CN112261626A

CN112261626A - D2D-assisted content-centric multi-hop cooperative routing method

Info

Publication number: CN112261626A
Application number: CN202011123667.2A
Authority: CN
Inventors: 李婕; 倪石建; 王兴伟; 洪韬; 郑昊; 李福亮
Original assignee: Northeastern University China
Current assignee: Northeastern University China
Priority date: 2020-10-20
Filing date: 2020-10-20
Publication date: 2021-01-22
Anticipated expiration: 2040-10-20
Also published as: CN112261626B

Abstract

The invention discloses a D2D-assisted multi-hop cooperative routing method taking content as a center, and belongs to the technical field of network communication. Firstly, designing a node structure suitable for D2D network equipment communication according to a CCN node structure, and designing a resource request packet and a resource data packet in a transmission process; then, the request packet forwarding process in the resource discovery is completed through dynamically maintaining the CCN flow table structure and using D2D communication; and after the matched resources are found, backtracking the resources, and designing a GO node topology maintaining process in the D2D network by referring to a routing protocol based on a link state in the traditional network. The invention uses content as center to discover resources, combines the thought of CCN, designs the CCN node structure suitable for D2D network, improves data transmission efficiency and enhances user service quality.

Description

D2D-assisted content-centric multi-hop cooperative routing method

Technical Field

The invention relates to the technical field of network communication, in particular to a D2D-assisted multi-hop cooperative routing method taking content as a center.

Background

D2D communication is a technology that allows nearby users to communicate directly without going through a base station. As more and more mobile application services require the use of user location information and require communication between neighboring users, D2D-based cellular networks have gained more and more research attention due to their inherently high-speed content sharing capabilities. In general, D2D communication can provide communication users with higher data transmission rates, lower content transmission delays, and achieve higher spectral efficiency. The information center network means that all the networks are regarded as information, namely, the networks are content-interconnected, unlike the current host interconnection network. All nodes and programs in the whole network are driven by various information request and response behaviors, the ICN network functions to coordinate transmission and caching of related named data and quickly respond to the request of a user by inquiring correct data through intelligent optimization, the user or an application program only focuses on the information data, and other attributes of the information block, such as where the information block comes from, are irrelevant to which copy of the data. In the existing D2D communication research, the concept of CCN is not basically utilized to discover resources, and a content-centric D2D transmission mechanism can improve the data transmission efficiency and enhance the user service quality.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention provides a D2D-assisted content-centric multi-hop cooperative routing method.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a D2D-assisted content-centric multi-hop cooperative routing method comprises the following steps:

step 1: the CCN structure design is that a node structure suitable for device communication in a D2D network is designed according to an underlying CCN node structure, and the process is as follows:

step 1.1: replacing a CS table in a traditional CCN with a Resource content table (RN), replacing a PIT table in the traditional CCN with a Query Record table (QR), and designing a Cache recommendation table (CR);

step 1.2: the RN table is only placed in the GO node and records the name information of all the owned resources of the current group of equipment;

step 1.3: the QR table is used to store request packet information for requests that are not satisfied.

When the request packet reaches the GO node, firstly traversing the QR table, and checking whether the same request information exists in the QR table or not; if the same request information exists, the RN table does not need to be traversed, and the request information is directly recorded in the QR table; if the QR has no same request, the RN table is inquired to check whether the resource meeting the request exists in the current group.

Step 1.4: the CR table is used to record the information of the requested resource passed by the current node, and in the data backtracking stage, it can be determined whether the backtracked resource should be cached by the current node according to the content of the CR table.

Step 2: a Resource request packet (RR) structure and a Resource data packet (RD) structure are designed corresponding to a data transmission process in a D2D network, and the process is as follows:

step 2.1: the RR structure comprises 5 fields, wherein TTL specifies the hop number which can be transmitted by the request packet, and the numerical value of TTL of the resource request packet is subtracted by 1 each time;

step 2.2: RRN MAC address records the source node information of the request packet, and Resource Name and Resource Type record the Resource request content of the request packet;

step 2.3: the Path field records the key node of the experience into the Path for the resource backtracking stage to use when the Path field is forwarded once;

step 2.4: the RR structure includes 5 fields, where a Path field is Path information recorded in the request packet, a basic data forwarding decision is made according to the Path field, and a Store-Path field records an internal storage location of the resource in the RON node, and when the resource is transmitted to the resource request node, the resource is stored in the same location as the source node. The last field is the resource data portion.

