A wireless edge caching method based on full-duplex relay in a heterogeneous wireless network

Abstract

This disclosure relates to a wireless edge caching method based on full-duplex relay in a heterogeneous wireless network. The method includes: constructing a heterogeneous wireless network; wherein the heterogeneous wireless network includes a core network, macro base stations, relay stations, and multiple users; employing a random caching strategy based on Scalable Video Coding (SVC) technology, whereby a video content server located in the core network pre-places some files requiring caching in the local cache of the relay stations; users sending request information to the relay stations; and analyzing the transmission rate and successful transmission probability in the heterogeneous wireless network. This disclosure employs a random caching scheme based on SVC under full-duplex relay to improve data transmission rate, achieving better caching efficiency, improving the user's content experience quality, and effectively alleviating network congestion problems.

Description

A wireless edge buffering method based on full-duplex relay in heterogeneous wireless networks Technical Field

[0001] This disclosure relates to the field of wireless communication technology, and in particular to a wireless edge caching method based on full-duplex relay in a heterogeneous wireless network. Background Technology

[0002] With the development of the internet and the widespread use of smart devices (mobile, tablets, etc.), data traffic has grown significantly and continuously. The growth of mobile video services has become a major challenge in effectively transmitting video content over wireless networks while meeting users' Quality of Service (QoS) requirements. Therefore, more efficient methods for transmitting video services are needed to meet the multimedia video needs of end users.

[0003] Wireless caching is a promising technology that brings content closer to the end user before it is requested, reducing the load on cellular data traffic and attracting significant attention in 5G and beyond networks. This is because the explosive growth in data traffic is causing network congestion, while mobile devices have limited battery capacity. Therefore, caching technology can avoid traffic bottlenecks between servers and application clients, reducing data interaction between the client and server, and thus greatly improving data retrieval speed.

[0004] In related technologies, depending on rapidly changing channel conditions and diverse user preferences, different users may prefer different qualities of the same video. This raises the fact that delivering high-quality video to every user is unnecessary, as it would consume enormous wireless resources. Scalable Video Coding (SVC), evolved from Advanced Video Coding, aims to provide mobile users with a diverse perceived viewing experience. However, this method cannot solve the network congestion problem, thus failing to effectively meet users' quality of experience requirements.

[0005] Therefore, it is necessary to improve one or more of the problems existing in the above-mentioned related technical solutions.

[0006] It should be noted that this section is intended to provide background or context for the technical solutions of this disclosure as set forth in the claims. The description herein does not constitute an admission that it is prior art simply because it is included in this section. Summary of the Invention

[0007] The purpose of this disclosure is to provide a wireless edge caching method based on full-duplex relay in heterogeneous wireless networks, thereby overcoming at least to some extent one or more problems caused by the limitations and defects of related technologies.

[0008] According to embodiments of this disclosure, a wireless edge buffering method based on full-duplex relay in a heterogeneous wireless network is provided, the method comprising:

[0009] Construct a heterogeneous wireless network; wherein the heterogeneous wireless network includes a core network, macro base stations, relay stations, and multiple users;

[0010] The SVC-based random caching strategy places some of the files that need to be cached in advance in cacheable relay stations;

[0011] In the heterogeneous network under study, users send request information to nearby relay stations. If the nearest relay station has cached the user's request file, then that relay station will serve the user. If the user's request content cannot be found in the local memory of the relay station, then the nearest macro base station will transmit the request content to the nearest relay station, and then that relay station will transmit the request content to the user.

[0012] The transmission rate and successful transmission probability in the heterogeneous wireless network were analyzed to verify the superior performance of the proposed content transmission and SVC-based caching strategy.

[0013] In one embodiment of this disclosure, the successful transmission probability set includes:

[0014] First successful transmission probability and second successful transmission probability;

[0015] The first successful transmission probability is the probability of successfully transmitting the required content from the relay station to the user, and the second successful transmission probability is the probability of successfully transmitting the content from the macro base station to the relay station, and then from the relay node to the user side.

