JP6945897B2 - Wireless mesh network opportunistic routing algorithm based on quality of service assurance - Google Patents

Description

The present invention belongs to the technical field of wireless communication, and specifically relates to a wireless mesh network opportunistic routing algorithm based on service quality assurance.

In a conventional wireless local area network (Wireless LAN), each user can access the network by connecting to a fixed access point (AP: Access Point) via a wireless link, which is a single-hop network. It belongs to the structure. This method provides more convenience to the user than the wired connection method. However, the range of wireless communication between the fixed AP and the user is limited, and obstacles greatly affect the communication between both points, so conventional wireless local area networks have ideal coverage and scalability. Is difficult to reach.

A wireless mesh network (WMN: Wireless Mesh Networks) is one of the typical wireless multi-hop networks, and has excellent points such as self-organization, flexible networking, and compatibility with multiple access methods. It is said to be one of the most promising networking technologies among self-organized wireless networks, and is currently making a great contribution to emergency communications and military applications, and is expected to have a wide range of applications. Compared to traditional wireless local area networks, in a wireless mesh network, each node may be an access point or a router, in which case it communicates with one or more other peer nodes. Thus, a multi-hop network structure can be formed. With such a multi-hop network structure, the wireless mesh network has the property of supporting NLOS transmission, which effectively avoids obstacles during data transmission by the network and communicates within the single-hop network environment. The blind spot can be eliminated. In addition, the multi-hop transmission structure of the wireless mesh network can achieve long-distance data transmission by selecting a series of relay nodes, and its coverage and scalability are compared with the conventional wireless local area network method. Has greatly improved.

On the other hand, wireless multi-hop networks pose a challenge to routing design. In the networking method, the wireless mesh network and the ad-hoc network are similar to some extent, but the conventional ad-hoc network networking method places more emphasis on the feasibility of communication. To further focus on the service quality requirements of data transmission for wireless mesh networks, traditional routing protocols used in wireless multi-hop networks are no longer able to meet the requirements, and new routing algorithms have been designed. , Data transmission service quality requirements need to be met.

Opportunity Routing (OP) is a routing strategy proposed by researchers at the Massachusetts Institute of Technology and is applicable to wireless multi-hop networks. Unlike traditional routing strategies, opportunistic routing does not form a fixed transmission path when transferring data, and uses the broadcast transmission characteristics of wireless networks to broadcast data to multiple neighboring nodes for constant routing. Based on the metric, select the best neighbor node as the next hop to continue data transfer. Such a routing strategy can be well adapted to the complex environment of a wireless network and can select and transmit the optimum next hop according to the real-time network state, greatly improving the routing performance of the wireless multi-hop network. It has been improved and has certain advantages in reliability and redundancy.

An object of the present invention is a service that effectively improves the utilization rate of network resources and the reliability of routing by referring to the real-time state of the network and the service quality requirements required for data transmission based on the concept of opportunistic routing. The purpose is to provide a wireless mesh network optimistic routing algorithm based on quality assurance.

To achieve the above objectives, the wireless mesh network opportunistic routing algorithm based on quality of service is
Each node in the wireless mesh network periodically exchanges information, holds and updates the neighbor table, and acquires the state information of the next hop neighbor node.
The node that needs to transfer the data broadcasts the routing request, and the neighboring node that receives the routing request calculates the distance to the target node and returns the routing response to the node that needs to transfer the data. Step S2 and
Based on the received routing response, the node that needs to transfer data builds the neighboring node that returned the routing response as a usable neighboring node set, the distance between itself and the target node, and the neighboring node and the target node. Step S3, which selects an appropriate neighboring node as a usable next hop node according to the difference from the distance to and builds a usable next hop node set,
Nodes that need to transfer data measure the ratio of channel capacity to information exchange delay as a metric, depending on the quality of service requirements required for the data and the estimated channel capacity to the next available next hop node. Step S4, in which the candidate next hop node set is selected, the nodes are prioritized based on the metric value in the candidate next hop node set, and the data is transferred in order according to the priority.
Each neighboring node that receives the transfer data sets a timer for returning a confirmation character according to the priority, and determines the time to start the data transfer in step S5.
When the node that needs to transfer data receives the confirmation character returned from any of the candidate next hop nodes, it ends the current routing process in step S6.
It includes step S7, which repeats the above steps S1 to S6 until the routing reaches the target node.

