技术领域technical field
本发明属于无线通信网络技术领域，尤其涉及一种异构网络中基于femtocell分簇和宏用户调度的干扰协调方法。The invention belongs to the technical field of wireless communication networks, in particular to an interference coordination method based on femtocell clustering and macro user scheduling in heterogeneous networks.
背景技术Background technique
随着无线数据量的爆炸式增长及人们对于数据速率需求的不断提升，对无线蜂窝网络的部署和设计提出了新的要求。小区分裂能够增大网络容量，smallcell出现，尤其是femtocell(家庭基站)能使用户端到基站端的距离大大减小，从而降低了路径损耗。另一方面，在宏小区端部署大规模天线(massive MIMO)能够增加天线的空间自由度，增加链路增益和可靠性。大规模天线系统能够使天线的辐射能量集中到某些特定的区域，从而增强期望用户的信号功率，降低对非期望用户的干扰。因此，部署大规模天线的宏小区和femtocell共存的异构网络不但能够提供可靠的室外覆盖，同时能弥补宏小区对室内覆盖的不足，增加系统的容量和用户的满意度。然而，在这种网络结构中，宏小区和femtocell使用相同的频谱资源，跨层干扰(宏小区和femtocell之间的干扰)是威胁系统性能的主要原因之一。With the explosive growth of wireless data volume and the increasing demand for data rates, new requirements have been placed on the deployment and design of wireless cellular networks. Cell splitting can increase network capacity, and the emergence of small cells, especially femtocells (home base stations), can greatly reduce the distance between the user end and the base station end, thereby reducing path loss. On the other hand, deploying a massive antenna (massive MIMO) at the macro cell side can increase the spatial freedom of the antenna, and increase the link gain and reliability. Large-scale antenna systems can concentrate the radiated energy of the antenna to certain specific areas, thereby enhancing the signal power of desired users and reducing interference to undesired users. Therefore, a heterogeneous network in which macro cells and femtocells coexist with large-scale antennas can not only provide reliable outdoor coverage, but also make up for the lack of indoor coverage of macro cells, increasing system capacity and user satisfaction. However, in this network structure, the macro cell and the femtocell use the same spectrum resources, and cross-layer interference (interference between the macro cell and the femtocell) is one of the main reasons for threatening system performance.
目前，有几种主要的技术削减这类干扰：一是干扰消除技术，这种技术是对接收到的混合信号进行处理，从中去除干扰成分，这种技术需要知道干扰信号的先验知识。另一种是干扰避免技术，这种技术使相互干扰的各方使用相互正交的资源(例如：频率，时间，码字或空间)，从而起到干扰避免的作用。At present, there are several main techniques to reduce this kind of interference: One is the interference cancellation technology, which processes the received mixed signal and removes the interference component. This technology requires prior knowledge of the interference signal. The other is the interference avoidance technology, which enables the parties that interfere with each other to use mutually orthogonal resources (for example: frequency, time, codeword or space), so as to play the role of interference avoidance.
现有的四种干扰削减技术：There are four interference reduction techniques available:
1.消除异构网中的干扰最简单的就是进行功率控制。如果一个femtocell基站的传输功率能够完全控制，而不会泄露到室外，那么就会有效的保护macrocell的数据传输。例如室内分布系统中的功率控制技术。然而，这种控制方式是非常复杂而且耗费时间的。1. The easiest way to eliminate interference in heterogeneous networks is to perform power control. If the transmission power of a femtocell base station can be completely controlled without leaking to the outdoors, the data transmission of the macrocell will be effectively protected. Such as power control technology in indoor distribution system. However, this control method is very complicated and time-consuming.
2.为了消除交互层的干扰，有一种下降链路资源分配算法。Macrocell可以将频谱资源划分为三个部分，分别归属femtocell使用部分和macrocell部分以及公用部分。并且用优化的方法决定了三者的比例。2. In order to eliminate the interference of the interaction layer, there is a downlink resource allocation algorithm. Macrocell can divide spectrum resources into three parts, which belong to femtocell use part, macrocell part and public part respectively. And the ratio of the three is determined by an optimized method.
3.一种认知的方法解决交互层干扰。通过感知周围的无线环境，通过overlay和underlay的方式进行频谱共享，来消除交互层的干扰。3. A cognitive approach to resolve interaction layer interference. By sensing the surrounding wireless environment, spectrum sharing is performed through overlay and underlay to eliminate interference at the interaction layer.
4.(Aliging guard zone coordination scheme)一种具有认知能力的femtocell的异构网中消除干扰的算法。在此算法中femtocell需要形成一些保护区域，这会降低通信网络的空间利用率。4. (Aliging guard zone coordination scheme) An algorithm for eliminating interference in a heterogeneous network of femtocells with cognitive capabilities. In this algorithm, the femtocell needs to form some protection areas, which will reduce the space utilization of the communication network.
