CN103825775B - The multi-hop wireless network available bandwidth real-time detection method of self-adaptive detection bag length - Google Patents

Abstract

The invention discloses a real-time detection method for the available bandwidth of a multi-hop wireless network with self-adaptive detection packet length. In the method, a source host sends a data packet string to a destination host, and the position and location of the bottleneck link are determined according to the delay signal returned by the measured node. An estimated available bandwidth value B, then reset the lifetime value of the packet string, and adjust the packet string length at the same time, after each measurement, the measured node will feed back the received delay information to the source host. The source host adjusts the length of the data packets in the packet string according to the feedback information and observes the delay information returned by each packet string to determine the actual available bandwidth. The invention realizes the real-time monitoring of the bandwidth of the wireless network, not only improves the accuracy of the measurement value of the available bandwidth of the wireless network, but also improves the reliability of the multi-hop wireless network, reduces the load of the network, and improves the performance of the network.

Description

Real-time detection method of available bandwidth in multi-hop wireless network based on self-adaptive detection packet length

technical field

The invention relates to a real-time detection mechanism of available bandwidth, in particular to a method for real-time detection of available bandwidth of wireless networks with self-adaptive detection packet length.

Background technique

With the wide application of wireless networks and the rapid growth of human demand for information services, how to ensure the quality of service (QoS) in wireless networks has become a hot research issue recently, and the acquisition of available bandwidth is the key to ensuring QoS in wireless networks ( An important prerequisite for quality of service). Network measurement is the basis for high-performance protocol design, network equipment development, network planning and construction, network management and operation, as well as the basis for developing high-performance network applications. With the continuous increase of new services such as real-time services and multimedia applications, people have put forward higher requirements for the quality of service (QoS) of the network. Although the network backbone bandwidth and access bandwidth have doubled, the network performance has not been doubled, mainly due to problems in network capacity design, network resource allocation and application design. The purpose of network bandwidth measurement is to accurately find the bottleneck link (tight link, the link with the smallest available bandwidth) in the network, so as to provide a basis for network capacity planning in the whole network. It can be seen that bandwidth measurement is important in network measurement. occupied an important position.

The network bandwidth measurement methods mainly include active measurement and passive measurement. The active measurement method obtains the network bandwidth measurement value by actively sending test packets, and the passive measurement method obtains the network bandwidth measurement data by analyzing the data flow existing in the network.

Contents of the invention

Aiming at the deficiencies of the prior art, the invention provides a method for real-time detection of the available bandwidth of a multi-hop wireless network with self-adaptive detection packet length. The invention can not only realize the real-time monitoring of the wireless network bandwidth, but also improve the accuracy of the measurement value of the available bandwidth of the wireless network, improve the reliability of the multi-hop wireless network, and improve the performance of the network.

The technical scheme of the present invention is: the multi-hop wireless network available bandwidth real-time detection method of self-adaptive detection packet length, it is characterized in that comprising the following steps:

(1) The source host S sends a series of data packets to the destination host D, and the position of the bottleneck link and an estimated available bandwidth value B are determined according to the delay signal returned by the node under test.

(2) Through the data of the bottleneck link position obtained in step (1), reset the life cycle value of the data packet string so that the packet string is located on the bottleneck link, and adjust the length of the packet in the packet string at the same time, by the step ( 1) The measured available bandwidth value B, the accurate value of the predicted actual available bandwidth is between [Bm, B+m], m takes 10%~20% of the available bandwidth B, and the first adjustment of the packet length refers to the actual available bandwidth The two upper and lower limits of the bandwidth value B±m, use the upper and lower limits of the actual available bandwidth to determine the adjustment range of the packet length, the first time the package is sent with B+m as the upper limit of the available bandwidth or Bm as the lower limit of the available bandwidth Value sending, the principle of the two kinds of sending packets is the same, the method of packet length adjustment needs to be changed, just change the packet length, send the adjusted packet string, and repeat the sending once every time t ₁ , send k times, k is 3 -5 for average;

(3) After each measurement, the measured node feeds back the received delay information to the source host, and the source host adjusts the length of the data packet in the packet string according to the feedback information and observes the delay information returned by each packet string to judge this measurement Whether it is successful or not, when the range of the actual available bandwidth measured last time is [Bm, B+m], it can be known from step (2) to adjust the packet length L so that (y _j ×B _i ^top )=B+m, where y _j represents the corresponding adjustment coefficient when the packet length L is adjusted for the jth time, B _i ^top represents the maximum transmission rate of the i-th node route, and the adjusted packet string is sent and measured, when the delay of returning the packet string is observed to increase monotonically , it is judged as successful, otherwise, it is judged as unsuccessful;