As a preferred proposal of the present invention, in step S1, each node in the wireless mesh network periodically exchanges Hello telegram information to obtain the state information of neighboring nodes, which is the information exchange delay and the estimated value of the channel capacitance. Acquire state information including in real time.

であり、ｉは、データを転送する必要のあるノード、ｊは、隣接ノード、γは、経路損失係数であり、ｈ_ｉｊは、データを転送する必要のあるノードｉと近隣ノードｊとの間のチャネルゲインを表し、Ｂは、利用可能な帯域幅、Ｐは、ノード送信信号パワー、ｎ_０／２は、ホワイトノイズのパワースペクトル密度、Ｄｉｓｔ（ｉ，ｊ）は、データを転送する必要のあるノードｉと近隣ノードｊとの間の距離である。 More preferably, the formula for calculating the estimated channel capacity is:

I is a node that needs to transfer data, j is an adjacent node, γ is a path loss coefficient, and _hij is between a node i that needs to transfer data and a neighboring node j. of represents channel gain, B is bandwidth available, P is a node transmitting signal power, n _0/2, the power spectral density of white noise, Dist (i, j) is the need to transfer data The distance between a certain node i and a neighboring node j.

Preferably, in step S2, the node that needs to transfer the data first determines if there is a target node in the neighboring node, if so, transfers it as is, otherwise broadcasts the routing request. do.

であり、Ｄｉｓｔ（ｉ，ｄ）は、データを転送する必要のあるノードｉと目的ノードｄとの間の距離、Ｄｉｓｔ（ｊ，ｄ）は、近隣ノードｊと目的ノードｄとの間の距離、Ｄ_ｉｊは、距離スパン値であり、距離スパン値Ｄ_ｉｊが０よりも小さければ、近隣ノードｊのほうが目的ノードｄから離れており、使用可能な次ホップノードとして適切ではないとし、距離スパン値Ｄ_ｉｊが０よりも大きければ、近隣ノードｊのほうが目的ノードｄに近づいており、使用可能な次ホップノードとして適切であるとし、使用可能な次ホップノードセットを構築する。 Preferably, in step S3, the formula for the difference between the distance between the node for which data needs to be transferred and the target node and the distance between the neighboring node and the target node is

Dist (i, d) is the distance between the node i and the target node d for which data needs to be transferred, and Dist (j, d) is the distance between the neighboring node j and the target node d. , D _ij is a distance span value, and if the distance span value D _ij is smaller than 0, it is assumed that the neighboring node j is farther from the target node d and is not suitable as a usable next hop node, and the distance span. If the value D _ij is greater than 0, it is assumed that the neighboring node j is closer to the target node d and is suitable as a usable next hop node, and a usable next hop node set is constructed.

Preferably, in step S4
If there is no candidate next hop node in the available next hop node set, select a predetermined number of nodes from the available neighbor node set to build the candidate next hop node set.
If the number of nodes in the available next hop node set is less than or equal to the predetermined upper limit of the number of candidate nodes, select it as the candidate next hop node set as it is, and select it as it is.
If the number of nodes in the available next hop node set exceeds a given candidate node limit, the heuristic algorithm will allow the available next hop node set to be candidate next hops as required for link quality and quality of service. Select a node set.

と等価し、レイリーフェージングに従うチャネルにおいて、データを転送する必要のあるノードｉと近隣ノードｊとの間のチャネルゲインｈ_ｉｊ同士は、互いに独立しており、且つ、｜ｈ_ｉｊ｜^２は、パラメータがσ_ｉｊ ^−２となる指数分布に従い、
もし、