前三种提到的干扰消除技术具有各自的局限性，并且它们只考虑了频率域和只存在单个用户的情况。第四种协议会丢失一些用户的多样性增益，并且在保护区的femtocell不能传输数据。The first three mentioned interference cancellation techniques have their own limitations, and they only consider the frequency domain and the presence of only a single user. The fourth protocol loses some of the user's diversity gain, and femtocells in protected areas cannot transmit data.
发明内容SUMMARY OF THE INVENTION
本发明的目的在于提供一种异构网络中基于femtocell分簇和宏用户调度的干扰协调方法，旨在解决现有干扰避免协作方法存在的macrocell的覆盖范围较小，频谱和功率利用率操作复杂的问题。The purpose of the present invention is to provide an interference coordination method based on femtocell clustering and macro user scheduling in a heterogeneous network, aiming to solve the problem that the existing interference avoidance cooperation method has a small coverage of macrocell, and the operation of spectrum and power utilization is complicated. question.
本发明是这样实现的，一种异构网络中基于femtocell分簇和宏用户调度的干扰协调方法，所述异构网络中基于femtocell分簇和宏用户调度的干扰协调方法采用在部署大规模天线的宏小区和femtocell共存的异构网络中的femtocell分簇和宏用户调度的干扰协调，每个具有认知能力的femtocell感知到周围是否存在宏用户，在每个宏用户周围就形成了一个femtocell干扰簇，请求接入网络的宏用户所对应的干扰簇通过反馈链路向宏基站报告反馈信息，宏小区根据反馈信息选择一组K备选的宏用户进行调度，宏小区依据当前时隙的宏用户的信道信息，选择K-1个宏用户传输数据，并通知剩余的宏用户对应的干扰簇在时隙正常通信，重复对宏用户进行调度，并保证在每个时隙都是不同的静默宏用户，直至完成整个调度。The present invention is implemented as follows: an interference coordination method based on femtocell clustering and macro user scheduling in a heterogeneous network. Interference coordination between femtocell clustering and macro user scheduling in a heterogeneous network where cells and femtocells coexist, each femtocell with cognitive ability senses whether there are macro users around, and a femtocell interference cluster is formed around each macro user. The interference cluster corresponding to the macro user requesting access to the network reports feedback information to the macro base station through the feedback link. The macro cell selects a set of K candidate macro users for scheduling according to the feedback information. Channel information, select K-1 macro users to transmit data, and notify the remaining macro users that the corresponding interference clusters communicate normally in the time slot, repeat the scheduling of the macro users, and ensure that each time slot is a different silent macro user , until the entire schedule is completed.
进一步，所述异构网络中基于femtocell分簇和宏用户调度的干扰协调方法具体包括以下步骤：Further, the interference coordination method based on femtocell clustering and macro user scheduling in the heterogeneous network specifically includes the following steps:
步骤一、构建部署大规模天线的宏小区和femtocell共存的异构网络，femtocell和宏小区都采用TDD和OFDM传输模式，FBS和UE均安装一个天线；Step 1. Build a heterogeneous network in which macro cells and femtocells coexist with large-scale antennas. Both femtocells and macro cells use TDD and OFDM transmission modes, and both FBS and UE install one antenna;
步骤二、FBS感知周围的MUE的存在和宏小区的频谱，将与特定MUE空间上接近的femtocell分成不同的只干扰MUE的IFC，调度周期为T，将T划分为K个调度时隙，K也是T内与MBS进行通信的MUE的个数；Step 2. The FBS senses the existence of the surrounding MUEs and the spectrum of the macro cell, and divides the femtocells that are spatially close to the specific MUE into different IFCs that only interfere with the MUE. The scheduling period is T, and T is divided into K scheduling time slots, and K is also The number of MUEs communicating with the MBS in T;
步骤三、在调度时隙j内，MBS只与K-1个激活态的MUE进行通信，与激活态MUE相关的IFC称为静默态，余下一个MUE称为静默态，与静默态MUE相关的IFC是激活的，正常进行通信，在T时间内每个MUE有唯一一次静默态；Step 3. In the scheduling time slot j, the MBS only communicates with K-1 MUEs in the active state. The IFC related to the active MUEs is called the silent state, and the remaining MUE is called the silent state. The IFC is activated, communicates normally, and each MUE has a unique silent state within T time;
步骤四、IFC选择子问题，首先用穷举法找到一个互不相交的IFC的集合{Cj j＝1，2，…,|G|}，结果是一个IFC只会干扰一个MUE，之后用迭代法得到MUE的集合，用类信号噪声干扰比来表征是否最优；Step 4. IFC selection sub-problem, first use an exhaustive method to find a set of disjoint IFC {Cj j = 1, 2, ..., |G|}, the result is that an IFC will only interfere with one MUE, and then use The iterative method is used to obtain the set of MUEs, and the signal-to-noise-interference ratio is used to characterize whether it is optimal;
步骤五、MUE用户调度，在步骤四基础上得到簇的规划，在某个确定的时隙内讨论使得信息最大化，得到调度指示向量，之后应用迭代算法得到T时间内最优的调度矩阵；Step 5, MUE user scheduling, obtain the cluster planning on the basis of step 4, discuss in a certain time slot to maximize the information, obtain the scheduling instruction vector, and then apply the iterative algorithm to obtain the optimal scheduling matrix within T time;
步骤六、方法结束。Step 6, the method ends.
