A c-v2x resource allocation method based on a delay acceptance algorithm

Abstract

The application discloses a C-V2X resource allocation method based on a delay acceptance algorithm. The model of the communication system is applied to a common highway scene, and the model comprises a base station and a plurality of V2I users and V2V users. The method decomposes the resource allocation problem into two subproblems of power control and spectrum resource block allocation, obtains the optimal transmission power through a closed-form solution, and then under the condition of satisfying the transmission power limitation, adopts an improved delay acceptance algorithm to realize the 'one-to-many' multiplexing of V2V users multiplexing a plurality of spectrum resource blocks of V2I users. The above method fully considers the reliability and delay of V2X communication users when the model is established, can guarantee the communication demand of V2I users, and maximizes the link capacity of V2I users under the condition of satisfying the multiplexing condition. Therefore, the application is more suitable for the V2X high-speed communication scene.

Description

TECHNICAL FIELD

[0001] The present application relates to the fields of wireless communication resource allocation and intelligent transportation, and more particularly to a C-V2X resource allocation method based on a deferred acceptance algorithm. BACKGROUND

[0002] 1. Vehicle to Everything (V2X) is a specific application of Internet of Things in the field of road traffic. V2X network has the ability to integrate different types of communication, i.e. Vehicle to Infrastructure (V2I), Vehicle to Vehicle (V2V) and Vehicle to Pedestrian (V2P), Vehicle to Network (V2N), etc. C-V2X is a vehicle networking technology based on the integration of cellular communication and terminal direct communication, which has the advantages of wide coverage, large capacity, high reliability and good mobility, and has the advantage of industrial scale, which can meet the needs of various services of vehicle networking. With the continuous growth of vehicle business demand, the demand for wireless access is increasing, and the scarcity of spectrum resources has become one of the main bottlenecks restricting the development of C-V2X.

[0003] 2. In order to support diversified vehicle networking applications, vehicle networking communication technology faces many challenges. Due to the high-speed movement of vehicles, the network topology formed has high-speed dynamics, introduces greater Doppler frequency offset, and the wireless propagation environment changes rapidly. High-density, multi-point-to-multipoint vehicle-to-vehicle communication is also affected by resource collision, near-far effect, etc., making the interference environment more complex. Reliable and efficient spectrum resource allocation is still facing severe challenges. At the same time, existing methods usually consider resource allocation based on perfect channel state information, but in high-speed mobile vehicle networking, it is difficult to achieve accurate and timely feedback. Therefore, the accuracy of such resource allocation methods is not high.

[0004] 3. The deferred acceptance algorithm is also called Gale-Shapley algorithm, which is an algorithm proposed by Gale and Shapley to solve the stable marriage matching strategy. This algorithm does not require the total number of matches, as long as the number of men and women is equal, and each person can give the other a score in their mind, then after applying this strategy, a stable marriage arrangement can always be obtained. This strategy reflects many real-life situations and is not limited to marriage matching. The traditional deferred acceptance algorithm is applied to resource allocation, and a V2V user can only reuse the resources of a V2I user, and a V2I user only allows a V2V user to reuse, i.e. only "one-to-one" reuse between the two. The utilization of spectrum resources is not high, and the link capacity is also limited. SUMMARY

[0005] 1. This invention addresses the shortcomings of existing methods, such as high computational complexity, low spectrum resource utilization, and insufficient consideration of the characteristics of V2X communication. It provides a C-V2X resource allocation method based on a delayed reception algorithm, suitable for highway scenarios. This method improves upon the traditional delayed reception algorithm, allowing V2V users to reuse multiple spectrum resource blocks, thus increasing spectrum utilization. The mathematical model fully considers the reliability and latency of V2X communication, transforming the spectrum resource allocation problem into two sub-problems: power control and resource block allocation, which are solved separately. While ensuring the quality of service for both V2I and V2V communication, it maximizes the link capacity for V2I users, providing a new approach to the V2X resource allocation problem.

[0006] 2. The communication model of the communication system of the present invention includes a base station, M V2I communication users, and K V2V communication users. Each V2V communication group includes one transmitting user and one receiving user. Each V2I user occupies mutually orthogonal spectrum resources, and V2V users reuse uplink resources, allowing for the reuse of multiple spectrum resource blocks. The proposed resource allocation method based on a delayed reception algorithm includes the following steps:

[0007] The signal-to-noise ratio of the V2I communication link is: For m∈M, the signal-to-noise ratio of a V2V communication link is: k∈K. Where: and The transmit power for V2V and V2I users are respectively, σ 2 α represents noise power. m,B α k α m,k This is a large-scale attenuation effect, including path loss and shadow fading. m,B h is the channel gain from the m-th V2I user to the base station. m,k For the interference channel gain between V2I and V2V users, information is fed back to the base station with a period of T, h k This is for small-scale, rapidly attenuating components. The channel state information of the V2V link is fed back to the base station with a period T, exhibiting a delay, and is processed using a first-order Gaussian Markov process. To perform modeling, ε=J0(2πf d T), where J0 is the zeroth-order Bessel function. ρ m,k Represents the spectrum reuse relationship, ρ m,k =1 indicates that the k-th V2V user reuses the uplink spectrum resource block of the m-th V2I user during communication; conversely, ρ m,k =0.

