CN114339692A - D2D communication channel distribution method under ultra-dense scene - Google Patents

Abstract

The invention provides a D2D communication channel distribution method under an ultra-dense scene, which comprises the following steps: constructing a D2D communication system model; determining channel allocation priority according to QoS requirement and transmission performance of cellular users; cellular users traverse all discrete transmit powers and the maximum number of reusable D2D users of the channel; determining the allocation priority of the D2D user; performing D2D user channel allocation, allocating D2D users to cellular user channels in the order of allocation priority until the allocated D2D users reach the maximum reusable number of D2D users of the channel; comparing the system performance gains to determine a channel allocation scheme and cellular user power selection; and D2D users and corresponding channels which have finished channel allocation are removed, the queue is updated, all channels are traversed, and channel allocation results are output. The invention can simply and quickly realize the D2D communication channel distribution under the ultra-dense scene under the condition that the number of D2D users is far larger than the number of available channels of a network, and can simultaneously improve the access rate and the system spectrum efficiency of D2D users.

Description

A D2D Communication Channel Allocation Method in Ultra-Dense Scenarios

technical field

The present invention relates to the technical field of mobile communication system resource management, in particular to a D2D communication channel allocation method in an ultra-dense scenario.

Background technique

With the rapid development of Internet services, the amount of mobile data shows explosive growth, which makes the mobile communication system face more severe challenges. In the field of industrial Internet of Things, a large number of mobile smart terminals represented by intelligent manufacturing, industrial robots, wireless sensor networks, etc. are widely used. In addition, emerging technologies such as connected drones, smart homes, autonomous driving, smart cities, and mobile wearables will also be deployed on a large scale in the next few years. All of the above new applications require mobile communication networks to have higher spectral efficiency, lower transmission delay, more device connections, and higher transmission energy efficiency. As a short-range wireless communication technology, data-to-device (device-to-device, D2D) communication allows users in close distances to directly communicate data instead of forwarding through the base station. Compared with the traditional cellular network technology that relies on uplink and downlink forwarding, D2D communication has the advantages of short transmission distance, small path loss, higher channel gain and faster transmission rate, etc. High energy efficiency, high spectral efficiency, high number of node access per unit area, and low latency business requirements have broad application prospects, and are considered to be one of the key technologies in future mobile communication systems.

When the number of users waiting to establish data transmission in the mobile communication system is far greater than the number of available channels in the resource pool, that is, an ultra-dense scenario. At this time, the base station cannot provide service transmission for most users. The users to be transmitted can use D2D communication technology to establish a connection and pass Reuse the channel resources of existing cellular users to access the network. Since the number of D2D users in this ultra-dense scenario is much larger than the number of available channels in the system, a pair of D2D users can not solve the problem of access rate of D2D users by multiplexing the channel of one cellular user alone. channel, that is, many-to-one multiplexing mode. However, since cellular users are subject to cross-layer interference from multiple different D2D users in ultra-dense scenarios, the quality of service (QoS) requirements of the primary cellular user cannot be guaranteed. Therefore, a design for D2D users is required. Reasonable channel allocation method to ensure that cellular users will not be subject to more cross-layer interference, and at the same time take advantage of the performance advantages brought by D2D communication, improve the system spectral efficiency and the access rate of D2D users. The invention mainly relates to research in the field of mobile communication system resource management, and specifically researches a D2D communication channel allocation method in an ultra-dense scenario.

At present, scholars at home and abroad have carried out certain research on D2D communication channel allocation methods in ultra-dense scenarios. The patent with the authorization number of CN 106954269 B proposes a QoS-based clustering channel allocation method. The method first constructs an interference graph between D2D users, uses graph coloring theory to allocate channels for D2D users, and based on this Users are clustered, and D2D users in the same cluster can share the channels of cellular users. However, this method needs to continuously add edges to remove the most interfering D2D users during the channel allocation process, and the computational load is too large in ultra-dense scenarios. In the paper "Interference-constrained pricing for D2D networks" published by Yuan Liu in the journal "IEEE Transactions on Wireless Communications", Vol. 1, Volume 1, the author proposes to model the D2D communication resource allocation problem in ultra-dense scenarios as a The Stackerberg game, assuming that the base station is the leader of the game, sets the interference price for each cellular user's channel and publishes it to D2D users. transmit power on the channel. However, the above method is only suitable for a flat fading channel environment, and cannot realize channel allocation in a frequency selective channel environment. In the "Journal of South China University of Technology (Natural Science Edition)", Vol. 43, No. 1, in the article "A Potential Game Resource Allocation Algorithm for High-Density D2D Users" published by Lan Bing, the author proposes to combine the total amount of D2D users received and generated. Interference is used as the user's utility function, and the game model is constructed based on this, and it is pointed out that the game model is a potential game model, and it is further pointed out that the potential game will always converge to a Nash equilibrium.

