CN104618945A - Link quality updating based route failure recovery method in wireless local area network (WLAN) - Google Patents

Abstract

The invention discloses a link quality updating based route failure recovery method in WLAN. The method is characterized by comprising following contents: increasing the broadcasting frequency by shortening Hello packet broadcasting interval; accelerating source node list updating by reducing cleaning time interval; improving the link quality RQ value and improving the convergence rate. By the aid of the method, by combining shortening of the Hello packet broadcasting interval to increase the broadcasting frequency, the routing table updating interval and the RQ value optimizing strategy, the network re-convergence time during node failures is shortened, and the network robustness is further enhanced.

Description

Based on the route restore method that link-quality upgrades in WLAN (wireless local area network)

Technical field

The invention belongs to technical field of communication network, particularly relate in WLAN (wireless local area network) based on the route restore method that link-quality upgrades.

Background technology

Routing Protocol is operated in data link layer to L2MPM (Layer 2Mesh Protocol for Mobile mobile device two layers of MESH agreement), is a kind of Proactive routing protocols.The basic thought of L2MPM Routing Protocol can reach node for the purpose of in neighbor node in all single-hops of source node to find the best neighbor node in respective path, and use best neighbor point as the next-hop node in data forwarding process, and do not need the topology and the routing iinformation that calculate, determine whole network.Determine best neighbor node according to being link-quality, the quality of link-quality determines network and sets up and the performance of the speed that upgrades and network.

The packet communicated between L2MPM agreement is Hello bag, wraps by periodically broadcasting Hello the neighbor node response message obtained in network, and then maintains routing table.It is as follows that Hello bag mainly contains effect in the protocol:

(1) existence of other node perceived source nodes is made.Neighbors determines the existence of source node after receiving Hello bag, sets up the routing table that self arrives source node, forward this bag subsequently after to processing data packets.

(2) as the judgment basis selecting down hop route in multi-hop strategy.RQ (Route Quality) in Hello bag, path quality weights) as the routing metric of L2MPM agreement, reflection be the quality of transmission path, value is higher shows that link-quality is better.

(3) L2MPM protocols work principle is as follows: first node periodically sends Hello bag, the routing table of oneself is set up according to the response message of neighbor node in network, it takes the Optimization route strategy overall route being decomposed into optimum down hop route, and the step that floods simply can be divided into following three steps:

A. source node periodic broadcast Hello wraps.

B. neighbor node can be transmitted to the neighbor node of oneself after receiving the Hello bag of source node, i.e. two hop nodes of source node.

C. two hop nodes again forward this Hello and wrap to its neighbor node, and namely three hop nodes of source node, circulate successively, and Hello bag will flood to whole network.Stop flooding, meanwhile, if the time-to-live of Hello bag expires or packet loss also can stop after nodes all in network all at least receive a Hello bag.

In L2MPM agreement, use following three values to calculate the transmission quality of link:

NQ (Node Quality, node link quality), node receives the count value of the Hello bag of certain local neighbor node.

EQ (Echo Quality, winding link-quality), node receives and is sent to certain local neighbor node and by the hello packet count value returned.

RQ (Route Quality, path quality weights), node mails to the percentage of the hello packet of certain local neighbor node.

Its computing formula is as follows:

RQ＝EQ/NQ

In network, each node calculates the local RQ value (RQ of oneself _local), source node initializes RQ value is 255, according to following formula

RQ _Globs＝RQ×RQ _Local

Calculate the overall RQ value (RQ in Hello bag _globe), then the Hello packet broadcast after renewal is gone out, so just can constantly update the transmission quality of link.

For weighing link-quality more accurately, L2MPM protocol RQ value is wrapped total RQ value by the Hello that nearest n time receives and is averaged and calculates, and wherein n is RQ-GLOBAL-WINDOW-SIZE, in L2MPM agreement, be defaulted as 5.There being multiple leading in the local neighbor node in this destination address path, according to the RQ value in each path, choosing RQ value soprano, carrying out transfer of data.

In existing L2MPM agreement, RQ value does on average by the RQ value of the Hello bag to receive for nearest n time that (n is overall window, acquiescence is 5), for the Hello bag lost, agreement acquiescence is by its RQ value zero setting, and null value is filtered out when calculating mean value, therefore the null value generated after packet loss does not participate in the calculating of RQ mean value, before Hello bag does not reach overall window, the RQ value of packet loss can not have an impact to mean value, to cause after certain link disconnects, wait for that overall window is for being just switched to another link time empty.Therefore RQ value can not reflect communication link quality in real time.

In L2MPM, Hello bag acquiescence broadcast interval is 1 second, i.e. Hello-BROADCAST-INTERVAL=1s, the Routing Protocol cleaning room interval of acquiescence cleaning is 200s, i.e. PURGE-TIMEOUT=200s.

In sum, there is following shortcoming in prior art: network convergence speed is comparatively slow, affects the quick renewal of routing policy, is difficult to the factors such as short time eliminating network equipment failure to the impact of network performance.