进一步，所述步骤一中设定的模式包括：信道模型和下行链路的传输。Further, the mode set in the step 1 includes: channel model and downlink transmission.
进一步，所述信道模型在调度周期T内，信道增益是不变的；Further, in the scheduling period T of the channel model, the channel gain is constant;
信道矩阵:Channel Matrix:
其中，in,
式中是大尺度衰落矩阵，包含了路径损耗和阴影衰落；rmkj是在时隙j内MBS和第k个MUE之间的距离；a是路径损耗指数，取值为a∈[2,6]；θ是阴影衰落变量，服从分布10log10θ～N(0,δshadow)；小尺度衰落矩阵Hmj中各个组成的向量是独立同分布hmkj～CN(0,1)。in the formula is the large-scale fading matrix, including path loss and shadow fading; rmkj is the distance between the MBS and the k-th MUE in time slot j; a is the path loss index, which is a∈[2,6]; θ is a shadow fading variable, which obeys the distribution 10log10 θ～N(0,δshadow ); the vectors of each component in the small-scale fading matrix Hmj are independent and identically distributed hmkj ～CN(0,1).
进一步，所述下行链路传输模型：Further, the downlink transmission model:
第j时隙内第k个MUE接收到的信号：Signal received by the kth MUE in the jth slot:
其中，pF是FBS发射出的功率，pi是MBS分配给各个MUE的功率，pk是pi的其中一个取值，采用等功率发送的方式，P为MBS发射总功率，A为T内所有进行通信的MUE的集合；xmkj和xmij是独立同分布随机变量服从CN(0，1)的分布；gmkj和gfkj分别是MBS信道增益和FBS信道增益；Among them, pF is the power transmitted by the FBS, pi is the power allocated by the MBS to each MUE, pk is one of the values of pi , and the equal power transmission method is adopted, P is the total transmit power of MBS, A is the set of all communicating MUEs in T; xmkj and xmij are independent and identically distributed random variables obeying CN(0, 1) distribution; gmkj and gfkj are the MBS channel gains, respectively and FBS channel gain;
同理，得到FUE接收的信号：In the same way, the signal received by the FUE is obtained:
其中F为IFC内的基站的集合。where F is the set of base stations within the IFC.
进一步，步骤一中的数据速率：Further, the data rate in step one:
MUE的信号干扰噪声比定义为：The signal-to-interference-noise ratio of MUE is defined as:
FUE的信号干扰噪声比定义为：The signal-to-interference-noise ratio of FUE is defined as:
根据香农定理有：According to Shannon's theorem:
时隙j内第k个MUE传输数据速率为：Rmkj＝log2(1+γmkj)；The transmission data rate of the kth MUE in time slot j is: Rmkj =log2 (1+γmkj );
时隙j内与第k个MUE相关的IFC内某个FUE传输数据速率为：Rffj＝log2(1+γffj)；The transmission data rate of a certain FUE in the IFC related to the kth MUE in time slot j is: Rffj =log2 (1+γffj );
传输速率与时隙j无关，得到任意一个时隙内与第k个MUE相关的IFC内所有FUE进行的数据速率为The transmission rate is independent of time slot j, and the data rate of all FUEs in the IFC related to the kth MUE in any time slot is
进一步，所述步骤三在得知信道传输模型和下行链路传输状态之后进行分簇选择和用户调度方法包括：Further, the method for performing cluster selection and user scheduling after learning the channel transmission model and the downlink transmission state in step 3 includes:
其中，Γkj＝1表示在第j个时隙内第k个设备处于激活态，正常进行通信，反之，处于静默态，目标函数是整个调度周期T内总的数据传输速率的最大化；Wherein, Γkj =1 indicates that the kth device is in the active state in the jth time slot and communicates normally, otherwise, in the silent state, the objective function is the maximization of the total data transmission rate in the entire scheduling period T;
用一个时隙j内的最大传输数据速率代替在整个时间的数据速率最优的问题：Replace the problem of data rate optimization over time with the maximum transmission data rate in a slot j:
进一步，所述步骤四具体实现方法是：Further, the concrete realization method of described step 4 is:
Step1:Step1 :
Step2:if|G|≤K，成立则令K＝|G|,A＝{A(1),A(2),…,A(|G|)},Step2 : If |G|≤K, if established, let K＝|G|, A＝{A(1),A(2),…,A(|G|)},
迭代结束；否则转到step3,执行循环，直到i＝K.The iteration ends; otherwise, go to step3, and execute the loop until i=K.