とすると、ノードｉは、ノードｊを介する転送の成功確率が、

となり、ノードｉは、近隣ノードｊを介するデータ転送のシングルホップ総遅延ｔ_Ｋが、

となり、Ｔ_Ｃは、データを転送する必要のあるノードｉがチャネル媒体を競争する時間、Ｔ_Ｈは、情報交換遅延、Ｔ_ＤＡＴＡは、データ伝送の時間、Ｔ_ＳＩＦＳは、短いフレーム間スペース、Ｔ_ＡＣＫは、ＡＣＫを送信するレスポンス時間であり、
もし選択した候補次ホップノードセットＦ（ｉ）にｎ個の候補ノードある場合、データを転送する必要のあるノードｉのデータ転送のシングルホップ平均総遅延Ｅ（Ｔ（ｉ））、シングルホップ平均チャネル容量Ｅ（Ｃ（ｉ））の式は、

となり、ｐ_ｉ，Ｋは、データを転送する必要のあるノードｉから優先順位がＫとなるノードまでデータ転送が成功する確率を表し、ｃ_ｉ，Ｋは、データを転送する必要のあるノードｉと優先順位がＫとなるノードとの間のチャネル容量を表し、もし、データを転送する必要のあるノードｉが、分析により、トラフィック遅延への要求がＬ、データ伝送速率への要求がＲ、ノード間の通信距離がｒ_ｃであるとして決定した場合、候補次ホップノードセットＦ（ｉ）の選択は、

に変換され、情報交換遅延Ｔ_Ｈに対するチャネル容量の推定値ｃ_ｉ，ｊの比の大きさに応じて、比が大きいほど、ノードの優先順位が高くなるようにデータ転送の優先順位を決定する。 More preferably, the quality of service includes the transfer success probability and the delay, and for the transfer success probability, the channel capacity estimates ci _{and j} are first obtained by the equation (1), and the channel capacity estimates ci _{and j} are used. Since the transfer via the neighboring node j can be successful only when the transmission rate R required for the traffic is larger, the transfer success probability _{pi, j} is _{pi, j} = P (ci _{, j} ≧). R) and
According to the equation (1), ci _{, j} ≧ R is

In a channel that is equivalent to and follows Rayleigh fading, the channel gains h _ij between the node i and the neighboring node j that need to transfer data are independent of each other, and | h _ij | ² is a parameter. According to the exponential distribution _{where is σ ij} ^-2
if,

Then, the node i has a success probability of transfer via the node j.

Therefore, the node i has a single-hop total delay t _{K of} data transfer via the neighboring node j.

Next, _{T C} is the time that needs to transfer data node i to compete the channel medium, _{T H} is information exchange _{delay, T DATA} is the time of data _{transmission, T SIFS} is shorter interframe space, T _ACK is the response time to send ACK,
If there are n candidate nodes in the selected candidate next-hop node set F (i), the single-hop average total delay E (T (i)), single-hop average of the data transfer of the node i for which data needs to be transferred. The formula for the channel capacitance E (C (i)) is

Next, p _{i, K} represents the probability that the data transfer from node i that need to transfer data to the node priority is K is successful, c _{i, K} is a node i that need to transfer data Represents the channel capacity between when the communication distance between nodes is determined as a r _c, the selection of candidate next hop node set F (i) is

Is converted into, depending on the estimated value c _i, the magnitude of the ratio of the _j channel capacity for information exchange delay T _H, the larger the ratio is large, prioritizing data transfer as priority node is higher ..

Preferably, in step S5, a timer K (T _SIFS + T _ACK ) for _{returning a confirmation character is set according to the priority K, T SIFS} is a short inter-frame space, and T _ACK is a response time for transmitting the confirmation character. And
If the node with the priority K does not receive confirmation for the confirmation character for data transfer returned from the node with the higher priority even if the timer expires, it considers itself as the next hop node and the confirmation character. Is broadcast, and steps S2 to S5 are repeated to transfer the data.
If a node with a priority of K receives a confirmation character broadcast by another node before its timer expires, it deletes the transfer data and terminates the routing process.

Preferably, in step S6, if the node that needs to transfer the data cannot receive the confirmation information for the confirmation character from any of the nodes, the cache resource is used to temporarily cache the data to be transferred. Steps S2 to S6 are repeated to continue the transfer process, and after the network state is restored, a suitable candidate next hop node is found and data transfer is continued.

As a beneficial effect of the present invention, the algorithm refers to the real-time state of the network link and takes into account the quality of service requirements in the process of selecting and transferring data to the candidate order hop node. By prioritizing hop nodes and guaranteeing the reliability of data transfer, the service quality requirements of data transfer are effectively guaranteed while improving the real-time utilization efficiency of the network.

