Multicast transmission method of wireless WBIER

Abstract

The invention discloses a multicast transmission method of a wireless WBIER. The method comprises the following steps: a node constructs a new multicast packet and forwards the new multicast packet; after receiving the multicast packet, the node carries out a receiving processing process; wherein the new multicast packet comprises a BitString label which is used for indicating a destination node, and a NbrBitString label which is used for indicating a next-hop neighbor node set for processing the multicast packet. According to the invention, a traditional multicast routing table is removed, only a stateless unicast routing table is reserved, the multicast service cannot be perceived by an intermediate router, the record of the multicast state is transferred to the head of the multicast packet, on one hand, the multicast table of the router can be eliminated, and on the other hand, the more intelligent multicast service can be realized.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a wireless WBIER multicast transmission method. Background Art

[0002] In traditional IP multicast technology, routers retain the multicast stream status, which is not conducive to the large-scale deployment of multicast services. To solve the problem of traditional IP multicast being difficult to expand, the IETF standard organization launched BIER (Bit Indexed Explicit Replication). BIER technology can improve the multicast service carrying capacity of operator networks. Its large-scale application can greatly improve the carrying efficiency of multicast applications and reduce the cost of network expansion and construction.

[0003] In a BIER network, a router that supports BIER technology is called a Bit-Forwarding Router (BFR), and a multicast forwarding domain composed of BFRs is a BFR domain. At the edge of the BIER domain, the device that performs BFIR encapsulation on multicast data is called a Bit-Forwarding ingress Router (BFIR), and the edge BFR device that decapsulates BIER data packets is called a Bit-Forwarding egress Router (BFER). Multicast data enters the BIER domain by BFIR encapsulation, relies on the BIER header for forwarding, and leaves the BIER domain through one or more BFER devices. In the BIER domain, a device that receives and forwards BIER messages is called a forwarding BFR. A BFR can be both a BFIR or a BFER role depending on the encapsulation and decapsulation messages.

[0004] When BFR acts as BFER or BFIR, the BIER protocol must assign it a forwarding router number (BFR-id). BFR-id is numbered in subdomains, and different subdomains can share BFR-id. BFR-id uniquely identifies a router within a subdomain.

[0005] BIER multicast designs a bit string (BitString) of a specific length to represent a group of BIER routers. Starting from the lowest bit of the BitString (the rightmost bit), each bit corresponds to a BFR-id. For example, the binary string "101" with a BitString length (BSL) of 3 represents two BIER routers with BFR-ids 1 and 3.

[0006] BIER's forwarding table BIFT is a key technology of BIER. The BIFT forwarding table consists of two items, namely: FBM and NBR (Next BFR). The physical meaning of FBM is to indicate the set of BIER subdomain edge nodes that can be reached through the neighbor when BFR replicates and sends multicast messages to the next-hop neighbor. Since the routing table is formed through the optimal path, each string of FBM in BIFT (routing table conversion) also represents the set of other BIER nodes that can be reached through the corresponding neighbor node in an optimal path manner.

[0007] However, the traditional BIER scheme cannot make good use of the broadcast characteristics of wireless signals, resulting in ineffective duplication of too many multicast packets, which not only wastes wireless bandwidth but also increases the probability of collision of wireless link layer packet transmission. Therefore, it is necessary to invent an efficient multicast transmission technology that adapts to the wireless environment. Summary of the invention

[0008] To achieve the above objectives, the present invention provides a highly efficient multicast transmission technology WBIER in wireless environments, which greatly increases the transmission efficiency of wireless networks. The benefits brought by the present invention will increase as the scale of the wireless network increases, and it is particularly suitable for high-density, high-coverage wireless networks.

[0009] The specific technical solutions are as follows:

[0010] A wireless WBIER multicast transmission method, specifically comprising:

[0011] The node constructs a new multicast packet and forwards it;

[0012] After receiving the multicast packet, the node performs the receiving processing;

[0013] The multicast grouping includes:

[0014] BitString tag, used to indicate the destination node;

[0015] NbrBitString tag, used to indicate the set of next-hop neighbor nodes that process the multicast packet.