[0008] 3. Considering that V2I users are mainly oriented to information services or entertainment services with high capacity requirements, and V2V users are mainly oriented to safety services with strict reliability constraints, the problem is decomposed into two sub-problems: power control and resource block allocation. The optimization objective of the power control process is the V2I link capacity wherein, The constraint condition is:

[0009] 4. The reliability constraint of V2V users is: wherein, p0 is the outage probability, is the minimum signal-to-noise ratio requirement for V2I users to establish a reliable link.

[0010] 5. The transmission power of V2I users and the transmission power of V2V users need to meet: and wherein, represents the maximum transmission power of the mth V2I user, represents the maximum transmission power of the kth V2V user.

[0011] 6. The minimum signal-to-noise ratio requirement of V2I link users is represented as: wherein, is the minimum link capacity requirement of V2I users.

[0012] 7. The implicit equation and and

[0013] Solving

[0014] 8. wherein,

[0015]

[0016]

[0017] 9. According to the expression, the optimal transmission power of V2V users and V2V users is obtained and

[0018] 10. wherein,

[0019]

[0020] 11. and

[0021] 12. Calculate the optimal transmission power Link capacity of V2I users under the condition Link capacity of V2V users

[0022] 13. Preference list matrix X of V2V users and V2I users is established according to the high and low of link capacity value k = [x i ] K×M and X M = [x i ] M×K , x i = 1, 2, …, m / k. The index value of the preference list matrix of the V2I user i with the highest link capacity value is x i = 1, the second highest is 2, and so on.

[0023] 14. Each V2I user sends an application to the V2V user ranked first in the preference list, the V2V user not receiving the application waits for the next round, the V2V user receiving an application from one V2I user temporarily accepts the application, and the V2V user receiving applications from multiple V2I users selects the V2I user ranked higher according to the ranking in the preference list and accepts the application, and rejects the other V2I users.

[0024] 15. The remaining V2I users not matched send applications to the V2V users ranked second in the preference list. At this time, if the V2V user having accepted an application in the first iteration receives an application again, the preference ranking of the V2V user accepted last time and the V2V user of the new application is compared, and the V2I user ranked higher is selected and the other is rejected.

[0025] 16. The above steps are repeated until all V2I users have sent applications. The index value of the V2I user having completed stable matching is set to 1, and the V2I user is removed.

[0026] 17. A new round of iteration is started, and the V2I users not matched send applications again according to the preference list. The V2V user receiving an application again selects a V2I user according to the steps. Whether the sum of the optimal power values of the V2I users selected in this round and the last round of iteration satisfies the following formula is calculated

[0027] 18. wherein Pmax is the maximum transmission power of the V2V user.

[0028] 19. When satisfied, the V2I user is selected for matching; when not satisfied, it is indicated that the power limit of the V2V user at this time has been reached, and no more matching can be performed, i.e., the upper limit of multiplexing is reached.

[0029] 20. Repeat multiple rounds of iterations until all V2V users reach the multiplexing upper limit or no more spectrum resources are available for multiplexing.

[0030] 21. Return the matching index matrix where y m,k = 1 when the kthV2V user multiplexes the spectrum resource of the mthV2I user; otherwise, y m,k = 0. Resource allocation ends. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the specific embodiments or prior art description will be briefly introduced below. In all the drawings:

[0032] Figure 1 The figure is a schematic diagram of the communication scenario of the embodiment of the present application.

[0033] Figure 2 The figure is a schematic diagram of the flow of the resource allocation method in the embodiment of the present application.

[0034] Figure 3 The figure is the cumulative distribution function of the V2I user communication link capacity in the embodiment of the present application.

[0035] Figure 4 The figure is the relationship between the V2I user communication link capacity and the vehicle speed in the embodiment of the present application.

[0036] Figure 5 The figure is the relationship between the V2I user communication link capacity and the maximum transmission power in the embodiment of the present application. DETAILED DESCRIPTION

[0037] 1. In order to clearly and completely describe the technical solutions of the present application and the specific working process thereof, in combination with the drawings in the specification, the specific embodiments of the present application are as follows: In order to deepen the understanding of the present application, the present application will be further described in combination with the embodiments below, which are only used to explain the present application and do not constitute a limitation on the protection scope of the present application.

