CN102131269A - Geographical-position-based routing method in wireless mesh network - Google Patents

Abstract

The invention takes characteristics of a wireless mesh network as a clue, combines a forwarding strategy of opportunistic routing, and provides a routing method in application programming (IAP) which is applicable to the wireless mesh network by improving a greedy perimeter stateless routing (GPSR) routing protocol. The IAP is functionally divided into two parts: 1) in a greedy mode, a data acquisition module and a data acquisition interface are arranged on an IEEE 802.11 multi-access computer (MAC) layer, the state information of a local node interface and link information between neighboring nodes are acquired on the MAC layer, the processed data is fed back to a routing layer in a call-back mode, and finally, comprehensive routing metrics are formed, so that packet node forwarding selection in the greedy mode is closer to actual conditions of the network; and 2) when the packet meets a routing hole in the wireless mesh network, a novel competition-based opportunistic routing hole detouring strategy is provided; moreover, on a hole edge, the neighboring nodes compete forwarding opportunity according to the mastered topology and link information to reduce the possibilities of increasing routing hops brought by blind detouring and generating network congestion.

Description

In the based on wireless mesh network based on the method for routing in geographical position

Technical field

The invention belongs to field of wireless communications networks, relate in particular in a kind of based on wireless mesh network (Wireless MeshNetwork) and improve one's methods based on the Routing Protocol in geographical position.

Background technology

The Routing Protocol design of wireless Mesh netword challenge abrim always is not because also have a kind of Routing Protocol can adapt to the dynamic change characteristic of wireless network environment fully at present.In recent years, be designed to provide the chance that improves existing wireless multi-hop network performance based on the geographical position routing mode to the Routing Protocol behind the attribute of the node point of addition perception in the wireless multi-hop network in order to study focus.GPSR (Greedy Perimeter Stateless Routing) agreement is the most representative in this quasi-protocol, GPSR uses the greedy method of transmitting, only utilize the topology information of the local perception of small number of nodes to select next-hop node, if grouped data has been forwarded to a zone that greedy pattern is no longer available, the GPSR algorithm will be enabled right-hand rule and select next-hop node, utilize peripheral pass-through mode to carry out the cavity and detour.

The wireless Mesh network backbone network deployment in should prevent the route cavity as far as possible, but under actual conditions, still be difficult to avoid fully the possibility in route cavity, because itself just be not suitable for laying Mesh node (as the marsh, big barrier etc.) on some position.When the source node of a grouping and destination node respectively during the both sides in the route hole region, grouped data is surrounded by very big probability will arrive the destination through one or more cavities strategy that detours.Moreover, in a lot of network applications, as multimedia communication or file transfer, data source usually can send the mass data bag to same destination node.Suppose that network topology is static, so all nodes probably will arrive destination node through identical path.In other words, if first packet arrives destination node through a long path, so next, all packets all can pass through same process in network transmission process, the shortcoming of bringing like this has two: the one, transmit the individual nodes that is overly dependent upon in the network, and the life-span of these nodes is reduced rapidly; The 2nd, the same node of the selection of repetition carries out transfer of data and is easy to cause the grouping at this node place congested, brings a large amount of packet losses.

The present Routing Protocol based on the geographical position comprises three major types: finite region inundation formula, the greedy forwarding in conjunction with cavity detour formula, the greedy formula of recurrence.

Finite region inundation formula, node went out an inundation zone according to the relation of the position between present node and the destination node " structure " earlier before transmitting packet, and the route searching of inundation formula will carry out in this zone.Greedy formula is transmitted in conjunction with the cavity formula that detours, the combination of these two kinds of strategies is by the decision of the particularity of geographical position route, when being each node forwarding grouping, the forwarding of greedy formula all select neighbor node middle distance destination node nearest, when proceeding to no available neighbor, change the cavity mode that detours again over to.Recursion, this is a kind of scheme in conjunction with greedy forwarding and node energy consumption, considers the positional information and the dump energy of neighbor node when selecting next hop neighbor, as link cost, the node of alternative costs minimum is transmitted with it.

Existing empty processing method has bigger shortcoming: the one, and the blindness of transmitting, do not consider the actual conditions of network, take right-hand rule or left and right sides rule blindly carried out packet forward, the result has improved the routed path length of grouping, and can not guarantee the transmission of packet, be absorbed in endless loop easilier; The 2nd, routing cost is excessive, and in the process on traversal limit, if fail to walk out local optimum always, a large amount of calculating need be used in defining of face border and choosing of routing direction, sometimes also needs to use the part mode of flooding to seek route; The 3rd, the route recovery difficulty only writes down limited routing information in the grouping, when finding that the cavity often is difficult to return the node that sets out and carries out the re-transmission of packet when detouring failure, causes packet loss.

