Transmission method based on ndn and vehicle speed and distance in internet of vehicles

Abstract

The application discloses a transmission method based on NDN and vehicle speed and distance in Internet of Vehicles, and is particularly suitable for Internet of Vehicles needing to transmit a large amount of data. The application proposes a method for constructing a dynamic transmission path based on the content nature of the NDN network and the speed of the vehicle and the distance between vehicles in view of the problem that the high dynamic nature of Internet of Vehicles easily leads to frequent disconnection of the transmission path. First, a plurality of forwarding vehicles are selected in the Internet of Vehicles through a limited broadcast mode. Second, the PIT table and the FIB table in the NDN network are extended, and the coordinate information of the content request vehicle and the content providing vehicle is recorded in the tables respectively. Finally, in the forwarding process of the interest packet and the data packet, the forwarding vehicles are dynamically selected based on the speed of the vehicle and the distance between the vehicle and the content providing vehicle and the content request vehicle, so that the transmission performance is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wireless multi-hop network, in particular to a content transmission method in a vehicle networking with high node mobility, and more particularly to a transmission method based on NDN and vehicle speed and distance in a vehicle networking by using the content-oriented idea of NDN network and vehicle speed and distance information. BACKGROUND

[0002] With the rapid development of Internet technology, wireless access has gradually become the mainstream choice for connecting networks. As a typical application of Internet of Things technology in the transportation field, vehicle networking not only promotes the construction of intelligent transportation management system, but also promotes the development of intelligent dynamic information service and vehicle control technology. Under this background, efficient content transmission has become the basis for the normal operation of various functions of vehicle networking.

[0003] For application scenarios such as vehicle entertainment and intelligent navigation, moving cars play the role of data requesters and need to ask other vehicles or roadside facilities for the required information. These interaction processes 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 completely suitable for the wireless network needs in a highly dynamic environment, especially in the face of a highly mobile scenario such as vehicle networking. Traditionally, we are used to directly migrating protocols designed based on fixed network architecture to the wireless field, such as widely using the IP address-based unicast mode in content distribution. This mechanism requires the establishment of an optimal path between the source and the target, and each data packet is forwarded along this path. Unfortunately, this method fails to fully utilize the broadcast nature of wireless signals; in addition, the selected optimal route is prone to frequent disruption due to the changing positions of participants, further exacerbating the problem complexity. SUMMARY

[0005] The purpose of the present application is to solve the above-mentioned problems in the prior art and provide a transmission method based on NDN and vehicle speed and distance in a vehicle networking.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] A transmission method based on NDN and vehicle speed and distance in a vehicle networking, the transmission method comprising the following steps:

[0008] S1, each vehicle in the vehicle networking extends the PIT table and the FIB table in the NDN network, records the coordinate information of the content request vehicle in the PIT table, and records the coordinate information of the content providing vehicle in the FIB table;

[0009] S2, the content request vehicle broadcasts a first interest packet when it needs target content; other vehicles, after receiving the interest packet, determine whether to continue forwarding in a limited broadcast manner, i.e., after receiving the interest packet, waiting for a random time T1, if within this time, it is listened that other neighbor vehicles have forwarded the interest packet, the vehicle cancels the forwarding, otherwise the vehicle forwards the interest packet after the random time ends until the interest packet reaches the maximum hop count or is received by a vehicle that has cached content; all vehicles that have forwarded the interest packet are recorded as forwarding vehicles, and the information of the interest packet is recorded in their PIT tables;

[0010] S3, the vehicle that has cached content returns a first data packet of content after receiving the interest packet, and all forwarding vehicles must forward the data packet, and the information of the data packet is added in the FIB table during the forwarding;

[0011] S4, if the content request vehicle receives a plurality of first data packets of content sent by content caching vehicles, it selects the caching vehicle corresponding to the first received data packet as the subsequent content providing vehicle, and sends a subsequent interest packet to the vehicle to request the corresponding data packet;

[0012] S5, the forwarding rule of the subsequent interest packet is that the forwarding vehicle waits for a random time T2 after receiving the interest packet, the length of the random time 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 within the random time, the forwarding vehicle listens that other forwarding vehicles that are closer to the content providing vehicle or have a distance to the content providing vehicle less than one-hop communication distance of wireless signal have forwarded the interest packet, the forwarding vehicle cancels the forwarding of the interest packet, otherwise the forwarding vehicle forwards the interest packet after the random time ends;

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

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

[0015] Further, the PIT table records "content name", "packet serial number", "requester identification" and "requester coordinates", and the FIB table records "content name", "packet serial number", "provider identification" and "provider coordinates".