[0038] 2. Referring to Figure 1 , the algorithm is verified in the two-way six-lane highway scenario specified in the 3GPP TR36.885 protocol, the road width is 4 meters, the base station height is 25 meters, the coverage radius is 500 meters, and the distance between the base station and the highway is 35 meters. Each vehicle is equipped with a single receiving and transmitting antenna.

[0039] The channel model selected for the V2V and V2I links is shown in the following table

[0040] Parameters V2V link V2I link Path loss model 128.1 + 37.6 log 10 d]] WINNER+B1 Shadow fading distribution Lognormal distribution Lognormal distribution Shadow fading standard deviation 8 dB 8 dB Fast fading Rayleigh fading Rayleigh fading

[0041] 3. Referring toFigure 2 Flow chart of the resource allocation method of the present application.

[0042] 4. Step 1: Initialization of parameters: carrier frequency 5.9 GHz, number of V2V link users K = 5, number of V2I link users M = 10, noise power σ 2 = -114 dB, minimum V2I link capacity requirement Minimum signal-to-noise ratio for reliable communication of V2V link Outage probability p0= 10 -3 .

[0043] 5. Step 2: In the power control phase, V2I users and V2V users adjust their own transmission power autonomously. In order to maximize the V2I user link capacity while ensuring the minimum signal-to-noise ratio requirement of user communication and reliable communication of the link, the interference between each other also needs to be considered, and the power is calculated by the implicit equation.

[0044] 6. Step 3: Calculate the link capacity of V2I users and the link capacity of V2V users under the condition of optimal transmission power

[0045] 7. Step 4: According to the high and low of the link capacity value, the preference list matrix X K = [x i ] k×m and X M = [x i ] m×k .

[0046] 8. Step 5: Initialize the matching matrix Y M×K .

[0047] 9. Step 6: Start the first round of iteration, each V2I user sends an application to the V2V user ranked first in its own preference list, the V2V user who does not receive the application waits for the next round, the V2V user who receives an application from a V2I user temporarily accepts the user, and the V2V user who receives multiple V2I user applications selects the V2I user with a higher ranking according to the ranking on its own preference list, accepts its application, and rejects other V2I users.

[0048] 10. Step 7: The remaining V2I users who have not been matched send an application to the V2V user ranked second in their preference list. At this time, if the V2V user who has accepted the application in the first iteration receives an application again, the preference ranking of the V2V user accepted last time and the newly applied V2V user needs to be compared, and the V2I user with a higher ranking is selected, and the other one is rejected.

[0049] 11. Step 8: Repeat steps 6-7 until all V2I users have applied. Set the index value of the V2I user who has completed the stable matching to 1 and exclude this V2I user.

[0050] 12. Step 9: Start a new round of iteration, and the unmatched V2I users apply again according to the preference list. The V2V users who receive the application again select V2I users according to steps 6-7. At the same time, calculate whether the sum of the optimal power values of the selected V2I users in this round and the last round of iteration meets the power limit.

[0051] 13. Step 10: When it is met, the V2I user is selected for matching; if it is not met, it means that the V2V user power limit at this time cannot be matched, i.e., the reuse upper limit is reached.

[0052] 14. Step 11: Repeat multiple rounds of iteration until all V2V users reach the reuse upper limit or there are no reusable spectrum resource blocks.

[0053] 15. Return the matching index matrix, and the resource allocation is completed.

[0054] 16. Referring to Figure 3 the cumulative distribution function of the V2I user link signal-to-noise ratio (SINR) of the present application. As can be seen from the figure, the signal-to-noise ratios of the various algorithms are distributed, and several algorithms can meet the minimum 5dB signal-to-noise ratio requirement of the V2I link. Among them, the signal-to-noise ratio based on the improved delay acceptance algorithm is mostly concentrated around 30dB, which is better than the delay acceptance algorithm and the random resource allocation algorithm.

[0055] 17. Referring to Figure 4 the relationship between the V2I user link capacity and the vehicle speed of the present application. As can be seen from the figure, as the vehicle speed increases, the link capacity decreases, because the faster the vehicle speed, the more unstable the channel, thereby affecting the link capacity. In the delay acceptance algorithm, a V2V user can only reuse the spectrum resource block of one V2I user, and a V2I user is only allowed to be reused by one V2V user, so the link capacity is not high. The improved method proposed in the present application can reuse more resource blocks, so the link capacity is greatly improved.