Hereinafter, the present invention will be further described with reference to the drawings.
FIG. 1 is a flowchart of an algorithm according to the present invention. FIG. 2 is a diagram of selecting a candidate next hop node according to an embodiment of the present invention.

Example 1 With reference to FIG. 1, the wireless mesh network opportunistic routing algorithm based on the quality of service assurance according to this embodiment is described.
Each node in the wireless mesh network periodically exchanges information, holds and updates the neighbor table, and acquires the state information of the next hop neighbor node.
The node that needs to transfer the data broadcasts the routing request, and the neighboring node that receives the routing request calculates the distance to the target node and returns the routing response to the node that needs to transfer the data. Step S2 and
Based on the received routing response, the node that needs to transfer data builds the neighboring node that returned the routing response as a usable neighboring node set, the distance between itself and the target node, and the neighboring node and the target node. Step S3, which selects an appropriate neighboring node as a usable next hop node according to the difference from the distance to and builds a usable next hop node set,
Nodes that need to transfer data measure the ratio of channel capacity to information exchange delay as a metric, depending on the quality of service requirements required for the data and the estimated channel capacity to the next available next hop node. Step S4, in which the candidate next hop node set is selected, the nodes are prioritized based on the metric value in the candidate next hop node set, and the data is transferred in order according to the priority.
Each neighboring node that receives the transfer data sets a timer for returning a confirmation character according to the priority, and determines the time to start the data transfer in step S5.
When the node that needs to transfer data receives the confirmation character returned from any of the candidate next hop nodes, it ends the current routing process in step S6.
It includes step S7, which repeats the above steps S1 to S6 until the routing reaches the target node.

In step S1, each node in the wireless mesh network periodically exchanges Hello message information to provide state information of neighboring nodes, including information exchange delay and an estimated value of channel capacity, in real time. Acquire.

であり、ｉは、データを転送する必要のあるノード、ｊは、隣接ノード、γは、経路損失係数であり、ｈ_ｉｊは、データを転送する必要のあるノードｉと近隣ノードｊとの間のチャネルゲインを表し、Ｂは、利用可能な帯域幅、Ｐは、ノード送信信号パワー、ｎ_０／２は、ホワイトノイズのパワースペクトル密度、Ｄｉｓｔ（ｉ，ｊ）は、データを転送する必要のあるノードｉと近隣ノードｊとの間の距離である。 The formula for calculating the estimated channel capacity is

I is a node that needs to transfer data, j is an adjacent node, γ is a path loss coefficient, and _hij is between a node i that needs to transfer data and a neighboring node j. of represents channel gain, B is bandwidth available, P is a node transmitting signal power, n _0/2, the power spectral density of white noise, Dist (i, j) is the need to transfer data The distance between a certain node i and a neighboring node j.

In step S2, the node that needs to transfer the data first determines if there is a target node in the neighboring node, if so, transfers it as is, and if not, broadcasts the routing request.

であり、Ｄｉｓｔ（ｉ，ｄ）は、データを転送する必要のあるノードｉと目的ノードｄとの間の距離、Ｄｉｓｔ（ｊ，ｄ）は、近隣ノードｊと目的ノードｄとの間の距離、Ｄ_ｉｊは、距離スパン値であり、距離スパン値Ｄ_ｉｊが０よりも小さければ、近隣ノードｊのほうが目的ノードｄから離れており、使用可能な次ホップノードとして適切ではないとし、距離スパン値Ｄ_ｉｊが０よりも大きければ、近隣ノードｊのほうが目的ノードｄに近づいており、使用可能な次ホップノードとして適切であるとし、使用可能な次ホップノードセットを構築する。 In step S3, the formula for the difference between the distance between the node for which data needs to be transferred and the target node and the distance between the neighboring node and the target node is

Dist (i, d) is the distance between the node i and the target node d for which data needs to be transferred, and Dist (j, d) is the distance between the neighboring node j and the target node d. , D _ij is a distance span value, and if the distance span value D _ij is smaller than 0, it is assumed that the neighboring node j is farther from the target node d and is not suitable as a usable next hop node, and the distance span. If the value D _ij is greater than 0, it is assumed that the neighboring node j is closer to the target node d and is suitable as a usable next hop node, and a usable next hop node set is constructed.