SUMMARY OF THE INVENTION

Aiming at the technical problem of large amount of calculation for D2D user channel allocation in existing ultra-dense scenarios, the purpose of the present invention is to provide a D2D communication channel allocation method in ultra-dense scenarios, which can effectively ensure the QoS requirements of cellular users as primary users while ensuring effective It solves the problem of high computational complexity of channel allocation, and at the same time improves the access rate of D2D users and system spectral efficiency in ultra-dense scenarios.

In order to achieve the above object, the present invention provides the following technical solutions:

A D2D communication channel allocation method in an ultra-dense scenario, comprising the following steps:

Step 1: Build a D2D communication system model in an ultra-dense scenario: set the number of D2D users to be accessed to be much larger than the number of cellular users, and the cellular users have discrete transmit power options, and set different channels according to the transmit power options of the cellular users Maximum number of multiplexable D2D users;

Step 2: Determine the channel allocation priority: according to the QoS requirements and transmission performance of the cellular user, the channel allocation priority is determined based on the multiplexing interference that the cellular user can bear;

Step 3: The cellular user traverses all discrete transmit powers: According to the order of channel allocation priorities in step 2, the cellular user traverses all the transmit powers and the maximum number of D2D users that can be multiplexed on the channel;

Step 4: Determine the allocation priority of the D2D user: determine the allocation priority of the D2D user according to the channel gain from the transmitting end of the D2D user to the transmitting and receiving end of the cellular user as a standard;

Step 5: Execute D2D user channel allocation: According to the determined allocation priority of D2D users, the transmit power of cellular users, and the maximum number of D2D users that can be multiplexed on the channel, the D2D users are allocated to the cellular user channel in the order of allocation priority, until the allocation is made. of D2D users reach the maximum number of D2D users that can be multiplexed on the channel;

Step 6: Compare system performance benefits, determine channel allocation scheme and cellular user power selection, and select the channel allocation scheme and cellular user power selection that bring the greatest increase in spectral efficiency;

Step 7: Eliminate the D2D users and corresponding channels that have completed channel allocation from the queue to be allocated, update the queue, and perform steps 2 to 6 in a loop until all channels are traversed, and the channel allocation result is output.

The D2D communication system model in the step 1 sets discrete transmit powers for cellular users, and sets the maximum number of D2D users that can be multiplexed on different channels according to the transmit power selected by the cellular users.

The channel allocation constraints of the D2D communication system model in the ultra-dense scenario in the first step are as follows:

为蜂窝用户i采用的离散发射功率，L为蜂窝用户可选择的离散发射功率数目，P_l为第l个可选择的离散发射功率，l表示离散发射功率的索引，P_L为第L个可选择的离散发射功率，num_i,l为蜂窝用户最大可复用D2D用户数目的数量等级，

为复用相同信道的最小D2D用户数目单元，

为向上取整函数，N为蜂窝用户的总数，M为D2D用户的总数，且M＞＞N；

为蜂窝用户i的信干噪比，

为满足蜂窝用户i的QoS需求的最小信干噪比，g_i,B为蜂窝用户i到基站的信道增益，

表示噪声功率，

表示D2D用户j发射端的发射功率，

表示D2D用户j发射端到基站的信道增益，f(i,j)表示信道分配指示函数，C＝{i|i＝1,2,...,N}表示蜂窝用户的集合，D＝{j|j＝1,2,...,M}表示D2D用户的集合。in,

is the discrete transmit power adopted by the cellular user i, L is the number of discrete transmit powers that can be selected by the cellular user, P _l is the l-th selectable discrete transmit power, l represents the index of the discrete transmit power, and P _L is the L-th selectable discrete transmit power. The selected discrete transmit power, num _{i, l} is the number level of the maximum number of D2D users that can be reused by cellular users,

is the unit of the minimum number of D2D users that multiplex the same channel,

is a round-up function, N is the total number of cellular users, M is the total number of D2D users, and M >>N;

is the signal-to-interference-noise ratio of cellular user i,

In order to meet the minimum signal-to-interference noise ratio of the QoS requirements of the cellular user i, g _i,B is the channel gain from the cellular user i to the base station,

represents the noise power,

represents the transmit power of the D2D user j transmitter,

represents the channel gain from the transmitter of D2D user j to the base station, f(i,j) represents the channel allocation indicator function, C={i|i=1,2,...,N} represents the set of cellular users, D={ j|j=1,2,...,M} represents the set of D2D users.

