Transmission method based on NDN, vehicle speed and distance in Internet of Vehicles

Abstract

The invention discloses a transmission method based on NDN (Named Data Networking), vehicle speed and distance in the Internet of Vehicles, which is particularly suitable for the Internet of Vehicles needing to transmit a large amount of data. The invention provides a method for constructing a dynamic transmission path on the basis of NDN (Named Data Networking) network content-oriented property, vehicle speed and inter-vehicle distance information in order to solve the problems that a transmission path needs to be specified on the basis of a traditional TCP / IP (Transmission Control Protocol / Internet Protocol) network and the high dynamic nature of the Internet of Vehicles easily causes frequent disconnection of the transmission path. Firstly, a plurality of forwarding vehicles are selected in the Internet of Vehicles in a limited broadcast mode; secondly, a PIT table and an FIB table in the NDN network are expanded, and coordinate information of the content requesting vehicle and coordinate information of the content providing vehicle are recorded in the PIT table and the FIB table respectively; finally, in the forwarding process of the interest packet and the data packet, based on the speed of the vehicle and the distance between the vehicle and the content providing vehicle and the distance between the vehicle and the content requesting vehicle, forwarding vehicles are dynamically selected for forwarding the interest packet and the data packet, so that the transmission performance is improved.

Description

Technical Field

[0001] The present invention relates to the field of wireless multi-hop networks, and more specifically to a method for content transmission in an Internet of Vehicles with high node mobility. More specifically, the present invention relates to a content-oriented NDN network and based on vehicle speed and distance information, and proposes a transmission method in an Internet of Vehicles based on NDN and vehicle speed and distance. Background Art

[0002] With the rapid development of Internet technology, wireless access has gradually become the mainstream choice for connecting to the network. As a typical application of Internet of Things technology in the field of transportation, the Internet of Vehicles has not only promoted the construction of an intelligent traffic management system, but also promoted the development of intelligent dynamic information services and vehicle control technology. In this context, efficient content transmission has become the basis for supporting the normal operation of various functions of the Internet of Vehicles.

[0003] For application scenarios such as in-car entertainment and smart navigation, the moving car plays the role of a data requester, and needs to request the required information from other vehicles or roadside facilities around it. These interactions may involve direct communication within a single hop, or may span multiple nodes to complete the data transmission task.

[0004] However, the current mainstream TCP / IP protocol system is not fully applicable to the wireless network requirements in highly dynamic environments, especially in the face of a highly mobile scenario such as the Internet of Vehicles. Traditionally, we are accustomed to directly migrating protocols designed based on fixed network architecture to the wireless field. For example, the unicast mode based on IP addresses is widely used in content distribution. This mechanism requires an optimal path to be established between the source and the target, and each data packet is forwarded step by step along this path. Unfortunately, this method fails to fully utilize the natural broadcast characteristics of wireless signals; coupled with the constant changes in the locations of participants, the selected optimal route is prone to frequent breaks, further exacerbating the complexity of the problem. Summary of the invention

[0005] The purpose of the present invention is to solve the above problems in the prior art and to propose a transmission method based on NDN and vehicle speed and distance in the Internet of Vehicles.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A transmission method based on NDN and vehicle speed and distance in an Internet of Vehicles, the transmission method comprising the following steps:

[0008] S1. Each vehicle in the IoV extends the PIT table and FIB table in the NDN network, records the coordinate information of the content requesting vehicle in the PIT table, and records the coordinate information of the content providing vehicle in the FIB table;

[0009] S2. The content requesting vehicle broadcasts the first interest packet when the target content is needed; after receiving the interest packet, other vehicles decide whether to continue forwarding in a limited broadcast manner, that is, after receiving the interest packet, they wait for a random time T1. If during this time, they hear that other neighboring vehicles have forwarded the interest packet, the vehicle cancels the forwarding, otherwise the vehicle will forward the interest packet after the random time ends until the interest packet reaches the maximum number of hops or is received by a vehicle with content cached; all vehicles that forward the interest packet are recorded as forwarding vehicles, and the information of the interest packet is recorded in their PIT tables;

[0010] S3. After receiving the interest packet, the vehicle with the content cached returns the first data packet of the content. All forwarding vehicles must forward the data packet and add the information of the data packet to the FIB table during the forwarding process.