In step S4
If there is no candidate next hop node in the available next hop node set, select a predetermined number of nodes from the available neighbor node set to build the candidate next hop node set.
If the number of nodes in the available next hop node set is less than or equal to the predetermined upper limit of the number of candidate nodes, select it as the candidate next hop node set as it is, and select it as it is.
If the number of nodes in the available next hop node set exceeds a given candidate node limit, the heuristic algorithm will allow the available next hop node set to be candidate next hops as required for link quality and quality of service. Select a node set.

と等価し、レイリーフェージングに従うチャネルにおいて、データを転送する必要のあるノードｉと近隣ノードｊとの間のチャネルゲインｈ_ｉｊ同士は、互いに独立しており、且つ、｜ｈ_ｉｊ｜^２は、パラメータがσ_ｉｊ ^−２となる指数分布に従い、
もし、

とすると、ノードｉは、ノードｊを介する転送の成功確率が、

となり、ノードｉは、近隣ノードｊを介するデータ転送のシングルホップ総遅延ｔ_Ｋが、

となり、Ｔ_Ｃは、データを転送する必要のあるノードｉがチャネル媒体を競争する時間、Ｔ_Ｈは、情報交換遅延、Ｔ_ＤＡＴＡは、データ伝送の時間、Ｔ_ＳＩＦＳは、短いフレーム間スペース、Ｔ_ＡＣＫは、ＡＣＫを送信するレスポンス時間であり、
もし選択した候補次ホップノードセットＦ（ｉ）にｎ個の候補ノードある場合、データを転送する必要のあるノードｉのデータ転送のシングルホップ平均総遅延Ｅ（Ｔ（ｉ））、シングルホップ平均チャネル容量Ｅ（Ｃ（ｉ））の式は、

となり、ｐ_ｉ，Ｋは、データを転送する必要のあるノードｉから優先順位がＫとなるノードまでデータ転送が成功する確率を表し、ｃ_ｉ，Ｋは、データを転送する必要のあるノードｉと優先順位がＫとなるノードとの間のチャネル容量を表し、もし、データを転送する必要のあるノードｉは、分析により、トラフィック遅延への要求がＬ、データ伝送速率への要求がＲ、ノード間の通信距離がｒ_ｃであるとして決定した場合、候補次ホップノードセットＦ（ｉ）の選択は、

に変換され、情報交換遅延Ｔ_Ｈに対するチャネル容量の推定値ｃ_ｉ，ｊの比の大きさに応じて、比が大きいほど、ノードの優先順位が高くなるようにデータ転送の優先順位を決定する。 The quality of service includes the transfer success probability and the delay. Regarding the transfer success probability, the channel capacity estimates ci _{and j} are first obtained by the equation (1), and the channel capacity estimates ci _{and j} are required for the traffic. Since the transfer via the neighboring node j can be successful only when the transmission rate is larger than R, the transfer success probability _{pi, j} becomes _{pi, j} = P (ci _{, j} ≧ R).
According to the equation (1), ci _{, j} ≧ R is

In a channel that is equivalent to and follows Rayleigh fading, the channel gains h _ij between the node i and the neighboring node j that need to transfer data are independent of each other, and | h _ij | ² is a parameter. According to the exponential distribution _{where is σ ij} ^-2
if,

Then, the node i has a success probability of transfer via the node j.

Therefore, the node i has a single-hop total delay t _{K of} data transfer via the neighboring node j.