[0016] In one embodiment of this disclosure, the steps of analyzing the transmission rate and successful transmission probability in the heterogeneous wireless network under study include:

[0017] Analyze the transmission rate in heterogeneous wireless networks;

[0018] Analyze the probability of the first successful transmission from the relay station to the user and the cache hit rate;

[0019] The probability of successful transmission from the macro base station to the user via the relay station and the cache miss rate are analyzed.

[0020] In one embodiment of this disclosure, the step of analyzing the transmission rate in a heterogeneous wireless network includes:

[0021] According to formula (1), the cache auxiliary data rate is determined as a performance metric to reflect the performance of SVC caching and content delivery (the total data rate of the content received by the user):

[0022]

[0023] The video library is located in the core network and contains J video files that users can request. The requested video files are preprocessed by SVC into multiple layers, and the number of layers is L. This includes a base layer and L-1 (L≥2) consecutive enhancement layers. The video containing the first l consecutive layers can provide the l-th level of viewing quality, which is defined here as super-layer l.

[0024] The request probability of the superlayer l of the j-th video is determined according to formula (2):

[0025]

[0026] In the formula, p(j) represents the popularity of the j-th content; Wherein, γ and q are the popularity skewness parameter and the flatness factor, respectively; Indicates the probability of the first successful transmission. R1 represents the cache hit rate of the relay in this scenario, and R2 represents the minimum data rate in this scenario. This indicates the probability of a second successful transmission. R1 represents the cache miss rate in this scenario, and R2 represents the minimum data rate in this scenario.

[0027] In one embodiment of this disclosure, the step of analyzing the first successful transmission probability and cache hit rate from the relay station to the user includes:

[0028] When the requested content required by the user is located closest to the user's geographical location and the cached file exists in the relay station, the received signal interference ratio at the user's location is determined according to formula (3):

[0029]

[0030] in, Channel gain for serving relay stations; For channel gain of other non-serving relay stations; The distance between the nearest relay station and the user; α represents the distance between the non-serving relay station and the user; α is the path loss exponent for relay transmission.

[0031] The success probability of relay transmission is determined according to formula (4):

[0032]

[0033] Where θ is a predetermined threshold used to guarantee the minimum data transmission rate.

[0034] In one embodiment of this disclosure, the probability density function of the distance between the nearest relay station r0 and the user it serves is determined according to formula (5):

[0035]

[0036] Among them, R R λ represents the coverage radius of the relay station. r Let the density of relay stations be denoted as ; then the probability of successful transmission in this case is:

[0037]

[0038] in,

[0039] The probability of finding the requested content at the nearest relay station is determined using formula (7):

[0040]

[0041] Where, q j,l R1 = Wlog2(1+θ) is the cache probability of the superlayer l from the j-th request content; R1 = Wlog2(1+θ) is the data rate; W is the system bandwidth allocated to the relay transmission.

[0042] In one embodiment of this disclosure, the step of analyzing the second successful transmission probability and cache miss rate of macro base station transmission to the user via the serving relay station includes:

[0043] When the cached file of the requested content by the user is not present in the relay station closest to the user's geographical location, the received signal interference ratio at the relay station is determined according to formula (8):

[0044]

[0045] in, The channel gain of the macro base station; For channel gain of other non-serving macro base stations; It is the distance between the nearest macro base station and the serving relay station; β is the distance between the non-serving macro base station and the serving relay station; β is the path loss exponent for macro base station transmission.

[0046] In one embodiment of this disclosure, the successful transmission probability of the macro base station is determined according to formula (9):

[0047]

[0048] Where θ is a predetermined threshold used to guarantee the minimum data transmission rate.

