A two-user, four-file encoding cache method with non-uniform file popularity

Abstract

The present invention discloses a two-user, four-file caching method under non-uniform file popularity, including obtaining valid points according to the probability of each file, designing pre-caching information and delivery information of the valid points, designing a user decoding process and cache sharing. The coding cache scheme will give different valid points under different file popularity distributions, and the average delivery rate is optimized by designing the pre-caching information, delivery information and user decoding process corresponding to the valid points. When the user cache size is not equal to the cache size of the obtained valid point, it is necessary to use two adjacent valid points to realize the corresponding scheme design through cache sharing.

Description

Technical Field

[0001] The invention belongs to the technical field of information theory, and in particular relates to a coding cache method for two users and four files under non-uniform file popularity. Background Art

[0002] In the coding cache problem, most studies focus on scenarios where the file probabilities are equal, and the target quantity of interest is the worst-case rate of delivery. However, in reality, the probability of users demanding different files is different, and the average rate of delivery is more important. Existing work only solves the optimal solution for this problem with two files and two users. Summary of the invention

[0003] The present invention aims to provide a coding cache method for two users and four files under non-uniform file popularity, so as to solve the technical problem that the existing work only solves the optimal solution for two files and two users.

[0004] In order to solve the above technical problems, the specific technical solutions of the present invention are as follows:

[0005] A method for encoding and caching two users and four files under non-uniform file popularity, characterized by comprising the following steps:

[0006] Step 1: Get valid points: Assume that the popularity probabilities of files W3, W2, W1, and W0 are p3, p2, p1, and p0 respectively, and p3 ≥ p2 ≥ p1 ≥ p0. The size of each file is F bits. According to the probability of each file, the valid points under the popularity distribution of the file are obtained through probability area calculation;

[0007] Step 2, designing pre-caching information and delivery information of effective points: according to the effective points obtained in step 1, designing corresponding pre-caching information and delivery information;

[0008] Step 3: Design the user decoding process: Users decode their requested files by combining local pre-cached information and server delivery information;

[0009] Step 4, cache sharing: When the user cache size is not equal to the cache size of the valid point obtained in step 1, it is necessary to use two adjacent valid points to implement the corresponding pre-cache information design, delivery information design and user decoding process design through cache sharing.

[0010] Furthermore, the process of obtaining valid points according to the file probability in step 1 is as follows:

[0011] If the file popularity probabilities p3, p2, p1, p0 satisfy the probability region π k , then point k is a valid point, otherwise it is an invalid point;

[0012] Probability region π1: p3 ≥ p2 ≥ p1 ≥ p0; probability region π2: λ 1,2 ≤λ 1,3 ,λ 1,4 ,λ 1,7 ;

[0013] Probability region π3: λ 1,3 ≤λ 1,2 ,λ 1,4 ,λ 1,7 ;

[0014] Probability region π4: λ 1,4 ≤λ 1,7 And 2,4 ≤λ 2,5 ,λ 2,6 ,λ 2,7 ,λ 2,8 ,λ 3,5 ,λ 3,7 ;

[0015] Probability region π5: λ 4,5 ≤λ 4,6 ,λ 4,7 And 2,5 ≤λ 2,8 And 5,10 ≤λ 4,10 ;

[0016] Probability region π6: λ 4,6 ≤λ 4,5 ,λ 4,7 And 2,6 ≤λ 2,8 And 6,10 ≤λ 4,10 ;

[0017] Probability region π7: λ 4,7 ≤λ 4,5 ,λ 4,6 And 2,7 ≤λ 2,8 And 7,10 ≤λ 4,10 ;

[0018] Probability region π8: λ 8,11 ≤λ 7,11 And 8,9 ≤λ 5,9 ,λ 7,9 ,λ 4,10 ,λ 5,10 ,λ 6,10 ,λ 7,10 ;

[0019] Probability region π9: λ 9,11≤λ 7,11 ,λ 8,11 ,λ 10,11 ; Probability region π 10 :λ 10,11 ≤λ 7,11 ,λ 8,11 ,λ 9,11 ;

[0020] Probability region π 11 :p3≥p2≥p1≥p0;

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[0037] Furthermore, the process of designing the pre-cached content and the delivered content of the effective point in step 2 is as follows:

[0038] File W i , i∈{0,1,2,3} is divided into two sub-files W of equal size and non-overlapping i,A and W i,B , where i represents the file number, and the sizes of the two sub-files are bits. Let d1,d2∈{0,1,2,3} represent the file indexes requested by users 1 and 2 respectively. Use W Ω Represents a file collection {W i :i∈Ω}, and When W Ω is 0.