When it is judged to be successful, readjust the packet length of the packet string and repeat steps (2) and (3), and count the delay d _k of the packet string for k times, D(d ₁ ,d ₂ ,...,d _k ) is the variance of the delay of k packets of the same L value, when D(d ₁ ,d ₂ ,...,d _k )≤Δd, the actual available bandwidth B ^* =(B _i ^top ) ² /( n×L/t ₁ +B ₁ ^top );

When the judgment is unsuccessful, the value of m will be increased by Δm on the original basis, Δm=(5%~10%)×m, the specific value is determined by the network situation, when the network condition is good, Δm is taken as 10% , when the network condition is poor, Δm is taken as 5%, and steps (2) and (3) are repeated, and when the judgment is still unsuccessful, return to step (1) for re-measurement.

Further, the packets in the packet string are user datagram protocol packets, which are composed of two parts, one part is a measurement packet for locating the bottleneck link; the other part is a load packet for For the measurement of available bandwidth, the measurement data packets are symmetrically distributed on both sides of the load data packet. The life cycle value of the measurement data packet at the head increases sequentially from 1, and the increase is determined by the path node. The life cycle value of the measurement data packet at the tail Decremented to 1 in turn.

Further, in step (2), the basis for resetting the life cycle value of each packet of the measurement data packet is to gradually increase the life cycle value from 1 to i, use _t1 to represent the time interval between packet strings, and _t2 to represent a bundle The time it takes for the packet string to pass through the first node router, B _i ^top represents the maximum sending rate of the i-th node router (i=1, 2, 3...), it is known, and y _j represents the packet The length L adjusts the adjustment coefficient corresponding to the jth time, where 0<y _j <1, n and L respectively represent the number of load data packets in a bundle of packets and the length of each packet, according to t ₁ / (t ₁ + t ₂ ) × B ₁ ^top = (y _j ×B _i ^top )(Formula 1.1), t ₂ = n×L/B ₁ ^top (Formula 1.2), from formulas 1.1 and 1.2, y _j =t ₁ ×( B ₁ ^top ) ² /(t ₁ ×B ₁ ^top ×B _i ^top +n×B _i ^top ×L) (formula 1.3), after setting n, adjust L according to formula 1.3 so that (y _j ×B _i ^top )=B±m, the L value obtained when the equation is established is the value to be adjusted.

Further, according to the delay information fed back in step (3) and whether it is successful, the specific method for judging the range of available bandwidth is:

When L is adjusted so that (y _j ×B _i ^top )=B+m, and the obtained delay signal increases monotonously, that is, the measurement is successful, then it is judged that the available bandwidth is less than (y _j ×B _i ^top ), and the next measurement will be Increase the value of L to reduce (y _j+1 ×B _i ^top ), thereby reducing the range of the actual available bandwidth. The specific method is to use formula 1.3 to increase the value of L, so that (y _j+1 ×B _i ^top ) decreases as small as the middle value of the available bandwidth range obtained from the last measurement;

When the monotonous increase of the delay in the next measurement indicates that the available bandwidth is less than (y _j+1 ×B _i ^top ), the available bandwidth range is [Bm, (y _j+1 ×B _i ^top )];

If there is no change in the delay in the next measurement, it means that the available bandwidth is greater than (y _i+1 ×B _i ^top ), then the available bandwidth range is [(y _j+1 ×B _i ^top ), B+m].

When adjusting the packet length for the first time, choose to adjust L so that (y _j ×B _i ^top )=Bm, when the obtained delay signal does not change, that is, the measurement is successful, then it is judged that the available bandwidth is greater than (y _j ×B _i ^top ) , reduce the value of L in the next measurement, so that (y _j+1 ×B _i ^top ) increases, thereby reducing the range of the actual available bandwidth. The specific method is to use formula 1.3 to reduce the value of L, so that (y _j +1 ×B i top B _i ^top ) increased to the middle value of the available bandwidth range measured last time;

When the delay increases monotonically in the next measurement, the available bandwidth range is [Bm, (y _j+1 ×B _i ^top )];

When the delay does not change in the next measurement, the available bandwidth range is [ (y _j+1 ×B _i ^top ), B+m];

Each measurement adjusts the packet length according to the available bandwidth range obtained from the previous measurement, and gradually uses the dichotomy method to narrow the range of available bandwidth.

