}^{(k)} = \min_{i} {SNR}_{m, i}^{(k)}, i = 1,2, . . ., M$ (4) $the s . t . : \min_{i} {SINR}_{m, i}^{(k)} = \min_{i} {SNR}_{m, i}^{(k)}, i = 1,2, . . ., m$ (4)

${R R}_{u u}^{((k k))} = = {Σ Σ}_{j j &Element; &Element; {U u}_{k k}} {log log}_{22} ((11 + + {SINR SINR}_{u u,, j j}^{((k k))})),, k k = = 1,2 1,2,, . . . . . .,, K K$

j∈U_k j∈U _k

其中(4)式的第一个条件表示单播信号对多播信道最差用户没有影响，即叠加单播信号后，多播最差链路用户的性能没有发生变化。第二个条件指的是第k个子载波上的单播总速率。The first condition in (4) indicates that the unicast signal has no effect on the worst user of the multicast channel, that is, the performance of the worst multicast link user does not change after superimposing the unicast signal. The second condition refers to the total unicast rate on the kth subcarrier.

2)通过BD和功率控制保证不会减小该载波上的多播业务速率，具体步骤如下：2) Ensure that the multicast service rate on the carrier will not be reduced through BD and power control, the specific steps are as follows:

由于式(4)是一个多变量的优化问题，将多个变量分离，即将波束赋形的设计、功率控制与用户的选择分开来求解。首先研究当用户确定时的波束赋形向量设计与功率控制；其次分别通过穷举法和低复杂度的次优算法来确定U。由于只考虑单个载波上的问题，为了书写简单，下面将“k”忽略不写。Since Equation (4) is a multivariate optimization problem, multiple variables are separated, that is, beamforming design, power control and user selection are solved separately. Firstly, the beamforming vector design and power control are studied when the user is determined; secondly, U is determined by exhaustive method and low-complexity suboptimal algorithm respectively. Since only the problem on a single carrier is considered, for simplicity of writing, "k" will be ignored below.

2-1)、通过BD解决不影响链路最差用户性能，即w_u的确定2-1), solve the worst user performance without affecting the link through BD, that is, the determination of w _u

要保证不影响多播速率，就要保证链路最差用户不受单播的干扰。采用BD来解决这个问题，对单播的波束赋形向量从最差链路用户的信道正交子空间上取得，这样就可以保证单播的数据的波束集中在别的用户的方向，而最差用户没有受到一点影响。To ensure that the multicast rate is not affected, it is necessary to ensure that the user with the worst link is not interfered by unicast. BD is used to solve this problem, and the beamforming vector for unicast is obtained from the channel orthogonal subspace of the user with the worst link, so that the beam of unicast data can be concentrated in the direction of other users, and the most Poor users are not affected at all.

由于单播数据间存在干扰，同时也要对选择的单播用户进行BD，因此要对U的用户和链路最差用户一起做BD，得到波束赋形向量w_u。于是，由于MS都是单天线，且BS共有N个天线，因此U_k的元素个数不能超过N-1。Since there is interference between unicast data, BD must be performed on the selected unicast users at the same time, so BD must be performed on the users of U and the users with the worst link to obtain the beamforming vector w _u . Therefore, since the MSs all have single antennas, and the BS has N antennas in total, the number of elements of U _k cannot exceed N-1.

通过和最差用户BD得到的波束赋形向量可以使原多播最差用户没有影响，但是会对别的用户的接收情况造成影响，为了保证叠加单播后的多播最小SINR和叠加前最小SNR一样大，就需要保证不会产生新的链路最差用户，这个问题可以通过对单播的功率控制来解决。The beamforming vector obtained by summing the worst user BD can make the original multicast worst user have no impact, but it will affect the reception of other users. In order to ensure the minimum multicast SINR after superimposing unicast and the minimum If the SNR is the same, it is necessary to ensure that no new users with the worst links will be generated. This problem can be solved by controlling the power of unicast.

2-2)、通过功率控制保证不会产生链路更差用户，即P_u的确定2-2), through power control to ensure that there will be no users with worse links, that is, the determination of P _u

单播功率控制策略：由于单播的干扰可能导致多播接收最差用户的变更，因此引入单播功率控制策略。Unicast power control strategy: Because unicast interference may cause the change of the user with the worst multicast reception, a unicast power control strategy is introduced.

为了保证单播数据对多播传输速率无影响，对BD后的单播数据进行功率控制，分配的功率P_u需要满足下面几个条件：In order to ensure that unicast data has no impact on the multicast transmission rate, power control is performed on unicast data after BD, and the allocated power P _u needs to meet the following conditions:

(1)、叠加单播所造成的干扰不影响多播传输速率，即多播最小的SINR；(1) The interference caused by superimposed unicast does not affect the multicast transmission rate, that is, the minimum SINR of multicast;

(2)、功率需尽可能大；(2), the power needs to be as large as possible;

(3)、功率不能超过某一上限，记为P_max。(3) The power cannot exceed a certain upper limit, which is denoted as P _max .