[0016] Furthermore, the node constructs a new multicast packet and forwards it, which specifically includes the following steps:

[0017] Step A1: Node M copies the obtained BitString label and obtains the set of next-hop neighbor nodes based on BIER technology.

[0018] Step A2: construct a new NbrBitString tag;

[0019] Step A3: Combine the BitString label in step A1 and the NbrBitString label in step A2 to obtain a multicast group of node M;

[0020] Step A4: Node M sends a new copy of the multicast packet to all surrounding neighbor nodes.

[0021] Furthermore, in step A2, constructing a new NbrBitString tag specifically includes the following steps:

[0022] Step S10: j=1; Note: j is the index of the BIFT table;

[0023] Step S11: Perform a bitwise AND operation on the BitString and the FBM[j] of BIFT, namely:

[0024] BS[j] = BitString & FBM[j];

[0025] Step S12: If BS[j] is not 0, then put the next hop NBR corresponding to FBM[j] into the set Φ;

[0026] Step S13: To prevent repeated processing of bits with a bit value of 1 in BitString, the following operation is performed on the copy of BitString, namely: BitString = BitString&~FBM[j];

[0027] Step S14: If the copied BitString is not 0, go to step S15, otherwise go to step S16

[0028] Step S15: j=j+1, go to step S11;

[0029] Step S16: Construct an NbrBitString label using the next hop NBR stored in the set Φ.

[0030] Furthermore, after receiving the multicast packet, the node performs a receiving process, which specifically includes the following steps:

[0031] Step B1, check the NbrBitString tag in the packet header to determine whether it is in the NbrBitString, if yes, continue to execute;

[0032] Step B2: Use the address y of the previous hop neighbor sending node of the multicast packet to search the BIFT table and obtain entry j, thereby obtaining the corresponding FBM(j);

[0033] Step B3, remove FBM(j) from the BIFT table and the FBMs corresponding to the nodes in NbrBitString except for node M, and perform a bitwise OR operation on all the remaining FBMs to obtain the IFBM. The specific formula is:

[0034] IFBM=∑ i∈Ω,i≠j,i≠m,m∈Ω, 0|FBM(i) (1)

[0035] Wherein, Ω represents the set of FBMs in the BIFT table; m represents the index number of the FBM corresponding to the node other than node M in NbrBitString, and | represents an OR operation;

[0036] Step B4: If IFBM=NULL, remove the multicast packet label and deliver the multicast packet to the upper layer; otherwise, proceed to step B5;

[0037] Step B5: perform a bitwise AND operation on the BitString of the received multicast packet and the IFBM to obtain the BitString of the multicast packet to be sent by the next hop of the M node. The specific formula is:

[0038] BitString=BitString&IFBM (2)

[0039] Among them, & represents the AND operation.

[0040] Furthermore, FBM represents a set of destination nodes that can be reached through the corresponding public next-hop node in an optimal path manner; IFBM represents a set of destination nodes to which a packet received from a certain ingress port can be allowed to be forwarded.

[0041] According to one aspect of the present invention, a storage medium is provided, wherein instructions are stored in the storage medium, and when a computer reads the instructions, the computer is enabled to execute any one of the wireless WBIER multicast transmission methods described above.

[0042] According to another aspect of the present invention, there is provided an electronic device, comprising a processor and the above-mentioned storage medium, wherein the processor executes instructions in the storage medium.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. The WBIER of the present invention solves the defects of BIER technology in the application of wireless networks, fully utilizes the broadcast characteristics of wireless signals, ensures that only one multicast packet is sent to the surrounding neighbor nodes, greatly increases the transmission efficiency of the wireless network, and not only increases the wireless bandwidth utilization, but also reduces the conflict probability of wireless link layer packet transmission. The benefits brought by the present invention will increase with the increase of the scale of the wireless network, and is particularly suitable for high-density and high-coverage wireless networks.

[0045] 2. The present invention removes the traditional multicast routing table and only retains the stateless unicast routing table, so that the intermediate routers cannot perceive the multicast service.