Summary of the invention

Technical problem: general all exists certain blindness based on dividing into groups in the Routing Protocol of geographical position in greedy forwarding and the empty direction selection of detouring, how carrying out greediness efficiently transmits, and select correct direction when how detouring in the cavity, be to need the emphasis problem that solves.For this reason, the present invention proposes in a kind of based on wireless mesh network the method for routing based on the geographical position.

Technical scheme: IAP is made up of two parts, and the one, the greedy forwarding used new link-quality criterion IAS (Interference Aware Speed); The 2nd, detour in the cavity, utilizes the chance formula packet forward based on competition, walks around the route hole region with try one's best few jumping figure and the least possible expense, returns greedy pattern.

This method is transmitted and empty detouring aspect two to present improving based on the geographical position Routing Protocol in greediness: under the greedy pattern, used balance to transmit the route criterion that distance and link-quality and channel insert difficulty and carried out the selection of next-hop node, made that being grouped in selection on the basis that guarantees to transmit distance more helps the link that transmits; When this greedy mode failures even based on the route cost, general title grouping has arrived local smallest point, at this moment IAP can enable based on the chance formula of competition and transmit, be different from position and the link quality information of only considering node in the general chance formula forwarding, the factor that has added the greedy forward mode possibility of dividing into groups to get back in the competition factor in the new algorithm by the cavity pattern of detouring, the neighbor node that might help to divide into groups to rotate back into greedy pattern in empty edge will obtain the highest priority in competition, obtain the chance of at first transmitting then.

IAP can be divided into two parts on function: 1) under greedy forward mode, by increasing data acquisition module and data acquisition interface at the MAC layer, obtain the state information of local node interface, and and neighbor node between link information, and deliver to the route layer in the readjustment mode, form comprehensive route criterion at last, make that the packet forward node under the greedy pattern selects to press close to more the network actual conditions; When 2) in being grouped in wireless Mesh netword, running into the route cavity, by the strategy that detours based on the chance formula route cavity of competition, in empty edge, each neighbor node is according to the topological sum link information of being grasped, the meeting of competition repeater-transmitter, the possibility that the path jumping figure increases and network congestion takes place that having reduced blindly detours brings.

Method for routing based on the geographical position in the based on wireless mesh network comprises:

Process one: based on the new greedy forward mode of real-time link quality detection: used in the new greedy forward mode and transmitted distance and available link quality and available link resource as disturbing perception IAS route criterion to carry out the selection of next-hop node, make that be grouped in selection on the basis that guarantees to transmit distance more helps the link that transmits

Process two: based on the chance formula route cavity method that detours of competition: when in being grouped in Wireless Mesh (netted) network, running into the route cavity, by the method that detours based on the chance formula route cavity of competition, in empty edge, each neighbor node is according to the topological sum link information competition repeater-transmitter meeting of being grasped, the possibility that the path jumping figure increases and network congestion takes place that having reduced blindly detours brings;

Under new greedy forward mode, by increasing data acquisition module and data acquisition interface at IEEE (IEEE-USA) 802.11MAC (medium access control) layer, in the state information of MAC layer to the node local interface, and the link information between node and the neighbours obtains, data are after treatment delivered to the route layer by the readjustment mode, form comprehensive route criterion at last, make that the packet forward node under the new greedy forward mode selects to press close to more the network actual conditions.

Described IAS route criterion is taken all factors into consideration distance, available link resource and three factors of link-quality transmitted; IAS route criterion formulate is

Wherein, be different from and only considered link overhead foundations such as packet loss, power consumption separately, use ETT _IAThe expense of expression Radio Link, distance is transmitted in ADV (n) expression,

${\mathrm{ETT}}_{\mathrm{IA}}\left(n\right)=\mathrm{ETX}\·\frac{S}{B\·\min \{{\mathrm{\α}}_i,{\mathrm{\α}}_n\}}$

Expectation transmission time ETT is as the improvement of expected transmission times ETX, physical significance is that the MAC layer successfully transmits a needed time of packet, the value of ETT increases along with increasing of link packet drop rate, its computing formula is ETT=ETXS/B, S is the size of packet, and B is that link bandwidth is a transmission rate; Min{ α _i, α _nRepresent to get minimum MAC layer interface idleness, ETX is an expected transmission times, and i is a present node, and n is the neighbor node of node i, definition MAC layer interface idleness α:

α＝β(C _idle/C _all)+(1-β)F

Wherein, C _AllAnd C _IdleBe illustrated respectively in survey in the detection window number of times of MAC layer interface and wherein MAC be detected idle number of times, F be the result of the last time detection, the busy then F=1 of MAC layer interface, otherwise F is 0, β is a modulation factor.