Step3:Step3 :
Step4:类信号噪声干扰比Step4 : Class Signal to Noise and Interference Ratio
Step5:选择准则返回Step2Step5 : Selection Criteria Back to Step2
其中A(i)、分别为候选调度宏用户集合和候选干扰簇集合，R(i)为之前定义的类信干噪比，|G|为穷举法得到的干扰簇的个数。where A(i) , are the set of candidate scheduling macro users and the set of candidate interference clusters, respectively, R(i) is the previously defined quasi-SINR, and |G| is the number of interference clusters obtained by the exhaustive method.
进一步，所述步骤五用户调度问题方法如下：Further, the method for the user scheduling problem in the step 5 is as follows:
本发明提供的异构网络中基于femtocell分簇和宏用户调度的干扰协调方法，不仅保证了macrocell的覆盖范围，并且为干扰MUE的FBS提供了额外的传输机会。该技术通过对干扰宏用户的femtocell进行分簇选择和用户调度来完成宏小区和femtocell之间的干扰协调。同时，为了使调度算法在实际中易于实现，本发明还设计了一种低复杂度的分层求解算法，将原问题分解为两个子问题：femtocell分簇问题和宏用户调度问题，通过求解这两个问题来计算宏用户调度指示向量，通过在不同的时隙合理选择静默宏用户，从而为femtocell簇提供通信机会，从而实现干扰协调，与现有技术相比可以实现更加高效的频谱和功率利用率。The interference coordination method based on femtocell clustering and macro user scheduling in the heterogeneous network provided by the present invention not only ensures the coverage of the macrocell, but also provides additional transmission opportunities for the FBS of the interference MUE. This technology completes the interference coordination between macro cells and femtocells by performing cluster selection and user scheduling on femtocells that interfere with macro users. At the same time, in order to make the scheduling algorithm easy to implement in practice, the present invention also designs a low-complexity hierarchical solution algorithm, which decomposes the original problem into two sub-problems: the femtocell clustering problem and the macro-user scheduling problem. A problem to calculate the macro user scheduling indication vector, by reasonably selecting silent macro users in different time slots, so as to provide communication opportunities for femtocell clusters, so as to achieve interference coordination, and more efficient spectrum and power utilization can be achieved compared with the existing technology. Rate.
附图说明Description of drawings
图1是本发明实施例提供的异构网络中基于femtocell分簇和宏用户调度的干扰协调方法流程图；1 is a flowchart of an interference coordination method based on femtocell clustering and macro user scheduling in a heterogeneous network provided by an embodiment of the present invention;
图2是本发明实施例提供的MBS的天线数Nt为自变量的时候三种协议的频谱和功率利用率仿真结果示意图；2 is a schematic diagram of simulation results of spectrum and power utilization of three protocols when the number of antennas Nt of the MBS provided by the embodiment of the present invention is an independent variable;
图3是本发明实施例提供的MUE的数目K为自变量的时候三种协议的频谱和功率利用率仿真结果示意图；3 is a schematic diagram of the simulation results of spectrum and power utilization of three protocols when the number K of MUEs provided by the embodiment of the present invention is an independent variable;
图4是本发明实施例提供的FBS的发射功率pF为自变量的时候三种协议的频谱和功率利用率仿真结果示意图。FIG. 4 is a schematic diagram of simulation results of spectrum and power utilization of three protocols when the transmit power pF of the FBS provided by the embodiment of the present invention is an independent variable.
具体实施方式Detailed ways
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.
本发明提出了一种异构网络中基于femtocell分簇和宏用户调度的干扰协调方法，通过对干扰宏用户的femtocell进行分簇，分簇选择和用户调度来完成宏小区和femtocell之间的干扰协调。同时，为了使调度算法在实际中易于实现，本发明还设计了一种低复杂度的分层求解算法，将原问题分解为两个子问题：femtocell分簇问题和宏用户调度问题，通过求解这两个问题来计算宏用户调度指示向量，通过在不同的时隙合理选择静默宏用户，从而为femtocell簇提供通信机会，从而实现干扰协调。The invention proposes an interference coordination method based on femtocell clustering and macro user scheduling in a heterogeneous network. The interference coordination between macro cells and femtocells is completed by clustering, clustering selection and user scheduling for femtocells that interfere with macro users. . At the same time, in order to make the scheduling algorithm easy to implement in practice, the present invention also designs a low-complexity hierarchical solution algorithm, which decomposes the original problem into two sub-problems: the femtocell clustering problem and the macro-user scheduling problem. A problem to calculate the macro user scheduling indication vector, through the reasonable selection of silent macro users in different time slots, so as to provide communication opportunities for femtocell clusters, so as to achieve interference coordination.