因此为了保证不会有新的链路最差用户诞生，单播功率必须满足Therefore, in order to ensure that no new worst link users will be born, the unicast power must satisfy

$\underset{i i}{min min} {{\frac{{P P}_{m m} {| | {w w}_{m m}^{H h} {h h}_{i i} | |}^{22}}{{P P}_{u u,, i i} \underset{j j &Element; &Element; U u}{Σ Σ} {| | {w w}_{j j}^{H h} {h h}_{i i} | |}^{22} + + {N N}_{00}}}} = = \underset{i i}{min min} {{\frac{{P P}_{m m} {| | {w w}_{m m}^{H h} {h h}_{i i} | |}^{22}}{{N N}_{00}}}} = = \frac{{P P}_{m m} {| | {w w}_{m m}^{H h} {h h}_{min min} | |}^{22}}{{N N}_{00}}$

求解得P_u，i，又因为单播功率不能超过P_max，因此分配给单播业务的总功率为P_u＝min{P_u，i，P_max}。P _u,i is obtained by solving, and because the unicast power cannot exceed P _max , the total power allocated to the unicast service is P _u =min{P _u,i ,P _max }.

于是，模型简化为下式：Therefore, the model is simplified to the following formula:

$\underset{U u}{max max} {R R}_{u u}$

$s the s . . t t . . : : \underset{i i}{min min} {SINR SINR}_{m m,, i i} = = \underset{i i}{min min} {SNR SNR}_{m m,, i i},, k k = = 1,2 1,2,, . . . . . .,, K K$

|U|≤N-1 (5)|U|≤N-1 (5)

${R R}_{u u} = = {Σ Σ}_{j j &Element; &Element; U u} {log log}_{22} ((11 + + \frac{{p p}_{j j} {| | {w w}_{j j} {h h}_{j j} | |}^{22}}{{N N}_{00}}))$

3)通过单播用户选择保证单播速率最大，具体步骤如下：3) Ensure the maximum unicast rate through unicast user selection, the specific steps are as follows:

在上述优化问题(5)式中只有U一个变量。首先明确U选择的原则：There is only one variable U in the above optimization problem (5). First, clarify the principles of U selection:

(1)、所选单播用户的信号对多播信号的干扰需尽可能集中在链路条件好的多播用户处，即不影响链路最差的用户，因此链路最差用户不会被选择；(1) The interference of the signal of the selected unicast user to the multicast signal should be concentrated on the multicast user with good link conditions as much as possible, that is, the user with the worst link will not be affected, so the user with the worst link will not be blocked choose;

(2)、U中单播用户要求相互之间的信道相关性不高，即保证BD后单播的和速率最大。(2) The unicast users in U require that the channel correlation between them is not high, that is, the maximum sum rate of unicast after BD is guaranteed.

3-1)、由于用户一共有M个，U中的用户数不超过N-1，因此只需要遍历所有可能的用户集，就可以得到最优的结果。遍历算法如下：3-1). Since there are M users in total, and the number of users in U does not exceed N-1, the optimal result can be obtained only by traversing all possible user sets. The traversal algorithm is as follows:

步骤1：首先寻找第k个子载波上的链路最差用户i，令Ω＝{1，2，...，M}\i，U＝φ；Step 1: First find the user i with the worst link on the kth subcarrier, let Ω={1, 2,...,M}\i, U=φ;

步骤2：从Ω列举所有可能的U，共L个，

记为U^(l)，l＝1，2，...，L；Step 2: Enumerate all possible U from Ω, a total of L,

Recorded as U ^(l) , l=1, 2, ..., L;

步骤3：对每种U进行BD，并分配功率；Step 3: Perform BD on each U and distribute power;

步骤4：计算每种U的速率 $R_{u}^{(l)} = Σ_{j &Element; U^{(l)}} \log_{2} (1 + \frac{p_{j} {| w_{j}^{H} h_{j} |}^{2}}{N_{0}});$ Step 4: Calculate the rate of each U $R_{u}^{(l)} = Σ_{j &Element; u^{(l)}} \log_{2} (1 + \frac{p_{j} {| w_{j}^{h} h_{j} |}^{2}}{N_{0}});$

步骤5：得到最优的U序号， $l_{opt} = \underset{1 \leq l \leq L}{\arg \max} R_{u}^{(l)} .$ Step 5: Get the optimal U serial number, $l_{opt} = \underset{1 \leq l \leq L}{\arg \max} R_{u}^{(l)} .$

3-2)、由于遍历算法复杂度高，下面提出一种降低复杂度的次优选择算法：3-2), due to the high complexity of the traversal algorithm, a sub-optimal selection algorithm to reduce the complexity is proposed below:

步骤2：Ω中的每个用户分别与用户i一起做BD后，进行功率控制，选择速率最大的用户π(1)，于是Ω＝Ω\π(1)，U＝U+{π(1)}，t＝1；Step 2: After each user in Ω does BD with user i, perform power control and select the user π(1) with the highest rate, so Ω=Ω\π(1), U=U+{π(1) },t=1;

步骤3：迭代：t＝t+1，若t＞N-1，算法结束。否则Ω中的用户寻找分别和用户i，π(1)，...，π(t-1)做BD，然后功率控制，选择与π(1)，...，π(t-1)的和速率最大的π(t)， $R_{u}^{(t)} = Σ_{j &Element; U^{(l)}} \log_{2} (1 + \frac{p_{j} {| w_{j}^{H} h_{j} |}^{2}}{N_{0}})$ 为和速率，其中对

若

算法结束。否则，Ω＝Ω-{π(t)}，U＝U+{π(t)}。Step 3: Iteration: t=t+1, if t>N-1, the algorithm ends. Otherwise, the users in Ω are looking for BD with users i, π(1), ..., π(t-1) respectively, and then power control, choose and π(1), ..., π(t-1) π(t) with the largest sum rate,

R_{u}^{(t)} = Σ_{j &Element; u^{(l)}} \log_{2} (1 + \frac{p_{j} {| w_{j}^{h} h_{j} |}^{2}}{N_{0}})

is the sum rate, where for

like

Algorithm ends. Otherwise, Ω=Ω-{π(t)}, U=U+{π(t)}.

上述解法可以得到三个参数：波束赋形向量w_u，单播的功率P_u以及单播业务用户集U，总的流程图如图4所示。The above solution can obtain three parameters: beamforming vector w _u , unicast power P _u and unicast service user set U. The overall flowchart is shown in Fig. 4 .

Claims

1. A user selection method for meeting unicast and multicast services at the same time is used for a cell, the cell comprises a base station with N antennas, M mobile stations with single antenna, M is more than N, and K carriers are used for transmitting data; the method is characterized in that:

1) overlaying unicast on original carrier waves distributed to multicast to establish a user selection model;

2) ensuring that the multicast traffic rate on the carrier is not reduced by block diagonalization and power control;

3) and selecting the unicast user set with the highest unicast and highest rate.

2. The method of claim 1, wherein the specific method in step 1) is as follows:

1-1) calculating SNR of multicast signals of a user i on a k-th subcarrier before superposition of unicast, wherein the calculation formula is as follows:

{SNR}_{m, i}^{(k)} = \frac{P_{m} {| w_{m, k}^{H} h_{i}^{(k)} |}^{2}}{N_{0}} - - - (1)

wherein, P_mRefers to the power of the multicast on a single subcarrier,

refers to the beamforming vector multicast on the k sub-carrier, which indicates that each antenna transmits the same signal,

representing the channel coefficient, N, of the ith user on the kth subcarrier₀Refers to the noise power spectral density;

1-2) calculating the SINR of the user i multicast signal on the kth subcarrier after superposition, wherein the calculation formula is as follows:

<math> <mrow> <msubsup> <mi>SINR</mi> <mrow> <mi>m</mi> <mo>,</mo> <mi>i</mi> </mrow> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </msubsup> <mo>=</mo> <mfrac> <mrow> <msub> <mi>P</mi> <mi>m</mi> </msub> <msup> <mrow> <mo>|</mo> <msubsup> <mi>w</mi> <mrow> <mi>m</mi> <mo>,</mo> <mi>k</mi> </mrow> <mi>H</mi> </msubsup> <msubsup> <mi>h</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </msubsup> <mo>|</mo> </mrow> <mn>2</mn> </msup> </mrow> <mrow> <msub> <mi>P</mi> <mi>u</mi> </msub> <munder> <mi>Σ</mi> <mrow> <mi>j</mi> <mo>&Element;</mo> <msub> <mi>U</mi> <mi>k</mi> </msub> </mrow> </munder> <msup> <mrow> <mo>|</mo> <msubsup> <mi>w</mi> <mrow> <mi>j</mi> <mo>,</mo> <mi>k</mi> </mrow> <mi>H</mi> </msubsup> <msubsup> <mi>h</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </msubsup> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>+</mo> <msub> <mi>N</mi> <mn>0</mn> </msub> </mrow> </mfrac> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein, P_uRefers to the power, w, of unicast on a single subcarrier_j，kRefers to the unicast signal beamforming vector, U, of the jth user on the kth subcarrier_kThe unicast user set selected on the kth subcarrier is referred to;

1-3) rate of superimposing multicast before unicast is

R_{m}^{(k)} = \log (1 + \min_{i} {{SNR}_{m, i}^{(k)}}), i = 1,2, . . ., M;