[0046] 3. The record of the multicast state of the present invention is transferred to the header of the multicast packet, which can eliminate the multicast table of the router on the one hand and realize a more intelligent multicast service on the other hand. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0048] Figure 1 A schematic diagram of the workflow of WBIER according to an embodiment of the present invention;

[0049] Figure 2 A schematic diagram of generating a BIER transfer table according to an embodiment of the present invention;

[0050] Figure 3 A schematic diagram of a BIER forwarding mechanism in a fixed communication network according to an embodiment of the present invention;

[0051] Figure 4 A schematic diagram of a traditional BIER forwarding mechanism for a wireless network according to an embodiment of the present invention;

[0052] Figure 5 A schematic diagram of a wireless network structure and multicast message forwarding according to an embodiment of the present invention;

[0053] Figure 6 A schematic diagram of constructing a multicast grouping for source node A in an embodiment of the present invention;

[0054] Figure 7 A schematic diagram of receiving and forwarding a multicast packet by a node B according to an embodiment of the present invention;

[0055] Figure 8 A schematic diagram of node C receiving and forwarding a multicast packet according to an embodiment of the present invention;

[0056] Fig. 9 This is a schematic diagram of destination node E receiving a multicast packet according to an embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0058] like Figure 1 As shown, the specific working steps of WBIER are as follows:

[0059] Step S1: Each BIER router in the network constructs multiple BIFT forwarding tables based on the routing table. Each BIFT contains two fields, namely: FBM and Nbr. The form of BIFT is as follows Figure 2 shown.

[0060] Step S2: If the node is a source node, the source node obtains the multicast member through the control layer to construct the BitString of the multicast packet and proceeds to step S7, otherwise proceeds to step S3.

[0061] Step S3: After receiving the multicast packet, the node first checks the NbrBitString tag in the packet header to determine whether its own BFR id is in the NbrBitString. If yes, it will execute step S4, otherwise it will discard the multicast packet and skip the following steps;

[0062] Step S4: Use the address y of the previous hop sending node of the multicast packet to search the BIFT table, find entry k, and obtain FBM(k) from the entry.

[0063] Step S5: Remove the FBM(k) in the BIFT table and the FBM corresponding to the node in NbrBitString (excluding the node that is processing the message), and perform a bitwise "OR" operation on all the remaining FBMs to obtain the IFBM, that is:

[0064] IFBM=∑ i∈Ω,i≠j,i≠m,m∈Ω, 0|FBM(i) (1)

[0065] Where Ω is the set of FBMs in the BIFT table, and m is the index number of the FBM corresponding to the node in NbrBitString (excluding the node that is processing the message).

[0066] Step S6: If IBFM is not empty, go to step S7, otherwise strip the NbrBitString and BitString labels in the header of the multicast packet, and then submit it to the upper layer, and end the following steps.

[0067] Step S7: Perform a bitwise AND operation on the BitString of the received multicast packet and the IFBM to obtain the BitString of the multicast packet to be sent by the next hop, that is:

[0068] BitString=BitString&IFBM (2)

[0069] Step S8: WBS = BitString. Search for bits with a value of "1" from the lowest bit to the highest bit in the BitString, and compare the bit k (bit corresponding to BFR id) corresponding to the value of "1" with the ID number of the router one by one.

[0070] Step S9: If the same description reaches the destination node, the destination node strips off the BitString tag and then submits it to the upper layer, ending the following steps, otherwise proceeding to step S10.

[0071] Step S10: j=1; Note: j is the index of the BIFT table;

[0072] Step S11: Perform a bitwise AND operation on the BitString and the FBM[j] of BIFT, namely:

[0073] BS[j] = BitString & FBM[j];

[0074] Step S12: If BS[j] is not 0, then put the next hop NBR corresponding to FBM[j] into the set Φ;

[0075] Step S13: To prevent repeated processing of bits with a bit value of 1 in BitString, the following operation is performed on the copy of BitString, namely: BitString = BitString&~FBM[j];

[0076] Step S14: If the copied BitString is not 0, go to step S15, otherwise go to step S16

[0077] Step S15: j=j+1, go to step S11;

[0078] Step S16: construct an NbrBitString label using the next hop NBR stored in the set Φ;

[0079] Step S17: The node puts the BitString tag (indicating the destination node) and the NbrBitString tag (indicating the next-hop neighbor node that processes the multicast packet) stored in the WBS into the newly constructed multicast packet.

[0080] Step S18: The node sends the newly constructed multicast packet to surrounding neighbor nodes only once, and deletes the original multicast packet.

