CN101557273A - Method simultaneously suitable for wired network real-time streaming media transport protocol and wireless network real-time streaming media transport protocol - Google Patents

Abstract

The invention relates to a method simultaneously suitable for a wired network real-time streaming media transport protocol and a wireless network real-time streaming media transport protocol, which is characterized by comprising the following steps: a, a sending end sends TFRC data packets; b, a receiving end receives the TFRC data packets and also calculates previous-time packet loss ratio p; c, the receiving end returns the information of the packet loss ratio p to the sending end through ACK packets, and when TFRC data packets with the number of b are received, one ACK packet is returned; and d, after the sending end receives the ACK packets, the TFRC data packets calculate a new sending speed rate Tcalc according to a Veno fomula. The invention enables the TFRCVeno to have good transmission performance in a wired network and a wireless network, greatly enhances the performance of the TFRC data packets in the wireless network, also ensures the fairness of the TFRC data packets and the friendliness of the TFRC data packets to other TCP transmissions, is simple and fast and has low cost.

Description

A kind of method that is applicable to the real time flow medium transmission of wired and wireless network simultaneously

Technical field

The present invention relates to a kind of method of procotol, particularly a kind of method that is applicable to the real time flow medium transmission of wired and wireless network simultaneously.

Background technology

TFRC (TCP Friendly Rate Control TCP compliant stream transmission control protocol) is a kind of in order to use the procotol (S.Floyd that the transmission service of high-quality is provided and designs to Streaming Media, M.Handley, andJ.Padhye et al. " Equation-Based Congestion Control for UnicastApplications. " ACM SIGCOMM ' 00, August 2000.).TFRC is on the basis of (UDP User DatagramProtocol User Datagram Protocol) procotol, utilize and a kind ofly can simulate TCP Reno (the congested control protocol of traditional TCP, the congested control protocol of TCP a kind of) computing formula (hereinafter referred to as " Reno formula ") of throughput behavior is controlled the speed that sends packet, thereby both utilized the real-time characteristic of UDP in Network Transmission, and avoided the unconfined transmission packet of UDP again and influence other TCP (TransmissionControl Protocol transmission control protocol) transmission performances.Concrete transmission course as shown in Figure 1.

The TFRC receiving terminal calculates the packet loss of this connection, and this result is returned to transmitting terminal by ACK bag (acknowledgement).After receiving the ACK bag, transmitting terminal is calculated new transmission rate according to new packet loss with the Reno formula, and adjusts the speed that sends packet thus.It is as follows to adjust the Reno formula that sends packet speed:

$T_{\mathrm{calc}}=\frac{S}{\mathrm{RTT}\sqrt{\frac{2\mathrm{bp}}{3}}+3{\mathrm{<figure-callout\; id="0"\; label="T"\; filenames="A20081006955300172.png,A20081006955300182.png"\; state="\{\{state\}\}">T</figure-callout>}}_0\sqrt{\frac{3\mathrm{bp}}{8}}p(1+32p^2)}$

T wherein _CalcBe calculate packet sending speed, S is the size of packet, RTT is packet two-way time (round trip time), p is the packet loss that receiving terminal is beamed back, T ₀=4RTT, b are meant that receiving terminal receives that whenever what packets return ACK bag, get 1 or 2 usually.

This shows that the Reno formula is the core of TFRC agreement, it has determined the transmission performance of TFRC.

In today, wireless network has become the important component part of computer network, and can play the part of more and more important role in the future.As everyone knows, wireless network has very high packet loss at random.TCP Reno is always the signal as network congestion lost of packet, and significantly reduces its transmission rate (reducing by half usually) behind packet loss.But this judgement is also inapplicable in wireless network, because in wireless network, most packet loss all is owing to signal noise, and connection interruption etc. causes, rather than network congestion, and we are referred to as packet loss at random, perhaps are the wireless network packet loss.Because TCP Reno thinks network congestion with a large amount of wireless network packet losses, so TCP Reno performance in wireless network is very low.And being result by the Reno formula, TFRC sends packet, so in wireless network, the performance of TFRC is also very poor.