The multicast rate after superposition is equal to the multicast rate before superposition, and the model is as follows:

\max_{U_{k}, P_{u}, w_{j, k}} R_{u}^{(k)}

s . t . : \min_{i} {SINR}_{m, i}^{(k)} = \min_{i} {SNR}_{m, i}^{(k)}, i = 1,2, . . ., M

(3)

<math> <mrow> <msubsup> <mi>R</mi> <mi>u</mi> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </msubsup> <mo>=</mo> <msub> <mi>Σ</mi> <mrow> <mi>j</mi> <mo>&Element;</mo> <msub> <mi>U</mi> <mi>k</mi> </msub> </mrow> </msub> <msub> <mi>log</mi> <mn>2</mn> </msub> <mrow> <mo>(</mo> <mn>1</mn> <mo>+</mo> <msubsup> <mi>SINR</mi> <mrow> <mi>u</mi> <mo>,</mo> <mi>j</mi> </mrow> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </msubsup> <mo>)</mo> </mrow> <mo>,</mo> <mi>k</mi> <mo>=</mo> <mn>1,2</mn> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <mi>K</mi> </mrow> </math>

j∈U_k

wherein,

indicating U on the k sub-carrier_kThe total rate of unicast users.

3. The method for selecting the user to satisfy both the unicast and the multicast services according to claim 1, wherein the step 2) comprises the following steps:

2-1) sending unicast streams on orthogonal subspaces of worst users of the link by block diagonalization to ensure that the unicast streams do not influence the performance of the worst users of the link;

2-2) controlling unicast power to ensure that unicast interference can not cause that the multicast generates worse users after unicast superposition than worst users before unicast superposition;

unicast power P_uMust not exceed P_u，i，P_u，iSatisfy the requirement of

<math> <mrow> <munder> <mi>min</mi> <mi>i</mi> </munder> <mo>{</mo> <mfrac> <mrow> <msub> <mi>P</mi> <mrow> <mi>m</mi> <mo>,</mo> <mi>k</mi> </mrow> </msub> <msup> <mrow> <mo>|</mo> <msubsup> <mi>w</mi> <mrow> <mi>m</mi> <mo>,</mo> <mi>k</mi> </mrow> <mi>H</mi> </msubsup> <msubsup> <mi>h</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </msubsup> <mo>|</mo> </mrow> <mn>2</mn> </msup> </mrow> <mrow> <msub> <mi>P</mi> <mrow> <mi>u</mi> <mo>,</mo> <mi>i</mi> </mrow> </msub> <munder> <mi>Σ</mi> <mrow> <mi>j</mi> <mo>&Element;</mo> <msub> <mi>U</mi> <mi>k</mi> </msub> </mrow> </munder> <msup> <mrow> <mo>|</mo> <msubsup> <mi>w</mi> <mrow> <mi>j</mi> <mo>,</mo> <mi>k</mi> </mrow> <mi>H</mi> </msubsup> <msubsup> <mi>h</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </msubsup> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>+</mo> <msub> <mi>N</mi> <mn>0</mn> </msub> </mrow> </mfrac> <mo>}</mo> <mo>=</mo> <munder> <mi>min</mi> <mi>i</mi> </munder> <mo>{</mo> <mfrac> <mrow> <msub> <mi>P</mi> <mi>m</mi> </msub> <msup> <mrow> <mo>|</mo> <msubsup> <mi>w</mi> <mrow> <mi>m</mi> <mo>,</mo> <mi>k</mi> </mrow> <mi>H</mi> </msubsup> <msubsup> <mi>h</mi> <mi>i</mi> <mrow> <mo>(</mo> <mi>k</mi> <mo>)</mo> </mrow> </msubsup> <mo>|</mo> </mrow> <mn>2</mn> </msup> </mrow> <msub> <mi>N</mi> <mn>0</mn> </msub> </mfrac> <mo>}</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>4</mn> <mo>)</mo> </mrow> </mrow> </math>

Unicast power cannot exceed P_maxTotal power allocated to unicast traffic is P_u＝min{P_u，i，P_maxIn which P is_maxRepresenting the maximum power that can be allocated by unicast on a single carrier.

4. The method for selecting the user to satisfy both the unicast and the multicast services according to claim 1, wherein the specific steps of step 3) are as follows:

and traversing all possible unicast user sets, calculating unicast rates under various unicast user sets according to the step 2), and selecting the unicast user set with the highest unicast and rate.

5. The method for selecting users to satisfy both unicast and multicast services according to claim 1, namely selecting an optimal unicast user set, wherein the specific steps of step 3) are as follows:

according to step 2), firstly selecting a user with the maximum rate, then selecting the next user on the basis of the selection of the user, if the rate is increased, continuing the selection, otherwise, the user selection is ended.