CN104105217B

CN104105217B - For multiple equipment to equipment allocation of communications resource allocation method and device

Info

Publication number: CN104105217B
Application number: CN201310129702.5A
Authority: CN
Inventors: 徐艳丽; 刘勇; 李栋; 杨凯
Original assignee: Nokia Shanghai Bell Co Ltd
Current assignee: Nokia Shanghai Bell Co Ltd
Priority date: 2013-04-15
Filing date: 2013-04-15
Publication date: 2019-03-29
Anticipated expiration: 2033-04-15
Also published as: WO2014170750A2; TW201505468A; CN104105217A; WO2014170750A3

Abstract

The present invention provides resource is distributed in communication system to accommodate the scheme of multiple simultaneous D2D communications.Firstly, all D2D UEs of the base station into cell send predetermined neighbours' distance；Each D2D UE is determined its respective neighbor information and its respective neighbor information is sent to base station based on received predetermined neighbours' distance；Base station is according to the respective neighbor information from all D2D UE received；Determine all D2D pairs of respective neighbor information；Then, the reception D2D UE of D2D centering determines the value of the interference-tolerant degree of their own, and identified value is sent to base station；Base station is using the value of the interference-tolerant degree of the reception D2D UE received as the value of affiliated D2D pairs of reception D2D UE of interference-tolerant degree；Finally, base station according to all D2D pairs of respective neighbor information and the value of interference-tolerant degree, and be based on greedy algorithm, by all D2D to be divided into several grouping in, and different resources is distributed for each grouping, it then will be each D2D pairs of resource notification of each D2D to distribution.

Description

Method and apparatus for allocating resources for multiple device-to-device communications

Technical Field

The present application relates to communication systems, and more particularly, to a method and apparatus for allocating resources for respective Device-to-Device pairs (Device-to-Device pairs) in a communication system to accommodate multiple simultaneous Device-to-Device communications.

Background

Device-to-Device (D2D) communication is a very promising technology, in which a D2D pair is constructed between User Equipments (UEs) having a better communication channel so that they can communicate directly with each other without relaying through a cellular evolved node b (eNB). Thereby, the performance (e.g. throughput and transmission delay) of the LTE cellular network can be improved. Because of the above-mentioned advantages, many companies and research institutes have attempted to introduce D2D communication into LTE cellular networks to improve the efficiency of the system. In the current 3GPP RAN conference #58, D2D communication is approved as a research project for LTE cellular networks.

Coexistence of D2D with cellular UEs generally has two ways, (1) D2D shares resources with cellular UEs; (2) D2D communicates with dedicated resources allocated by the cellular eNB that are orthogonal to the resources of the cellular UEs. The second coexistence approach allows D2D communications to be beneficial and non-interfering with existing cellular UEs. However, if these D2D pairs share the same resources, they may interfere with each other, thereby canceling out the throughput gain they bring. On the other hand, if all of these D2D pairs use orthogonal resources, the resource shortage will become more severe.

At present, some existing schemes consider the application scenario of the second coexistence manner. For mutexample, for The application scenario of The second co mutexistence manner, "Xiaogang r., Gaohui t.and Zhongpei z., The research of imt-a _3GPP _12108on D2 regrouping algorithm (in chinese)," proc.33th conference of imt-mutextrapolation group of 3GPP project, Beijing, 2012, 1-8 "proposes a scheme (hereinafter, simply referred to as" degree of freedom scheme ") to enable simultaneous transmission of multiple D2D pairs. In this scheme, pairs of D2D with fixed link distances are divided into groups, each group using one resource. The D2D pairs are ranked according to their degree of freedom (i.e., the number of neighbors of a D2D pair), and each pair is allocated resources sequentially. The number of allocated resources is minimized based on a color algorithm (coloring algorithm).

However, the above solution has the following drawbacks:

1. most of the D2D pairs have low data rates. This scheme allows most of the D2D pairs to be grouped into the first group. Thus, the interference is greatest in the first group, where the D2D link is more prone to disruption, resulting in low throughput.

2. Total-interference (sum-interference) is not considered. Since the interference pattern is plotted by a pairwise model (pairwise model) and the total effect of interference from all other transmission links is ignored, it fails to achieve the target data rate for D2D communication.

The distances of the 3.D2D links are assumed to be all the same. In a real wireless environment, the distances of the D2D links are typically different from each other, and the link quality is affected by their distance. Therefore, a better solution needs to consider their distance and link quality.

The other scheme is a random scheme. In this random scheme, each resource tends to hold the same number of pairs of D2D. Therefore, if the individual link quality of the D2D pair is not considered, then the scheme will be able to achieve better throughput. However, this stochastic scheme consumes more resources.

Therefore, how to effectively introduce D2D communication into a cellular network, i.e. to obtain higher throughput with less dedicated resources, is a problem to be solved urgently.

Disclosure of Invention

The present invention aims to provide a scheme that can accommodate multiple D2D communications occurring simultaneously in an LTE cellular network.

It is assumed that a plurality of UEs are randomly deployed in the cell of the present invention. If the wireless link between UEs communicating with each other is good enough, then a pair of D2D are formed between them. The D2D pairs transmit data via the resources allocated by the eNB, and two UEs in one D2D pair do not transmit data at the same time. Thus, each D2D pair is treated as a Vertex (Vertex) and its position hypothesis is determined by the transmitting UE in that D2D pair. UEs in the cell that are not selected as a pair of D2D are referred to as cellular UEs and transmit data via resources orthogonal to the resources of the pair of D2D. Thus, in the present invention, the cellular UEs have a negligible impact on the performance of D2D pair.

The technical scheme of the invention aims to realize the following two aims: (1) maximizing the resource efficiency of these D2D pairs, i.e., maximizing the throughput per resource for multiple D2D pairs; (2) each D2D pair is capable of meeting the signal to interference plus noise ratio (SINR) requirements to achieve a certain quality of service (QoS).