And step 3: the request packet forwarding process in resource discovery is completed by dynamically maintaining a CCN related flow table structure and using various D2D communication mechanisms, and the process is as follows:

step 3.1: dynamically updating the RR packet, the QR table and the CR table;

step 3.2: when a GO node receives an RR request packet, firstly, checking whether a record corresponding to the request exists in a QR table;

step 3.3: if the identical request exists, the forwarding of the request packet is indicated to generate a loop, and the current GO node directly discards the request packet;

step 3.4: if only the request resource names are the same and the request node information is different, it is indicated that the current GO receives a similar request but does not receive resource backtracking, and at this time, the request should be added into the QR record table and the CR table and waits for backtracking of the corresponding resource;

step 3.5: if no matched record is found in the QR table, which indicates that the current GO node does not process a similar request at the current time, the request needs to be matched with all records in the RN table. And if the RN table does not have the matched resource name, adding the request packet information into the QR table and the CR table. And finally, updating TTL and Path fields in the request packet and acquiring a GW node set to be forwarded through a GWT node table.

And 4, step 4: the RN table is placed on the GO node, so only the GO node can determine whether a certain resource request is matched. After finding the matched resources, the GO node needs to provide coordination service and informs the RON node to start resource backtracking, and the process is as follows:

step 4.1: when the GO node is the RON node, the GO node acquires Path information from the RR, acquires the storage position of the resource in the RON equipment, and serializes the data;

step 4.2: and then directly sending the resource data to the previous hop GW node through the file stream. Starting to backtrack resources at the previous hop GW node according to Path information;

step 4.3: if the Client node is RON, the GO sends the resource name and the storage position of the resource to the Client according to the field in the RN table;

the Client node comprises a GW node and a GM node;

step 4.4: after receiving the notification, the Client directly serializes the Path information in the notification with the resource data, and starts a resource backtracking process according to the Path information.

And 5: with reference to a routing protocol based on a link state in a traditional network, a GO node topology maintenance process in a D2D network is designed, and the process is as follows:

step 5.1: first, three types of information are defined, namely first variability information: a First Variable Information (FVI) is generated if and only if a new GW node is present in the network or if an old GW node is removed; connection information: the connection information is generated under the excitation of first variability information, and the connection information is GOT information stored by the current GO node; second variability information: second Variable Information (SVI) is generated by the connection Information, when the newly connected GW node receives the GOT topology Information maintained by the current group owner;

step 5.2: the three kinds of information are utilized to maintain the GOT topological structure in the whole D2D network;

the maintaining of the GOT topology:

1) inputting: updating the state of the GW node;

2) and (3) outputting: GOT topology in key nodes (adjacency linked list);

3) when a new GW node establishes connection or an old GW node leaves a network, the GW node generates a GW node state update data packet GMup (namely, FVI information) and sends the GMup to the connected GO node;

4) the nodes begin to process Gmup, the nodes process SVI information, if the processing nodes are GO, the GO updates GOT and forwards the GOT to other GW nodes through multicast, otherwise, the GW nodes update GOT and forward the GOT to a second GO node;

step 5.3: and storing the GOT topological structure into a Map structure, wherein the key value of the Map is the MAC address information of the GO node in the current group, and the value of the Map is the list of other GO nodes connected by the GW node in the current group.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:

1. the method provided by the invention uses the content as the center to discover the resources. In the mobile equipment self-organizing network, resources required by a user are stored in a user terminal, and data access is usually not based on the position information of the equipment but is requested by data content, so that a content-centered resource discovery mechanism is more suitable for mobile intelligent terminal data transmission services.

2. The routing strategy in the D2D network is researched, a CCN node structure and a data packet structure suitable for the D2D network are designed by combining the thought of CCN, and in the D2D network constructed based on the WFD technology, the inter-group communication mechanism in the invention can realize the communication among any communicated devices in the network. The main advantages of the mechanism are the routing success rate, the average routing hop count, and the cache overhead.