The beneficial effect of the present invention is that: the present invention not only realizes the real-time monitoring of the wireless network bandwidth, but also improves the accuracy of the measurement value of the available bandwidth of the wireless network, improves the reliability of the multi-hop wireless network, and improves the performance of the network.

Description of drawings

FIG. 1 is a flow chart of the specific realization of available bandwidth measurement of a multi-hop wireless network in the present invention.

FIG. 2 is a schematic diagram of sending detection packet strings at intervals of _t1 during the specific implementation of the present invention.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings, but the embodiments of the present invention are not limited thereto.

As shown in Figure 1, the steps of the real-time detection method for the available bandwidth of the multi-hop wireless network with adaptive detection packet length are:

(1) The source host S sends a series of UDP packets to the destination host D, and the position of the bottleneck link and an estimated available bandwidth value B are determined according to the delay signal returned by the tested node. As shown in Figure 2, the UDP packet consists of two parts, one part is the measurement data packet, which is used to locate the bottleneck link; the other part is the load data packet, which is used to measure the available bandwidth. The measurement data packets are distributed symmetrically on both sides of the payload data packets. The TTL value of the measurement data packets at the head increases sequentially from 1, and the specific increase is determined by the path node, where the path is known. The TTL values of the measurement data packets at the tail are decremented to 1 in turn. When a packet arrives at a node and is ready to be forwarded to the next node, the TTL value of the IP header of the packet will be reduced by 1 first. If TTL=0 is detected, the packet is discarded, and the node sends an ICMP (Internet Control Message Protocol, Internet Control Message Protocol) packet to the source host at the same time; if TTL≠0 is detected, the packet can continue to be sent. In order to reduce the packet loss rate, the number of measurement data packets P _{t_num} =40 is set in the experiment, that is, the number of measurement data packets distributed on both sides of the head and tail of the load data packet is 20 respectively, and the size of each packet is P _{t_len} (its typical value is 60B), the number of load data packets P _{l_num} =40, the size of each packet is P _{l_len} (the typical value is 500B), and the TTL value of the load data packets is set to a maximum value of 255. This measurement can locate the bottleneck link between nodes R _i and R _i+1 and the bottleneck node R _i and an estimated available bandwidth value B.

(2) Through the data of the bottleneck link position obtained in step (1), reset the life cycle (TTL for short) value of the UDP packet string so as to locate the packet string on the bottleneck link, so that it gradually increases from 1 to i , use t ₁ to represent the time interval between packets, t ₂ represents the time it takes for a bundle of packets to pass through the first node router, B _i ^top represents the maximum sending rate of the ith node router (i=1, 2, 3 ......), it is known, y _j represents the corresponding adjustment coefficient when the packet length L is adjusted for the jth time, where 0<y _j <1, n and L respectively represent the load data in a bundle of packets The number of packets and the length of each packet. According to t ₁ / (t ₁ + t ₂ ) × B ₁ ^top = (y _j × B _i ^top ) (Formula 1.1), t ₂ = n × L/B ₁ ^top (Formula 1.2). From formulas 1.1 and 1.2, y _j =t ₁ ×(B ₁ ^top ) ² /(t ₁ ×B ₁ ^top ×B _i ^top +n×B _i ^top ×L) (formula 1.3), after setting n, Adjusting L according to formula 1.3 can make (y _j ×B _i ^top )=B±m, and the L value obtained when the equation is established is the value to be adjusted. Also adjust the length of the packets in the packet string. From the available bandwidth value B measured in step (1), it is predicted that the accurate value of the actual available bandwidth is between [Bm, B+m], and m takes 10%~20% of the available bandwidth B, then the first packet length The adjustment needs to refer to the two upper and lower limits of the actual available bandwidth value B±m. The adjustment range of the packet length can be determined by using the upper and lower limits of the actual available bandwidth. The first time you need to send a packet with B+m as the upper limit of the available bandwidth (you can also send a packet with Bm as the lower limit of the available bandwidth), you only need to change the packet length. Send the adjusted packet string, and send it repeatedly at intervals of t ₁ , and send k times (k takes 3-5) for average.