下面结合附图1对本发明的应用原理作详细的描述。The application principle of the present invention will be described in detail below with reference to FIG. 1 .
如图1所示，本发明实施例的异构网络中基于femtocell分簇和宏用户调度的干扰协调方法包括以下步骤：As shown in FIG. 1 , the interference coordination method based on femtocell clustering and macro user scheduling in a heterogeneous network according to an embodiment of the present invention includes the following steps:
S101：在异构网络环境下，每个具有认知能力的femtocell都能感知到周围是否存在宏用户，在每个宏用户周围就形成了一个femtocell干扰簇(IFC)；S101: In a heterogeneous network environment, each femtocell with cognitive ability can sense whether there are macro users around, and a femtocell interference cluster (IFC) is formed around each macro user;
S102：请求接入网络的宏用户所对应的干扰簇通过反馈链路向宏基站报告反馈信息，信息包含：干扰簇中所有femtocell发送数据速率的估计值以及干扰簇所对应的宏用户的身份(ID)；S102: The interference cluster corresponding to the macro user requesting access to the network reports feedback information to the macro base station through the feedback link, and the information includes: an estimated value of the data rate sent by all femtocells in the interference cluster and the identity of the macro user corresponding to the interference cluster ( ID);
S103：宏小区根据反馈信息选择一组(K)备选的宏用户进行调度，这类宏用户的特征是，宏用户所对应的干扰簇应该包含互不相同的femtocell；S103: The macro cell selects a group (K) of candidate macro users for scheduling according to the feedback information. The characteristics of this type of macro users are that the interference clusters corresponding to the macro users should contain different femtocells;
S104：宏小区依据当前时隙的宏用户的信道信息，选择K-1个宏用户传输数据，并通知剩余的宏用户(静默宏用户)对应的干扰簇在该时隙正常通信；S104: The macro cell selects K-1 macro users to transmit data according to the channel information of the macro users in the current time slot, and notifies the remaining macro users (silent macro users) corresponding to the interference clusters to communicate normally in this time slot;
S105：重复S104的步骤，并保证在每个时隙都是不同的静默宏用户，直至完成整个调度周期。S105: Repeat the step of S104, and ensure that each time slot is a different silent macro user until the entire scheduling period is completed.
以下结合本发明的具体实施例对本发明的原理做进一步的描述：The principle of the present invention is further described below in conjunction with the specific embodiments of the present invention:
本发明实施例的异构网络中基于femtocell分簇和宏用户调度的干扰协调方法具体包括以下步骤：The interference coordination method based on femtocell clustering and macro user scheduling in the heterogeneous network according to the embodiment of the present invention specifically includes the following steps:
步骤一、构建一个部署大规模天线的宏小区和femtocell共存的异构网络，femtocell和宏小区都采用TDD和OFDM传输模式，假设FBS(femtocell base station)和UE(user equipment)均安装一个天线，且已经完全了解了信道状态信息；Step 1. Build a heterogeneous network in which a macro cell and a femtocell coexist with large-scale antennas. Both the femtocell and the macro cell use TDD and OFDM transmission modes. The channel state information has been fully understood;
步骤二、FBS可以感知周围的MUE(宏用户)的存在和宏小区的频谱，将与特定MUE空间上接近的femtocell分成不同的只干扰该MUE的IFC，调度周期为T，将T划分为K个调度时隙(与MUE信道相关时间相同)，K也是T内与MBS(macrocellbase station)进行通信的MUE的个数；Step 2. The FBS can perceive the existence of the surrounding MUEs (macro users) and the spectrum of the macro cell, and divide the femtocells that are spatially close to a specific MUE into different IFCs that only interfere with the MUE. The scheduling period is T, and T is divided into K Scheduling time slot (same as MUE channel correlation time), K is also the number of MUEs communicating with MBS (macrocellbase station) in T;
步骤三、在调度时隙j内，MBS只与(K-1)个激活态的MUE进行通信，与激活态MUE相关的IFC称为静默态(j内不进行通信)，余下一个MUE称为静默态，与静默态MUE相关的IFC是激活的，正常进行通信，在T时间内每个MUE都会有唯一一次静默态，由于上述算法太过于复杂将其分为两个子问题；Step 3. In the scheduling time slot j, the MBS only communicates with (K-1) MUEs in the active state. The IFC related to the active MUEs is called the silent state (no communication is performed in j), and the remaining MUE is called the silent state. In the silent state, the IFC related to the silent state MUE is activated and communicates normally. Each MUE will have a unique silent state within T time. Because the above algorithm is too complicated, it is divided into two sub-problems;
步骤四、IFC(干扰簇)选择子问题，首先用穷举法找到一个互不相交的IFC的集合{Cj j＝1，2，…,|G|}，结果是一个IFC只会干扰一个MUE，之后用迭代法得到MUE的集合，用类信号噪声干扰比来表征是否最优；Step 4. IFC (interfering cluster) selection sub-problem, first use the exhaustive method to find a set of disjoint IFC {Cj j = 1, 2, ..., |G|}, the result is that an IFC will only interfere with one MUE, and then use the iterative method to obtain the set of MUEs, and use the signal-to-noise-interference ratio to characterize whether it is optimal;
步骤五、MUE用户调度，在步骤四基础上得到簇的规划，在某个确定的时隙内讨论使得信息最大化，得到调度指示向量，之后应用迭代算法得到T时间内最优的调度矩阵；Step 5, MUE user scheduling, obtain the cluster planning on the basis of step 4, discuss in a certain time slot to maximize the information, obtain the scheduling instruction vector, and then apply the iterative algorithm to obtain the optimal scheduling matrix within T time;
步骤六、方法结束。Step 6, the method ends.