At present, the existing improvement of much TFRC being carried out is to be implemented in the superperformance in the wireless network.These improvement can be divided into two big classes: need the improvement of go-between support and need not the improvement that go-between is supported.

Need the improvement of go-between support to be meant, this improvement not only need be carried out at transmission/receiving terminal, also can relate to the intermediate node of network, as router (router), and acting server (proxy), wireless network access device (access point) etc.Representational example has ECN-based TFRC (R.Chaudhary, and L.Jacob. " ECN Based TCP-friendly Rate Control for Wireless MultimediaStreaming. " IEEE ICCCN ' 03, October 2003.), Proxy-based TFRC (L.Huang, U.Horn, and F.Hartung et al. " Proxy-based TCP-friendly Streaming overMobile Networks. " ACM WoWMoM ' 02, September 2002.), WM-TFRC (J.Y.Pyun, Y.Kim, and K.H.Jang et al. " Wireless Measurement Based ResourceAllocation for QoS Provisioning over IEEE 802.11 Wireless LAN. " IEEETrans.On Computer Electronics, vol.49, Issue 3,2003), AED-based TFRC (V.Arya, and T.Turletti. " Accurate and Explicit Differentiation ofWireless and Congestion Losses. " IEEE ICDCSW ' 03, May 2003) etc.

Router (router) in the middle of ECN-based TFRC utilizes judges whether network is congested, and notifies receiving terminal this information by ECN (the congested alerting signal of the ExplicitCongestion Notification) sign that IP (Internet Protocol Internet protocol) packet header is set.Receiving terminal only calculates Loss Rate according to the bag of ECN sign, and by ACK bag notice transmitting terminal.Like this, transmitting terminal just only uses the packet loss that is caused by network congestion to calculate transmission rate, thereby avoids the influence of the packet loss generation of other reasons, has improved the performance of TFRC.

Proxy-based TFRC uses acting server (proxy) with transmitting terminal and receiving terminal separated into two parts, and only this part between transmitting terminal and acting server uses TFRC to transmit data.At another part, just acting server and receiving terminal then transmit data by RTP (the Real-time TransportProtocol RTP) agreement based on TCP.This method can be utilized the bandwidth of wireless network fully, thereby improves whole performance.

WM-TFRC utilizes the access node (access point) of wireless network to measure the packet loss of wireless network, and the result is returned to transmitting terminal.Meanwhile, receiving terminal then returns total packet loss.Like this, transmitting terminal can deduct the packet loss of wireless network by total packet loss, obtains the real packet loss that is caused by network congestion.Packet loss calculates transmission rate thus, can improve the performance of TFRC.

AED-based TFRC uses a kind of new packet loss resolution method that is called Accurate and ExplicitDifferentiation (AED) to improve the performance of TFRC.It all is provided with an acting server (agent) on the border of wireless network border and cable network.Acting server in the wireless network is regarded packet loss as packet loss at random, and the acting server in the cable network is then regarded packet loss as congestion packet loss.These information will be passed to receiving terminal, thereby allow the correct congestion packet loss rate that obtains of receiving terminal, improve the performance of TFRC.

In sum, wireless network needs improving one's methods of go-between support must add new function on intermediate node, perhaps add new intermediate node, this makes troubles for improved implementation, because change or change the equipment of existing already present Internet in a large number, be a very thing of difficulty.This situation has then been avoided in the improvement of another type, promptly need not the improvement that go-between is supported.This improvement is only made amendment to a side or two sides of transmission/receiving terminal.Representative wherein is MULTFRC (March 2004. for M.Chen, and A.Zakhor. " Rate Control for Streaming Video over Wireless. " IEEEINFOCOM ' 04).