Drawings

Fig. 1 is a flowchart illustrating resource discovery in a content-centric multi-hop cooperative routing method assisted by D2D according to an embodiment of the present invention;

fig. 2 is a flowchart illustrating resource backtracking in a content-centric multi-hop cooperative routing method assisted by D2D according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a node structure according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of the structure design of a resource request packet and a resource structure packet according to an embodiment of the present invention;

FIG. 5 illustrates TCP unicast throughput in an embodiment of the present invention;

FIG. 6 illustrates a range-throughput impact in an embodiment of the present invention;

FIG. 7 illustrates distance and obstacle-signal strength effects in an embodiment of the present invention;

fig. 8 is a diagram illustrating an influence of communication hop count-delay in a small data amount according to an embodiment of the present invention;

fig. 9 is a diagram illustrating an influence of communication hop count-delay under a large data volume in an embodiment of the present invention;

FIG. 10 illustrates node energy consumption in store-and-forward mode according to an embodiment of the present invention;

fig. 11 shows node energy consumption in the direct forwarding mode according to an embodiment of the present invention.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

As shown in fig. 1 and 2, the method of the present embodiment is as follows.

In this embodiment, a schematic structure of the node flow table is shown in fig. 3.

step 2.4: the RD structure comprises 3 fields, wherein a Path field is Path information recorded in the request packet, a basic data forwarding decision is made according to the Path field, a Store-Path field records an internal storage location of the resource in the RON node, and when the resource is transmitted to the resource request node, the resource is stored in the same location as the source node. The last field is the resource data portion.

In this embodiment, the specific structure of the resource request packet RR and the resource data packet RD is shown in fig. 4.

step 3.1: dynamically updating the RR packet, the QR table and the CR table;

the Client node comprises a GW node and a GM node;

the maintaining of the GOT topology:

1) inputting: updating the state of the GW node;

2) and (3) outputting: GOT topology in key nodes (adjacency linked list);

Experimental Environment and analysis

Simulation experiments are carried out on the method of the embodiment, a small D2D network is constructed based on an Android smart phone and a WFD communication technology, and prototype system implementation is carried out on the Android phone. For the prototype system implemented, the main objective is to verify the feasibility of the proposed content-centric multi-hop collaborative routing approach in D2D networks in an indoor environment. First, this embodiment tests throughput and signal strength indexes in basic intra-group communication, then measures the influence of transmission hop count on overall delay when different sizes of data are transmitted under the conditions of cache and non-cache in the multi-hop communication process, and finally, this embodiment measures the influence of transmission of different sizes of data on energy consumption of different role nodes in the D2D multi-hop network established in this embodiment.

In the intra-group single-hop communication, two indexes of throughput and signal strength in the communication process are mainly measured, and factors influencing the two indexes are mainly the communication distance and the interference existing in the communication. In order to measure the relationship between the communication index and the influencing factor, three sets of experiments are designed in the embodiment.

Throughput experiments: in an indoor environment, the present embodiment uses ipref software to measure the throughput of the GO node and the GM node in the same group. Firstly, a prototype system is utilized to connect two devices, then through an ipref command, one device is a server side, the other device is a client side, the client side sends a data packet to the server side, and the throughput of the client side in a period of time is measured. Meanwhile, the embodiment notes that the setting of different numbers of data sending threads on the client has a certain influence on the throughput, and fig. 5 is an experimental result of the embodiment, which shows that the throughput of single-hop communication based on the WFD technology is about 50 Mbps;

distance-throughput experiments: in an indoor environment, a fixed client starts 4 sending threads, the client moves 2 meters distance each time, the throughput of device communication is measured through an ipref, and the measurement result is shown in fig. 6. It can be seen that throughput drops sharply with increasing distance, but data has significant jitter, because in an indoor environment, wireless signals interfere with each other, but it can still be determined that in an indoor environment, when the communication distance exceeds 10 meters, the D2D communication rate is greatly affected;