本发明先建立通信模型，在此基础上，通过迭代算法得到最优的分簇选择和用户调度；在宏小区混合femtocell的异构网络中，通过应用上述方法，可以得到更高的频谱利用率和功率效率；通过将该问题分解为两个子问题，使得该算法能够物理实现。The present invention first establishes a communication model, and on this basis, obtains optimal cluster selection and user scheduling through an iterative algorithm; in a heterogeneous network where macro cells are mixed with femtocells, higher spectrum utilization can be obtained by applying the above method and power efficiency; the algorithm can be physically implemented by decomposing the problem into two subproblems.
在本发明实施例的中进一步包括：In the embodiment of the present invention, it further includes:
步骤一中设定的模型下，信道模型和下行链路的传输:Under the model set in step 1, the channel model and downlink transmission:
1.1信道模型：认为在调度周期T内，信道增益是不变的，传统的只考虑小尺度衰落的信道是不切合实际的，并且也不适用于所提出的方法，所以只考虑大尺度衰落信道的特性。1.1 Channel model: It is considered that the channel gain is constant within the scheduling period T, and the traditional channel that only considers small-scale fading is unrealistic, and it is not suitable for the proposed method, so only large-scale fading channels are considered. characteristics.
信道矩阵:Channel Matrix:
其中，in,
式中是大尺度衰落矩阵，包含了路径损耗和阴影衰落。rmkj是在时隙j内MBS和第k个MUE之间的距离。a是路径损耗指数，取值为a∈[2,6]。θ是阴影衰落变量，服从分布10log10θ～N(0,δshadow)。小尺度衰落矩阵Hmj中各个组成的随机变量是独立同分布hmkj～CN(0,1)。in the formula is the large-scale fading matrix, including path loss and shadow fading. rmkj is the distance between the MBS and the k-th MUE in slot j. a is the path loss index, which takes the value a∈[2,6]. θ is the shadow fading variable, which obeys the distribution 10log10 θ～N(0,δshadow ). The random variables of each composition in the small-scale fading matrix Hmj are independent and identically distributed hmkj ~CN(0,1).
1.2下行链路传输模型：1.2 Downlink transmission model:
第j时隙内第k个MUE接收到的信号：Signal received by the kth MUE in the jth slot:
其中，pF是FBS发射出的功率，假设其为一个定值。pi是MBS分配给各个MUE的功率(pk是pi的其中一个取值)，为了方便，采用等功率发送的方式，(P为MBS发射总功率，A为T内所有进行通信的MUE的集合)。xmkj和xmij是独立同分布随机变量服从CN(0，1)的分布。gmkj和gfkj分别是MBS信道增益和FBS信道增益。Among them, pF is the power emitted by the FBS, which is assumed to be a constant value. pi is the power allocated to each MUE by the MBS (pk is one of the values of pi ). For convenience, the mode of equal power transmission is adopted. (P is the total transmit power of MBS, and A is the set of all communicating MUEs in T). xmkj and xmij are independent and identically distributed random variables obeying the CN(0,1) distribution. gmkj and gfkj are the MBS channel gain and the FBS channel gain, respectively.
同理，也可以得到FUE接收的信号：Similarly, the signal received by the FUE can also be obtained:
(其中F为IFC内的基站的集合)。(where F is the set of base stations within the IFC).