[0039] For valid point 1, the pre-cached information Z1 and Z2 of users 1 and 2 are both 0, and the delivery information for

[0040] For valid point 2, the pre-cached information Z1 and Z2 of users 1 and 2 are both W3, and the delivery information for

[0041] For valid point 3, the pre-cached information Z1 and Z2 of users 1 and 2 are W respectively. 3,A ,W 2,A and W 3,B ,W 2,B , delivery information for

[0042] For valid point 4, the pre-cached information Z1 and Z2 of users 1 and 2 are W respectively. 3,A ,W 2,A ,W 1,A and W 3,B ,W 2,B ,W 1,B , delivery information for

[0043] For valid point 5, the pre-cached information Z1 and Z2 of users 1 and 2 are both W3 and W2, and the delivery information for

[0044] For valid point 6, the pre-cached information Z1 and Z2 of users 1 and 2 are W3 and W 2,A ,W 1,A and W3,W 2,B ,W 1,B , delivery information for

[0045] For valid point 7, the pre-cached information Z1 and Z2 of users 1 and 2 are W respectively. 3,A ,W 2,A ,W 1,A ,W 0,A and W 3,B ,W 2,B ,W1,B ,W 0,B , delivery information for

[0046] For valid point 8, the pre-cached information Z1 and Z2 of users 1 and 2 are W3 and W3 respectively. 2,A ,W 1,A ,W 0,A and W3,W 2,B ,W 1,B ,W 0,B , delivery information for

[0047] For valid point 9, the pre-cached information Z1 and Z2 of users 1 and 2 are W3, W2, W 1,A ,W 0,A and W3,W2,W 1,B ,W 0,B , delivery information for

[0048] For valid point 10, the pre-cached information Z1 and Z2 of users 1 and 2 are both W3, W2, W1, and the delivery information for

[0049] For valid point 11, the pre-cached information Z1 and Z2 of users 1 and 2 are both W3, W2, W1, W0, and the delivery information is 0;

[0050] Furthermore, the user decoding process is designed in step 3, which specifically includes the following steps: and For user 1, the pre-cached information is W θ and W Ω,A ; For user 2, the pre-cached information is W θ and W Ω,B .

[0051] Step 3.1. From delivery information In this case, user 1 can use the pre-cached Decoded Combined with pre-caching Get the file User 2 can use the pre-cached Decoded Combined with pre-caching Get the file

[0052] Step 3.2: From delivery information In the example, user 1 can obtain the file θ∪Ω} , combined with the pre-cached W θ , available files User 2 can get the file Combined with the pre-cached W θ , available files

[0053] So, user 1 uses the obtained and Finally get the file User 2 uses the obtained and Finally get the file

[0054] The coding caching method for two users and four files under non-uniform file popularity of the present invention has the following advantages: the present invention can solve the situations of two users and three files and two users and four files. By setting the popularity probability p0=0, the situation of four files can be correspondingly transformed into the situation of three files, that is, the coding caching scheme of four files is compatible with three files. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a schematic diagram of effective points of the present invention;

[0056] Figure 2 It is a schematic diagram of the probability area of ​​the present invention;

[0057] Figure 3 It is a parameter schematic diagram of the present invention;

[0058] Figure 4 A schematic diagram of the pre-caching information and delivery information design of the present invention. DETAILED DESCRIPTION

[0059] In order to better understand the purpose, structure and function of the present invention, a coding cache method for two users and four files under non-uniform file popularity of the present invention is further described in detail below with reference to the accompanying drawings.

[0060] The present invention comprises the following steps:

[0061] Step 1: Get valid points. Assume that the popularity probabilities of files W3, W2, W1, and W0 are p3, p2, p1, and p0 respectively, and p3 ≥ p2 ≥ p1 ≥ p0. from Figure 1 , Figure 2 , Figure 3 The valid points under the probability distribution of the file popularity are obtained. Assuming that the length of each file is F bits, when the user cache When the file probabilities p3, p2, p1, p0 satisfy the probability region π k, then point k is a valid point, otherwise it is an invalid point. For example, when M = F, either point 2 is a valid point or point 3 is a valid point or both points 2 and 3 are not valid points. Points 1 and 11 are always valid points, and the corresponding probability region is π1: p3 ≥ p2 ≥ p1 ≥ p0.