其中，

为最小信干噪比，信道质量

且g_i,B为蜂窝用户i到基站的信道增益，

表示噪声功率。In the second step, the channel priority factor is set according to the QoS requirements and transmission performance of the cellular users

in,

is the minimum signal-to-interference-noise ratio, the channel quality

And g _i,B is the channel gain from cellular user i to the base station,

represents the noise power.

Perform the following operations on the channel priority factor _xi to obtain the priority of channel allocation: remove the channel i with _xi ≤ 1; the smaller the value of _xi , the higher the allocation priority of channel i.

n表示优化后优先级序列的个数，

为修饰后的第i个优先级。The method for optimizing the channel allocation priority sequence X is as follows: eliminating cellular users i with priorities x _i ≤ 1; arranging the remaining cellular users in ascending order to obtain a new channel allocation priority sequence

n represents the number of priority sequences after optimization,

is the i-th priority after modification.

对D2D用户进行降序排序，确定D2D用户j的分配优先级，即干扰信道增益较小的D2D用户具有更高的分配优先级。In the step 4, for the cellular user channel i, the base station compares the channel gain of the D2D user j to the base station

The D2D users are sorted in descending order to determine the allocation priority of D2D user j, that is, the D2D user with smaller interference channel gain has a higher allocation priority.

The implementation method of the step 5 is: when the cellular user i selects the transmit power P ₁ to transmit, according to the allocation priority of the D2D users, find out c _size D2D users with the highest allocation priority and allocate them to the cellular user i; When the user uses the transmit power P ₂ as the transmit power, find out the 2c _size D2D users with the highest allocation priority and assign them to the cellular user i. At this time, the 2c _size D2D users reuse the channel of the cellular user i at the same time; the cycle is executed until the The cellular user adopts the maximum transmit power P _L . At this time, Lc _size D2D users with the highest priority are found and allocated to the cellular user i. At this time, the Lc _size D2D users simultaneously reuse the channel of the cellular user i.

In the step 6: the cellular user i compares the increase in spectral efficiency brought about by all possible channel allocation schemes, selects the D2D user that brings the most increase in spectral efficiency, and determines the corresponding discrete transmit power and channel allocation scheme;

The calculation method of the spectral efficiency increase ΔR _i is:

为D2D用户j复用蜂窝用户信道时的频谱效率，

为蜂窝用户i在非复用模式下与复用模式下的频谱效率差值；in,

Spectral efficiency when multiplexing cellular user channels for D2D user j,

is the spectral efficiency difference between the cellular user i in the non-reuse mode and the multiplex mode;

Solve the optimization problem by comparing all possible discrete transmit power and channel allocation schemes:

分别为信道分配指示函数值f(i,j)与发射功率

的最优值，argmax表示求使函数取得最大值的自变量函数。where f ^* (i,j) is the same as

Assign the indicator function value f(i,j) and transmit power to the channel respectively

The optimal value of , argmax represents the independent variable function that seeks to maximize the function.

频谱效率差值

The spectral efficiency

Spectral Efficiency Difference

为D2D用户j的发射功率，

为D2D用户j的信干噪比，其表达式为：in,

is the transmit power of D2D user j,

is the signal-to-interference-noise ratio of D2D user j, and its expression is:

为D2D用户j复用蜂窝用户i信道时发射端到接收端的信道增益，h_i,j为蜂窝用户i到D2D用户j接收端的信道增益，D_i表示复用同一蜂窝用户i信道的D2D用户集合，m表示复用同一信道下的其他D2D用户，

表示D2D用户m的发射功率，

表示D2D用户j受到的来自复用相同信道的其他D2D用户m发射端的信道增益。in,

is the channel gain from the transmitter to the receiver when the channel of the cellular user i is reused for the D2D user j, hi _,j is the channel gain from the cellular user i to the receiver of the D2D user j, D _i is the set of D2D users that multiplex the channel of the same cellular user i , m denotes multiplexing other D2D users under the same channel,

represents the transmit power of D2D user m,

Indicates the channel gain received by D2D user j from the transmitters of other D2D users m multiplexing the same channel.