(3) After each measurement, the measured node feeds back the received delay information to the source host, and then the source host adjusts the length of the data packet in the packet string according to the feedback information and observes the delay information returned by each packet string to judge the time delay. Whether the measurement was successful. For example, the range of the actual available bandwidth measured last time is [Bm, B+m], then it can be known from step (2) to adjust the packet length L so that (y _j ×B _i ^top )=B+m, where y _j represents Packet length L adjusts the adjustment coefficient corresponding to the jth time, B _i ^top represents the maximum transmission rate of the i-th node route, sends the adjusted packet string and measures it, and if it is observed that the delay of returning the packet string increases monotonously, then judge for success. Otherwise, it is judged as unsuccessful;

Judge the range of available bandwidth according to the feedback delay and success information. Adjust L so that (y _j ×B _i ^top )=B+m, and the obtained delay signal increases monotonously, that is, the measurement is successful, then it is judged that the available bandwidth is less than (y _j ×B _i ^top ), then the next measurement will be Increasing the value of L makes (y _j+1 ×B _i ^top ) decrease, thereby narrowing the range of the actual available bandwidth. The specific method is to use formula 1.3 to increase the value of L, so that (y _j+1 ×B _i ^top ) is reduced to the middle value of the available bandwidth range obtained from the last measurement.

When the monotonous increase of the delay in the next measurement indicates that the available bandwidth is less than (y _j+1 ×B _i ^top ), the available bandwidth range is [Bm, (y _j+1 ×B _i ^top )];

If there is no change in the delay in the next measurement, it means that the available bandwidth is greater than (y _i+1 ×B _i ^top ), then the available bandwidth range is [(y _j+1 ×B _i ^top ), B+m].

Each measurement adjusts the packet length according to the available bandwidth range obtained from the previous measurement, and gradually uses the dichotomy method to narrow the range of available bandwidth. Similarly, if you choose to adjust L so that (y _j ×B _i ^top )=Bm when adjusting the packet length for the first time, then the principle of adjusting the packet length is the same, and the method is changed accordingly.

(4) If it is judged to be successful, readjust the packet length of the packet string and repeat steps (2) and (3). The time delay d _k of k times of packet strings is counted, and D(d ₁ , d ₂ ,...,d _k ) is the variance of the time delay of k times of packet strings with the same L value. When D(d ₁ ,d ₂ ,...,d _k )≤Δd, the actual available bandwidth B ^* =(B _i ^top ) ² /(n×L/t ₁ +B ₁ ^top ) can be obtained.

(5) If the judgment is unsuccessful, increase the value of m by Δm on the original basis, Δm=(5%~10%)×m, the specific value is determined by the network situation. When the network condition is good, Δm takes 10%; when the network condition is poor, Δm takes 5%. Repeat steps (2) and (3). If the judgment is still unsuccessful, return to step (1) and measure again.

The embodiments of the present invention described above are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims (4)

1. the multi-hop wireless network available bandwidth real-time detection method of self-adaptive detection bag length, it is characterised in that including following step Suddenly：

(1) burst of data bag string is sent from source host S to destination host D, bottle is determined according to the delay time signal that tested node is returned The available bandwidth value B that the position on neck chain road and one estimate；

(2) data of the bottleneck link position obtained by step (1), reset the Lifetime values of packet string to incite somebody to action Bag string is navigated on bottleneck link, while the length wrapped in adjusting bag string, the available bandwidth value B measured by step (1), prediction are real Between [B-m, B+m], m takes the 10%～20% of available bandwidth B to the exact value of border available bandwidth, wraps long first time adjustment ginseng Two bounds of actual available bandwidth value B ± m are examined, using the bound of actual available bandwidth, it is determined that the long adjusting range of bag, Higher limit with B+m as available bandwidth is given out a contract for a project or the lower limit with B-m as available bandwidth is given out a contract for a project, two kinds of principles given out a contract for a project for the first time Identical, the method for the long adjustment of bag needs to make to change, and need to only change bag length, send the bag string after adjustment, and be separated by t often₁Time Repeat to send once, send k time, k takes 3-5, to be averaging；

(3) after measuring every time, the Delay for receiving is fed back to source host by measured node, and source host is according to feedback information The length of packet and observe the Delay that each bag string returns and judge this measurement whether success in adjustment bag string, when obtaining The scope of the actual available bandwidth of last time measurement is [B-m, B+m], then understand that the long L of adjustment bag makes (y by step (2)_j×B_i ^top)= B+m, y in formula_jCorresponding adjustment factor when representing that the long L adjustment jth of bag is secondary, B_i ^topRepresent that i-th maximum transmission of node-routing is fast Rate, sends the bag after adjustment and goes here and there and measure, and when the time delay monotone increasing for observing that bag string is returned, then is judged as successfully, otherwise, sentencing Break as unsuccessful；