To achieve the above object, according to one aspect of the present invention, there is provided a method for allocating resources in a base station of a communication system, wherein the coverage area of the base station includes a plurality of D2D pairs, each D2D pair includes two D2D user equipments, the method includes the following steps: i. sending the preset neighbor distance to all D2D user equipment in the coverage area of the base station; receiving respective neighbor information from all of the D2D user devices; determining respective neighbor information for the plurality of D2D pairs from the respective neighbor information for all of the D2D user devices; obtaining values of respective interference tolerances of the plurality of D2D pairs; v. according to the neighbor information of each of the D2D pairs and the value of the interference tolerance, dividing the D2D pairs into a plurality of groups based on a greedy algorithm, and allocating different resources for each group, wherein the D2D pairs divided into the same group are not neighbors of each other. Informing each D2D pair of the resources allocated for each D2D pair of the plurality of D2D pairs.

Advantageously, after step i, step iv is preceded by the following steps: -receiving a query message from one or more D2D user devices of said all D2D user devices regarding D2D peers of the one or more D2D user devices; -notifying the one or more D2D user devices of information of the D2D companion of the one or more D2D user devices.

Advantageously, said step iv comprises the following steps: -obtaining from a receiving D2D user equipment of each D2D pair of the plurality of D2D pairs a value of interference tolerance for that receiving D2D user equipment; -taking the value of the interference tolerance of the receiving D2D user equipment as the value corresponding to the interference tolerance of the D2D pair to which the receiving D2D user equipment belongs;

wherein the value of the interference tolerance of the receiving D2D user equipment is obtained by:

-calculating a value of interference tolerance of the receiving D2D user equipment by

Wherein,a received power, I, representing a desired signal received by the receiving D2D user equipment from its transmitting D2D user equipment₀Represents the received power, N, of the receiving D2D user equipment to receive signals from its nearest non-neighbor D2D₀Representing thermal noise, gamma_thRepresenting the SINR threshold value, α representing the path loss factor;

-quantifying the value of the calculated interference tolerance byTo obtain a quantized interference tolerance value

Wherein M is the number of D2D pairs in the coverage area of the base station,indicating a rounding down.

Advantageously, said step iv comprises the following steps: -obtaining from a receiving D2D user equipment of each D2D pair of the plurality of D2D pairs a value of interference tolerance for that receiving D2D user equipment, and obtaining from a transmitting D2D user equipment a value of interference tolerance for that transmitting D2D user equipment; -taking the lesser of the value of the interference tolerance of the receiving D2D user equipment and the value of the interference tolerance of the transmitting D2D user equipment as the value of the interference tolerance of the D2D pair to which the receiving D2D user equipment and the transmitting D2D user equipment belong;

Wherein,a received power, I, representing a desired signal received by the receiving D2D user equipment from its transmitting D2D user equipment₀Represents the received power, M, of the receiving D2D user equipment to receive signals from its nearest non-neighbor D2D₀Representing thermal noise, gamma_thRepresenting the SINR threshold value, α representing the path loss factor;

Wherein M is the number of D2D pairs in the coverage area of the base station,represents rounding down; and

wherein the value of the interference tolerance of the transmitting D2D user equipment is obtained by:

-calculating a value of interference tolerance of said transmitting D2D user equipment by

Wherein,a reception power, I, representing a reception of a desired signal by the transmitting D2D user equipment from the receiving D2D user equipment₀Represents the received power, N, of the transmitting D2D user equipment to receive signals from its nearest non-neighbor D2D₀Representing thermal noise, gamma_thRepresenting an SINR threshold value;

Advantageously, said step v comprises the steps of: v1. arranging the plurality of D2D pairs in a non-decreasing order with a value of interference tolerance of each D2D pair of the plurality of D2D pairs to generate an ordered set of D2D pairs; v2. creating a group and putting the first D2D pair in the sorted set of D2D pairs into the group and removing the first D2D pair from the sorted set of D2D pairs to update the set of D2D pairs; v3. sequentially selecting from the updated set of D2D pairs a D2D pair that is not a neighbor to any member of the group and placing the selected D2D pair in the group and removing the selected D2D pair from the set of D2D pairs to update the set of D2D pairs and reduce the value of the interference tolerance of each member of the group by 1; v4. repeating the above step v3 until the value of the interference tolerance of at least one member of the group is less than or equal to zero; v5. arranging the remaining D2D pairs in non-decreasing order with updated values of interference tolerance of the remaining D2D pairs of the set of D2D pairs to generate an ordered set of D2D pairs; v6. repeating the above steps v2 to v5 until the set of D2D pairs is empty; v7. allocate different resources for each of the established plurality of packets.

According to another aspect of the present invention, a method for assisting a base station in allocating resources in a receiving D2D user equipment of a communication network is presented, wherein the method comprises the following steps: I. receiving a predetermined neighbor distance from the base station; determining neighbor information for the intended receiving D2D user device based on the received predetermined neighbor distance; sending the determined neighbor information of the receiving D2D user equipment to the base station; determining the value of the interference tolerance of the receiving D2D user equipment, and sending the determined value of the interference tolerance of the receiving D2D user equipment to the base station; v. receiving resource allocation information from the base station.

Advantageously, after step I, step IV further comprises the following steps: -determining whether the receiving D2D user equipment is aware of its D2D peer; -if not, sending a query message to the base station for querying a D2D peer of a receiving D2D user equipment; -receiving information from the base station of a D2D companion of the present receiving D2D user equipment.

Advantageously, said step IV comprises the following steps:

-receiving D2D user equipment by calculating the equationValue of interference tolerance of

Wherein,indicating the received power, I, at which the intended receiving D2D user equipment receives a desired signal from its transmitting D2D user equipment₀Indicating the received power, N, of the received signal from its nearest non-neighbor D2D for the receiving D2D user equipment₀Representing thermal noise, gamma_thRepresenting the SINR threshold value, α representing the path loss factor;

According to another aspect of the present invention, a method for assisting a base station in allocating resources in a transmitting D2D user equipment of a communication network is presented, wherein the method comprises the following steps: A. receiving a predetermined neighbor distance from the base station; B. determining neighbor information of the intended transmitting D2D user device based on the received predetermined neighbor distance; C. transmitting the determined neighbor information of the transmitting D2D user equipment to the base station; E. resource allocation information is received from a base station.