[0081] BIER's forwarding table BIFT is a key technology of BIER, such as Figure 2As shown, the BFR-prefix routing table (BIRT) of R1, R2, R3, R5, and R6 is calculated on the R7 router, that is, the routing table corresponding to the BFR-id. R4 combines several BFR-ids (1:000001, 1:000010, 1:010000) of the same R8 export in the BIRT to form a forwarding bit mask (ForwardBitMask, FBM) (1:000111), and combines several BFR-ids (1:10000, 1:010000) of the same R4 export in the BIRT to form a forwarding bit mask (1:110000), that is, generating the BFR forwarding table (BIFT).

[0082] like Figure 3 As shown, source node A first searches its routing table and finds that the identifiers of the multicast member nodes are: D (0001), F (0010), and E (0100). Source node A first constructs BitString (0111), encapsulates the LS message with it, and then sends it to the next hop node B.

[0083] After node B receives the multicast message sent by the source node, it uses the BitString (0111) of the multicast packet and its own BIFT table. The specific operations are as follows: 1. The first operation performed by node B is: BS[1] = BitString & FBM[1] = 0111 & 0011 = 0011. Node B constructs multicast packet M1. The label encapsulated in the header of multicast packet M1 is (0011), and multicast packet M1 is sent to the next hop node C corresponding to FBM[1]. 2. Node B performs the following operation on the BitString of the original multicast packet, namely: BitString = BitString & ~FBM[1] = 0111 & ~0011 = 0111 & 1100 = 0100. 3. Node B performs the following operation: BS[2] = BitString & FBM[2] = 0100 & 0100 = 0100, and Node B constructs multicast packet M2, the header of which is encapsulated with 0100, and sends multicast packet M2 to the next hop node E corresponding to FBM[2]. 4) Node B performs the following operation on the BitString of the original multicast packet, namely: BitString = BitString & ~FBM[2] = 0100 & ~0100 = 0.

[0084] After receiving the multicast message M2 sent by node B, node E finds that BitString (0100) is the same as its own node number 0100. Node E strips off the encapsulated label header, takes out the multicast message, and then processes it.

[0085] Node C processes the multicast message M1 in exactly the same way as node B does.

[0086] Nodes D and F process multicast messages in the same way as node E.

[0087] The above traditional BIER forwarding mechanism works well in fixed networks, but it is not suitable for wireless networks. Figure 4 For example, if wireless links are used between BIER routers, the scenario becomes the forwarding of the traditional BIER forwarding mechanism in the wireless network. Now let's look at the situation of router B forwarding multicast packets. Through a series of operations, router B copies the multicast packet forwarded by router A into two multicast packets with BS "0011" and BS "0100" (the two multicast packets have exactly the same payload), and sends them to routers C and E respectively. However, routers C and E can receive the wireless signal sent by router B at the same time. This not only wastes wireless bandwidth, but may also greatly increase the probability of packet transmission conflicts at the wireless link layer.

[0088] Embodiment 1: Wireless network structure and source node constructing multicast packets

[0089] Figure 5 This is the network topology of this example. The wireless nodes in the network learn the network topology through a routing protocol (such as the OLSR wireless routing protocol) and construct a routing table. Then, each node constructs a BIFT table through the routing table. The method for constructing the BIFT table is as follows: Figure 1 shown.

[0090] exist Figure 5 Each node in the displayed network is connected by a wireless link. Nodes within one hop are adjacent nodes and are within the wireless communication range of each other. Nodes two hops or more away must communicate through multi-hop wireless relay. For example: for the signal sent by node B, nodes A, C, and E can all receive the signal, but nodes D and F cannot receive the signal sent by node B. To establish a communication relationship between node B and node D, it must be forwarded through node C.

[0091] exist Figure 5 Displays the transmission of multicast packets sent by source node router A. During multicast transmission, nodes B and C are forwarding nodes, D, E, and F are leaf nodes, and each node is assigned a BFR-id. The use of WBIER and BIER in the network is very different. The wireless router only forwards multicast packets once to the adjacent router, which solves the problem of redundant multicast copies.