distance-signal strength, interference-signal strength experiments: under the indoor environment, use three equipment, GO equipment, LC GO equipment and GW equipment carry out the network deployment communication. Experiments are respectively carried out in a classroom environment and an indoor corridor, and the signal intensity values corresponding to the GW node P2P network card and the WLAN network card are obtained under an Android ADB/proc/net/wireless directory. The main difference between the classroom environment and the indoor corridor is that two walls are arranged at the place of 0 meter and 12 meters in the classroom environment respectively. The measurement results are shown in fig. 7, and it can be seen that the wireless signal strength is significantly weaker in an indoor environment where a large obstacle exists than in an environment without the obstacle. Meanwhile, when the signal strength is below-60 dBm, the normal communication quality is not maintained, so that the communicable range is within 10 meters in an indoor environment where an obstacle exists, and is about 20 meters or so in an indoor environment where an obstacle does not exist.

Through the measurement of the throughput and the signal strength of the single-hop communication in the group, the maximum range of the feasible D2D communication in the indoor environment is determined to be about 10 meters. Such a communication range enables an indoor D2D multi-hop communication scenario assumed by the present invention, such as D2D multi-hop communication in an office building area scenario or a residential area scenario. In a network established by the mobile device, the two most important performance indexes of the multi-hop communication are time delay and node energy consumption, and based on the D2D network established by this embodiment, this embodiment measures the two performance indexes step by step.

Firstly, 7 devices are used in a room of a teaching building for networking, and three interconnected groups are established. Through the three groups, a multi-hop communication experiment from 1 hop to 6 hops can be performed, and the embodiment transmits text, pictures, audio and video resources respectively and tests the time delay in the multi-hop communication. Meanwhile, in order to show the influence of the cache and non-cache forwarding modes on the time delay, the cache conditions are relaxed in the experiment, so that all key nodes through which resources pass are required to be stored and forwarded in the cache forwarding mode. The calculation of the whole time delay is obtained according to the difference value between the resource acquisition time and the resource request packet sending time, and the two time points are acquired according to the system. The results of the specific experiments are shown in fig. 8 and 9. It can be seen that the time delay and the number of communication hops basically present a linear relationship, and by calculating that the time required for forwarding 1MB data resources per hop is 228.3ms on average in the direct forwarding mode, while the time required for forwarding 1MB data resources per hop is 257.23ms on average in the store-and-forward mode, the time delay of direct forwarding is low, mainly because the direct forwarding process is performed in the memory, and the forwarding rate is fast.

Another important performance indicator in a D2D multihop network constructed by mobile connected devices is node energy consumption. Similar to the delay measurement experiment, in this embodiment, 6 devices are used in an indoor environment to connect into two groups, including an RON node, a GO node, an LC GO node, a GW node, an RRN node, and a common Client node. The threshold of the resource cache is also relaxed, so that all the key nodes passed by the resource backtracking in the store-and-forward mode store the resource locally. Under the modes of full direct forwarding and full storage forwarding, the energy consumption condition of the current node equipment is initialized through a dumpsys bytes-reset command in the ADB, and the energy consumption of the current node in the resource transmission process is acquired by using the dumpsys bytes command after resource discovery and resource backtracking are finished. The energy consumption situations of nodes with different roles in the resource transmission process in the store-and-forward and direct-forward modes are respectively shown in fig. 10 and fig. 11. As can be seen from the figure, when the resource acquisition process of the data resources with the same size in the D2D network is completed, the node energy consumption in the direct forwarding mode is generally less than that in the store-and-forward mode. Energy consumption of common member nodes which do not participate in the resource obtaining process in the network is basically zero, and higher energy consumption exists in the resource obtaining process of the GW nodes and the GO nodes, through calculation, the energy consumption of the GO nodes which averagely obtain resources with the size of 100MB is 0.475mAh in the direct forwarding mode, the energy consumption of the GW nodes is 0.276mAh, the energy consumption of the GO nodes is 0.562mAh in the storage forwarding mode, and the energy consumption of the GW nodes is 0.66 mAh. The larger energy consumption of the store-and-forward mode may be caused by the local storage process of resources, and the higher energy consumption of the GW node in this mode than that of the GO node may be caused by the longer time of the store-and-forward mode in completing the inter-group communication process, and the gradually increased energy consumption of the GW node in maintaining the dual-network card communication.