Advantageously, after step a, step E further comprises the following steps: -determining whether the sending D2D user equipment is aware of its D2D peer; -if not, sending a query message to the base station for querying a D2D peer of a transmitting D2D user equipment; -receiving information from the base station of a D2D peer of the present transmitting D2D user equipment.

Advantageously, after step C, step E further comprises the following steps: D. and determining the value of the interference tolerance of the transmitting D2D user equipment, and transmitting the value of the interference tolerance of the transmitting D2D user equipment to the base station.

Advantageously, said step D comprises the steps of:

-calculating the value of the interference tolerance of the transmitting D2D user equipment by

Wherein,indicating the received power, I, at which the transmitting D2D user equipment receives the desired signal from its receiving D2D user equipment₀Indicating the received power, N, of the signal received by the transmitting D2D user equipment from its nearest non-neighbor D2D₀Representing thermal noise, gamma_thRepresenting an SINR threshold value;

In the technical solution of the above embodiment of the present invention, since the neighbors of each D2D pair in the cell are grouped into different groups, better control is obtained between D2D. In addition, a feedback, i.e. a interference Tolerance (TID), is newly defined in the technical solution of the present invention, which makes it easy to evaluate the total interference of the D2D pair. Further, by using TIDs, signaling overhead as well as energy consumption is reduced.

By applying the technical solution of the above embodiment of the present invention, firstly, a plurality of D2D links can communicate simultaneously with less occupied resources. Second, the SINR of each D2D pair meets the communication requirements. Again, the cell achieves higher resource efficiency.

According to another aspect of the present invention, a method for allocating resources in a base station of a communication system is presented, wherein the coverage area of the base station comprises a plurality of D2D pairs, each D2D pair comprising two D2D user equipments, the method comprising the steps of: a. transmitting a predetermined cooperation distance and a predetermined interference distance to all D2D user equipment in the coverage of the base station; b. receiving respective cooperating and interfering source sets from all of the D2D user devices; c. constructing an interference map for the plurality of D2D pairs from the respective cooperating and interfering source sets of all D2D user devices; d. dividing the D2D pairs into a plurality of groups according to the saturation degrees of the D2D pairs and based on the interference graphs of the D2D pairs and a greedy algorithm, and allocating different resources for each group, wherein for a certain D2D pair, the saturation degree represents the number of D2D pairs which are already allocated with resources in the neighborhood; e. notifying each D2D pair of the plurality of D2D pairs of the allocated resources for each D2D pair.

According to another aspect of the present invention, a method for assisting a base station in allocating resources in a D2D user equipment of a communication network is proposed, wherein the method comprises the following steps: receiving a predetermined cooperation distance and a predetermined interference distance from the base station; determining a cooperation set and an interference source set of the D2D user equipment based on the received predetermined cooperation distance and the predetermined interference distance; sending the determined cooperation set and interference source set of the D2D user equipment to the base station; resource allocation information is received from a base station.

In the technical solution of the above embodiment of the present invention, because the mutual interference sources are divided into different groups, the interference between the pair of D2D can be well controlled based on the interference source set. Further, a D2D alternative cooperation set is defined that reduces the search range of the eNB and guarantees D2D link quality. The eNB can adjust the set so that D2D communication meets the application requirements without spending too much signaling overhead.

By applying the technical solution of the above embodiment of the present invention, firstly, a plurality of D2D links can communicate simultaneously with less occupied resources. Second, each resource is allocated to a similar number of pairs of D2D, so the resource allocation is more uniform. Again, the SINR of the D2D pair is greatly improved.

Various aspects of the invention will become apparent from the following description of specific embodiments.

Drawings

The above and other features of the invention will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:

fig. 1 shows a schematic diagram of a plurality of D2D pairs of communication in a cell according to an embodiment of the invention;

FIG. 2 illustrates an example of neighbor relations for a UE according to an embodiment of the present invention;

FIG. 3 illustrates an example of the neighbor relationship of a D2D pair, according to an embodiment of the invention;

FIG. 4 shows a flow diagram of a method of allocating resources according to one embodiment of the invention;

FIG. 5 shows an example of a neighbor map for a cell in accordance with one embodiment of the present invention;

FIG. 6 shows a schematic diagram of resource allocation according to an embodiment of the invention;

FIG. 7 is a schematic diagram showing the comparison of the amount of resources used by the solution of the present invention with the two prior art solutions;

FIG. 8 is a diagram illustrating a comparison of throughput between the present invention and two prior art schemes;

FIG. 9 is a schematic diagram showing the comparison of the resource efficiency of the technical solution of the present invention and the two prior art solutions;

fig. 10 shows an example of interference relationship for one UE, where the interference source of the UE is located in a circular area;

FIG. 11 shows an example of the interference relationship of a D2D pair;

FIG. 12 shows a flow diagram of a method of allocating resources according to another embodiment of the invention;

fig. 13 shows an example of an interference map for a cell containing 100D 2D pairs;

figure 14 shows a schematic diagram of one example of allocating resources for multiple D2D pairs in a cell;

FIG. 15 is a diagram showing the comparison of the uniformity of the solution of the present invention with that of the two prior art solutions when the interference distance is 100 m;

fig. 16 is a diagram showing the comparison of the signal to interference plus noise ratio of the present invention and the existing two schemes when the interference distance is 100 m;

fig. 17 shows a schematic diagram comparing the signal to interference plus noise ratio of the technical solution of the present invention with that of the two prior art solutions when the interference distance is 150 m;

fig. 18 is a diagram illustrating a comparison between the number of resources used in the present invention and the existing two schemes when the interference distance is 100 m.

The same or similar reference numbers in the drawings identify the same or similar elements.

Detailed Description

Embodiments of the present invention are described below with reference to the drawings.