, MULTFRC transmits very low of its bandwidth availability ratio if finding only to be connected in the wireless network with a TFRC.Therefore MULTFRC can set up many connections simultaneously in the process of transfer of data, and Chuan Shu efficient has just improved greatly like this.The number that connects is according to being come out by specific algorithm computation the two-way time (round trip time) of packet, and changes dynamically in the process of transmission.MULTFRC only needs transmitting terminal is improved, and is therefore very convenient.MULTFRC improves again subsequently, be called AIO-TFRC (M.Chen, and A.Zakhor. " AIO-TFRC:A Light-weight Rate Control Schemefor Streaming over Wireless. " IEEE WirelessCom ' 05, June 2005.).AIO-TFRC has simplified the programming implementation procedure of MULTFRC, and has solved its bad result that might produce when quantizing linking number.

Yet, no matter be MULTFRC AIO-TFRC, though they can increase substantially the performance of TFRC in wireless network, but sacrificed other advantage of TFRC, i.e. fairness and to the friendly of other TCP transmission.That is to say that when a plurality of MULTFRC transmitted data simultaneously, they can not equality enjoyed bandwidth.Simultaneously, if when MULTFRC and other TCP transmit data simultaneously, MULTFRC can seize the bandwidth that TCP should enjoy.

Summary of the invention

The purpose of this invention is to provide a kind of method that is applicable to the real time flow medium transmission of wired and wireless network simultaneously.Adopt the inventive method, TFRC Veno is had in wireless network and the good transmission performance of cable network, increasing substantially the performance of TFRC in wireless network simultaneously, guaranteed the fairness of TFRC and the friendly that other TCP are transmitted again, and simple and fast is arranged, the advantage that cost is low.

Technical scheme of the present invention has following steps:

A. transmitting terminal sends the TFRC packet;

B. receiving terminal receives the TFRC packet, calculates packet loss p for the previous period simultaneously,

C. receiving terminal returns to transmitting terminal with the information of packet loss p by ACK bag (acknowledgement), receives that whenever b TFRC packet returns an ACK bag;

D. after transmitting terminal was received the ACK bag, TFRC calculated the transmission rate T that makes new advances according to the Reno formula _Calc, wherein

$T_{\mathrm{calc}}=\frac{S}{\mathrm{RTT}\sqrt{\frac{2b(1-\mathrm{\&gamma;})\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="A20081006955300181.png"\; state="\{\{state\}\}">p</figure-callout>}}{1+\mathrm{\&gamma;}}}+3T_0\sqrt{\frac{b(1-{\mathrm{\&gamma;}}^2)p}{2}}p(1+32p^2)}$

In the formula: S is the size of the new packet of TFRC, and RTT is packet two-way time (round triptime), and b is that receiving terminal receives that whenever 1～2 packet returns an ACK bag, and p is the packet loss that receiving terminal is beamed back, T ₀=4RTT, γ for the present invention to the resulting characteristic parameter of TCP Veno modeling, its computing formula is

$\mathrm{\&gamma;}=\min ({\mathrm{\&theta;}}_1,{\mathrm{\&theta;}}_2+({\mathrm{\&theta;}}_1-{\mathrm{\&theta;}}_2)\&times;\frac{\mathrm{\&beta;}\&times;\mathrm{RTT}}{(\mathrm{RTT}-\mathrm{BaseRTT})\&times;W_{\max }})$

In the formula, θ ₁For TCP Veno is judging that packet loss is the speed that is reduced to during packet loss at random and the ratio of original speed, θ ₂The speed that is reduced to when judging that packet loss is congestion packet loss for TCP Veno and the ratio of original speed, BaseRTT is RTT minimum in the transmission course, W _Max=65535/S, S are the size of packet, and β is the constant that uses among the TCP Veno, gets 3 usually.

The inventive method adopts the computing formula (hereinafter referred to as " Veno formula ") of simulation TCP Veno (the congested control protocol of novel TCP, the congested control protocol of TCP a kind of) throughput behavior, and uses this formula instead and control the speed that TFRC gives out a contract for a project.TCP Veno is a kind of TCP procotol that good transmission performance is arranged under wireless network and cable network environment, so has used the performance of TFRC (hereinafter referred to as " TFRCVeno ") in wireless network behind the Veno formula to be greatly improved.