Next, _{T C} is the time that needs to transfer data node i to compete the channel medium, _{T H} is information exchange _{delay, T DATA} is the time of data _{transmission, T SIFS} is shorter interframe space, T _ACK is the response time to send ACK,
If there are n candidate nodes in the selected candidate next-hop node set F (i), the single-hop average total delay E (T (i)), single-hop average of the data transfer of the node i for which data needs to be transferred. The formula for the channel capacitance E (C (i)) is

Next, p _{i, K} represents the probability that the data transfer from node i that need to transfer data to the node priority is K is successful, c _{i, K} is a node i that need to transfer data Represents the channel capacity between and the node of priority K, and if the node i that needs to transfer data is analyzed, the request for traffic delay is L, the request for data transmission speed is R, when the communication distance between nodes is determined as a r _c, the selection of candidate next hop node set F (i) is

Is converted into, depending on the estimated value c _i, the magnitude of the ratio of the _j channel capacity for information exchange delay T _H, the larger the ratio is large, prioritizing data transfer as priority node is higher ..

_{In step S5, a timer K (T SIFS} + T _ACK ) for returning a confirmation character is set according to the priority K, T _SIFS is a short inter-frame space, and T _ACK is a response time for transmitting the confirmation character.
If the node with the priority K does not receive confirmation for the confirmation character for data transfer returned from the node with the higher priority even if the timer expires, it considers itself as the next hop node and the confirmation character. Is broadcast, and steps S2 to S5 are repeated to transfer the data.
If a node with a priority of K receives a confirmation character broadcast by another node before its timer expires, it deletes the transfer data and terminates the routing process.

In step S6, when the node that needs to transfer the data cannot receive the confirmation information for the confirmation character from any of the nodes, the data to be transferred is temporarily cached by using the cache resource, and the data to be transferred is temporarily cached in steps S2 to S2. S6 is repeated to continue the transfer process, and after the network state is restored, a suitable candidate next hop node is found and data transfer is continued.

In this embodiment, as shown in FIG. 2, there are nodes i, h, j, k, l, u, v, d, in which node i is a node transferring data and d is a transfer. The target node for the data. The communication distance of each node in the network is assumed to be r _{c. By periodically exchanging Hello message information, the node i acquires the state information including the information exchange delay TH} and the estimated value c of the available channel capacity, which is the state information of the one-hop neighboring node. Update and keep this information in the neighborhood table. As shown by the circle 1 in FIG. 2, the nodes h, j, k, and l are all one-hop neighbor nodes of the node i.

The process of selecting a candidate next hop node from the neighboring nodes of node i is as follows.

(1) The node i first determines whether or not the target node d exists in the neighboring node, and in this embodiment, the target node d is not a neighboring node of the node i, so that the node i requests a routing request (RRQ). ) Is broadcast. The neighboring node j that received the routing request calculates the distance Dist (j, d) from the target node based on the geolocation information, and the distance information Dist (j, d) from the target node is calculated. The included routing response (RREP) information is returned to node i.

(2) The node i extracts the distance information between the neighboring node and the target node from the received routing response (RREP), and calculates the distance Dist (i, d) to the target node. _{The distance span value D ij} , which is the difference between the distance between i and the target node d and the distance between the neighboring node and the target node d, is defined. As shown by the circle 2 in FIG. 2, the distance span between the node i and the node j is defined as the difference between the Dist (i, d) and the Dist (j, d). As shown by the circle 3 in FIG. 2, since the values of the node i and the nodes j, k, l are larger than 0, the nodes j, k, l become the usable next hop nodes of the node i, and the nodes Constructed as the available next hop node set V (i) for i, but node h is not considered as the next hop.

(3) Node i processes and analyzes the traffic data, determines the QoS request corresponding to the traffic, estimates the available channel quality by referring to the real-time network state information, and can be used by the heuristic algorithm. Select the candidate next hop node set F (i) from the next hop node set V (i). First, the number n of the nodes in the candidate next hop node set F (i) is determined, and in this embodiment, the value of n is set to 2, so that the node k and the node j, the node k and the node l, Both node j and node l can be one combination of F (i). If any of the nodes j, k, and l can satisfy the data transfer service quality requirement, the node k and the node l are not neighboring nodes to each other, but immediately t, Dist (j, d)> r _c , and the expression ( Since it does not satisfy the third constraint in 11), it is impossible to receive each other's ACK messages, and it is not suitable for constructing the candidate next hop node set F (i). Then, as shown by the circle 4 in FIG. 2, the single hop average total delay E (T (i)) with respect to the single hop average channel capacity E (C (i)) of the node k and node j and the node j and node l). Node j and node l are selected according to the magnitude of the ratio of, and the candidate next hop node set F (i) is constructed. Then, the nodes in F (i) are prioritized according to a certain metric value, and the data and the priority are transferred to the nodes j and l in F (i).