1.3数据速率：1.3 Data rate:
MUE的信号干扰噪声比定义为：The signal-to-interference-noise ratio of MUE is defined as:
FUE的信号干扰噪声比定义为：The signal-to-interference-noise ratio of FUE is defined as:
根据香农定理有：According to Shannon's theorem:
a)时隙j内第k个MUE传输数据速率为：Rmkj＝log2(1+γmkj)；a) The transmission data rate of the kth MUE in time slot j is: Rmkj =log2 (1+γmkj );
b)时隙j内与第k个MUE相关的IFC内某个FUE传输数据速率为：Rffj＝log2(1+γffj)；b) The transmission data rate of a certain FUE in the IFC related to the k-th MUE in time slot j is: Rffj =log2 (1+γffj );
c)假设b)中传输速率与时隙j无关，得到任意一个时隙内与第k个MUE相关的IFC内所有FUE进行的数据速率为c) Assuming that the transmission rate in b) has nothing to do with time slot j, the data rate of all FUEs in the IFC related to the kth MUE in any time slot is obtained as
本发明的实现还在于：步骤三在知道信道传输模型和下行链路传输状态之后进行分簇选择和用户调度方法：The realization of the present invention also lies in: step 3, after knowing the channel transmission model and the downlink transmission state, the cluster selection and the user scheduling method are performed:
用在整个调度周期T内总的数据传输速率的最优化来衡量分簇选择和用户调度的最优性。S2约束条件保证了每个j时隙内有且只有一个MUE是静默的。S3保证了在调度周期T内每个MUE都会平均的静默一个时隙长度。The optimization of the total data transmission rate in the whole scheduling period T is used to measure the optimality of cluster selection and user scheduling. The S2 constraint guarantees that in each j slot, only one MUE is silent.S3 ensures that in the scheduling period T, each MUE will be silent for an average time slot length.
考虑用一个时隙j内的最大传输数据速率代替在整个时间的数据速率最优的问题：Consider the problem of substituting the maximum transmission data rate in a time slot j for the optimal data rate over time:
本发明的实现还在于:步骤四IFC选择子问题，IFC选择子问题，首先用穷举法找到一个互不相交的IFC的集合{Cj j＝1，2，…,|G|}，结果是一个IFC只会干扰一个MUE，之后用迭代法得到MUE的集合，用类信号噪声干扰比来表征是否最优。具体实现方法是：The realization of the present invention also lies in: step 4 IFC selection sub-problem, IFC selection sub-problem, firstly find a set of disjoint IFC {Cj j = 1, 2, . . . , |G|} by exhaustive method, the result It is an IFC that only interferes with one MUE, and then an iterative method is used to obtain the set of MUEs, and the quasi-signal-to-noise-interference ratio is used to characterize whether it is optimal. The specific implementation method is:
Step1:Step1 :
Step2:if|G|≤K，成立则令K＝|G|,A＝{A(1),A(2),…,A(|G|)},Step2 : If |G|≤K, if established, let K＝|G|, A＝{A(1),A(2),…,A(|G|)},
迭代结束；否则转到step3,执行循环，直到i＝K.The iteration ends; otherwise, go to step3, and execute the loop until i=K.
Step3:Step3 :
Step4:类信号噪声干扰比Step4 : Class Signal to Noise and Interference Ratio
Step5:选择准则返回Step2Step5 : Selection Criteria Back to Step2
本发明的实现还在于:步骤五用户调度问题，算法如下：The realization of the present invention also lies in: step 5 user scheduling problem, the algorithm is as follows:
由上述方法找到一个时隙内最优的簇选择，在后续的选择方案中，只需要保证之前已经被选择的IFC不被重复选择，则K个时隙结束后就完成了一个周期的调度。The optimal cluster selection in a time slot is found by the above method. In the subsequent selection scheme, it is only necessary to ensure that the IFC that has been selected before is not repeatedly selected, and a period of scheduling is completed after the K time slots are over.
本发明的仿真结果Simulation results of the present invention
参数的设定：在时隙j内假设只有一个FUE接入femtocell；假定IFC内的femtocell的数目是(1～5)；femtocell的信道增益只考虑大尺度衰落；载频为2.6GHz；macrocell覆盖半径是1km；白噪声功率谱密度-174dBm/Hz；信道带宽20MHz；MBS的阴影标准偏差8dB；路径损耗指数a＝4；femtocell覆盖半径10m；FBS的阴影标准偏差6dB。Parameter setting: assume that only one FUE accesses the femtocell in time slot j; assume that the number of femtocells in the IFC is (1 to 5); the channel gain of the femtocell only considers large-scale fading; the carrier frequency is 2.6GHz; macrocell coverage The radius is 1km; the power spectral density of white noise is -174dBm/Hz; the channel bandwidth is 20MHz; the shadow standard deviation of MBS is 8dB; the path loss index a=4; the femtocell coverage radius is 10m;
图2表示了MBS的天线数Nt为自变量的时候三种协议的频谱和功率利用率仿真结果示意图；MBS传输功率P＝46dBm；FBS发射功率为pF＝10dBm；时序安排MUE数目K＝10；可以得出CSUS协议(簇选择和时序安排协议)比AGZ协议(Aliging guard zone coordinationscheme)和传统消除干扰协议都有更高的频谱和功率利用率。系统性能随着天线数的增加而提高。Figure 2 shows a schematic diagram of the simulation results of spectrum and power utilization of the three protocols when the number of MBS antennas Nt is an independent variable; MBS transmission power P = 46dBm; FBS transmission power is pF = 10dBm; sequence arrangement MUE number K = 10; It can be concluded that the CSUS protocol (cluster selection and scheduling protocol) has higher spectrum and power utilization than the AGZ protocol (Aliging guard zone coordination scheme) and the traditional interference cancellation protocol. System performance improves as the number of antennas increases.