The present invention can be suitable for wired and formula wireless network simultaneously and replaces the Reno formula with a kind of, fundamentally solves the problem that TFRC runs in wireless network.TFRC Veno does not sacrifice other advantages of original TFRC when promoting the TFRC performance significantly, as fairness with to the friendly of other TCP transmission, and the stationarity that sends packet.In addition, TFRC Veno only need carry out minor modifications at the transmitting terminal of TFRC agreement: replace the Reno formula to get final product with the Veno formula.Therefore, be connected performance in the wireless network, only need to use the Veno formula to replace the Reno formula calculate packet sending speed at the TFRC transmitting terminal if want to improve existing TFRC, other mechanism need not change, can improve its performance, have use simple and convenient, the advantage that cost is low.

Our emulation experiment and live network experiment show, adopt the Veno formula of simulation TCP Veno throughput behavior to control the speed that TFRC gives out a contract for a project, when the packet loss at random of network during in 10% left and right sides, the transmission speed of TFRC Veno can reach more than 3 times of TFRC speed.

Description of drawings

Fig. 1 is the transmission course schematic diagram of TFRC and TFRC Veno agreement;

Fig. 2 is the comparative experiments result schematic diagram of TFRC Veno and the throughput of TFRC under wireless network environment;

Fig. 3 is the comparative experiments result schematic diagram of TFRC Veno and the fairness of TFRC under wireless network environment;

Fig. 4 is TFRC Veno and the TFRC comparative experiments result schematic diagram to the friendly of other TCP transmission under wireless network environment;

The comparative experiments result schematic diagram of the stationarity that Fig. 5 transmits under wireless network environment for TFRC Veno and TFRC.

Embodiment

Explanation of nouns:

1.TFRC:TCP Friendly Rate Control (TCP compliant stream transmission control protocol)

2.UDP:User Datagram Protocol (User Datagram Protocol)

3.TCP:Transmission Control Protocol (transmission control protocol)

4.IP:Internet Protocol (Internet protocol)

5.TCP the congested control protocol of Reno:(tradition TCP, the congested control protocol of TCP a kind of)

6.TCP the congested control protocol of the novel TCP of Veno:(, the congested control protocol of TCP a kind of)

7.ECN:Explicit Congestion Notification (congested alerting signal)

8.RTP:Real-time Transport Protocol (RTP)

(9.ACK:Acknowledgement affirmation packet)

The transmission course of one .TFRC Veno agreement

Referring to Fig. 1, the transmission course of TFRC Veno agreement is as described below:

1. transmitting terminal and receiving terminal are computer, therebetween by Internet connection.

2. transmitting terminal sends the TFRC packet, and the packet loss in not receiving ACK bag or ACK bag is 0 o'clock, and transmitting terminal strengthens its transmission speed T _{Send (i)}, get last time transmission speed T usually _{Send (i-1)}Twice and inbound pacing T last time _{Receive (i-1)}The minimum value of twice, i.e. T _{Send (i)}=min (2T _{Send (i-1)}, 2T _{Receive (i-1)}), inbound pacing T last time wherein _{Receive (i-1)}Inform by the ACK bag.

3. receiving terminal receives the TFRC packet, calculates packet loss p for the previous period simultaneously, and concrete computational process is as follows:

Note A _iBe the number of the packet of receiving of the i time packet loss and the i-1 time packet loss centre, we are to 8 nearest A _iBe weighted on average,

$\stackrel{\&OverBar;}{A}=\frac{\underset{i=1}{\overset{8}{\mathrm{\&Sigma;}}}{w}_i{A}_i}{\underset{i=1}{\overset{8}{\mathrm{\&Sigma;}}}{w}_i}$

W wherein ₁=w ₂=w ₃=w ₄=1, w ₅=0.8, w ₆=0.6, w ₇=0.4, w ₈=0.2, last, obtain average packet loss ratio for the previous period:

$p=\frac{1}{\stackrel{\&OverBar;}{A}}$

4. receiving terminal returns to transmitting terminal with the information of packet loss p by the ACK bag, receives that whenever b TFRC packet returns an ACK bag (b is generally 1 or 2).