(4) Node j and node l that have received the transfer data from node i set a timer for returning ACK according to the priority. Since node j has a higher priority, its timer is set to (T _SIFS + T _ACK ), while the timer of node l is set to 2 (T _SIFS + T _ACK ), which enables data transfer to be started. Time is decided,
1) If the node l does not receive the ACK for the data transfer returned from the higher priority node j even if the timer expires, the node l broadcasts the ACK with itself as the next hop node, and the above process. Repeat to continue data transfer,
2) If the node l receives the ACK broadcast from the node j by the time the timer expires, the node l deletes the transfer data and terminates the routing process.

(5) When node i receives the ACK confirmation information returned from a certain candidate next hop node (either node j or node l), the current routing process is terminated, and node i is sent from any node. If the ACK confirmation information is not received, use the storage resource to temporarily save the data to be transferred, repeat the above process to continue the transfer process, and after the network status is restored, the appropriate neighboring node. Find and continue the data transfer.

(6) According to the route discovery process described above, routing is performed until the target node d is reached.

In addition to the above examples, the present invention can have other embodiments. All technical proposals formed by equal substitutions and equivalent transformations fall within the scope of protection claimed by the present invention.

Claims (9)

Each node in the wireless mesh network within the click is exchanged periodically information, holds and updates the neighbor table, a step S1 for acquiring the status information of the next hop neighbor node,
Nodes that need to transfer data, broadcasts a routing request, neighbor node receiving the routing request, calculates the distance between the destination node, a routing response to a node needs to transfer the data Step S2 to reply and
Nodes that need to transfer the data, based on said routing response received to construct a neighbor node which has returned the routing response as a neighbor sets available, the distance between itself and the destination node, close according to the difference between the distance between the node and the destination node, and select the appropriate neighbor node as the next hop node available, and step S3 to build available next hop node set,
The node that needs to transfer data, the data service quality requirements necessary, and, depending on the estimate of the channel capacity between the available next hop node, the ratio of the channel capacity for information exchange delay set as the metric value selects a candidate next hop node set, prioritize the node based on the metric values by the candidate next hop nodes in the set, a step S4 for transferring data sequentially according to the priority,
Each neighbor node receiving the transfer data, a timer for returning an acknowledgment character set according to the priority order, and step S5 of determining the time to start data transfer,
Nodes that need to transfer the data, upon receiving the confirmation characters returned from one of the candidate next hop node, and step S6 to terminate the current routing process,
Routing until arrive to the destination node, the wireless mesh network opportunistic routing algorithm based on service quality assurance, characterized in that it comprises a step S7 to repeat the above steps S1 to S6, the. In step S1, each node in the wireless mesh network periodically to exchange Hello message information, a the state information of the neighboring nodes, including the estimated value of the channel capacities and the information exchange delay The wireless mesh network opportunistic routing algorithm based on the service quality assurance according to claim 1, wherein the state information is acquired in real time. The formula for calculating the estimated channel capacity is

And a, i is the node which need to forward the data, j is the adjacent node, gamma is a path loss coefficient, h _ij is the node i and the neighboring nodes j which need to forward the data represents a channel gain between the, B is bandwidth available, P is a node transmitting signal _{power, n} 0/2, the power spectral density of white noise, Dist (i, j) is transferred to the data The wireless mesh network opportunistic routing algorithm based on the service quality assurance according to claim 1 or 2, characterized in that it is the distance between the node i and the neighboring node j that need to be In step S2, the node that needs to transfer the data, it is determined whether there is the destination node to the neighboring nodes first, if located in, as it is transferred, otherwise, the routing request A wireless mesh network opportunistic routing algorithm based on the service quality assurance according to claim 1 or 2, characterized in that it broadcasts. In step S3, wherein the difference between the need to transfer the data node and the distance between the target node, and the distance between the neighboring node and the destination node,