Detour in the method in the chance formula route cavity of competition, changed the RTS among the MAC802.11 (request sends) frame into BRTS (broadcast request transmission) frame, what comprise in the BRTS frame is the destination address of the grouping that will transmit, all receive that the node of this frame need calculate a priority parameters P, the forwarding distance has been considered in the design of priority parameters simultaneously, transmit success rate, and link-quality.Now the priority of node is converted to answer CTS (the allowing to send) timer of cooperation, according to the MAC802.11 agreement, after node sends the BRTS frame, will receive the CTS acknowledgement frame that neighbors is replied, the node of replying CTS at first will obtain current repeater-transmitter meeting, and the node that the corresponding P of being value is high more should have many more chances as forward node.

Beneficial effect: under greedy forward mode based on the real-time link quality detection, owing to utilize the quality of link between the MAC layer information analysis node, with the grouping forward travel distance under the unit routing cost as the route criterion, emulation experiment proves, new greediness is transmitted the route criterion can make the throughput of network increase, and improves the success of packet and sends to rate.When running into the route cavity, employing is based on the chance formula route cavity method that detours of competition, no longer be blindly with the right hand or left and right sides rule, but the selection of making behind all neighbor nodes of consideration node s, removed the blindness in the original agreement, improve the delivery of packets rate, reduced average number of hops and average delay end to end.

Description of drawings

Fig. 1 is the Routing Protocol improvement project that the present invention is based on the geographical position;

The simulation performance that Fig. 2 is to use the inventive method and existing Routing Protocol based on the geographical position relatively.Wherein: (a) being the influence change curve of data fluxion to average end-to-end delay, (b) is that the node number (c) is the change curve of the relation of delivery of packets rate and number of data streams to the change curve of the influence of delivery of packets rate in the network;

Fig. 3 is the chance formula cavity schematic diagram that detours.

Embodiment

1. transmit the route criterion of distance under the maximization unit cost

The present invention uses a kind of new criterion IAS, has taken all factors into consideration distance, available link resource and three factors of link-quality transmitted; Its expression formula is as follows:

$\mathrm{IAPS}\left(n\right)=\frac{\mathrm{ADV}\left(n\right)}{{\mathrm{ETT}}_{\mathrm{IA}}\left(n\right)}---\left(1\right)$

Wherein, be different from and only considered link overhead foundations such as packet loss, power consumption separately, use ETT among the present invention _IAThe expense of (Expected Transmit time with Interference Aware) expression Radio Link, ETT _IABe formulated as formula 2:

${\mathrm{ETT}}_{\mathrm{IA}}\left(n\right)=\mathrm{ETX}\·\frac{S}{B\·\min \{{\mathrm{\α}}_i,{\mathrm{\α}}_n\}}---\left(2\right)$

ETT is as the improvement of ETX, physical significance is that the MAC layer successfully transmits a needed time of packet, the value of ETT increases along with increasing of link packet drop rate, its computing formula is ETT=ETXS/B, S is the size of packet, B is that link bandwidth is a transmission rate, though ETT has represented certain channel quality really, but it can only represent that link successfully inserts the success rate that the back grouping sends, and can not represent the complexity that link inserts, therefore we have defined MAC layer interface idleness α, are formulated as formula 3:

α＝β(C _idle/C _all)+(1-β)F (3)

C _AllAnd C _IdleBe illustrated respectively in survey in the detection window number of times of MAC layer interface and wherein MAC be detected the number of times of free time, F is the last result who surveys, the busy then F=1 of MAC layer interface, otherwise F is 0, β is a modulation factor, generally getting β is 0.5, the balanced MAC layer interface state of considering that MAC layer interface idleness in the time window and current time are surveyed of expression, link only can insert when the MAC of communicating pair layer interface is the free time, so the quality criteria of certain bar link should be the minimum value of two end nodes herein.

2. the route cavity detours

The broadcasting of the route of improving the occasion-forwarding thought, the hole region that can no longer " blindly " detour, so the present invention cavity of proposing chance formula method that detours.Introduce in two sub-sections below.