Referring to fig. 1, it is assumed that a cell includes a plurality of cellular UEs (which transmit data in a conventional manner) and a plurality of D2D pairs (which D2D directly transmit data over resources allocated by an eNB). Since cellular UEs and D2D employ separate resources, there is negligible mutual interference between them. In D2D communications, the communication link is typically short, which enables simultaneous transmission of multiple D2D pairs. On the other hand, due to the nature of wireless broadcasting, there may be interference between pairs of D2D. Therefore, there is a need to control interference and ensure that multiple D2D pairs are efficiently introduced into the communication needs of the cellular network.

Based on this, SINR γ at random D2D link v_vShould exceed a given threshold value gamma_thTo provideA particular QoS. Furthermore, the goal of resource efficiency is to maximize. These considerations can be modeled as follows:

s.t.γ_v≥γ_th (1)

wherein r is_effDenotes resource efficiency, C_throughputIs the total throughput, N, of multiple D2D pairs of set Ψ_resourceIs the corresponding amount of resources used. The above-described optimization problem can be transformed into a sub-optimization problem that maximizes throughput while minimizing the amount of resources used.

For maximum throughput, the interference between the D2D pairs needs to be controlled. In a wireless environment, each UE has a direct link to certain UEs (the channel quality between UEs is above a threshold), which are defined as its neighbors. In general, the interference of one UE is assumed to be from its neighbors. Here, assume that for two random UEs i and j, if the distance d between them is_ijLess than a predetermined neighbor distance d_neigThen, they are neighbors of each other, that is:

d_ij≤d_neig (2)

d_neigis an a priori value stored at the eNB side, whose value is usually larger than the distance of the actual communication link to control the interference. Fig. 2 shows an example of a neighbor relation of one UE, whose neighbors are located within the illustrated circle. Since only one UE transmits data at a time in each D2D pair, the interference of the D2D link comes from the transmitting UEs of the other D2D pairs. Thus, each D2D link as a whole may be represented by a Vertex (Vertex) because the link distance of the D2D pair is shorter. If two UEs are neighbors, then the two D2D pairs to which they belong are also neighbors. Fig. 3 shows an example of the neighbor relation of one D2D pair.

Referring to FIG. 4, in this documentIn the technical solution of the invention, first, in step S41, the eNB broadcasts the predetermined neighbor distance D to all D2D pairs (i.e., all D2D UEs) in the cell_neig. Then, in step S42, each D2D UE in the D2D pair is based on the received predetermined neighbor distance D_neigThe neighbor information for their respective D2D UEs is determined according to equation (2) above. In practical applications, a UEj may be considered a neighbor of a UEi if the following equation is satisfied.

Wherein, P_tIs the transmit power of the UE, α is the path loss factor,UE i receives the received power of the signal from UE j. That is, in practical applications, whether two UEs are neighbors or not can be determined according to the received power rather than the distance.

After each D2D UE determines its own neighbor information, it feeds back the own neighbor information to the eNB in step S43.

Since not every D2D UE is aware of its D2D companion (D2D peer), therefore,

advantageously, before or after the step S42, a step S42' may be further included, in which each D2D UE determines whether it knows the respective D2D peer; if not, transmitting a query message to the eNB for querying the D2D companion of the present D2D UE in step S42 a'; the eNB informs the D2D UE of the information of the D2D companion of the D2D UE according to the received query message in step S42 b'.

After receiving the respective neighbor information from all D2D UEs, the eNB determines the respective neighbor information of all D2D pairs in the cell according to the respective neighbor information of all D2DUE in step S44. For example, the eNB may determine the neighbors of the D2D pair according to the following principles: if any of the D2D UEs in one D2D pair is a neighbor to one D2D UE in another D2D pair, then the two D2D pairs are neighbors. Fig. 5 shows an example of a neighbour map of a cell comprising 100D 2D pairs, where each D2D pair is represented by a star and the neighbours are interconnected by edges.

Since the neighbor map of a cell reflects interference information between pairs of D2D to some extent, the neighbor map of a cell may also be referred to as an interference map of multiple pairs of D2D. To accommodate simultaneous communication of these D2D pairs, the eNB allocates different resources for the neighbors. To achieve high resource efficiency, the eNB also needs to know the total interference, link quality and signal-to-interference-and-noise ratio (SINR) threshold γ for each D2D pair_th. However, such a pair of feedback would result in a large signaling overhead. Based on this, the technical solution of the present invention introduces a new parameter, namely the interference Tolerance (TID), and for the vertex i (i.e., the pair D2D), the interference tolerance is expressed asIn order for the SINR of each D2D link to meet the SINR requirements of the communication, i.e., the constraint in equation (1) above, the following expression needs to be satisfied:

whereinIs the sum of the interference of vertices i, d_iDistance, ψ, of D2D link_iIs a neighbor set of vertex i, N₀Is thermal noise. To satisfy inequality (4), obtain

As can be seen from equation (5) above, the sum interference of the D2D pair should be less than a threshold value determined by its link quality (e.g., link quality and attenuation factor). Therefore, the sum interference of the D2D pairs needs to be controlled based on their respective link qualities.

According to previous research work (see Mordachev, v.and Loyka, s., On node sensitivity, selectivity, IEEE Journal On selected domains in Communications, vo1.27, 2009, 1120-. Here, interference from other non-neighboring vertices is approximated as thermal noise N₀And assuming interference from nearest non-neighbor vertices as I₀. The TID is then defined as follows, i.e. represents the number of vertices that can be tolerated to co-exist with vertex i:

in the above-mentioned formula (6),denotes the received power, I, of a receiving D2D UE of one D2D pair from which the transmitting D2D UE received a useful signal₀Represents the received power of the signal received by a D2D UE from its nearest non-neighbor vertex for one D2D pair.