Summary of the invention

In order to solve the above-mentioned problems in the prior art, the object of this invention is to provide in WLAN (wireless local area network) based on the route restore method that link-quality upgrades, it can improve the multi-hop transmission performance of wireless network and the robustness of network, reduce the loss that network failure causes, recover network as early as possible to reach.

To achieve these goals, the technical solution used in the present invention is: a kind of route restore method upgraded based on link-quality in WLAN (wireless local area network) comprises following content:

A: by shortening the broadcast interval of Hello bag, increase broadcasting frequency;

B: by reducing clearance time interval, acceleration source node listing upgrades;

C: link-quality RQ value is improved, convergence speedup speed.

Preferred technical scheme, describedly comprises the following steps the process that link-quality RQ value is improved:

The optimization of step S1, link RQ mean value: if when certain node does not receive the Hello bag via its neighbors, the RQ value of this node be set to " 1 ", and when calculating this link RQ value, the unreceived Hello of this node wraps RQ value and participates in mean value calculation.

Further preferred technical scheme, describedly also comprises step S2 to the process that link-quality RQ value is improved:

The threshold value SNR of a signal strength signal intensity is set, when certain node receives the Hello bag from certain source node by its neighbors, extracts the signal strength signal intensity snr that its neighbors sends _t, and the penalty value of RQ is calculated by following formula

Wherein RQ _excellentfor the RQ value after optimization, RQ is initial value.

Further preferred technical scheme, described also step S3 is comprised to the process that link-quality RQ value is improved: if when certain node forwarding performance declines, RQ value is optimized by Acquisition Processor utilization rate CPU, memory usage MEM and network interface card load LOAD, make per=CPU+MEM+LOAD, adopt the mode of hysteresis loop to add two threshold value PER _land PER _h;

If certain a moment, the performance of t node was per _t,

Work as per _t<PER _ltime,

Work as per _t>PER _htime,

Wherein, RQ _newlyfor the RQ value after renewal.

Adopt above technical scheme, the present invention has following beneficial effect:

1., by shortening the broadcast interval (prior art gives tacit consent to 1 second) of Hello bag, increasing broadcasting frequency, thus finding malfunctioning node faster.

2., by reducing clearance time interval (prior art acquiescence 200s), acceleration source node listing upgrades, to fix a breakdown node faster, realizes fault recovery.

3. the invention solves packet loss problem, the RQ value of being wrapped by unreceived Hello is set to ' 1 ', in the case, if when certain node A does not receive the Hello bag via its neighbors B, its RQ value is put 1, when such first time gets average, the RQ value of this link is (255*4+1)/5, namely 204.When this link continues packet loss, average owing to being worth 1 participation, the RQ value at this place will be more and more less, thus accelerate convergence greatly, accelerate the speed finding fault.

4. invention introduces penalty mechanism; if certain node signal continues low in network, this node can be judged to be high-risk node, even if high-risk Nodes link is in connected state; but its network congestion and transmission rate are comparatively slow, adopt penalty mechanism to its punishment (signal to noise ratio rQ value will be affected with ratio forms), the failure predication function of agreement can be realized.

If 5. node device is in operation when occurring that cpu performance, internal memory use and the network port etc. goes wrong, node forwards and routing performance declines, if still functional with it and a large amount of forwarding data of neighbors, easily causes this node collapses.The present invention optimizes RQ value by collection utilization rate CPU, memory usage MEM and network interface card load LOAD tri-major parameters, in conjunction with the broadcast interval of Hello bag, the optimisation strategy of routing table update interval and RQ value, the time of network re-convergence when making this agreement shorten nodes break down, thus further enhancing the robustness of network.

Accompanying drawing explanation

Fig. 1 is the link transmission principle schematic in network.

Embodiment

For making the object, technical solutions and advantages of the present invention clearly understand, below in conjunction with instantiation also with reference to accompanying drawing, the present invention is described in more detail.Should be appreciated that, these describe just exemplary, and do not really want to limit the scope of the invention.In addition, in the following description, the description to known features and technology is eliminated, to avoid unnecessarily obscuring concept of the present invention.

Embodiment one:

The invention provides a kind of new routing convergence strategy, to realize the recovery of routing failure in time.Its packet when the transmission caused due to link quality and external interference continues packet loss, according in the present invention to the computed improved of its RQ value after Hello packet loss, the serious routed path of packet loss can be got rid of fast, avoid recipient to communicate impaired.

As shown in Figure 1, wherein, host As all in network, B, C, D all have two pieces of network interface cards to be responsible for link transmission, therefore from host A to host C, transmission has two paths, respectively: A0-B1-B2-C1 and A1-D1-D2-C2, if serious packet loss occurs A1 to C2 link, if the RQ value of being wrapped by the Hello of loss is set to 0, and 0 value can be filtered when calculating RQ value, then need the deterioration that just can find link when packet loss reaches overall window size n by the time, RQ result is calculated as follows:

							RQ average
								For the first time:	A1	——	255	255	255	255	255
	A0	166	172	174	178	165	171
								For the second time:	A1	——	——	255	255	255	255
	A0	164	176	178	163	179	172
								For the third time:	A1	——	——	——	255	255	255
	A0	171	167	173	167	177	171
								4th time:	A1	——	——	——	——	255	255
	A0	168	170	178	177	162	171
								5th time:	A1	——	——	——	——	——	0
	A0	169	171	176	173	166	171