[0016] Further, the interest packet for searching content contains "content name", "packet serial number", "requester identification", "requester coordinates", "forwarding vehicle identification", "forwarding vehicle coordinates", "forwarding vehicle speed" and "remaining maximum forwarding hop count" information. If the forwarding vehicle needs to forward the interest packet, the "content name", "packet serial number", "requester identification" and "requester coordinates" information are added to the PIT table when forwarding, the "forwarding vehicle identification", "forwarding vehicle coordinates" and "forwarding vehicle speed" information in the interest packet are updated to the corresponding values of the current forwarding vehicle, the "remaining maximum forwarding hop count" is reduced by 1, and then the interest packet is forwarded.

[0017] Further, the data packet contains "content name", "requester identification", "provider identification", "provider coordinates", "forwarding vehicle identification", "forwarding vehicle coordinates" and "forwarding vehicle speed" information. If the forwarding vehicle needs to forward the data packet, the "content name", "packet serial number", "provider identification" and "provider coordinates" information are added to the FIB table when forwarding the data packet, the "forwarding vehicle identification", "forwarding vehicle coordinates" and "forwarding vehicle speed" information in the data packet are updated to the current forwarding vehicle, and then the data packet is forwarded.

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

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

[0020] wherein 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 time length of the IEEE 802.11p protocol adopted by the Internet of Vehicles in the link layer.

[0021] Further, the forwarding vehicle can calculate the distance between the content providing vehicle and the requesting vehicle by providing the vehicle coordinates in the FIB table and the requesting vehicle coordinates in the PIT table; calculate the distance between the last hop forwarding vehicle and the content providing vehicle by the "forwarding vehicle coordinates" information in the received interest packet and the content providing vehicle coordinates in the FIB table, calculate the distance between the last hop forwarding vehicle and the content requesting vehicle by the "forwarding vehicle coordinates" information in the received data packet and the content requesting vehicle coordinates in the PIT table; and calculate the distance between the vehicle and the content providing vehicle and the content requesting vehicle respectively by the coordinates of the vehicle itself and the coordinates in the FIB table and the PIT table.

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

[0023]

[0024] wherein, V s is the speed of the last hop forwarding vehicle, V r is the speed of the current forwarding vehicle, Delta V = |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 time length of the IEEE 802.11p protocol adopted by the vehicle networking in the link layer.

[0025] Further, the random waiting time of the forwarding vehicle after receiving the data packet is:

[0026]

[0027] wherein, V s is the speed of the last hop forwarding vehicle, V r is the speed of the current forwarding vehicle, Delta V = |V r -V s |, W is a fixed integer (such as 100), D r 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 time length of the IEEE 802.11p protocol adopted by the vehicle networking in the link layer.

[0028] The present application has the following advantages and effects relative to the prior art:

[0029] (1) The vehicle networking in the present application can use a broadcast mode for content transmission, increasing the robustness of the transmission link.

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

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

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

[0033] To make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0034] EMBODIMENT

[0035] As shown in the vehicle networking content transmission schematic diagram, vehicle R is a content request vehicle, and vehicle P is a providing vehicle that buffers target content. The target content is divided into several data packets in vehicle P. The content transmission can be divided into two stages of content searching and content acquisition. Figure 1

[0036] 1) Content searching stage

[0037] The requester R broadcasts the first interest packet for searching content, and other vehicles in the vehicle networking forward in a limited broadcast mode. For example, when R broadcasts the interest packet, A1, A2, A3, A4 and A5 all receive the interest packet, and then they wait for a random time T:

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

[0039] ​where 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 time of IEEE 802.11p protocol used in link layer of V2V. A4 and A5 cancel the forwarding because they have heard other neighbor nodes have forwarded the interest packet in the waiting time. On the contrary, A1, A2 and A3 continue to forward the interest packet because they have not heard any neighbor node forwarding the interest packet in their waiting time. Similarly, B1, B2 and B3 also forward the interest packet after receiving the interest packet. Moreover, each vehicle updates the request vehicle related information in the PIT table according to the information in the interest packet when forwarding the interest packet. As shown in Fig. 2(a), the content name, data packet flag, requester identifier and requester coordinate information are recorded in the PIT table of the forwarding vehicle according to the information in the interest packet. Figure 2 (a) shows that the content name, data packet flag, requester identifier and requester coordinate information are recorded in the PIT table of the forwarding vehicle according to the information in the interest packet.