[0092] Figure 6This is the case where source node A constructs a multicast packet. The multicast members obtained by source node A through the control layer are: D (000001), F (000010) and E (000100), and then they are used to construct the BitString (000111) of the multicast packet. The BitString (000111) is stored in WBS, and then the FBM[1] and BitString are operated on "AND", that is: BitString = BitString & FBM[1] = 000111 & 110111 = 000111, then the next hop B (010000) corresponding to FBM[1] is put into the set Φ, and the following operation is performed on the BitString: BitString = BitString & ~ FBM[1] = 000111 & 001000 = 0. Node A constructs a multicast packet. The header of the multicast packet contains two parts, where BitString (000111) is taken from WBS and NbrBitString (010000) is generated by the next hop node in the set Φ. Node A sends the constructed multicast packet to neighboring nodes.

[0093] Embodiment 2: Wireless network node processes and forwards multicast packets

[0094] Figure 7 This is the processing of node B after receiving the multicast packet. Node B first checks the NbrBitString in the multicast packet header, finds its own BFR-id in the NbrBitString, and then does the following:

[0095] 1. Since the multicast packet received by node B is sent from node A, node B calculates IFBM, that is, IFBM = FBM[1] | FBM[2] = 000011 | 0001000 = 000111;

[0096] 2. Calculate BitString = BitString & IFBM = 000111 & 000111 = 000111, and store BitString in WBS; Node B finds that its BFR-id (010000) is not in BitString, and continues with the following steps;

[0097] 3. Node B uses BitString to perform an AND operation with FBM[1] and FBM[2] (the reason for not performing an operation with FBM[3] is that the Nbr corresponding to FBM[3] is node A). The details are as follows:

[0098] BitString=BitString&FBM[1]=000111&000011=000011(not 0); put the node C of Nbr corresponding to FBM[1] into the set Φ, that is: Φ={C}; BitString=original BitString&~FBM[1]=000111&111100=000100;

[0099] BitString=BitString&FBM[2]=000100&000100=000100(not 0); put the node E of Nbr corresponding to FBM[2] into the set Φ, that is: Φ={C,E}; BitString=BitString&~FBM[2]=000100&111011=000000;

[0100] 4. Node B constructs a multicast packet. The multicast packet header contains two parts, where BitString (000111) is taken from WBS and NbrBitString (100100) is generated by the set Φ = {C, E}. Node B sends the constructed multicast packet to the surrounding neighbor nodes once;

[0101] Figure 8 This is the processing of node C after receiving the multicast packet sent by node B. Node C first checks the NbrBitString (100100) in the header of the multicast packet, finds that its own BFR-id is in the NbrBitString, and then performs the following processing:

[0102] 1. Remove the FBM corresponding to node B in the BIFT table and the FBM corresponding to the nodes in NbrBitString (excluding node C), and perform a bitwise "OR" operation on all the remaining FBMs to obtain the IFBM, that is, IFBM = FBM[1] | FBM[2] = 000001 | 0000010 = 000011;

[0103] 2. Calculate BitString = BitString & IFBM = 000111 & 000011 = 000011, and store BitString in WBS; Node C finds that its BFR-id (010000) is not in BitString, and continues with the following steps;

[0104] 3. Node B uses BitString to perform an AND operation with FBM[1] and FBM[2] (the reason for not performing an operation with FBM[3] is that the Nbr corresponding to FBM[3] is node B). The details are as follows:

[0105] BitString=BitString&FBM[1]=000011&000001=000001(not 0); put the node D of Nbr corresponding to FBM[1] into the set Φ, that is: Φ={D}; BitString=original BitString&~FBM[1]=000011&111110=000010;

[0106] BitString=BitString&FBM[2]=000010&000010=000010(not 0); put the node F of Nbr corresponding to FBM[2] into the set Φ, that is: Φ={D,F}; BitString=BitString&~FBM[2]=000010&111101=000000;

[0107] 4. Node C constructs a multicast packet. The header of the multicast packet contains two parts, where BitString (000011) is taken from WBS and NbrBitString (000011) is generated by the set Φ = {D, F}. Node C sends the constructed multicast packet to its neighboring nodes once.