图3表示了MUE的数目K为自变量的时候三种协议的频谱和功率利用率仿真结果示意图；MBS传输功率P＝46dBm；FBS发射功率为pF＝10dBm；MBS的天线数Nt＝200；从图4中可以看出系统的性能随着MUE的个数的增加而提高；然而，MUE的功率效率提升速度是随着MUE数目的增加而减少的；这是由于MUE数目增加会使得越来越多的femtocell进入IFC内而失去正常传输数据的机会；这些femtocell会进行干扰协作，不会比正常数据传输效率高；进而整个系统性能下降。Figure 3 shows a schematic diagram of the simulation results of the spectrum and power utilization of the three protocols when the number K of MUEs is the independent variable; MBS transmission power P=46dBm ; FBS transmit power is pF=10dBm; MBS antenna numberNt =200 ; It can be seen from Figure 4 that the performance of the system increases with the increase of the number of MUEs; however, the power efficiency improvement speed of MUEs decreases with the increase of the number of MUEs; this is because the increase of the number of MUEs will make the more More and more femtocells enter the IFC and lose the opportunity of normal data transmission; these femtocells will interfere and cooperate, and the efficiency of data transmission will not be higher than that of normal data transmission; and then the performance of the whole system will decrease.
图4表示了FBS的发射功率pF为自变量的时候三种协议的频谱和功率利用率仿真结果示意图；MBS传输功率P＝46dBm；MBS的天线数Nt＝200；时序安排MUE数目K＝10；从图中可以看出，当femtocell的发射功率增加时，传统消除干扰协议的系统性能不会提高；而AGZ和CSUS协议会先增加后减小。造成这个现象的原因有两个1)femtocell的发射功率的增加不仅会提高FBS的信号功率同时还会提高高人的功率；2)femtocell的发射功率的增加会是IFC内的femtocell增加，使得这部分femtocell丧失一部分传输机会。Figure 4 shows a schematic diagram of the simulation results of the spectrum and power utilization of the three protocols when the transmit power pF of the FBS is an independent variable; MBS transmission power P = 46dBm; MBS antenna number Nt = 200; sequence arrangement MUE number K = 10; It can be seen from the figure that when the transmit power of the femtocell increases, the system performance of the traditional interference cancellation protocol will not improve; while the AGZ and CSUS protocols will increase first and then decrease. There are two reasons for this phenomenon: 1) the increase of the transmit power of the femtocell will not only increase the signal power of the FBS but also the power of the tall people; 2) the increase of the transmit power of the femtocell will be the increase of the femtocell in the IFC, making this Some femtocells lose some transmission opportunities.
本发明在一个部署大规模天线的宏小区和femtocell共存的异构网络中提出了一种创新型的干扰协作方法(这种方法的名称为CSUS)；这个方法包含分簇选择和宏用户调度；首先，MBS选出包含不同与MUE相关的femtocell的IFC的集合，以符合信号干扰噪声比的要求；之后不同的MUE在不同的时隙内静默，使与其相关的IFC有机会激活来进行通信；其他与激活态MUE相关的IFC处于静默态。为了使协议成为可实现的将其分为两个子问题：分簇选择和用户调度。仿真结果显示，CSUS方法可以很大程度上提高系统的频谱和功率利用效率。The present invention proposes an innovative interference cooperation method (the name of this method is CSUS) in a heterogeneous network in which macro cells and femtocells coexist with large-scale antennas; this method includes cluster selection and macro user scheduling; firstly , the MBS selects a set of IFCs containing different femtocells related to the MUE to meet the requirements of the signal-to-interference-to-noise ratio; then different MUEs are silent in different time slots, so that the related IFCs have the opportunity to activate for communication; other The IFC associated with the active MUE is in the silent state. To make the protocol achievable divide it into two subproblems: cluster selection and user scheduling. The simulation results show that the CSUS method can greatly improve the spectrum and power utilization efficiency of the system.
以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.
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