[0040] Vehicles A1, A2, A3, B1, B2 and B3 forward the interest packet in this process, so they will become the forwarding vehicles of the next interest packet and data packet.

[0041] Vehicle P returns the first data packet of the content after receiving the first interest packet, and all forwarding vehicles forward the data packet; and the related information of the providing vehicle is recorded in the FIB table during the forwarding process, as shown in Fig. 2(b). Figure 2 (b) shows the related information of the providing vehicle recorded in the FIB table during the forwarding process.

[0042] 2) Content acquisition stage

[0043] The request vehicle sends a subsequent interest packet to the content providing vehicle, and the content providing vehicle returns the corresponding data packet.

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

[0045]

[0046] where V s is the speed of the sending vehicle R, V r is the speed of the current receiving 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, and D rp is the distance between the content providing vehicle and the content request vehicle, and slotTime is the unit backoff time of IEEE 802.11p protocol used in link layer of V2V.

[0047] If Al hears that A2 or A3 has forwarded the interest packet within its waiting time, and the distance between A2 or A3 and the providing vehicle is less than its own distance to the providing vehicle, Al will cancel the forwarding, otherwise it will continue to forward the interest packet. The same rule applies to A2 and A3. Suppose A2 continues to forward the interest packet, and Al and A3 hear that A2 has sent, and Al and A3 find that A2 is closer to the providing vehicle P by calculation, so they will cancel the forwarding.

[0048] Next, Bl, B2 and B3 receive the interest packet sent by A2, and also wait for a random time calculated by formula (2) to listen whether other nodes have forwarded the interest packet. Suppose Bl's random time arrives first, then it will forward the interest packet; B2 and B3 hear that Bl has forwarded, and they find that Bl is within one-hop distance of the providing vehicle P by calculation, 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 the providing vehicle P.

[0050] The providing vehicle P receives the interest packet and returns the corresponding data packet. Bl, B2 and B3 receive the data packet sent by P, and wait for a random time:

[0051]

[0052] where V s is the speed of the sending vehicle P, V r is the current receiving forwarding vehicle's 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 time length of IEEE 802.11p protocol used in the link layer of the Internet of Vehicles.

[0053] If Bl hears 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 Bl. Suppose Bl forwards the data packet, and Al, A2, A3 receive the data packet, then they will wait for a random time calculated by formula (3). Suppose A2 arrives at its random time first, then it will forward the data packet, and Al and A3 hear that A2 has sent the data packet, and find that A2 is within one-hop distance 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 the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A transmission method in a vehicle-to-everything (V2X) network based on NDN, vehicle speed, and distance, characterized in that, The transmission method includes the following steps: S1. Each vehicle in the vehicle-to-everything (V2X) network extends the PIT table and FIB table in the NDN network. The PIT table records the coordinate information of the requested vehicle, and the FIB table records the coordinate information of the provided vehicle. S2. When a content requesting vehicle needs the target content, it broadcasts the first interest packet. After receiving the interest packet, other vehicles decide whether to continue forwarding it using a restricted broadcast method. That is, after receiving the interest packet, they wait for a random time T1. If, during this time, they detect that another neighboring vehicle has 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 hop count or is received by a vehicle with cached content. All vehicles that forward the interest packet are recorded as forwarding vehicles, and the information of the interest packet is recorded in their PIT table. S3. After a vehicle with cached content receives an interest packet, it returns the first data packet containing the content. All forwarding vehicles must forward this data packet, and during the forwarding process, the information of this data packet is added to the FIB table. S4. If the content requesting vehicle receives the first data packet of 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 subsequent interest packets are sent to that vehicle to request the corresponding data packets. S5. The forwarding rule for subsequent interest packets is as follows: After receiving an interest packet, the forwarding vehicle waits for a random time T2. The length of this random time is related to the speed difference between the forwarding vehicle and the sending vehicle, as well as the distance between the forwarding vehicle and the content providing vehicle. If, within this random time, the forwarding vehicle detects that another forwarding vehicle is closer to the content providing vehicle than itself, or that the distance to the content providing vehicle is less than one hop of the wireless signal communication distance, has already 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. Data packets are forwarded according to 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 this random time is related to the speed difference between the forwarding vehicle and the sending vehicle, as well as the distance between the forwarding vehicle and the content requesting vehicle. If, within this random time, the forwarding vehicle detects that another forwarding vehicle is closer to the requesting vehicle than itself, or that the distance to the requesting vehicle is less than one hop of the wireless signal communication distance, has already 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. The transmission method in a vehicle-to-everything (V2X) network based on NDN, vehicle speed, and distance according to claim 1, characterized in that, The PIT table records "Content Name", "Packet Sequence Number", "Requester Identifier", and "Requester Coordinates", while the FIB table records "Content Name", "Packet Sequence Number", "Provider Identifier", and "Provider Coordinates".