Describe with accompanying drawing 3, suppose that node A is the node that data source produces, grouping has run into the route cavity when routing to node S, because do not have in the neighbor node of node S than its own point nearer apart from destination node, though the forwarding neighbours that are best suited for of node F as can be seen, but according to traditional limit ergodic algorithm, node S may select two paths: the one, go back to greedy pattern behind S → C → D → E → F → G, four jumpings of having arrived more than the node F compared with direct transmission, not only increased grouping routed path length, taken more Internet resources, also caused herein easily network congestion finally to cause a large amount of packet losses; The 2nd, S → I → J → K → S produces circulation and packet loss, and grouping finally can't be sent to destination node.Can see that from example we need investigate the situation of each neighbor node when transmitting, could determine best forward node after comprehensive the comparison.

In the accompanying drawing 3, the inventive method at first adopts greedy mode to transmit grouping, suppose that grouping is forwarded to node S, because node S not than it self more near the neighbours of node d, suppose that present network topology has been UDG (Unit DiskGraph) figure, we revise RTS (the Request to Send) frame among the IEEE 802.11MAC, make it become broadcast frame, promptly the neighbor node of all S can both receive this broadcast frame, be referred to as BRTS (BroadcastRTS) herein, be different from original RTS, what comprise in the new BRTS frame is the destination address of the grouping that will transmit, all receive that the node of this frame need calculate a priority parameters P, and we define P and are:

$P(d,s,x)=[(1-\mathrm{\α})\frac{L(d,x^{\′})}{L(d,s)}+\mathrm{\α}\frac{N_c\left(x\right)}{N_{\max }\left(s\right)}]\·[1-\mathrm{per}\left(x\right)]---\left(4\right)$

(s) expression node x is transmitting from node s P for d, x, the priority parameters when destination node is the grouping of d, L (d, x ') expression

Projected length on the direction, N _Max(s) maximum of the secondary neighbor node number of expression node S, this value is 5 in the drawings because the neighbor node of node F several 5 is maximum in the neighbor node of all S, this be for second in assurance formula 4 brackets less than 1, N _c(X) in the neighbor node of expression nodes X, the position is than the neighbours' nearer apart from destination node of the appointment among the BRTS number (than node S), can be so that the node of greedy forward mode be got back in grouping, this number is big more, and the chance that can successfully walk around the cavity after then grouping is transmitted through this node is just big more.α is a coordination parameter wherein, and according to the observed value in the experiment, setting this α value among the present invention is 0.7, because the proportion that the forwarding success rate should be considered in routing Design than forwarding progress is bigger.Per (x) then is the packet loss of link between node S and the nodes X, is the inverse of the ETX (x) that asks for.

Here the forwarding distance has been considered in the design of priority parameters simultaneously, transmit success rate, and link-quality, according to top analysis, P (d, x, s) node that value is high more should have many more chances as forward node, because that receive is BRTS, the node of then replying CTS at first will obtain current repeater-transmitter meeting, therefore, the priority of node should convert the answer CTS timer of cooperation to, and each receives that the formula that the setting timer of BRTS frame uses is:

C wherein _SlotsLatency period number for maximum is provided with according to the network bandwidth, and C is set in the emulation _SlotsBe 30, T _RandomBe a random value in 0.1～0.5s scope, be used to avoid neighbor node to respond simultaneously and produce conflict.

NS2 simulation result of the present invention

We utilize NS2 to carry out simulating, verifying to the algorithm that the present invention proposes, and IAP method and existing EPD+GSGR, GPSR algorithm are compared.At 1500 * 1500m ²The rectangular area in place 100 nodes at random, the maximum rate of node motion is 2m/s, adds up the variation of time delay by the number that changes data flow in the network, each data flow sends 800 groupings, simulation time continues 200s.The simulation result that end-to-end time delay changes with the data flow number is shown in Fig. 2 (a).Increase along with data fluxion in the network, the packeting average end-to-end delay of three kinds of Routing Protocols all increases to some extent, this is because the probability that data bump in the network increases gradually, and the IAP algorithm is by the real-time detection to MAC layer idleness between perception of data flow disturbance and the neighbor node, can in time avoid congested concentrated zone in the network, reduce end-to-end time delay.Fig. 2 (b) has shown the variation of delivery rate with node density of dividing into groups successfully.When node in the network distributes when rarer, there are many route cavities in the network or even open circuit, therefore the delivery rate of grouping is very undesirable.Owing to lack grasp to network topological information, the periphery that EPD+GSGR and GPSR carry out using right-hand rule blindly or lefft-hand rule to begin when detour in the cavity after local smallest point is delivered in grouping is again transmitted, and IAP realizes that by the positional information of utilizing two hop neighbors the cavity of chance formula detours at empty node place, grasps more network topology knowledge when detouring in the cavity.Therefore, along with increasing of node number in the network, the delivery of packets rate improves can be faster, at first the delivery of packets rate brought up to 1, and EPD+GSGR takes second place, and GPSR is the slowest.Fig. 2 (c) has shown the influence of number of data streams to packeting average delivery rate.GPSR and GSGR are when running into the route cavity, blindly from utilize right-hand rule to transmit packet along empty edge, and subsequent all grouped datas wrap in and have all adopted identical path when detour in the cavity, such mode can the data rheology in network cause a large amount of collisions of empty edge for a long time, cause the delivery of packets rate on the low side, and IAP has at first considered network topological information when running into route cavity selection forward node, avoided blindly transmitting, in the same dominant neighbor node of positional factor, consider its link-quality factor again, finally can choose the neighbor node that link-quality comparatively speaking better and more can help to divide into groups to go back to greedy pattern and transmit as next-hop node.Therefore IAP can remain delivery of packets rate preferably when number of data streams increases.