[0011] S4. If the content requesting vehicle receives the first data packet of the content sent by multiple content caching vehicles, the caching vehicle corresponding to the first received data packet is selected as the subsequent content providing vehicle, and a subsequent interest packet is sent to the vehicle to request the corresponding data packet;

[0012] S5. The forwarding rule of subsequent interest packets is: after receiving the interest packet, the forwarding vehicle waits for a random time T2, the length of which is related to the speed difference between the forwarding vehicle and the sending vehicle, and the distance between the forwarding vehicle and the content providing vehicle; if during the random time, the forwarding vehicle monitors that there are other forwarding vehicles that are closer to the content providing vehicle than itself, or whose distance to the content providing vehicle is less than the one-hop communication distance of the wireless signal, and have forwarded the interest packet, then the forwarding vehicle cancels the forwarding of the interest packet, otherwise the forwarding vehicle will forward the interest packet after the random time ends;

[0013] S6. After receiving the interest packet, the content providing vehicle returns the corresponding data packet;

[0014] S7. The data packet is forwarded using the following rules until the content requesting vehicle: after receiving the data packet, the forwarding vehicle waits for a random time T3, the length of which is related to the speed difference between the forwarding vehicle and the sending vehicle, and the distance between the forwarding vehicle and the content requesting vehicle; if within this random time, the forwarding vehicle monitors that other forwarding vehicles that are closer to the requesting vehicle than itself or whose distance to the requesting vehicle is less than the one-hop communication distance of the wireless signal have forwarded the data packet, the forwarding vehicle cancels the forwarding of the data packet, otherwise the forwarding vehicle will forward the data packet after the random time ends.

[0015] Furthermore, the PIT table records "content name", "data packet number", "requester ID" and "requester coordinates", and the FIB table records "content name", "data packet number", "provider ID" and "provider coordinates".

[0016] Furthermore, the interest packet for searching the content includes the information of "content name", "data packet number", "requester identifier", "requester coordinates", "forwarding vehicle identifier", "forwarding vehicle coordinates", "forwarding vehicle speed" and "remaining maximum forwarding hops". If the forwarding vehicle needs to forward the interest packet, the "content name", "data packet number", "requester identifier" and "requester coordinates" information are added to the PIT table during forwarding, and the "forwarding vehicle identifier", "forwarding vehicle coordinates" and "forwarding vehicle speed" information in the interest packet are updated to the corresponding values ​​of the current forwarding vehicle, and the "remaining maximum forwarding hops" are reduced by 1 before forwarding the interest packet.

[0017] Furthermore, the data packet contains "content name", "requester identifier", "provider identifier", "provider coordinates", "forwarding vehicle identifier", "forwarding vehicle coordinates" and "forwarding vehicle speed" information. If the forwarding vehicle needs to forward the data packet, the "content name", "data packet sequence number", "provider identifier" and "provider coordinates" information are added to the FIB table when forwarding the data packet, and the "forwarding vehicle identifier", "forwarding vehicle coordinates" and "forwarding vehicle speed" information in the data packet are updated to the current forwarding vehicle before forwarding the data packet.

[0018] Furthermore, in the restricted broadcast mechanism of the first interest packet sent by the content requester for finding content, the random waiting time of the forwarding vehicle is:

[0019] T1=random{1,W}*slotTime (1)

[0020] Among them, W is a fixed integer (such as 100), random{1, W} represents a random integer between 1 and W, and slotTime is the unit backoff duration of the IEEE 802.11p protocol adopted by the Internet of Vehicles at the link layer.

[0021] Furthermore, the forwarding vehicle can calculate the distance between the content providing vehicle and the requesting vehicle through the providing vehicle coordinates in the FIB table and the requesting vehicle coordinates in the PIT table; calculate the distance between the previous hop forwarding vehicle and the content providing vehicle through the "forwarding vehicle coordinates" information in the received interest packet and the content providing vehicle coordinates in the FIB table, and calculate the distance between the previous hop forwarding vehicle and the content requesting vehicle through the "forwarding vehicle coordinates" information in the received data packet and the content requesting vehicle coordinates in the PIT table; calculate the distance between the vehicle and the content providing vehicle and the content requesting vehicle respectively through the vehicle's own coordinates and the coordinate information in the FIB table and the PIT table.

[0022] Furthermore, after the content providing vehicle is determined, during the forwarding process of the interest packet, the random waiting time of the forwarding vehicle after receiving the interest packet is:

[0023]

[0024] Among them, V s is the speed of the previous hop forwarding vehicle, V r is the current forwarding vehicle speed, ΔV=|V r -V s |, W is a fixed integer (such as 100), D p is the distance between the current forwarding vehicle and the content providing vehicle, D rp is the distance between the content providing vehicle and the content requesting vehicle, and slotTime is the unit backoff duration of the IEEE 802.11p protocol adopted by the Internet of Vehicles at the link layer.