In can seeing the above table, only when lasting packet loss number of times reaches maximized window number, the H data on (herein maximized window number n=5) Cai Huijiangci road forwards another routed path to; After the RQ value of being wrapped by the Hello of loss changes 1 into, being calculated as follows of its RQ value:

							RQ average
								For the first time:	A1	1	255	255	255	255	204
	A0	166	172	174	178	165	171
								For the second time:	A1	1	1	255	255	255	153
	A0	164	176	178	163	179	172

After improvement of the present invention, after link continues less packet loss several times, as above second time packet loss in table, can lower fast by RQ average, now the data on A1 path can be pass on A0 path after contrast, thus reduce lasting packet loss path to the impact of Internet Transmission.

Because nodes is deteriorated because load increases the weight of the efficiency of transmission that causes, or cause wireless network Local Property unstable because of dtr signal, the present invention, by the real-time performance parameter in conjunction with node, introduces penalty value mechanism, dynamic conditioning RQ value, and then Optimal performance.

Have multiple node in the wireless network, node A receives the Hello bag transmitted from Node B, can process this bag in node A, and to calculate the RQ value that makes new advances to upgrade routing table, the treatment step making RQ value=168 the present invention at node A place increase is as follows:

Signal strength optimization:

(1) node A extracts the signal strength values snr receiving data interior joint B _b=-35dBm.

(2) node A is by snr ^bsignal threshold value SNR=-50dBm with presetting, does following computing

$1-\frac{{\mathrm{snr}}_t-\mathrm{SNR}}{\mathrm{SNR}}$

Obtaining signal strength signal intensity penalty value is 1.3.

(3) penalty value brought in RQ signal optimizing formula, i.e. RQ=RQ*1.3=218.4, this is the RQ value after signal optimizing.

Joint behavior parameter regulates:

(4) extract the performance parameter of Node B, per=CPU+MEM+LOAD, if per now _b=84.

(5) per is judged _bwith the PER of predetermined threshold value _land PER _hsize, PER herein _l=40 and PER _h=70; Be greater than higher limit as seen.Calculating upper limit penalty value:

$1-{\left(\frac{{\mathrm{per}}_t-{\mathrm{PER}}_H}{{\mathrm{PER}}_H}\right)}^3$

Obtaining penalty value is 0.992.

(6) the RQ value that binding ability punishment calculation of parameter is new.RQ=218.4*0.992=216.65, this is the penalty value that node A place upgrades.

As can be seen from the above, after introducing signal parameter and performance parameter penalty value, the RQ value of node A more can the characteristic reflecting neighbor node of science, dynamic equalization for wireless network overall load regulates to be optimized, and then the localised load decreased in path and avoid high load capacity node to occur collapse due to large quantity process.

Should be understood that, above-mentioned embodiment of the present invention only for exemplary illustration or explain principle of the present invention, and is not construed as limiting the invention.Therefore, any amendment made when not departing from thought of the present invention and scope, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.In addition, claims of the present invention be intended to contain fall into claims scope and border or this scope and border equivalents in whole change and amendment.

Claims (4)

1. in WLAN (wireless local area network) based on link-quality upgrade a route restore method, it is characterized in that, it comprises following content:

By shortening the broadcast interval of Hello bag, increase broadcasting frequency;

By reducing clearance time interval, acceleration source node listing upgrades;

Link-quality RQ value is improved, convergence speedup speed.

2. in a kind of WLAN (wireless local area network) according to claim 1 based on the route restore method that link-quality upgrades, it is characterized in that, described the process that link-quality RQ value is improved to be comprised the following steps:

The optimization of step S1, link RQ mean value: if when certain node does not receive the Hello bag via its neighbors, the RQ value of this node be set to " 1 ", and when calculating this link RQ value, the unreceived Hello of this node wraps RQ value and participates in mean value calculation.

3. in a kind of WLAN (wireless local area network) according to claim 2 based on the route restore method that link-quality upgrades, it is characterized in that, described also step S2 is comprised to the process that link-quality RQ value is improved:

The threshold value SNR of a signal strength signal intensity is set, when certain node receives the Hello bag from certain source node by its neighbors, extracts the signal strength signal intensity snr that its neighbors sends _t, and the penalty value of RQ is calculated by following formula

Wherein RQ _excellentfor the RQ value after optimization, RQ is initial value.

4. in a kind of WLAN (wireless local area network) according to claim 3 based on link-quality upgrade route restore method, it is characterized in that, described also step S3 is comprised to the process that link-quality RQ value is improved: if when certain node forwarding performance declines, RQ value is optimized by Acquisition Processor utilization rate CPU, memory usage MEM and network interface card load LOAD, make per=CPU+MEM+LOAD, adopt the mode of hysteresis loop to add two threshold value PER _land PER _h;

If certain a moment, the performance of t node was per _t,

Work as per _t<PER _ltime,

Work as per _t>PER _htime,

Wherein, RQ _newlyfor the RQ value after renewal.