[0049] The probability density function for determining the distance between the nearest macro base station and the serving relay station is given by formula (10):

[0050] f m (r)=2πλ m rexp(-λ m πr 2 (10)

[0051] Where, λ m The density of macro base stations;

[0052] The successful transmission probability of the macro base station can be obtained from the above formula:

[0053]

[0054] The probability of successful transmission in this case is determined using formula (12):

[0055]

[0056] Determine the cache miss rate using formula (13):

[0057]

[0058] The data rate in this case is determined using formula (14):

[0059] R2=Wlog2(1+θ) (14)

[0060] Where W represents the system bandwidth.

[0061] In one embodiment of this disclosure, when the content requested by the user is cached and uncached at the relay station closest to the user, the total data rate received by the user at each content layer is formulated in both cases and weighted by the probability that the user needs the content:

[0062]

[0063] Where R is the total data rate of the content received by the user.

[0064] In one embodiment of this disclosure, the step of placing some files that need to be cached in advance in the relay station according to the SVC-based random caching strategy includes:

[0065] The content servers in the core network place content layers in relay stations near users based on the random caching probability of each content layer. The technical solutions provided by the embodiments of this disclosure may include the following beneficial effects:

[0066] In the embodiments of this disclosure, the wireless edge caching method based on full-duplex relay in the above heterogeneous wireless network adopts a random caching scheme based on SVC under full-duplex relay to improve the data transmission rate, thereby achieving better caching efficiency, improving the quality of user content experience, and alleviating network congestion problems. Attached Figure Description

[0067] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0068] Figure 1 illustrates the steps of a wireless edge buffering method based on full-duplex relay in a heterogeneous wireless network according to an exemplary embodiment of the present disclosure;

[0069] Figure 2 illustrates a schematic diagram of a heterogeneous wireless network in an exemplary embodiment of this disclosure;

[0070] Figure 3(a) shows the curve of the success transmission probability change in case 1 of the exemplary embodiments of this disclosure;

[0071] Figure 3(b) shows the curve of the success probability change from the first-hop macro base station to the relay communication in case 2 of the exemplary embodiments of this disclosure;

[0072] Figure 4 shows the curves of the data transmission rate changing under different QoS requirements in the exemplary embodiments of this disclosure for different caching schemes;

[0073] Figure 5 shows a simulation comparison of the changes between the baseline scheme and the proposed scheme under different popularity skewness parameters in an exemplary embodiment of this disclosure. Detailed Implementation

[0074] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0075] Furthermore, the accompanying drawings are merely illustrative diagrams of embodiments of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0076] This example embodiment first provides a wireless edge caching method based on full-duplex relay in a heterogeneous wireless network. Referring to Figure 1, this wireless edge caching method based on full-duplex relay in a heterogeneous wireless network may include steps S101 to S104.

[0077] Step S101: Construct a heterogeneous wireless network; wherein the heterogeneous wireless network includes a core network, macro base stations, relay stations, and multiple users;

[0078] Step S102: The SVC-based random caching strategy places some of the files that need to be cached in the relay station in advance;

[0079] Step S103: The user sends a request message to the relay station; wherein, if the request content corresponding to the request message exists in the cache file of the relay station, the relay station transmits the request content to the user; if the request content corresponding to the request message does not exist in the cache file of the relay station, the macro base station transmits the request content to the cache node of the relay station, and the relay station then transmits the request content to the user;

[0080] Step S104: Analyze the transmission rate and successful transmission probability group in the heterogeneous wireless network respectively to obtain the optimal transmission strategy.

[0081] By employing the wireless edge caching method based on full-duplex relay in the above heterogeneous wireless network, and using a random caching scheme based on SVC under full-duplex relay to improve the data transmission rate, a better caching efficiency is achieved, which improves the user content experience quality and alleviates network congestion problems.

[0082] The steps of the wireless edge caching method based on full-duplex relay in the above-described heterogeneous wireless network in this example embodiment will now be described in more detail with reference to Figures 1 to 5.