When being judged as successfully, then bag length repeat step (2), (3) of bag string are readjusted, time delay d of k bag string is counted_k, D (d₁,d₂,...,d_k) be k time of same L-value bag string time delay variance, as D (d₁,d₂,...,d_kDuring)≤Δ d, reality is obtained Available bandwidth B^*=(B_i ^top)²/(n×L/t₁+B₁ ^top), n represents load data bag number in a branch of bag string；

It is unsuccessful when judging, then the value of m is increased into Δ m, Δ m=(5%～10%) × m on the basis of its original, specifically Value determine that by network condition when network condition is good, Δ m takes 10%, when network condition is poor, and Δ m takes 5%, repeat to walk Suddenly (2), (3), when judging still as unsuccessful, then return to step (1) is remeasured.

2. the multi-hop wireless network available bandwidth real-time detection method of self-adaptive detection bag length according to claim 1, its It is characterised by：Bag in described bag string is all UDP packet, and the bag is made up of two parts, and a part is Measurement data bag, for positioning bottleneck link；Another part is load data bag, for the measurement of available bandwidth, measurement data Bag is symmetrically dispersed in load data bag both sides, and the Lifetime values of the measurement data bag of head increase successively from 1, increase to many Few to be determined according to path node, the Lifetime values of the measurement data bag of afterbody are decremented to 1 successively.

3. the multi-hop wireless network available bandwidth real-time detection method of self-adaptive detection bag length according to claim 1, its It is characterised by：Reset in step (2) Lifetime values of measurement data Bao Gebao according to be make Lifetime values from 1 gradually Increase to i, use t₁Represent the time interval between bag string, t₂Represent that a branch of bag string is taken time by first node router, B_i ^topI-th node router maximum transmission rate (i=1,2,3......) is represented, it is known, y_jRepresent the long L adjustment of bag Corresponding adjustment factor during jth time, wherein 0<y_j<1, n and L represents load data bag number and each bag in a branch of bag string respectively Length, according to formula 1.1：t₁/(t₁+t₂)×B₁ ^top=(y_j×B_i ^top) and formula 1.2：t₂=n × L/B₁ ^topFormula can be obtained 1.3：y_j=t₁×(B₁ ^top)²/(t₁×B₁ ^top×B_i ^top+n×B_i ^top× L) (formula 1.3), after setting n, adjusted according to formula 1.3 L can make (y_j×B_i ^top)=B ± m, when equation is set up, resulting L-value seeks to the numerical value for adjusting.

4. the multi-hop wireless network available bandwidth real-time detection method of self-adaptive detection bag length according to claim 1, its It is characterised by：According to the Delay fed back in step (3) and whether successfully, the concrete side of the scope of available bandwidth is judged Method is：

When adjustment L makes (y_j×B_i ^top)=B+m, and the delay time signal for obtaining is monotone increasing, that is, measure successfully, then judge available Bandwidth is less than (y_j×B_i ^top), just increasing L-value in measurement next time makes (y_j+1×B_i ^top) reduce, so as to reduce actual available bandwidth Scope, concrete grammar is increasing L-value, to make (y using formula 1.3_j+1×B_i ^top) it is reduced to the available band that last time measurement is obtained The intermediate value of wide scope；

When in measurement next time, time delay monotone increasing explanation available bandwidth is less than (y_j+1×B_i ^top), then available bandwidth scope is in [B- m,(y_j+1×B_i ^top)]；

When in measurement next time, time delay is not changed in illustrating that now available bandwidth is more than (y_i+1×B_i ^top), then now available bandwidth model It is trapped among [(y_j+1×B_i ^top), B+m]；

Adjustment L is selected to make (y when first time adjustment bag is long_j×B_i ^top)=B-m, when the delay time signal for obtaining is to be not changed in, i.e., Measure successfully, then judge that available bandwidth is more than (y_j×B_i ^top), next time, measurement reduced L-value, made (y_j+1×B_i ^top) increase, so as to contract The scope of little actual available bandwidth, concrete grammar are reducing L-value, to make (y using formula 1.3_j+1×B_i ^top) increase to last time survey The intermediate value of the available bandwidth scope for measuring；

When time delay monotone increasing in measurement next time, then available bandwidth scope is in [B-m, (y_j+1×B_i ^top)]；

When in measurement next time, time delay is not changed in, then available bandwidth scope is in [(y_j+1×B_i ^top), B+m]；

The available bandwidth scope adjustment bag length that measurement is all obtained according to front one-shot measurement every time, progressively reduces available using two way classification The scope of bandwidth.