Claims

1. A method for D2D assisted content-centric multi-hop cooperative routing, comprising the steps of:

step 1: the CCN structure design is that a node structure suitable for equipment communication in a D2D network is designed according to a basic CCN node structure;

step 2: designing a resource request packet RR structure and a resource data packet RD structure corresponding to a data transmission process in a D2D network;

and step 3: the method comprises the steps of jointly completing a request packet forwarding process in resource discovery by dynamically maintaining a CCN related flow table structure and using various D2D communication mechanisms;

and 4, step 4: placing the RN table on the GO node, and judging whether the resource requests are matched or not only by the GO node; after finding the matched resources, the GO node provides coordination service and informs the RON node to start resource backtracking;

and 5: the GO node topology maintenance process in the D2D network is designed by referring to a routing protocol based on the link state in the traditional network.

2. The D2D-assisted content-centric multi-hop cooperative routing method according to claim 1, wherein: the process of the step 1 is as follows:

step 1.1: replacing a CS table in the traditional CCN with a resource content table RN, replacing a PIT table in the traditional CCN with a query record table QR, and designing a cache recommendation table CR;

step 1.3: the QR table is used for storing the request packet information of the unsatisfied request;

3. The D2D-assisted content-centric multi-hop cooperative routing method according to claim 2, wherein: the process of step 1.3 is as follows:

4. The D2D-assisted content-centric multi-hop cooperative routing method according to claim 1, wherein: the process of the step 2 is as follows:

step 2.4: the RD structure comprises 3 fields, wherein the Path field is Path information recorded in the request packet, a basic data forwarding decision is made according to the Path field, the Store-Path field records the internal storage position of the resource in the RON node, and when the resource is transmitted to the resource request node, the resource is stored to the same position as the source node; the last field is the resource data portion.

5. The D2D-assisted content-centric multi-hop cooperative routing method according to claim 1, wherein: the process of the step 3 is as follows:

step 3.1: dynamically updating the RR packet, the QR table and the CR table;

step 3.5: if no matched record is found in the QR table, indicating that the current GO node does not process a similar request at the current moment, matching the request with all records in the RN table; if the RN table does not have a matched resource name, adding the request packet information into the QR table and the CR table; and finally, updating TTL and Path fields in the request packet and acquiring a GW node set to be forwarded through a GWT node table.

6. The D2D-assisted content-centric multi-hop cooperative routing method according to claim 1, wherein: the process of the step 4 is as follows:

step 4.2: then directly sending the resource data to the previous hop GW node through the file flow, and starting to backtrack the resources at the previous hop GW node according to the Path information;

step 4.3: if the Client node is RON, the GO node sends the resource name and the storage position of the resource to the Client according to the field in the RN table;

the Client node comprises a GW node and a GM node;

7. The D2D-assisted content-centric multi-hop cooperative routing method according to claim 1, wherein: the process of the step 5 is as follows:

step 5.1: firstly, three types of information are defined, which are respectively: first variability information FVI, linkage information, second variability information SVI;

the first variability information is that the first variability information FVI is generated if and only if a new GW node appears in the network or an old GW node leaves; the connection information is generated under the excitation of first variability information, and the connection information is GOT information stored by the current GO node; the second kind of variability information SVI is generated by the excitation of the connection information, when the newly connected GW node receives the GOT topology information maintained by the current group owner;

8. The method of D2D-assisted content-centric multi-hop cooperative routing according to claim 6, wherein the step 5.2 of maintaining the GOT topology is:

1) inputting: updating the state of the GW node;

2) and (3) outputting: GOT topological structure or adjacent linked list in key node;

3) when a new GW node establishes connection or an old GW node leaves a network, the GW node generates a GW node state update data packet GMup, namely, the FVI information; and sending the GMup to the connected GO node;

4) and the nodes begin to process Gmup, the nodes process SVI information, if the processing nodes are GO, the GO updates GOT and forwards the GOT to other GW nodes through multicast, otherwise, the GW nodes update GOT and forward the GOT to a second GO node.