[0083] As shown in Figure 2, the application scenario of this application is as follows: In a communication network consisting of a core network, macro base stations, relays, and users, a two-layer heterogeneous network composed of multiple macro base stations and full-duplex relays is established. A user requiring video services is randomly selected as a typical user, and its location is considered the origin of the network. Relay stations, users, and macro base stations are spatially distributed according to independent and identical Poisson point processes, with densities of λ. r , λ u and λ m .

[0084] To demonstrate the practicality of the various mechanisms in this application, multiple simulation implementation experiments were conducted. The network model in the experimental system is the application scenario shown in Figure 2, and the simulation results are shown in Figures 3(a), 3(b), 4, and 5.

[0085] As shown in Figures 3(a) and 3(b), Figure 3(a) verifies the correctness of the successful transmission probability from relay to user. It can be seen that the performance difference between the analysis results and the Monte Carlo simulation results is negligible. It can be seen that higher QoS requirements lead to a lower successful transmission probability. Similarly, the above conclusions also apply to Figure 3(b).

[0086] Figure 4 illustrates the cache auxiliary data rate performance under two caching strategies: Most Popular Content Placement (MPCP) and Equal Probability Content Placement (EPCP). MPCP is a special probabilistic caching scheme where the superlayer from the most popular content is cached with probability 1, while the rest are cached with probability 0. The EPCP scheme involves randomly storing all superlayers with the same caching probability until the cache capacity in each relay is exhausted. It can be seen that MPCP outperforms EPCP, while EPCP ignores the content popularity and viewing quality preferences of different videos and layers.

[0087] As shown in Figure 5, the case without a relay cache is selected as the baseline scheme. It can be seen that the cache-assisted data rate performance improves with increasing γ. A larger γ indicates that user requests are more concentrated on the most popular content, and the cached content is more likely to be requested, further improving cache efficiency and cache-assisted data rate performance. It can be seen that the proposed scheme has better caching efficiency and data rate than the baseline scheme.

[0088] This application defines the buffered auxiliary data rate. By modeling and deriving the successful transmission probability using random geometric tools and the Poisson point process, an analytical expression for the buffered auxiliary data rate is obtained. Compared with existing buffering schemes, the proposed SVC-based full-duplex relay random buffering scheme has advantages in improving data transmission rate. This application has advantages such as simple method and high data transmission rate, and can be applied in the field of communication technology.

[0089] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0090] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A wireless edge buffering method based on full-duplex relay in a heterogeneous wireless network, characterized in that, The method includes: constructing a heterogeneous wireless network; wherein the heterogeneous wireless network includes a core network, macro base stations, relay stations, and multiple users; a random caching strategy based on Scalable Video Coding (SVC) technology, pre-placing some files that need to be cached in cacheable relay stations; users in the heterogeneous network send request information to surrounding relay stations; wherein, if the relay station closest to the user has cached the user's requested file, then that relay station serves the user; if the user's requested content cannot be found in the local storage of the relay station, then the macro base station closest to the user transmits the requested content to the relay station closest to the user, and then that relay station transmits the requested content to the user; analyzing the transmission rate and successful transmission probability in the heterogeneous wireless network respectively to verify the performance of the proposed content transmission and the SVC-based caching strategy; the successful transmission probability includes: a first successful transmission probability... The first successful transmission probability is the probability of successfully transmitting the required content from the relay station to the user, and the second successful transmission probability is the probability of successfully transmitting from the macro base station to the relay station and then from the relay station to the user. The steps for analyzing the transmission rate and successful transmission probability in the heterogeneous wireless network under study include: analyzing the transmission rate in the heterogeneous wireless network; analyzing the first successful transmission probability and cache hit rate from the relay station to the user; analyzing the second successful transmission probability and cache miss rate of the macro base station transmission via the relay station to the user; the steps for analyzing the transmission rate in the heterogeneous wireless network include: determining the cache auxiliary data rate as a performance metric to reflect the performance of SVC caching and content delivery according to formula (1): (1) The video library is located in the core network, and contains videos that users can request. The requested video file is preprocessed by SVC into multiple layers, and the number of layers is L; including a base layer and L-1 consecutive enhancement layers, where L≥2; the video containing the first l consecutive layers can provide the l-th level of viewing quality, which is defined here as super-layer l; the l-th layer is determined according to formula (2). The first video Request probability of layer: (2) In the formula, For the first The popularity of each piece of content; ,in, and These are the popularity skewness parameter and the flatness factor, respectively; This indicates the probability of the first successful transmission. This represents the cache hit rate of the relay in this scenario. This represents the minimum data rate under this condition; This indicates the probability of a second successful transmission. This represents the cache miss rate in this scenario. This represents the minimum data rate under this condition.