That is, in the technical solution of the invention, after the D2D UE determines its neighbor information and obtains its D2D companion information, further, in step S45, the receiving D2D UE in the D2D pair calculates the value of its interference tolerance according to the above equation (6)Then, in step S46, the receiving D2D UE tolerates the calculated interference value according to the following equationPerforming quantization to obtain a quantized value of interference tolerance

Wherein M is the number of D2D pairs in the cell,indicating a rounding down. That is, when the calculated interference tolerance valueWhen the value is larger than M, taking M as the final value of the interference tolerance; when the calculated interference tolerance valueWhen the interference tolerance is less than 1, taking 1 as a final interference tolerance value; when the calculated value of the interference toleranceGreater than or equal to 1 and less than or equal to M is a value of the calculated interference toleranceRounded down as the final interference tolerance value.

When the receiving D2D UE determines its interference tolerance value, the determined interference tolerance value is transmitted to the eNB, for example, through the PUSCH or EPDCCH channel in step S47. After receiving the value of the interference tolerance of the received D2DUE in the D2D pair, the eNB sets the value of the interference tolerance of the received D2D UE to be a value corresponding to the interference tolerance of the D2D pair to which the received D2D UE belongs in step S48.

In another example, the receiving D2D UE and the transmitting D2D UE in the D2D pair each determine their respective values of interference tolerance and provide their respective values of interference tolerance to the eNB. The eNB takes the smaller of the two interference tolerance values as the interference tolerance value of the D2D pair.

After the eNB obtains the respective interference tolerance values of all D2D pairs in the cell, in step S49, according to the respective neighbor information of all D2D pairs and the interference tolerance values, based on a greedy algorithm, all D2D pairs are divided into a plurality of groups, and different resources are allocated to each group, where the D2D pairs divided into the same group are not neighbors to each other, as shown in fig. 6. Then, in step S410, each pair of D2D is notified of the resources allocated for each pair of D2D. The resources allocated by the eNB for each D2D pair may be transmitted to each D2D pair, for example, in a broadcast manner. Each D2D pair may receive information of the resources allocated to it via, for example, PDSCH or EPDCCH.

In the greedy algorithm, all vertices in a cell (i.e., pairs of D2D) are arranged non-descending order according to their respective values of interference tolerance, and then placed in different groups in sequence. After s cycles, all vertices are divided into s groups (G)₁……G_s) Wherein each packet is allocated a resource, i.e. the resources allocated to the respective packets of the s packets are different from each other. In this algorithm, vertices that are neighbors of each other will not be placed into the same packet, and non-neighbor vertices are placed sequentially into a packet until the sum of the interference of one of the D2D pairs is no longer tolerable. That is, the values of the interference tolerance of the individual vertices in each packetSatisfies the following formula

The number of vertices in the s-th group is represented as n(s), and its initial value is 0. The greedy algorithm of the invention is specifically shown as follows:

suppose S is 1

Inputting: set Ψ of all D2D pairs₁＝{v₁，v₂····v_M}, neighbor graph { psi_i}_i＝1......MAnd a set T of TIDs₁＝{x₁，x₂····x_M}

And (3) outputting: group G₁……G_s

Repetition of

1) In the s-th cycle, the vertices in the vertex set (i.e., the set of D2D pairs) are non-descending order based on their TIDsWherein N (k) represents a packet G_kThe number of middle vertices. A sorted set of vertices is then obtained

2) Establishing a packet G_sAnd the first vertex v in the vertex set_s，1Put into the packet, i.e. G_s＝v_s，1. At the same time, v is_s，1From Ψ_sOf, i.e. Ψ_s＝Ψ_s\v_s，1. Let n(s) ═ n(s) + 1.

3) Selecting in order with G_sIs not a neighbor's vertex and put it in G_sIn (1).

Repetition of

i. Selection and G_sIs not a neighbor and has the vertex v of the largest TID_s，iAnd placing it in G_sIn (i) i.e. G_s＝{G_s，v_s，i}. At the same time, v is_s，iFrom Ψ_sOf, i.e. Ψ_s＝Ψ_s\v_s，i。

Update G_sMembers of (1)TID value of (i.e. i)And the number of vertices in the packet s, i.e., n(s) ═ n(s) +1, is updated.

Up to G_sIn which at least one vertex has a TID of 0 or less, i.e.T_j≤0。

4)S＝s+1。

Until no vertices remain, i.e. Ψ_s＝φ。

In the technical solution of the present invention, since TID feedback is used, the eNB does not need to know the location and interference of each UE. Thus, signaling overhead and complexity are reduced.

In order to further evaluate the technical solution of the above embodiment of the present invention, relevant simulations were performed and compared with the degree of freedom scheme and the random scheme. The simulation parameters are shown in table 1 below.

TABLE 1

Fig. 7 shows that the amount of resources used by the inventive solution is greatly reduced (by about 94%) compared to the amount of resources used by the random solution. This is because in the random scheme, the number of pairs of D2D sharing the same resource tends to be equal, whereas the resources in the technical scheme of the present invention are allocated by a greedy algorithm, which is similar to the scheme of the degree of freedom.

Fig. 8 shows that the cell throughput of the inventive solution is greatly improved (from 135% to 220%) compared to the free degree solution, since the sum interference and link quality of each D2D pair is considered in the inventive solution. In addition, in the technical scheme of the invention, because the interference is better controlled, the throughput is similar to that of the random scheme, and the random scheme uses more resources.

Fig. 9 shows that the solution of the present invention has better resource efficiency, which is 4 times of the solution with freedom degree and 17 times of the solution with random degree. This is because the solution of the invention provides a great improvement in throughput and uses less resources.