Claims (3)

1. In the based on wireless mesh network based on the method for routing in geographical position, it is characterized in that this method comprises:

   Process one: based on the new greedy forward mode of real-time link quality detection: used in the new greedy forward mode and transmitted distance and available link quality and available link resource as disturbing perception IAS route criterion to carry out the selection of next-hop node, make that be grouped in selection on the basis that guarantees to transmit distance more helps the link that transmits

   Process two: based on the chance formula route cavity method that detours of competition: when in being grouped in wireless Mesh netword, running into the route cavity, by the method that detours based on the chance formula route cavity of competition, in empty edge, each neighbor node is according to the topological sum link information competition repeater-transmitter meeting of being grasped, the possibility that the path jumping figure increases and network congestion takes place that having reduced blindly detours brings;

   Under new greedy forward mode, by increasing data acquisition module and data acquisition interface at the IEEE802.11MAC layer, in the state information of MAC layer to the node local interface, and the link information between node and the neighbours obtains, data are after treatment delivered to the route layer by the readjustment mode, form comprehensive route criterion at last, make that the packet forward node under the new greedy forward mode selects to press close to more the network actual conditions.
2. 2. based on the method for routing in geographical position, it is characterized in that described IAS route criterion in the based on wireless mesh network as claimed in claim 1, take all factors into consideration distance, available link resource and three factors of link-quality transmitted; IAS route criterion formulate is

   

   Wherein, be different from and only considered link overhead foundations such as packet loss, power consumption separately, use ETT _IAThe expense of expression Radio Link, distance is transmitted in ADV (n) expression,

   ${\mathrm{ETT}}_{\mathrm{IA}}\left(n\right)=\mathrm{ETX}\·\frac{S}{B\·\min \{{\mathrm{\α}}_i,{\mathrm{\α}}_n\}}$

   Expectation transmission time ETT is as the improvement of expected transmission times ETX, physical significance is that the MAC layer successfully transmits a needed time of packet, the value of ETT increases along with increasing of link packet drop rate, its computing formula is ETT=ETXS/B, S is the size of packet, and B is that link bandwidth is a transmission rate; Min{ α _i, α _nRepresent to get minimum MAC layer interface idleness, ETX is an expected transmission times, and i is a present node, and n is the neighbor node of node i, definition MAC layer interface idleness α:

   α＝β(C _idle/C _all)+(1-β)F

   Wherein, C _AllAnd C _IdleBe illustrated respectively in survey in the detection window number of times of MAC layer interface and wherein MAC be detected idle number of times, F be the result of the last time detection, the busy then F=1 of MAC layer interface, otherwise F is 0, β is a modulation factor.
3. 3. in the based on wireless mesh network as claimed in claim 1 based on the method for routing in geographical position, it is characterized in that the chance formula route cavity of competing detours in the method, request among the MAC802.11 is sent the RTS frame changed broadcast request transmission BRTS frame into, what comprise in the BRTS frame is the destination address of the grouping that will transmit, all receive that the node of this frame need calculate a priority parameters P, the forwarding distance has been considered in the design of priority parameters simultaneously, transmits success rate, and link-quality.Now the priority of node is converted to the answer CTS timer of cooperation, according to the MAC802.11 agreement, after node sends the BRTS frame, will receive the CTS acknowledgement frame that neighbors is replied, the node of replying CTS at first will obtain current repeater-transmitter meeting, and the node that the corresponding P of being value is high more should have many more chances as forward node.

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