5. after transmitting terminal was received the ACK bag, TFRC Veno calculated the transmission rate that makes new advances according to the Veno formula, and sends new packet with this speed:

A) S is the size of packet, is preestablished by agreement.

B) RTT is packet two-way time (round trip time), and transmitting terminal is whenever received an ACK bag, all can upgrade current RTT value, and its computing formula is:

Note t is that the up-to-date packet that is once measured is issued to its ACK bag and receives institute's elapsed time, then

RTT _i＝αRTT _i-1+(1-α)t

Wherein α gets 0.9 usually, is preestablished by agreement; RTT _iBe current up-to-date RTT value; RTT _I-1RTT value for the last time.

C) p is the packet loss that receiving terminal is beamed back, and its computational process is referring to step 3;

d)T ₀＝4RTT；

E) b is meant that receiving terminal receives that whenever what packets return ACK bag, gets 1 or 2 usually, is preestablished by agreement;

F) calculated characteristics parameter γ:

I) θ ₁Be TCP Veno judging that packet loss is the speed that is reduced to during packet loss at random and the ratio of original speed, be generally 0.95, preestablish by agreement;

Ii) θ ₂Be TCP Veno judging the speed that packet loss is reduced to when being congestion packet loss and the ratio of original speed, be generally 0.5, preestablish by agreement;

Iii) BaseRTT is RTT minimum in the transmission course, whenever obtaining a new RTT, capital and original BaseRTT compare, if more than or equal to original BaseRTT, then original BaseRTT is constant, if less than original BaseRTT, then original BaseRTT becomes new RTT value, i.e. BaseRTT _i=min (BaseRTT _I-1, RTT _i);

Iv) β is the constant that uses among the TCP Veno, gets 3 usually, is preestablished by agreement;

Iv) W _Max=65535/S, S are the sizes of packet;

V) γ is calculated by the parameter of step (i)～(iv)

$\mathrm{\&gamma;}=\min ({\mathrm{\&theta;}}_1,{\mathrm{\&theta;}}_2+({\mathrm{\&theta;}}_1-{\mathrm{\&theta;}}_2)\&times;\frac{\mathrm{\&beta;}\&times;\mathrm{RTT}}{(\mathrm{RTT}-\mathrm{BaseRTT})\&times;W_{\max }})$

G) obtain packet sending speed T by the Veno formula at last _Calc

$T_{\mathrm{calc}}=\frac{S}{\mathrm{RTT}\sqrt{\frac{2b(1-\mathrm{\&gamma;})\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="A20081006955300181.png"\; state="\{\{state\}\}">p</figure-callout>}}{1+\mathrm{\&gamma;}}}+3T_0\sqrt{\frac{b(1-{\mathrm{\&gamma;}}^2)p}{2}}p(1+32p^2)}.$

The Veno formula is the formula that obtains according to the throughput behavior of simulating TCP Veno.TCP Veno is a kind of TCP procotol that good transmission performance is arranged under wireless network and cable network environment, and therefore the packet sending speed that draws according to this formula can not descend significantly because of the influence of wireless network.Obtain new packet sending speed T _CalcAfter, transmitting terminal will send the TFRC packet according to new packet sending speed constantly at the next one.

Below we are example with the (SuSE) Linux OS, illustrate how to utilize TFRC Veno agreement to send packet.

TFRC Veno agreement is arranged in linux system core (Linux Kernel) as a system module (system module).When (SuSE) Linux OS was installed, the user can select whether to install TFRC Veno protocol module.TFRC Veno protocol module provides some network interface function (Socket API), so that the user calls when writing the software of oneself.

The computer of supposing transmitting terminal and receiving terminal all uses (SuSE) Linux OS, and the TFRCVeno protocol module all has been installed.