[0025] Furthermore, after receiving the data packet, the forwarding vehicle randomly waits for:

[0026]

[0027] Among them, V s is the speed of the previous hop forwarding vehicle, V r is the current forwarding vehicle speed, ΔV=|V r -V s |, W is a fixed integer (such as 100), D r is the distance between the current forwarding vehicle and the requesting vehicle, D rp is the distance between the content providing vehicle and the content requesting vehicle, and slotTime is the unit backoff duration of the IEEE 802.11p protocol adopted by the Internet of Vehicles at the link layer.

[0028] Compared with the prior art, the present invention has the following advantages and effects:

[0029] (1) The Internet of Vehicles in the present invention can use broadcasting to transmit content, thereby increasing the robustness of the transmission link.

[0030] (2) The present invention constructs a dynamic transmission path based on vehicle speed and distance in the Internet of Vehicles, thereby improving the content transmission performance of the Internet of Vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of vehicle networking content transmission of the present invention;

[0032] Figure 2 It is the extended PIT table and FIB table of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example

[0035] like Figure 1 The schematic diagram of content transmission in the Internet of Vehicles is shown, where vehicle R is a content request vehicle and vehicle P is a providing vehicle with target content cached. The target content is divided into several data packets in vehicle P. Content transmission can be divided into two stages: content search and content acquisition.

[0036] 1) Content search phase

[0037] The requester R broadcasts the first interest packet of the search content; other vehicles in the connected vehicle network will forward it in a limited broadcast manner. For example, when R broadcasts the interest packet, A1, A2, A3, A4, and A5 all receive the interest packet, and they will wait for a random time T:

[0038] T=random{1,W}*slotTime (1)

[0039] Among them, W is a fixed integer (such as 100), random{1, W} represents a random integer between 1 and W, and slotTime is the unit backoff duration of the IEEE 802.11p protocol adopted by the Internet of Vehicles at the link layer. A4 and A5 heard during the waiting time that other neighboring nodes have forwarded the interest packet, so they will cancel the forwarding. On the contrary, A1, A2, and A3 did not hear any neighboring node forwarding the interest packet during their waiting time, so they will continue to forward the interest packet. Similarly, B1, B2, and B3 also forwarded the interest packet after receiving it. Moreover, when forwarding the interest packet, each vehicle will update the requesting vehicle related information in the PIT table according to the information in the interest packet. Such as Figure 2 As shown in (a), based on the information in the interest packet, the content name, data packet flag, requester identifier, and requester coordinate information are recorded in the PIT table of the forwarding vehicle.

[0040] Vehicles A1, A2, A3, B1, B2, and B3 all forwarded the interest packet during this process, so they will become the forwarding vehicles for the next interest and data packets.

[0041] After vehicle P receives the first interest packet, it returns the first data packet of the content, and all forwarding vehicles will forward the data packet; and in the forwarding process, the relevant information of the providing vehicle is recorded in the FIB table, such as Figure 2 (b) as shown.

[0042] 2) Content acquisition stage

[0043] The requesting vehicle sends subsequent interest packets to the content providing vehicle, and the content providing vehicle returns the corresponding data packets.

[0044] After the requesting vehicle R sends the interest packet, the forwarding vehicles A1, A2, and A3 will participate in the forwarding process of the interest packet and determine whether to actually forward it. After they receive the interest packet, they wait for a random time:

[0045]

[0046] Among them, V s is the speed of the sending vehicle R, V r is the speed of the current receiving and forwarding vehicle, ΔV=|V r -V s |, W is a fixed integer (such as 100), D p is the distance between the current forwarding vehicle and the content providing vehicle, D rp is the distance between the content providing vehicle and the content requesting vehicle, and slotTime is the unit backoff duration of the IEEE 802.11p protocol adopted by the Internet of Vehicles at the link layer.

[0047] If A1 hears that A2 or A3 has forwarded the interest packet during its waiting time, and the distance between A2 or A3 and the providing vehicle is less than its own distance from the providing vehicle, then A1 will cancel the forwarding, otherwise it will continue to forward the interest packet. The same applies to A2 and A3. Assume that A2 continues to forward the interest packet during this process, and A1 and A3 hear that A2 has sent it, and A1 and A3 find through calculation that A2 is closer to the content providing vehicle, so they will cancel the forwarding.