One embodiment of the present invention is described in detail above. In another embodiment of the invention, still referring to fig. 1, if two neighboring UEs have data to transmit and their direct channels are good enough, the eNB selects them as a set of D2D pairs. Here, the cooperative relationship is defined by a distance. Suppose that for any UEj it will be an alternative partner of D2D for UEi, as long as the distance D between them_ijLess than a predetermined cooperation distance d_partnerI.e. by

d_ij≤d_partner (9)

This makes it possible to transmit multiple D2D links simultaneously, since D2D links are often relatively short and the link quality is good. On the other hand, interference between the D2D pairs may exist due to the wireless broadcast nature. Therefore, there is a need to control interference and guarantee signal to interference and noise ratio requirements to ensure efficient D2D communication. To achieve this, UEs with intolerable interference with each other are allocated different resources. In a wireless environment, a communication link is typically only interfered with by transmission signals of a range of UEs due to path loss. In this range, the channel between UEs is better than a certain threshold, and these UEs are called mutual interference sources. According to the documents "Mordachev, V.and Loyka, S., On node diversity of wireless networks, IEEEjournal On Selected Areas in Communications, vo1.27, 2009, 1120-. This means that the dominant interference to a certain UE can be assumed to be within a certain range. Therefore, the mutual interference source will allocate different resources to control the power in the technical solution of the present invention.

It is assumed here that for any two UEs i and j, if the distance d between them is_ijLess than a predetermined interference distance d_interferenceThen they are sources of mutual interference, i.e.

d_ij≤d_interference (10)

d_interferenceFor an a priori value stored at the eNB, this value is typically greater than d_partnerTo limit interference. Fig. 10 shows an example of interference relationship of one UE, where the interference source of the UE is located in a circular area.

Since only one UE transmits information at a time in one D2D pair, it is subject to interference for the link of one D2D pair from transmitting UEs of other D2D pairs. Therefore, we consider each pair of D2D as a whole, represented by a vertex. If two UEs interfere with each other, the pair of D2D to which they belong is also considered to interfere with each other. Fig. 11 shows an example of the interference relationship of one D2D pair.

Assuming that the D2D pairs are grouped into different groups, the D2D pairs in the same group use the same resources for transmission. A metric sigma is defined to judge the uniformity of resource allocation. The number of pairs D2D in a group is represented by a random variable M, and σ can be expressed as follows

Where μ denotes the mean value of M, M_iIndicating the number of members in the ith group and N indicating the number of groups. The smaller the value of σ, the more evenly the resource allocation scheme allocates resources. This scheme will be described in detail in steps below.

As shown in fig. 12, first, in step S1201, the eNB broadcasts the D2D cooperation distance D_partnerAnd interference distanced_interference. In practice, the eNB may set d_partnerAnd d_interferenceTo manage the received signal and interference of the receiving UE. Their values can be obtained by measuring deployment location of the UE or other information such as transmission power, distance, etc. fed back by the UE through an empirical value or TA (timing advance).

The UE receives the cooperation distance d from the eNB_partnerAnd interference distance d_interferenceThen, UE transmits the packet containing self identity information in a time slot by using a random channel or a distributed channel; at another time, it listens for information from other UEs. The UE then resolves the received packet and estimates the distance of the packet-sending UE from itself, and then, in step S1202, the UE obtains the above two sets by equations (9) and (10). In practice, the UE may also determine the UE by receiving power. The UE j is considered as an alternative partner of UE i if the received power of the UE j transmission signal at UE i satisfies the following equation (12).

Wherein P is_tIs the transmission power of the UE, α is the path loss factor,the signal power of UEj is received for UE i. Similarly, the interference source of UE i can be determined by the following formula

After these comparisons, the UE can obtain its cooperative set Φ_PAnd set of interferers Φ_I. In general, a cooperative set of slaves and interferers is set, i.e.This is due toIs d_partner≤d_interference。

Then, in step S1203, each UE feeds back its own cooperation set and interference source set to the eNB. Due to phi_PAnd phi_IPartially overlapping, the UE only needs to be phi_PAnd only the UE in the set of interferers Φ_I/Φ_PAnd (5) feedback is carried out. Using a cooperation set phi_PThe eNB may decide whether the UE transmits information in a legacy manner or D2D. This set may help the eNB to decide the transmission mode of the UE and narrow the search range of D2D partners. Thus, signaling overhead will be reduced. Given a UE, if another UE is the object it intends to receive and belongs to its cooperative set, then the two UEs will form a D2D pair and directly transmit information. By using interference sets phi_IThe eNB may obtain interference patterns for all UEs. In step S1204, the eNB may construct an interference map of all D2D pairs according to the feedback information of the UE. Fig. 13 shows an example of an interference graph for a cell containing 100D 2D pairs. Wherein, the asterisk represents a vertex, and the interference sources are connected by edges.

Then, in step S1205, the eNB allocates resources to these D2D pairs according to a greedy coloring algorithm. Each pair of D2D is considered a vertex that is arranged non-incrementally with respect to their degrees of freedom. They are assigned to different groups according to saturation. For a pair of D2D, saturation is defined as the number of vertices in its neighborhood that have been allocated resources. After s cycles, the vertices are grouped into N groups (G)₁……G_N) Each group's D2D pair uses one resource. In this process, the pair of D2D interfering with each other is determined by using phi₁Are divided into different groups. The packet with the fewest members has priority to accommodate the new D2D pair first. The greedy algorithm proposed is specifically as follows:

① eNB according to phi_IAnd phi_PEstablishing an interference graph, each pair of D2D being represented by a vertex;

② calculating the degree of freedom of each vertex and arranging them in non-increasing order according to the degree of freedom of the vertex

③ dyeing the first vertex with random colors and calculating the saturation of the other vertices

④, the vertex with the highest saturation is selected, and if the same saturation is encountered, one of them is selected arbitrarily.

⑤ giving the selected vertex the current available color set Φ_AThe color staining with the least number of uses in the dyeing process. Phi_AAll color sets not already colored by this vertex interferer are included. If phi_AIf it is empty, a new color is created. The saturation of the vertex interferer is updated.

⑥ return to step ④ until all vertices are stained.

After the above process is finished, each vertex is assigned a color, as shown in fig. 14. Pairs of D2D with the same color share the same resources. The number of colors is the number of allocated resources. By this greedy algorithm, the number of allocated resources is minimized. Meanwhile, the number of pairs of D2D using each resource is similar.

Finally, in step S1206, the eNB notifies each D2D pair of the resource allocated for each D2D pair. Each pair of D2D then transmits data according to the allocated resources.