[0056] 18. Referring to Figure 5 the relationship between the V2I user link capacity and the feedback period T of the present application. As can be seen from the figure, as the feedback time T increases, the channel state information feedback to the base station is delayed, thereby the link capacity decreases. The method proposed in the present application is still better than the other two algorithms.

[0057] 19. The above examples are to be understood only as illustrative of the application and not as limiting the scope of the present application. After reading the specification, skilled persons will be able to carry out various modifications or alterations to the application, which fall within the scope of the application as defined by the claims.

Claims

1. A C-V2X resource allocation method based on a delay acceptance algorithm, characterized in that, According to a V2X communication model, the V2X communication model is a highway scene, including a base station, M V2I communication users and K V2V communication users, wherein: a vehicle representing V2I communication, a vehicle representing V2V communication; V2I users use mutually orthogonal spectrum resources, V2V users multiplex uplink resources of V2I users, and are one-to-many multiplexing, that is, V2V users can multiplex multiple mutually orthogonal V2I spectrum resource blocks; the method comprises the following steps: Step 1. The V2X resource allocation problem is divided into two sub-problems of power control and resource block allocation, and the optimization goal is to maximize the link capacity of V2I users; Step 2. In the power control process, the optimal transmit power of V2I users is obtained according to the V2I user maximizing link capacity, satisfying the reliability of V2V users and the minimum signal-to-noise ratio requirement of V2I users and the optimal transmit power of V2V users ; The reliability of the V2V link user is represented as: wherein, is the outage probability, is the minimum signal-to-noise ratio requirement for the V2I user to establish a reliable link; the minimum signal-to-noise ratio requirement of the V2I link user is represented as: wherein, is the minimum link capacity requirement of the V2I user; meanwhile, the transmission power of the V2I user and the transmission power of the V2V user need to satisfy: , ; wherein, and are the maximum transmission power of the V2V link and the V2I link respectively, and the transmission power cannot exceed the maximum transmission power. Step 3. The preference lists of V2V users and V2I users are established according to the link capacity under the optimal transmission power obtained in step 2, and the delay acceptance algorithm is used to select the number of multiplexed V2I user resource blocks under the condition of meeting the power limit, and the spectrum resource sharing result is obtained. 2.The C-V2X resource allocation method based on delay acceptance algorithm of claim 1, wherein: The link capacity of the V2I user in step 1 Is: wherein, is the signal-to-noise ratio of the V2I user, ; and are the transmit powers of the V2V user and the V2I user, respectively, denotes the noise power, , is the large-scale attenuation effect including path loss and shadow fading, is the communication channel gain of the m-th V2I user to the base station, is the small-scale fast fading component, denotes the spectrum reuse relationship, denotes that the k-th V2V user reuses the uplink spectrum resource of the m-th V2I user when communicating, and vice versa, . 3.The C-V2X resource allocation method based on delay acceptance algorithm of claim 1, wherein: The step 3 comprises: Step 3.

1. Calculate the link capacity of V2I users and V2V users under the optimal transmit power, sort the maximum value to the minimum value of the link capacity, assign preference values in turn, and establish a preference list matrix; the preference list matrix of V2I users and V2V users is and respectively; wherein the preference value and the preference is 1, 2; Step 3.

2. The first round of iteration starts, each V2I user sends an application to the V2V user ranked first in the preference list, the V2V user who does not receive the application waits for the next time, and the V2V user who receives an application from a V2I user temporarily accepts the user; the V2V user who receives multiple V2I user applications needs to select the V2I user with a higher ranking according to the ranking in the preference list, accept the application, and reject other V2I users; Step 3.

3. The remaining V2I users who have not been matched send an application to the V2V user ranked second in the preference list, at this time, if the V2V user who has accepted the application in the first iteration receives an application again, the preference ranking of the V2V user accepted last time and the V2V user of the new application needs to be compared, and the V2I user with a higher ranking is selected and the other one is rejected; Step 3.

4. Repeat the above steps until all V2I users have sent an application, and a round of iteration is completed; in the matching matrix, the index value of the V2I user who has completed stable matching is set to 1, and the V2I user is removed; Step 3.

5. Start a new round of iteration, and the V2I users who have not been matched send an application again according to the preference list; the V2V user who receives the application again selects the V2I user according to step 3.2 and step 3.3; at the same time, whether the sum of the optimal power values of the V2I users selected in this round and the last round of iteration meets the V2V link power limit is calculated; Step 3.

6. When it is met, the V2I user is selected for matching; if it is not met, it means that the V2V user power limit has been reached and no more resource blocks can be multiplexed, i.e., the multiplexing upper limit is reached; Step 3.

7. Repeat multiple rounds of iteration until all V2V users reach the multiplexing upper limit or there are no more resource blocks to multiplex, return the resource matching index matrix, and the resource allocation is completed.

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