[0108] Fig. 9 This is the processing of node E after receiving the multicast packet sent by node B. Node E first checks the NbrBitString (100100) in the header of the multicast packet, finds that its own BFR-id is in the NbrBitString, and then performs the following processing:

[0109] 1. Remove the FBM corresponding to node B in the BIFT table and the FBM corresponding to the nodes in NbrBitString (excluding node E), and perform a bitwise "OR" operation on all the remaining FBMs to obtain the IFBM, that is, IFBM = NULL, which indicates that the multicast packet has reached the destination node;

[0110] 2. Node E strips off the NbrBitString and BitString labels in the multicast packet header and then submits it to the upper layer for processing.

[0111] The process of destination nodes F and D processing multicast packets is the same as the process of node E processing multicast messages.

[0112] The examples described in the present invention are merely descriptions of the preferred implementation modes of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by engineers and technicians in this field should all fall within the protection scope of the present invention.

Claims

1. A wireless WBIER multicast transmission method, characterized in that: Specifically include: The node constructs a new multicast packet and forwards it; After receiving the multicast packet, the node performs the receiving processing; The multicast grouping includes: BitString tag, used to indicate the destination node; NbrBitString tag, used to indicate the set of next-hop neighbor nodes that process the multicast packet.

2. The method according to claim 1, characterized in that The node constructs a new multicast packet and forwards it, which includes the following steps: A1. Node M copies the obtained BitString label and obtains the set of next-hop neighbor nodes based on BIER technology. A2. Construct a new NbrBitString tag; A3, combining the BitString label in step A1 and the NbrBitString label in step A2 to obtain a multicast grouping of node M; A4. Node M sends a new copy of the multicast packet to all surrounding neighbor nodes.

3. The method according to claim 2, characterized in that In step S02, a new NbrBitString tag is constructed. The following steps are involved: Step S10: j=1; Note: j is the index of the BIFT table; Step S11: Perform a bitwise AND operation on the BitString and the FBM[j] of BIFT, namely: BS[j] = BitString & FBM[j]; Step S12: If BS[j] is not 0, then put the next hop NBR corresponding to FBM[j] into the set Φ; Step S13: To prevent repeated processing of bits with a bit value of 1 in BitString, the following operation is performed on the copy of BitString, namely: BitString = BitString&~FBM[j]; Step S14: If the copied BitString is not 0, go to step S15, otherwise go to step S16 Step S15: j=j+1, go to step S11; Step S16: Construct an NbrBitString label using the next hop NBR stored in the set Φ.

4. The method according to claim 1, characterized in that: After receiving the multicast packet, the node performs the receiving process, which specifically includes the following steps: B1. Check the NbrBitString tag in the packet header to determine whether it is in the NbrBitString. If so, continue to execute; B2. Use the address y of the previous hop neighbor sending node of the multicast packet to search the BIFT table and obtain entry j, thereby obtaining the corresponding FBM(j); B3. Remove FBM(j) from the BIFT table and the FBMs corresponding to the nodes in NbrBitString except for node M, and perform a bitwise OR operation on all the remaining FBMs to obtain the IFBM. The specific formula is: IFBM=∑ i∈Ω,i≠j,i≠m,m∈Ω, 0|FBM(i) (1) Wherein, Ω represents the set of FBMs in the BIFT table; m represents the index number of the FBM corresponding to the node other than node M in NbrBitString, and | represents an OR operation; B4. If IFBM=NULL, remove the multicast packet label and deliver the multicast packet to the upper layer, otherwise go to step B5; B5. Perform a bitwise AND operation on the BitString of the received multicast packet and the IFBM to obtain the BitString of the multicast packet to be sent by the next hop of the M node. The specific formula is: BitString=BitString&IFBM (2) Among them, & represents the AND operation.

5. The method according to claim 4, characterized in that FBM represents the set of destination nodes that can be reached through the corresponding public next-hop node in an optimal path manner; IFBM represents the set of destination nodes to which a packet received from a certain ingress port can be forwarded.

6. A storage medium, characterized in that: The storage medium stores instructions, and when a computer reads the instructions, the computer executes the wireless WBIER multicast transmission method according to any one of claims 1 to 6.

7. An electronic device, characterized in that: The invention comprises a processor and the storage medium as claimed in claim 6, wherein the processor executes instructions in the storage medium.

Images