2. The wireless edge buffering method based on full-duplex relay in a heterogeneous wireless network according to claim 1, characterized in that, The step of analyzing the first successful transmission probability and cache hit rate from the relay station cache node to the user includes: when the requested content required by the user is closest to the user's geographical location and the cache file exists in the relay station cache node, the received signal interference ratio at the user's location is determined according to formula (3): (3) Among them, Channel gain for serving relay stations; For channel gain of other non-serving relay stations; The distance between the nearest relay station and the user; The distance between the non-service relay station and the user; The path loss index for relay transmission is given; the success probability of relay transmission is determined according to formula (4): (4) Among them, It is a predetermined threshold used to guarantee the minimum data transmission rate.

3. The wireless edge buffering method based on full-duplex relay in a heterogeneous wireless network according to claim 2, characterized in that, The nearest relay station cache node is determined according to formula (5). The probability density function of the distance between the user it serves and the user it serves: (5) Among them, This represents the coverage radius of the relay station. Let the density of relay stations be denoted as ; then the probability of successful transmission in this case is: (6) Among them, The probability of finding the requested content at the nearest relay station is determined according to formula (7): (7) Among them, For from the The super-level of the request content Cache probability, For data rate, The system bandwidth allocated to relay transmission.

4. The wireless edge buffering method based on full-duplex relay in a heterogeneous wireless network according to claim 3, characterized in that, The step of analyzing the second successful transmission probability and cache miss rate of the macro base station transmission to the user via the relay station includes: when the cache file of the requested content required by the user does not exist at the relay station closest to the user's geographical location, the received signal interference ratio at the relay station is determined according to formula (8): (8) Among them, This is the fading channel of the macro base station. For the fading channels of the other non-serving macro base stations, It is the distance between the nearest macro base station and the relay station cache node; The distance between the macro base station and the relay station cache node that is not serving; It is the path loss index for transmission from the macro base station.

5. The wireless edge buffering method based on full-duplex relay in a heterogeneous wireless network according to claim 4, characterized in that, The probability of successful transmission of a macro base station is determined according to formula (9): (9) Among them, It is a predetermined threshold to guarantee the minimum data transmission rate; the probability density function of the distance between the nearest macro base station and the serving relay station is determined according to formula (10): (10) Among them, Let be the density of macro base stations; the successful transmission probability of the macro base stations can be obtained using the above formula: (11) Determine the probability of successful transmission in this case according to formula (12): (12) Determine the cache miss rate according to formula (13): (13) Determine the data rate in this case according to formula (14): (14) Among them, This indicates the system bandwidth.

6. The wireless edge buffering method based on full-duplex relay in a heterogeneous wireless network according to claim 5, characterized in that, When the content requested by the user is cached or not cached at the nearest relay station, the total data rate received by the user at each content layer is formulated in both cases and weighted by the probability that the user needs the content: (15) Where R is the total data rate of the content received by the user.

7. The wireless edge buffering method based on full-duplex relay in a heterogeneous wireless network according to claim 1, characterized in that, The step of placing some cached files in the relay station according to the SVC-based random caching strategy includes: the content server in the core network placing the content layer in the relay station near the user according to the random caching probability of each content layer.

Images