To further evaluate the technical solution of the above embodiments of the present invention, relevant simulations were performed and compared with the degree of freedom solution and the random solution. The simulation parameters are shown in table 2 below.

TABLE 2

Fig. 15 compares the uniformity of the three protocols. As can be seen from the figure, as a reference, the random scheme has the best uniformity and the degree of freedom scheme has the worst uniformity. In addition, compared with the technical scheme of the degree of freedom, the technical scheme of the invention reduces the sigma value by 50%. That is, from the perspective of uniformly allocating resources, the technical solution of the present invention is due to the technical solution of the degree of freedom.

Fig. 16 shows that the scheme with one-half of the degrees of freedom has a very low probability signal-to-interference-and-noise ratio and does not meet the requirements of actual communication. The reason is that in this scheme the vast majority of D2D pairs are grouped into the first group, i.e. the vast majority of D2D pairs share the same resources. In order to make the value of the signal to interference and noise ratio meet the practical requirement, the interference distance needs to be further enlarged, which in turn leads to high resource consumption. In the technical scheme of the invention, the signal-to-interference-and-noise ratio can be improved by two times at most because the scheme more uniformly allocates resources and the interference set controls the interference.

Figure 17 shows that the signal to interference ratio of the solution of the invention is similar to that of the random solution. This is because as the interference distance increases, the mutual interference sources are more easily allocated to different resources in the technical solution of the present invention. In the random scheme, the interference in the D2D pair is not considered by only uniformly allocating resources. Moreover, the technical scheme of the invention improves the drying ratio of the freedom degree scheme by 6 times at most. That is, the proposed scheme has the advantage that the interference distance becomes larger Φ₁This is more pronounced when the ratio is small, since the benefits from evenly distributing the resources are more pronounced.

Fig. 18 shows that the solution and the degree of freedom solution of the present invention use similar number of resources but much better signal to interference plus noise ratio than the latter. In addition, the random scheme has the best signal-to-interference-and-noise ratio at the cost of huge resource consumption.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and any reference signs in the claims shall not be construed as limiting the claim concerned. It will furthermore be obvious that the word "comprising" does not exclude other elements or steps, and the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. Several of the elements recited in the product claims may also be implemented by one element in software or hardware. The terms first, second, etc. are used to denote names, but not any particular order.

Claims

1. A method in a base station of a communication system for allocating resources, wherein the base station comprises a plurality of D2D pairs within its coverage area, each D2D pair comprising two D2D user equipments, the method comprising the steps of:

i. transmitting a predetermined neighbor distance to all D2D user equipment within the coverage of the base station;

receiving respective neighbor information from all of the D2D user devices;

determining respective neighbor information for the plurality of D2D pairs from the respective neighbor information for all of the D2D user devices;

obtaining values of respective interference tolerances of the plurality of D2D pairs;

v. according to the neighbor information of each of the D2D pairs and the value of the interference tolerance, dividing the D2D pairs into a plurality of groups based on a greedy algorithm, and allocating different resources for each group, wherein the D2D pairs divided into the same group are not neighbors of each other;

informing each D2D pair of the resources allocated for each D2D pair of the plurality of D2D pairs.

2. The method according to claim 1, wherein after step i, before step iv, further comprising the steps of:

-receiving a query message from one or more D2D user devices of said all D2D user devices regarding D2D peers of the one or more D2D user devices;

-notifying the one or more D2D user devices of information of the D2D companion of the one or more D2D user devices.

3. The method according to claim 1, wherein said step iv comprises the steps of:

-obtaining from a receiving D2D user equipment of each D2D pair of the plurality of D2D pairs a value of interference tolerance for that receiving D2D user equipment;

-taking the value of the interference tolerance of the receiving D2D user equipment as the value corresponding to the interference tolerance of the D2D pair to which the receiving D2D user equipment belongs;

Wherein, P_tIs the transmit power of the transmitting D2D user equipment j, D_iRepresenting the distance of the D2D link between the receiving D2D user device i and its transmitting D2D user device j, α representing the path loss factor,indicating the received power, I, of the useful signal received by the receiving D2D user device I from its transmitting D2D user device j₀Represents the received power, N, of the received signal by the receiving D2D user device j from its nearest non-neighbor D2D₀Representing thermal noise, gamma_thRepresenting an SINR threshold value;

4. The method according to claim 1, wherein said step iv comprises the steps of:

-obtaining from a receiving D2D user equipment of each D2D pair of the plurality of D2D pairs a value of interference tolerance for that receiving D2D user equipment, and obtaining from a transmitting D2D user equipment a value of interference tolerance for that transmitting D2D user equipment;

-taking the lesser of the value of the interference tolerance of the receiving D2D user equipment and the value of the interference tolerance of the transmitting D2D user equipment as the value of the interference tolerance of the D2D pair to which the receiving D2D user equipment and the transmitting D2D user equipment belong;

Wherein, P_tIs the transmit power of the transmitting D2D user equipment j, D_iRepresenting the distance of the D2D link between the receiving D2D user device i and its transmitting D2D user device j, α representing the path loss factor,a received power, I, representing a desired signal received by the receiving D2D user equipment from its transmitting D2D user equipment₀Represents the received power, N, of the receiving D2D user equipment to receive signals from its nearest non-neighbor D2D₀Representing thermal noise, gamma_thRepresenting an SINR threshold value;

Wherein, P_tIs the received transmission power of D2D user equipment i, D_jRepresenting the distance of the D2D link between the transmitting D2D user device j and its receiving D2D user device i, α representing the path loss factor,represents the reception power, I, of the useful signal received by the transmitting D2D user equipment j from the receiving D2D user equipment I₀Represents the received power, N, of the transmitted D2D user device j from its nearest non-neighbor D2D pair received signals₀Representing thermal noise, gamma_thRepresenting an SINR threshold value;