Beneficial effects of the present invention: the present invention can solve the problem of D2D user channel allocation in an ultra-dense scenario, and by using a discretized power control method and a method for setting and assigning priorities for cellular user channels and D2D users, the implementation is simple and fast. It reduces the computational complexity of channel allocation, and improves the performance of D2D user access rate and system spectrum efficiency under the premise of ensuring the QoS requirements of cellular users.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic flow chart of the present invention.

FIG. 2 is a schematic diagram of a D2D communication system model of the present invention.

FIG. 3 is a comparison diagram of the performance comparison curves of the system spectrum efficiency under different QoS requirements of cellular users according to the present invention.

FIG. 4 is a comparison diagram of D2D user access rate performance comparison curves under different cellular user QoS requirements of the present invention.

FIG. 5 is a comparison diagram of the system spectral efficiency performance comparison curves under different D2D user density levels of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

As shown in Figure 1, a D2D communication channel allocation method in an ultra-dense scenario, the steps are as follows:

Step 1: Build a D2D communication system model in an ultra-dense scenario. The number of D2D users to be accessed is set to be much larger than the number of cellular users, and the cellular users have discrete transmit power options, and the maximum number of D2D users that can be multiplexed on different channels is set according to the transmit power options of the cellular users.

其中，

为蜂窝用户i采用的离散发射功率，L为蜂窝用户可选择的离散发射功率数目，P_l为第l个可选择的离散发射功率，l表示离散发射功率的索引，P_L为第L个可选择的离散发射功率。Taking the uplink as an example, the D2D communication system model in the ultra-dense scenario is shown in Figure 2. The number of D2D users to be accessed is set to be much larger than the number of cellular users. It is assumed that there are N cellular users and M pairs in the uplink of the cell. D2D users, and satisfy M>>N, respectively use sets C={i|i=1,2,...,N} and D={j|j=1,2,...,M} to represent cells users and D2D users. And consider the resource allocation problem under full load, that is, N cellular users occupy all available uplink channel resources, and the channel allocation of cellular users has been completed. There is no co-channel interference problem between users. It is assumed that the channel resources of each cellular user can be multiplexed by multiple pairs of D2D users at the same time, and each pair of D2D users can at most multiplex the channel resources of one cellular user. Cellular users employ discrete transmit power

in,

is the discrete transmit power adopted by the cellular user i, L is the number of discrete transmit powers that can be selected by the cellular user, P _l is the l-th selectable discrete transmit power, l represents the index of the discrete transmit power, and P _L is the L-th selectable discrete transmit power. Selected discrete transmit power.

为复用相同信道的最小D2D用户数目单元，

为向上取整函数。系统模型所描述的信道分配约束条件如公式(1)所示：According to the number of discretized powers selectable by cellular users, the maximum number of D2D users that can be multiplexed on the corresponding channel is set. When cellular users choose different fixed powers, in order to restrain cellular users from cross-layer interference from D2D users and ensure the QoS requirements of cellular users, the maximum number of D2D users that can be reused by cellular users is limited to different quantity levels num _{i, l} ∈[c _size ,2c _size ,…,lc _size ,…,Lc _size ], where,

is the unit of the minimum number of D2D users that multiplex the same channel,

is the round-up function. The channel assignment constraints described by the system model are shown in formula (1):

为蜂窝用户i的信干噪比，

为满足蜂窝用户i的QoS需求的最小信干噪比，g_i,B为蜂窝用户i到基站的信道增益，

表示噪声功率，

表示D2D用户j发射端的发射功率，

表示D2D用户j发射端到基站的信道增益。f(i,j)表示信道分配指示函数，其构造方法如公式(2)所示：in,

is the signal-to-interference-noise ratio of cellular user i,

In order to meet the minimum signal-to-interference noise ratio of the QoS requirements of the cellular user i, g _i,B is the channel gain from the cellular user i to the base station,

represents the noise power,

represents the transmit power of the D2D user j transmitter,

Indicates the channel gain from the transmitter of D2D user j to the base station. f(i,j) represents the channel assignment indicator function, and its construction method is shown in formula (2):

Step 2: Determine the channel allocation priority: According to the QoS requirements and transmission performance of the cellular user, the channel allocation priority of the cellular user is determined based on the multiplexing interference that the cellular user can bear.