The network interface function socket () that transmitting terminal and receiving terminal use TFRC Veno protocol module to provide packs TFRC Veno protocol module into so that the transmission data.Transmitting terminal has a software that sends Streaming Media, has called the network interface function listen () of TFRC Veno, at certain computer port (port), and for example 3912, monitor.The user of receiving terminal has the software (being generally media player) of a receiving stream media, has called the network interface function recv () of TFRC Veno, impels the TFRC Veno protocol module of receiving terminal just to connect to No. 3912 port request of transmitting terminal.After the TFRC of transmitting terminal Veno protocol module obtains connection request, just notice is called its upper layer software (applications), this software calls TFRC Veno network interface function send () subsequently, sends stream medium data to receiving terminal with the form of TFRC packet by TFRC Veno.Constant in the TFRCVeno agreement, for example big or small S of packet etc. is set in advance by transmitting terminal routine call TFRC Veno network interface function setsockopt ().

Notice that only for convenient for example, its real title may be different in each operating system for the title of the network interface function here.

In the process of transmitting of data, the TFRC Veno protocol module of transmitting terminal can calculate the speed of giving out a contract for a project according to the Veno formula what are.For example,

The TFRC Veno of transmitting terminal receives the ACK bag that receiving terminal returns, and the packet loss p that wherein informs network is 0.1 (receiving terminal is to the calculating of network packet loss rate p, referring to the explanation of accompanying drawing 1);

Simultaneously, the size of the TFRC packet that the TFRC Veno of transmitting terminal is provided with is 1000 bytes (Byte), and b is 1, θ ₁Be 0.95, θ ₂Be 0.5, β is 3 (meaning of various parameter presets is referring to the explanations of accompanying drawing 1);

Measuring packet two-way time (round trip time) RTT is 0.1 second (to the calculating of RTT, referring to the explanation of accompanying drawing 1), then T ₀=4RTT is 0.4 second;

Measure RTT minimum in the transmission course, promptly BaseRTT is 0.09 (to the calculating of BaseRTT, referring to the explanation of accompanying drawing 1);

Calculate W _Max=65535/S=65535/1000=65.535;

$\mathrm{\&gamma;}=\min ({\mathrm{\&theta;}}_1,{\mathrm{\&theta;}}_2+({\mathrm{\&theta;}}_1-{\mathrm{\&theta;}}_2)\&times;\frac{\mathrm{\&beta;}\&times;\mathrm{RTT}}{(\mathrm{RTT}-\mathrm{BaseRTT})\&times;W_{\max }})$

$=\min (\mathrm{0.95,0.5}+(0.95-0.5)\&times;\frac{3\&times;0.1}{(0.1-0.09)\&times;65.535}$

$=\min \left(\mathrm{0.95,0.7}\right)$

$=0.7$

Then last packet sending speed (byte per second) is:

$T_{\mathrm{calc}}=\frac{S}{\mathrm{RTT}\sqrt{\frac{2b(1-\mathrm{\&gamma;})\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="A20081006955300181.png"\; state="\{\{state\}\}">p</figure-callout>}}{1+\mathrm{\&gamma;}}}+3T_0\sqrt{\frac{b(1-{\mathrm{\&gamma;}}^2)p}{2}}p(1+32p^2)}$

$=\frac{1000}{0.1\&times;\sqrt{\frac{2\&times;(1-0.7)\&times;0.1}{1+0.7}}+3\&times;0.4\&times;\sqrt{\frac{(1-{0.7}^2)\&times;0.1}{2}}\&times;0.1\&times;(1+32\&times;{0.1}^2)}$

$=22576$

Two. embodiment

The comparison (emulation experiment) of embodiment 1:TFRC Veno and the TFRC throughput under wireless network environment

Referring to Fig. 2, use network simulation instrument NS-2 to come the analog wireless networks environment, and set its packet loss at random.In experiment, transmitting terminal and receiving terminal upright 8 TFRC that build together are connected, begin to transmit data simultaneously by transmitting terminal, time is 5 minutes, and writes down the average throughput (bag/second) of 8 connections, and transmitting terminal and receiving terminal upright 8 the TFRC Veno that build together are connected then, transmitting terminal is in same environment transmission data, time also is 5 minutes, writes down its average throughput equally, and and the throughput of TFRC compare.Same experiment repeats 20 times, gets its average data and confidence level and be 0.95 confidential interval.We also will be at random packet loss progressively increase to 0.1 from 0.0001, repeat above experiment, experimental result is seen Fig. 2.