[0048] Next, after receiving the interest packet sent by A2, B1, B2, and B3 will also wait for a random time calculated by formula (2) to monitor whether other nodes have forwarded the interest packet. Assuming that B1's random time arrives first, it will forward the interest packet; B2 and B3 monitor that B1 has forwarded it, and they find through calculation that the distance between B1 and the providing vehicle P is less than the one-hop distance of the wireless signal, so B2 and B3 will cancel the forwarding.

[0049] Finally, all forwarding vehicles decide whether to forward the interest packet according to the above rules until vehicle P is provided.

[0050] After vehicle P receives the interest packet, it will return the corresponding data packet. After B1, B2 and B3 receive the data packet sent by P, they wait for a random time:

[0051]

[0052] Among them, V s is the speed of the sending vehicle P, V r is the speed of the current receiving and forwarding vehicle, ΔV=|V r -V s |, W is a fixed integer (such as 100), D r is the distance between the current forwarding vehicle and the requesting vehicle, D rp is the distance between the content providing vehicle and the content requesting vehicle, and slotTime is the unit backoff duration of the IEEE 802.11p protocol adopted by the Internet of Vehicles at the link layer.

[0053] If B1 detects that B2 or B3 has forwarded the data packet within the random time calculated by formula (3), and B2 or B3 is closer to the content requesting vehicle than itself, it will cancel the forwarding, otherwise it will continue to forward. The forwarding rules of B2 and B3 are the same as B1. Assuming that after B1 forwards the data packet, A1, A2, and A3 receive the data packet, they will wait for a random time calculated by formula (3). Assuming that A2 arrives at its random time first, it will forward the data packet, and after A1 and A3 detect the data packet sent by A2, they find that A2 is within one hop of the requesting vehicle R, so they will cancel the forwarding.

[0054] Finally, all forwarding vehicles decide whether to forward the data packet according to the above rules until the requester vehicle.

[0055] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A transmission method based on NDN and vehicle speed and distance in a vehicle network, characterized in that: The transmission method comprises the following steps: S1. Each vehicle in the IoV extends the PIT table and FIB table in the NDN network, records the coordinate information of the content requesting vehicle in the PIT table, and records the coordinate information of the content providing vehicle in the FIB table; S2. The content requesting vehicle broadcasts the first interest packet when the target content is needed; after receiving the interest packet, other vehicles decide whether to continue forwarding in a limited broadcast manner, that is, after receiving the interest packet, they wait for a random time T1. If during this time, they hear that other neighboring vehicles have forwarded the interest packet, the vehicle cancels the forwarding, otherwise the vehicle will forward the interest packet after the random time ends until the interest packet reaches the maximum number of hops or is received by a vehicle with content cached; all vehicles that forward the interest packet are recorded as forwarding vehicles, and the information of the interest packet is recorded in their PIT tables; S3. After receiving the interest packet, the vehicle with the content cached returns the first data packet of the content. All forwarding vehicles must forward the data packet and add the information of the data packet to the FIB table during the forwarding process. S4. If the content requesting vehicle receives the first data packet of the content sent by multiple content caching vehicles, the caching vehicle corresponding to the first received data packet is selected as the subsequent content providing vehicle, and a subsequent interest packet is sent to the vehicle to request the corresponding data packet; S5. The forwarding rule of subsequent interest packets is: after receiving the interest packet, the forwarding vehicle waits for a random time T2, the length of which is related to the speed difference between the forwarding vehicle and the sending vehicle, and the distance between the forwarding vehicle and the content providing vehicle; if during the random time, the forwarding vehicle monitors that there are other forwarding vehicles that are closer to the content providing vehicle than itself, or whose distance to the content providing vehicle is less than the one-hop communication distance of the wireless signal, and have forwarded the interest packet, then the forwarding vehicle cancels the forwarding of the interest packet, otherwise the forwarding vehicle will forward the interest packet after the random time ends; S6. After receiving the interest packet, the content providing vehicle returns the corresponding data packet; S7. The data packet is forwarded using the following rules until the content requesting vehicle: after receiving the data packet, the forwarding vehicle waits for a random time T3, the length of which is related to the speed difference between the forwarding vehicle and the sending vehicle, and the distance between the forwarding vehicle and the content requesting vehicle; if within this random time, the forwarding vehicle monitors that other forwarding vehicles that are closer to the requesting vehicle than itself or whose distance to the requesting vehicle is less than the one-hop communication distance of the wireless signal have forwarded the data packet, the forwarding vehicle cancels the forwarding of the data packet, otherwise the forwarding vehicle will forward the data packet after the random time ends.