信道质量

的构造方法如公式(3)所示：Cellular user channels that can withstand small multiplexing interference have high priority, and cellular user channels that can withstand large multiplexing interference have low priority. First, the signal-to-noise ratio of the cellular user is used to represent the channel quality between it and the base station

channel quality

The construction method is shown in formula (3):

与最小信干噪比

的比值来构造信道分配优先级因子x_i，其构造方法如公式(4)所示：Second, use the channel quality

with the minimum signal-to-interference-noise ratio

The ratio of , to construct the channel allocation priority factor _xi , and its construction method is shown in formula (4):

The priority is set according to the QoS requirements and transmission performance of cellular users; cellular users with high QoS requirements or poor transmission performance have higher priority.

Then, perform the following operations on the channel priority factor _xi to get the priority of the channel assignment:

1. Eliminate the channel i with x _i ≤ 1,

2. The smaller the value of x _i , the higher the allocation priority of channel i.

Step 3: The cellular user traverses all discrete transmit powers: According to the order of channel assignment priorities in step 2, the cellular user traverses all its discrete transmit powers and determines the corresponding maximum number of multiplexable D2D users.

中的蜂窝用户遍历其所有的离散发射功率

及相应的最大可复用D2D用户数目num_i,l∈[c_size,2c_size,…,lc_size,…,Lc_size]。以

为例，此时蜂窝用户i选择发射功率P₁为自身的发射功率，相应的其信道最大可复用D2D用户数目取num_i,l＝c_size，并以此类推。Assign a priority sequence to new channels in turn

A cellular user in traverses all of its discrete transmit powers

and the corresponding maximum number of multiplexed D2D users num _i,l ∈[c _size ,2c _size ,…,lc _size ,…,Lc _size ]. by

For example, at this time, the cellular user i selects the transmit power P ₁ as its own transmit power, and the corresponding maximum number of D2D users that can be multiplexed on its channel takes num _i,l =c _size , and so on.

Step 4: Determine the allocation priority of the D2D user: according to the channel gain from the D2D user transmitter to the cellular user transmission receiver as a standard, determine the allocation priority of the D2D user.

对D2D用户进行降序排序，这样传输性能较差的蜂窝用户将优先选择干扰信道增益较小的D2D用户进行信道复用。此外，在上行链路中，基站作为蜂窝用户的信号接收端，基站获得

不需要额外的信令开销。Taking cellular user i as an example, the base station compares the channel gain of the D2D user to the base station

The D2D users are sorted in descending order, so that cellular users with poor transmission performance will preferentially select D2D users with smaller interference channel gains for channel multiplexing. In addition, in the uplink, the base station acts as the signal receiving end of the cellular user, and the base station obtains

No additional signaling overhead is required.

According to the channel gain of the interference link of the D2D user to the primary user, the priority of the D2D user is determined; the higher the channel gain of the interference link to the primary user, the lower the priority of the D2D user, and vice versa, the higher the priority of the D2D user . Setting the priority in this way enables each cellular user channel to access as many D2D users as possible while ensuring its own QoS requirements, thereby increasing the access rate of D2D users and improving the spectral efficiency of the system.

Step 5: Execute D2D user channel allocation: According to the determined allocation priority of D2D users, the transmit power of cellular users, and the maximum number of D2D users that can be multiplexed on the channel, the D2D users are allocated to the cellular user channel in the order of allocation priority, until the allocation is made. of D2D users reaches the maximum number of D2D users that can be multiplexed on the channel.

When cellular user i selects the transmit power P ₁ to transmit, according to the assignment priority of D2D users, find out c _size D2D users with the highest priority and assign them to cellular user i. At this time, c _size D2D users reuse cellular users at the same time. i's channel. Since the cellular user i traverses all possible discrete powers, when the cellular user uses the transmit power P ₂ as the transmit power, find out 2c _size D2D users with the highest allocation priority and assign them to the cellular user i. At this time, there are 2c _size D2D users. At the same time, the channel of the cellular user i is multiplexed. The above operations are performed cyclically until the cellular user adopts the maximum transmit power _PL . At this time, Lc _size D2D users with the highest priority are found and assigned to cellular user i. At this time, Lc _size D2D users simultaneously reuse the channel of cellular user i. .