3. The method for transmission based on NDN, vehicle speed, and distance in a vehicle-to-everything (V2X) network according to claim 1, characterized in that, The interest packet containing the searched content includes "content name", "data packet sequence number", "requester identifier", "requester coordinates", "forwarding vehicle identifier", "forwarding vehicle coordinates", "forwarding vehicle speed", and "remaining maximum forwarding hops". If a forwarding vehicle needs to forward this interest packet, it adds the "content name", "data packet sequence number", "requester identifier", and "requester coordinates" information to the PIT table during forwarding, 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, decrements the "remaining maximum forwarding hops" by 1, and then forwards the interest packet.

4. The transmission method based on NDN, vehicle speed, and distance in a vehicle-to-everything (V2X) network according to claim 1, characterized in that, The data packet contains information such as "content name", "requester identifier", "provider identifier", "provider coordinates", "forwarding vehicle identifier", "forwarding vehicle coordinates", and "forwarding vehicle speed". If a forwarding vehicle needs to forward this 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, updates the "forwarding vehicle identifier", "forwarding vehicle coordinates", and "forwarding vehicle speed" information in the data packet to the current forwarding vehicle, and then forwards the data packet.

5. The transmission method based on NDN, vehicle speed, and distance in a vehicle-to-everything (V2X) network according to claim 1, characterized in that, In a restricted broadcast mechanism where a content requester sends the first packet of interest to find content, the random waiting time for forwarding vehicles is: T1=random{1,W}*slotTime (1) Where W is a fixed integer, random{1,W} represents a random integer between 1 and W, and slotTime is the unit backoff time of the IEEE 802.11p protocol used by the vehicle-to-everything (V2X) network at the link layer.

6. The transmission method in a vehicle-to-everything (V2X) network based on NDN, vehicle speed, and distance according to claim 1, characterized in that, The forwarding vehicle can calculate the distance between the content provider and the requesting vehicle using the coordinates of the providing vehicle in the FIB table and the coordinates of the requesting vehicle in the PIT table; it can also calculate the distance between the previous-hop forwarding vehicle and the content provider using the "forwarding vehicle coordinates" information in the received interest packet and the coordinates of the content provider in the FIB table, and the distance between the previous-hop forwarding vehicle and the content requesting vehicle using the "forwarding vehicle coordinates" information in the received data packet and the coordinates of the content requesting vehicle in the PIT table; and finally, it can calculate the distances between the vehicle and both the content provider and the content requesting vehicle using its own coordinates and the coordinate information in the FIB and PIT tables.

7. The method for transmission based on NDN, vehicle speed, and distance in a vehicle-to-everything (V2X) network according to claim 1, characterized in that, After the content provider vehicle is identified, during the forwarding process of the interest packet, the random waiting time for the forwarding vehicle after receiving the interest packet is as follows: Among them, V s It is the speed of the vehicle that forwarded in the previous hop, V r It is the speed of the currently forwarding vehicle, ΔV=|V r -V s | W is a fixed integer, D p D is the distance between the currently forwarding vehicle and the content-providing vehicle. rp It is the distance between the content-providing vehicle and the content-requesting vehicle, and slotTime is the unit backoff time of the IEEE 802.11p protocol used by the Internet of Vehicles at the link layer.

8. The transmission method in a vehicle-to-everything (V2X) network based on NDN, vehicle speed, and distance according to claim 1, characterized in that, After receiving the data packet, the forwarding vehicle waits for a random amount of time: Among them, V s It is the speed of the vehicle that forwarded in the previous hop, V r It is the speed of the currently forwarding vehicle, ΔV=|V r -V s | W is a fixed integer, D r D is the distance between the currently forwarding vehicle and the requesting vehicle. rp It is the distance between the content-providing vehicle and the content-requesting vehicle, and slotTime is the unit backoff time of the IEEE 802.11p protocol used by the Internet of Vehicles at the link layer.

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