2. According to claim 1, a transmission method based on NDN and vehicle speed and distance in a vehicle network is characterized in that: The PIT table records "content name", "data packet number", "requester ID" and "requester coordinates", and the FIB table records "content name", "data packet number", "provider ID" and "provider coordinates".

3. The transmission method based on NDN and vehicle speed and distance in a vehicle network according to claim 1, characterized in that: The interest packet for searching content contains "content name", "data packet number", "requester identifier", "requester coordinates", "forwarding vehicle identifier", "forwarding vehicle coordinates", "forwarding vehicle speed" and "remaining maximum forwarding hops" information. If the forwarding vehicle needs to forward the interest packet, it adds the "content name", "data packet number", "requester identifier" and "requester coordinates" information to the PIT table during forwarding, and updates the "forwarding vehicle identifier", "forwarding vehicle coordinates" and "forwarding vehicle speed" information in the interest packet to the corresponding values ​​of the current forwarding vehicle, subtracts 1 from the "remaining maximum forwarding hops" and then forwards the interest packet.

4. The transmission method based on NDN and vehicle speed and distance in a vehicle network according to claim 1, characterized in that: The data packet contains "content name", "requester identifier", "provider identifier", "provider coordinates", "forwarding vehicle identifier", "forwarding vehicle coordinates" and "forwarding vehicle speed" information. If the forwarding vehicle needs to forward the data packet, it adds the "content name", "data packet sequence number", "provider identifier" and "provider coordinates" information to the FIB table when forwarding the data packet, and updates the "forwarding vehicle identifier", "forwarding vehicle coordinates" and "forwarding vehicle speed" information in the data packet to the current forwarding vehicle before forwarding the data packet.

5. The transmission method based on NDN and vehicle speed and distance in a vehicle network according to claim 1, characterized in that: In the restricted broadcast mechanism of the first interest packet sent by the content requester to find the content, the random waiting time of the forwarding vehicle is: T1=random{1,W}*slotTime (1) Among them, W is a fixed integer (such as 100), random{1, W} represents a random integer between 1 and W, and slotTime is the unit backoff duration of the IEEE 802.11p protocol adopted by the Internet of Vehicles at the link layer.

6. The transmission method based on NDN and vehicle speed and distance in a vehicle network according to claim 1, characterized in that: The forwarding vehicle can calculate the distance between the content providing vehicle and the requesting vehicle through the providing vehicle coordinates in the FIB table and the requesting vehicle coordinates in the PIT table; calculate the distance between the previous hop forwarding vehicle and the content providing vehicle through the "forwarding vehicle coordinates" information in the received interest packet and the content providing vehicle coordinates in the FIB table, and calculate the distance between the previous hop forwarding vehicle and the content requesting vehicle through the "forwarding vehicle coordinates" information in the received data packet and the content requesting vehicle coordinates in the PIT table; calculate the distance between the vehicle and the content providing vehicle and the content requesting vehicle respectively through the vehicle's own coordinates and the coordinate information in the FIB table and the PIT table.

7. The transmission method based on NDN and vehicle speed and distance in a vehicle network according to claim 1, characterized in that: After the content providing vehicle is determined, during the forwarding process of the interest packet, the random waiting time of the forwarding vehicle after receiving the interest packet is: Among them, V s is the speed of the previous forwarding vehicle, V r is the current forwarding vehicle speed, ΔV=|V r -V s |, W is a fixed integer (such as 100), D p is the distance between the current forwarding vehicle and the content providing vehicle, D rp is the distance between the content providing vehicle and the content requesting vehicle, and slotTime is the unit backoff duration of the IEEE 802.11p protocol adopted by the Internet of Vehicles at the link layer.

8. The transmission method based on NDN and vehicle speed and distance in a vehicle network according to claim 1, characterized in that: After receiving the data packet, the forwarding vehicle randomly waits for: Among them, V s is the speed of the previous hop forwarding vehicle, V r is the current forwarding vehicle speed, ΔV=|V r -V s |, W is a fixed integer (such as 100), D r is the distance between the current forwarding vehicle and the requesting vehicle, D rp is the distance between the content providing vehicle and the content requesting vehicle, and slotTime is the unit backoff duration of the IEEE 802.11p protocol adopted by the Internet of Vehicles at the link layer.

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