Step 6: Compare system performance benefits, determine channel allocation scheme and cellular user power selection, and select the channel allocation scheme and cellular user power selection that bring the greatest increase in spectral efficiency.

The present invention measures the system performance benefit according to the increase of the system spectral efficiency. Choose the channel assignment and discrete power scheme that delivers the highest system performance benefit. Cellular user i compares the spectral efficiency gains brought by all possible channel allocation schemes, selects the allocated user that brings the most spectral efficiency gains, and determines discrete transmit power and channel allocation schemes.

The increase in spectral efficiency ΔR _i can be calculated as follows:

为D2D用户j复用蜂窝用户信道时的频谱效率，

为蜂窝用户i在非复用模式下与复用模式下的频谱效率差值。两者的计算公式分别如下：in,

Spectral efficiency when multiplexing cellular user channels for D2D user j,

is the spectral efficiency difference between cellular user i in the non-reuse mode and in the reuse mode. The calculation formulas for the two are as follows:

为D2D用户j的发射功率，

为D2D用户j的信干噪比，其计算公式如下：in,

is the transmit power of D2D user j,

is the signal-to-interference-noise ratio of D2D user j, and its calculation formula is as follows:

为D2D用户j复用蜂窝用户i信道时发射端到接收端的信道增益，h_i,j为蜂窝用户i到D2D用户j接收端的信道增益，D_i表示复用同一蜂窝用户i信道的D2D用户集合，m表示复用同一信道下的其他D2D用户，

表示D2D用户m的发射功率，

表示D2D用户j受到的来自复用相同信道的其他D2D用户m发射端的信道增益。in,

is the channel gain from the transmitter to the receiver when the channel of the cellular user i is reused for the D2D user j, hi _,j is the channel gain from the cellular user i to the receiver of the D2D user j, D _i is the set of D2D users that multiplex the channel of the same cellular user i , m denotes multiplexing other D2D users under the same channel,

represents the transmit power of D2D user m,

Indicates the channel gain received by D2D user j from the transmitters of other D2D users m multiplexing the same channel.

的最优值，其数学表达式如下：By comparing all possible discrete transmit power and channel allocation schemes, find the channel allocation indicator function value f(i,j) and transmit power

The optimal value of , its mathematical expression is as follows:

分别为信道分配指示函数值f(i,j)与发射功率

的最优值，argmax表示输出使函数取得最大值的自变量函数。where f ^* (i,j) is the same as

Assign the indicator function value f(i,j) and transmit power to the channel respectively

The optimal value of , argmax represents the independent variable function that outputs the maximum value of the function.

It should be pointed out that the present invention mainly relates to the power control of cellular users and the channel allocation method of D2D users, which does not involve the power control of D2D users. Existing techniques for implementing power control may be employed.

Step 7: Eliminate the D2D users and corresponding channels that have completed channel allocation from the queue to be allocated, update the queue, and perform steps 2 to 6 in a loop until all channel allocations are traversed, end the operation and output the channel allocation result.

The beneficial effects of the present invention are further described below in conjunction with specific embodiments.

D2D用户最大发射功率设置为21dBm，其功率控制采用自适应功率控制。D2D用户数目设置为100，蜂窝用户数目即信道数目设置为20，蜂窝用户最小SINR(信号与干扰加噪声比)要求设置为0dB～20dB。信道模型建模为频率选择性信道，信道增益建模为包括基于传输距离的大尺度路径损耗模型以及基于多径传输与多普勒效应引起的小尺度衰落模型。D2D用户之间的路径损耗模型建模为148+40lg(d)，单位为dB，其中d为发射用户与接收用户之间的距离，单位为公里。其他用户之间的路径损耗模型建模为128.1+37.6lg(d)，单位为dB。小尺度衰落建模为均值为1的指数分布。噪声功率设置为-114dBm。Under the MATLAB simulation conditions, it is assumed that the simulation environment is a single-cell uplink, the base station is located in the center of the cell, and the cell coverage radius is 1 km. All cellular users and D2D user transmitters are randomly distributed at any radius and at any angle in the cell, while the D2D user receivers are randomly distributed at any radius and at any angle within a circle with the D2D user transmitter as the center and a maximum transmission distance of 100 meters. The discrete transmit power of cellular users is [10, 15, 18, 20, 23] dBm, where dBm is the unit of power. The calculation method is that the ratio of the transmit power to 1 mW is 10 times the logarithm. The calculation expression is: :