[0062] Step 2: Design the pre-caching information and delivery information of the effective point. Let the pre-caching information of users 1 and 2 be Z1 and Z2 respectively, and the delivery information be X d1,d2 , where d1,d2∈{0,1,2,3} represent the indexes of the files requested by users 1 and 2 respectively. Figure 4 Designed for specific pre-caching and delivery information, file W i , i∈{0,1,2,3} is divided into two sub-files W of equal size and non-overlapping i,A and W i,B , Figure 4 Middle W Ω Represents a file collection {W i :i∈Ω},

[0063] Step 3: Design the user decoding process. For the 11 points in step 2, users can decode their requested files based on the pre-cached information and delivery information.

[0064] when and For user 1, the pre-cached information is W θ and W Ω,A ; For user 2, the pre-cached information is W θ and W Ω,B .

[0065] Step 3.1. From delivery information In this case, user 1 can use the pre-cached Decoded Combined with pre-caching Get the file User 2 can use the pre-cached Decoded Combined with pre-caching Get the file

[0066] Step 3.2: From delivery information In the example, user 1 can obtain the file Combined with the pre-cached W θ , available files User 2 can get the file Combined with the pre-cached W θ , available files

[0067] So, user 1 uses the obtained and Finally get the file User 2 uses the obtained and Finally get the file

[0068] Step 4: Cache sharing. Since the cache size of the valid point in step 1 meets the specific requirements, if the user cache size does not meet the specific requirements, it can be achieved by cache sharing between two adjacent valid points. The details are as follows:

[0069] Step 4.1: When the user cache size M satisfies M1<M<M2, the two adjacent valid points are set to and and Represents the corresponding average rate, and we can get M = αM1 + (1-α)M2, that is The average rate is defined as the expected delivery rate under all user requests, that is, in Indicates delivery information The number of bits.

[0070] Step 4.2: W i Split into two non-overlapping parts and in The length of is αF bits, The length of is (1-α)F bits.

[0071] Step 4.3: As a valid point The initial file input of the scheme obtains the pre-cached information of users 1 and 2 respectively Z1 α and Z2 α , delivery information is by As a valid point The initial file input of the scheme obtains the pre-cached information of users 1 and 2 respectively and Delivery information is

[0072] Step 4.4: For user cache size M (M1<M<M2), the pre-cache information of user 1 is The pre-cached information of user 2 is Delivery information is Accordingly, the average rate