5. The method according to claim 1, wherein said step v comprises the steps of:

v1. arranging the plurality of D2D pairs in a non-decreasing order with a value of interference tolerance of each D2D pair of the plurality of D2D pairs to generate an ordered set of D2D pairs;

v2. creating a group and putting the first D2D pair in the sorted set of D2D pairs into the group and removing the first D2D pair from the sorted set of D2D pairs to update the set of D2D pairs;

v3. sequentially selecting from the updated set of D2D pairs a D2D pair that is not a neighbor to any member of the group and placing the selected D2D pair in the group and removing the selected D2D pair from the set of D2D pairs to update the set of D2D pairs and reduce the value of the interference tolerance of each member of the group by 1;

v4. repeating the above step v3 until the value of the interference tolerance of at least one member of the group is less than or equal to zero;

v5. arranging the remaining D2D pairs in non-decreasing order with updated values of interference tolerance of the remaining D2D pairs of the set of D2D pairs to generate an ordered set of D2D pairs;

v6. repeating the above steps v2 to v5 until the set of D2D pairs is empty;

v7. allocate different resources for each of the established plurality of packets.

6. A method in a receiving D2D user equipment of a communication network for assisting a base station in allocating resources, wherein the method comprises the steps of:

I. receiving a predetermined neighbor distance from the base station;

determining neighbor information for the receiving D2D user device based on the received predetermined neighbor distances;

sending the determined neighbor information of the receiving D2D user equipment to the base station;

determining a value of interference tolerance for the receiving D2D user equipment and sending the determined value of interference tolerance for the receiving D2D user equipment to the base station;

v. receiving resource allocation information from the base station.

7. The method of claim 6, wherein after step I, before step IV, further comprising the steps of:

-determining whether the receiving D2D user device is aware of its D2D peer;

-if not, sending a query message to the base station for querying the D2D peer of the receiving D2D user equipment;

-receiving information of a D2D companion of the receiving D2D user equipment from the base station.

8. The method according to claim 6, wherein the step IV comprises the steps of:

9. A method in a transmitting D2D user equipment of a communication network for assisting a base station in allocating resources, wherein the method comprises the steps of:

A. receiving a predetermined neighbor distance from the base station;

B. determining neighbor information for the transmitting D2D user device based on the received predetermined neighbor distances;

C. transmitting the determined neighbor information of the transmitting D2D user equipment to the base station;

D. determining a value of interference tolerance of the transmitting D2D user equipment and transmitting the value of interference tolerance of the transmitting D2D user equipment to the base station; and

E. resource allocation information is received from a base station.

10. The method of claim 9, wherein after step a, step E is preceded by the steps of:

-determining whether the sending D2D user equipment is aware of its D2D peer;

-if not, sending a query message to the base station for querying a D2D peer of the sending D2D user equipment;

-receiving information of a D2D companion of the transmitting D2D user equipment from the base station.

11. The method of claim 9, wherein said step D comprises the steps of:

Wherein, P_tIs the received transmission power of D2D user equipment i, D_iRepresenting the distance of the D2D link between the receiving D2D user device i and its transmitting D2D user device j, α representing the path loss factor,represents the reception power, I, of the useful signal received by the transmitting D2D user equipment j from the receiving D2D user equipment I₀Represents the received power, N, of the transmitted D2D user device j from its nearest non-neighbor D2D pair received signals₀Representing thermal noise, gamma_thRepresenting an SINR threshold value;

12. An apparatus for allocating resources in a base station of a communication system, wherein the base station comprises a plurality of D2D pairs within its coverage area, each D2D pair comprising two D2D user equipments, the apparatus comprising:

a first sending unit, configured to send a predetermined neighbor distance to all D2D ue devices within the coverage of the base station;

a first receiving unit, configured to receive respective neighbor information from all the D2D user equipments;

a first determining unit, configured to determine respective neighbor information of the plurality of D2D pairs according to the respective neighbor information of all D2D user devices;

an obtaining unit configured to obtain values of respective interference tolerances of the plurality of D2D pairs;

a resource allocation unit, configured to divide the multiple D2D pairs into multiple groups based on a greedy algorithm according to respective neighbor information of the multiple D2D pairs and a value of interference tolerance, and allocate different resources to each group, where the D2D pairs divided into the same group are not neighbors of each other;

a second transmitting unit to inform each of the plurality of D2D pairs of the allocated resources for each of the D2D pairs of the each D2D pair.

13. An apparatus in a receiving D2D user equipment of a communication network for assisting a base station in allocating resources, wherein the base station comprises a plurality of D2D pairs within its coverage area, each D2D pair comprising two D2D user equipments, the apparatus comprising:

a second receiving unit for receiving a predetermined neighbor distance from the base station;

a second determining unit for determining neighbor information of the receiving D2D user equipment based on the received predetermined neighbor distance;

a third transmitting unit, configured to transmit the determined neighbor information of the receiving D2D user equipment to the base station;

a third determining unit, configured to determine a value of interference tolerance of the receiving D2D user equipment, and send the determined value of interference tolerance of the receiving D2D user equipment to the base station;

a third receiving unit, configured to receive resource allocation information from the base station;

wherein the resource allocation comprises: and dividing the D2D pairs into a plurality of groups according to the neighbor information of the D2D pairs and the value of the interference tolerance, and allocating different resources for each group based on a greedy algorithm, wherein the D2D pairs divided into the same group are not neighbors of each other.

14. An apparatus in a transmitting D2D user equipment of a communication network for assisting a base station in allocating resources, wherein the base station comprises a plurality of D2D pairs within its coverage area, each D2D pair comprising two D2D user equipments, the apparatus comprising:

a fourth receiving unit for receiving a predetermined neighbor distance from the base station;

a fourth determining unit, configured to determine neighbor information of the sending D2D user equipment based on the received predetermined neighbor distance;

a fourth transmitting unit, configured to transmit the determined neighbor information of the transmitting D2D user equipment to the base station;

a fifth determining unit, configured to determine a value of interference tolerance of the transmitting D2D user equipment, and transmit the value of interference tolerance of the transmitting D2D user equipment to the base station; and

a fifth receiving unit, configured to receive resource allocation information from the base station;