The maximum transmit power of D2D users is set to 21dBm, and its power control adopts adaptive power control. The number of D2D users is set to 100, the number of cellular users, that is, the number of channels, is set to 20, and the minimum SINR (Signal to Interference plus Noise Ratio) requirement for cellular users is set to 0dB to 20dB. The channel model is modeled as a frequency selective channel, and the channel gain is modeled as a large-scale path loss model based on transmission distance and a small-scale fading model based on multipath transmission and Doppler effect. The path loss model between D2D users is modeled as 148+40lg(d), in dB, where d is the distance between the transmitting user and the receiving user, in kilometers. The path loss model between other users is modeled as 128.1+37.6lg(d) in dB. Small-scale fading is modeled as an exponential distribution with mean 1. The noise power is set to -114dBm.

As shown in FIG. 3 and FIG. 4 , compared with other existing algorithms, the method of the present invention greatly improves the access rate and spectral efficiency performance of the D2D communication system in the ultra-dense scenario while ensuring the QoS requirements of cellular users. Among them, the existing algorithm 1 adopts a random channel allocation algorithm that allows multiple D2D users to reuse the same channel resources, and the existing algorithm 2 is a Hungarian allocation algorithm that only allows a single D2D user to reuse the cellular user channel. At the same time, Fig. 5 shows that the method of the present invention has more advantages than the existing algorithm as the density of D2D users increases, which further proves the superiority of the method of the present invention in the ultra-dense D2D communication scenario.

The present invention can meet the performance requirements of high access rate and high spectral efficiency of the D2D communication system in the ultra-dense scenario at the same time when the number of D2D users to be accessed is far more than the number of available channels in the network.

The invention utilizes the discrete power control method, sets discrete transmission power selection for cellular users, and sets the maximum number of D2D users that can be reused in the channel according to the transmission power of cellular users; During data transmission, in order to protect its QoS requirements, the base station will allocate fewer D2D users for channel multiplexing, otherwise, more D2D users will be allowed to multiplex channels; D2D users set different allocation priorities to ensure allocation performance on the basis of reducing computational complexity. The invention can realize the D2D user channel allocation problem in the ultra-dense scenario, and achieve beneficial effects in the aspects of main user QoS requirement guarantee, D2D user access rate, system spectrum efficiency and the like. The present invention can solve the problem of D2D user channel allocation in an ultra-dense scenario when the number of D2D users is much larger than the number of available channels in the network, realize simple and fast channel allocation, and achieve high access rate of D2D users and system spectrum efficiency It has a wide range of application value and is of great significance to the field of mobile cellular communication technology resource management.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (9)

1. A D2D communication channel distribution method under an ultra-dense scene is characterized by comprising the following steps:

the method comprises the following steps: constructing a D2D communication system model in an ultra-dense scene;

step two: determining a channel allocation priority: determining channel allocation priority by taking multiplexing interference which can be borne by a cellular user as a standard according to QoS (quality of service) requirements and transmission performance of the cellular user;

step three: the cellular user traverses all discrete transmit powers: according to the sequence of the channel allocation priority in the step two, the cellular users traverse all the transmitting power and the maximum reusable D2D user number of the channel;

step four: determining the allocation priority of the D2D user: determining the distribution priority of D2D users according to the standard of channel gain from a D2D user transmitting end to a cellular user transmitting receiving end;

step five: perform D2D user channel assignment: according to the determined distribution priority of the D2D users, the transmission power of cellular users and the maximum reusable D2D user number of the channel, distributing the D2D users to the cellular user channels according to the distribution priority sequence until the distributed D2D users reach the maximum reusable D2D user number of the channel;

step six: comparing the system performance gains to determine a channel allocation scheme and cellular user power selection;

step seven: and D2D users and corresponding channels which are distributed by the channels are removed from the queue to be distributed, the queue is updated, the steps from the second step to the sixth step are executed in a circulating mode until all the channels are traversed, and the channel distribution result is output.

2. The method for allocating D2D communication channels in ultra-dense scene according to claim 1, wherein: the D2D communication system model in the step one sets discrete transmission power for cellular users, and sets the maximum reusable D2D user number of different channels according to the transmission power selected by the cellular users.