[0073] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A two-user, four-file encoding caching method under non-uniform file popularity, characterized in that: The following steps are involved: Step 1: Get valid points: Assume that the popularity probabilities of files W3, W2, W1, and W0 are p3, p2, p1, and p0 respectively, and p3 ≥ p2 ≥ p1 ≥ p0. The size of each file is F bits. According to the probability of each file, obtain the valid points under the popularity distribution of the file; Step 2, designing pre-caching information and delivery information of effective points: according to the effective points obtained in step 1, designing corresponding pre-caching information and delivery information; Step 3: Design the user decoding process: Users decode their requested files by combining local pre-cached information and server delivery information; Step 4, cache sharing: When the user cache size is not equal to the cache size of the valid point obtained in step 1, it is necessary to use two adjacent valid points to implement the corresponding pre-cache information design, delivery information design and user decoding process design through cache sharing; In step 1, valid points are obtained according to the file popularity probability, as follows: If the file popularity probabilities p3, p2, p1, p0 satisfy the probability region π i , then point i is a valid point, otherwise it is an invalid point; Probability region π1: p3 ≥ p2 ≥ p1 ≥ p0; probability region π2: λ 1,2 ≤λ 1,3 ,λ 1,4 ,λ 1,7 ; Probability region π3:λ 1,3 ≤λ 1,2 ,λ 1,4 ,λ 1,7 ; Probability region π4: λ 1,4 ≤λ 1,7 and λ 2,4 ≤λ 2,5 , λ 2,6 , λ 2,7 , λ 2,8 , λ 3,5 , λ 3,7 ; Probability region π5: λ 4,5 ≤λ 4,6 ,λ 4,7 And 2,5 ≤λ 2,8 And 5,10 ≤λ 4,10 ; Probability region π6: λ 4,6 ≤λ 4,5 ,λ 4,7 And 2,6 ≤λ 2,8 And 6,10 ≤λ 4,10 ; Probability region π7: λ 4,7 ≤λ 4,5 ,λ 4,6 And 2,7 ≤λ 2,8 And 7,10 ≤λ 4,10 ; Probability region π8: λ 8,11 ≤λ 7,11 and λ 8,9 ≤λ 5,9 , λ 7,9 , λ 4,10 , λ 5,10 , λ 6,10 , λ 7,10 ; Probability region π9: λ 9,11 ≤λ 7,11 ,λ 8,11 ,λ 10,11 ; Probability region π 10 :λ 10,11 ≤λ 7,11 ,λ 8,11 ,λ 9,11 ; Probability region π 11 :p3≥p2≥p1≥p0; in The pre-caching information and delivery information design at each point in step 2 are as follows: File W i , i∈{0,1,2,3} is divided into two sub-files W of equal size and non-overlapping i,A and W i,B , where i represents the file number, and the sizes of the two sub-files are bits; d1,d2∈{0,1,2,3} represent the file indexes requested by users 1 and 2 respectively; when the set Use W Ω Represents a file collection {W i :i∈Ω}, and When W Ω is 0; For valid point 1, the pre-cached information Z1 and Z2 of users 1 and 2 are both 0, and the delivery information for For valid point 2, the pre-cached information Z1 and Z2 of users 1 and 2 are both W3, and the delivery information for For valid point 3, the pre-cached information Z1 and Z2 of users 1 and 2 are W respectively. 3,A ,W 2,A and W 3,B ,W 2,B , delivery information for For valid point 4, the pre-cached information Z1 and Z2 of users 1 and 2 are W respectively. 3,A ,W 2,A ,W 1,A and W 3,B ,W 2,B ,W 1,B , delivery information for For valid point 5, the pre-cached information Z1 and Z2 of users 1 and 2 are both W3 and W2, and the delivery information for For valid point 6, the pre-cached information Z1 and Z2 of users 1 and 2 are W3 and W 2,A ,W 1,A and W3,W 2,B ,W 1,B , delivery information for For valid point 7, the pre-cached information Z1 and Z2 of users 1 and 2 are W respectively. 3,A ,W 2,A ,W 1,A ,W 0,A and W 3,B ,W 2,B ,W 1,B ,W 0,B , delivery information for For valid point 8, the pre-cached information Z1 and Z2 of users 1 and 2 are W3 and W3 respectively. 2,A ,W 1,A ,W 0,A and W3,W 2,B ,W 1,B ,W 0,B , delivery information for For valid point 9, the pre-cached information Z1 and Z2 of users 1 and 2 are W3, W2, W 1,A ,W 0,A and W3,W2,W 1,B ,W 0,B , delivery information for For valid point 10, the pre-cached information Z1 and Z2 of users 1 and 2 are both W3, W2, W1, and the delivery information for For valid point 11, the pre-cached information Z1 and Z2 of users 1 and 2 are both W3, W2, W1, W0, and the delivery information is 0; Step 3 specifically includes the following steps: for the 11 points in step 2, the users can decode the files they requested according to the pre-cached information and the delivery information; when and For user 1, the pre-cached information is W θ and W Ω,A ; For user 2, the pre-cached information is W θ and W Ω,B ; Step 3.

1. From delivery information In this case, user 1 can use the pre-cached Decoded Combined with pre-caching Get the file User 2 can use the pre-cached Decoded Combined with pre-caching Get the file Step 3.2: From delivery information In the example, user 1 can obtain the file Combined with the pre-cached W θ , get the file User 2 can get the file Combined with the pre-cached W θ , get the file So, user 1 uses the obtained and Finally get the file User 2 uses the obtained and Finally get the file Step 4 specifically includes the following steps: Since the cache size of the valid point in step 1 meets the specific requirements, if the user cache size does not meet the specific requirements, it is achieved by two adjacent valid points through cache sharing, where the specific requirements refer to hour; Step 4.1: When the user cache size M satisfies M1<M<M2, the two adjacent valid points are set to and and Represents the corresponding average rate, and we get M = αM1 + (1-α)M2, that is, The average rate is defined as the expected delivery rate under all user requests, that is, in Indicates delivery information The number of bits; Step 4.2: W i Split into two non-overlapping parts and in The length of is αF bits, The length of is (1-α)F bits; Step 4.3: As a valid point The initial file input of the scheme obtains the pre-cached information of users 1 and 2 respectively Z1 α and Z2 α , delivery information is by As a valid point The initial file input of the scheme obtains the pre-cached information of users 1 and 2 respectively and Delivery information is Step 4.4: For user cache size M, where M1<M<M2, the pre-cache information of user 1 is The pre-cached information of user 2 is Delivery information is Average rate

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