In and, Dist (i, d) is the distance between the said data and node i that need to transfer the destination node d, Dist (j, d) includes a neighboring node j of the destination node d the distance between, D _ij is the distance span value, if the distance span value D _ij is smaller than zero, the better the neighbor j is away from the destination node d, suitable as the available next-hop node and no, if the distance span value D _ij is greater than 0, and towards the neighboring node j closer to the destination node d, and is suitable as the available next hop node, the available next-hop node set A wireless mesh network opportunistic routing algorithm based on the service quality assurance according to claim 1, wherein the node is constructed. In step S4 above
Without candidate next hop node to the next available hop node set, and constructing the candidate next hop node set by selecting a predetermined number of nodes from a neighboring node sets available the use,
If the number of nodes of the available next-hop nodes in the set is equal to or less than a predetermined candidate node number limit, select it as the candidate next hop node set,
If the number of nodes in the available next-hop node set exceeds the predetermined candidate node number limit, the heuristic algorithm, said from the available next-hop node set, in accordance with the requirements of the link quality and service quality The wireless mesh network opportunistic routing algorithm based on the quality of service assurance according to claim 1, wherein the candidate next hop node set is selected. The quality of service includes a transfer success probability and delay, for the transfer success probability, initially acquire an estimate c _{i, j} of the channel capacity by the formula (1), channel capacity estimation value c _{i, j} traffic Since the transfer via the neighboring node j can be successful only when the transmission rate R is larger than the transmission rate R required for the above, the transfer success probabilities _{pi and j} are _{pi, j} = P (ci _{, j} ≧). R), and according to equation (1), c _{i, j} ≧ R is

In the equivalent to the channel according to the Rayleigh fading and the channel gain h _ij between between node i and neighboring nodes j which need to forward the data are independent of each other, and, | h _ij | ² is According to the exponential distribution where the parameter is σ _ij ^-2
if,

Then, the node i has a success probability of transfer via the node j.

Therefore, the node i has a single-hop total delay t _{K of} data transfer via the neighboring node j.

Next, _{T C} is the time a node i that need to transfer the data to compete the channel medium, _{T H,} the information exchange _{delay, T DATA} is the time of data _{transmission, T SIFS} is shorter interframe space , T _ACK is the response time for sending the ACK, if the the selected the candidate next hop node set F (i) is the n candidate nodes, data transfer node i that need to transfer the data The equations for the single-hop average total delay E (T (i)) and the single-hop average channel capacity E (C (i)) are:

Next, p _{i, K} is the priority from a node i that need to transfer the data represents the probability that the data transferred to the node from which K is successful, c _{i, K} is the need to transfer the data represents a channel capacity between nodes the priority and a node i is K, if node i that need to transfer the data, by analysis, demand for traffic delay L, the data transmission speed ratio If the request for R, the communication distance between nodes is determined as a r _c, the selection of the candidate next hop node set F (i) is

Is converted to the estimated value c _i of the channel capacity for the information exchange delay T _H, in accordance with the magnitude of the ratio of _j, the larger the ratio is large, the priority of the data transfer so that the priority of the node becomes higher A wireless mesh network opportunistic routing algorithm based on quality of service assurance according to claim 1 or 6, characterized in determining ranking. In step S5, in accordance with the priority K, to set the timer _{K (T} SIFS ₊ T _ACK) to return the confirmation _{letter, T SIFS} is shorter interframe _{space, T ACK} is the response to send the confirmation letter It's time
Nodes the priority becomes K is, even if its timer expires, the case where the priority of not received confirmation for the confirmation letter for the data transfer to be returned from a higher node, itself as the next hop node it broadcasts the check character, and transfers the data by repeating steps S2 to S5,
Nodes the priority is K, before the timer expires, the case of receiving the confirmation letter broadcast by other nodes, characterized in that to terminate the routing process to remove the transferred data A wireless mesh network opportunistic routing algorithm based on the quality of service assurance according to claim 1. In step S6, the node that needs to transfer the data, from any node, when that did receive the confirmation information for the confirmation text, temporarily cached data to be transferred using the cache resources, Based on the service quality assurance according to claim 1, wherein the transfer process is continued by repeating steps S2 to S6, and after the network state is restored, an appropriate candidate next hop node is found and the data transfer is continued. Wireless mesh network optimistic routing algorithm.

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