3. The method for allocating D2D communication channels in ultra-dense scene according to claim 2, wherein: in the first step, the channel allocation constraint conditions of the D2D communication system model under the ultra-dense scenario are as follows:

wherein,

discrete transmit power for cellular user i, L discrete transmit power number selectable by cellular user, P_lFor the ith selectable discrete transmit power, l denotes the index of the discrete transmit power, P_LFor the Lth selectable discrete transmission power, num_i,lA quantity rating of the maximum number of reusable D2D users for cellular users,

to multiplex the minimum D2D user number units of the same channel,

for the ceiling function, N is the total number of cellular users, M is the total number of D2D users, and M is>>N；

For the signal to interference plus noise ratio of cellular user i,

minimum signal to interference plus noise ratio, g, to meet QoS requirements of cellular user i_i,BFor the channel gain of cellular user i to the base station,

which is indicative of the power of the noise,

representing the transmit power at the transmit end of user j of D2D,

denotes the channel gain from the transmitting end of D2D user j to the base station, f (i, j) denotes the channel allocation indication function, C ═ { i | i ═ 1, 2.., N } denotes the set of cellular users, D ═ j | j ═ 1, 2.., M } denotes the set of D2D users.

4. The method for allocating D2D communication channels in ultra-dense scene according to any one of claims 1-3, wherein: in the second step, the channel priority factor is set according to the QoS requirement and the transmission performance of the cellular user

Wherein,

for minimum signal-to-interference-and-noise ratio, channel quality

And g is_i,BFor the channel gain of cellular user i to the base station,

representing the noise power.

5. The method for allocating D2D communication channels in the ultra-dense scene according to claim 4, wherein: for the channel priority factor x_iExecuteThe following operations result in the priority of the channel allocation: reject x_iA channel i is less than or equal to 1; x is the number of_iThe smaller the value, the higher the allocation priority of channel i.

6. The method for allocating D2D communication channels in ultra-dense scene according to claim 5, wherein: in step four, the base station compares the channel gains of D2D user j to the base station for cellular user channel i

And D2D users are sorted in descending order, and the allocation priority of the D2D user j is determined, namely the D2D user with smaller interference channel gain has higher allocation priority.

7. The method for allocating D2D communication channels in ultra-dense scene according to claim 1 or 6, wherein: the implementation method of the fifth step is as follows: when cellular user i selects transmission power P₁During transmission, according to the distribution priority of D2D user, find out c with front distribution priority_sizeA D2D user is assigned to cellular user i; when cellular user is at transmission power P₂When the transmission power is used, 2c with the front distribution priority is found_sizeA D2D user is assigned to cellular user i, at which time 2c_sizeD2D user multiplexes the channel of cellular user i at the same time; is executed circularly until the cellular user adopts the maximum transmitting power P_LAt this time, Lc with the top priority is found_sizeA D2D user is assigned to cellular user i, Lc at this time_sizeThe D2D users simultaneously multiplex the channels of cellular user i.

8. The method for allocating D2D communication channels in ultra-dense scene according to claim 7, wherein: in the sixth step, the cellular user i compares the increases of the spectral efficiency brought by all the possible channel allocation schemes, selects the D2D user bringing the most increase of the spectral efficiency, and determines the corresponding discrete transmitting power and the channel allocation scheme;

increase of the spectral efficiency Δ R_iThe calculation method comprises the following steps:

wherein,

spectral efficiency when multiplexing cellular user channels for D2D user j,

the difference value of the spectrum efficiency of the cellular user i in the non-multiplexing mode and the frequency efficiency of the cellular user i in the multiplexing mode is obtained;

by comparing all possible discrete transmit powers with the channel allocation scheme, the optimization problem is solved:

wherein f is^*(i, j) and

respectively allocating indication function value f (i, j) and transmitting power to channel

Argmax represents an argument function for maximizing the function.

9. The method for allocating D2D communication channels in ultra-dense scene according to claim 8, wherein: the spectral efficiency

Difference in spectral efficiency

Wherein,

for the transmit power of D2D user j,

the signal to interference plus noise ratio of D2D user j is expressed as:

wherein,

channel gain, h, from transmitting end to receiving end when multiplexing cellular user i channel for D2D user j_i,jChannel gain at the receiving end for cellular users i to D2D user j, D_iRepresenting a set of D2D users multiplexing the same cellular user i-channel, m representing other D2D users multiplexing the same channel,

representing the transmit power of D2D user m,

indicating the channel gain experienced by D2D user j from the transmitting end of the other D2D user m multiplexing the same channel.

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