The abscissa of Fig. 2 is represented the packet loss of wireless network, from 0.0001 to 0.1, and ordinate is represented average throughput (Throughput), unit is bag/second (packet/s).From scheming to go up us as can be seen, after the packet loss of wireless network rose to 0.002, the throughput of TFRC Veno just began greater than TFRC.When packet loss reached 0.1, the throughput of TFRC Veno was 3 times of TFRC.This has illustrated that TFRC Veno performance to TFRC in wireless network has greatly improved.

The comparison (emulation experiment) of embodiment 2:TFRC Veno and the TFRC fairness under wireless network environment

Fairness is meant when the connection of a plurality of same protocol is transmitted data simultaneously, and they should be able to equality enjoys bandwidth.Here we quote the fair index (Fairness Index) of R.Jain as the standard (R.Jain. " The art of computer systems performance analysis. " Wiley, New York, 1991.) of weighing fairness.Fair formula of index is as follows:

$f=\frac{{\left(\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{T}_i\right)}^2}{\left(n\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{T}_i^2\right)}$

Wherein f is fair index, and n is the linking number that transmits simultaneously, T _iIt is the throughput that the i bar connects.Wherein, fair index illustrates then that more near 1 the fairness of this agreement is good more.

Fig. 3 has provided the comparison of the fair index of TFRC Veno and TFRC agreement.Its experimental situation is identical with the experiment of method of operation and Fig. 2, equally also transmits data with 8 TFRC or 8 TFRC Veno, and what just need record is fair index at every turn.Fig. 3 abscissa is represented the packet loss of wireless network, from 0.0001 to 0.1, and ordinate is represented fair index (Fairness Index).As can be seen from the figure, the fair index of TFRC Veno and TFRC is basic identical, and all near 1, illustrates that the improvement of TFRC Veno do not sacrifice the good fairness of TFRC.

The comparison (emulation experiment) of the friendly that embodiment 3:TFRC Veno and TFRC transmit other TCP under wireless network environment

Friendly to other TCP transmission is meant that when this agreement and Transmission Control Protocol transmitted data simultaneously, this agreement should not seized the bandwidth that TCP should enjoy.Why consider the friendly with TCP transmission, be because nowadays on the Internet most transfer of data all be to use Transmission Control Protocol, therefore new agreement should not cause bad influence to existing TCP transmission.The regrettably received index of the still undefined energy of the dotcom world about friendly, we make and observe friendly with the following method:

Experimental situation is identical with the experiment of Fig. 2 with method of operation.At first allow 8 TCP Sack connect the transmission data, the time is 5 minutes, and writes down its average throughput Throughput _PureTCP Sack (TCP withSelected Acknowl edgement) is the most a kind of Transmission Control Protocol of current application.Then 4 connections are wherein replaced to TFRC, transmit data again, the time still is 5 minutes, and writes down the average throughput Throughput that 4 remaining TCP connect _CoexistentIf,

Value near 1, illustrate that then replacing TCP to connect the remaining TCP of not influence with TFRC connects, transmission is friendly to TFRC to TCP.We use the same method TFRC Veno are observed, and compare with TFRC.

Fig. 4 has provided the comparison to the friendly of TCP transmission of TFRC Veno and TFRC agreement, and abscissa is represented the packet loss of wireless network, and from 0.0001 to 0.1, ordinate is represented Value.As can be seen from the figure, TFRC Veno and TFRC

Value basic identical, and all near 1, illustrate that the improvement of TFRC Veno do not sacrifice the good friendly to the TCP transmission of TFRC.

The comparison of the stationarity that embodiment 4:TFRC Veno and TFRC transmit under wireless network environment (emulation experiment)

The stationarity of transmission is meant that number of data packets that this bargaining units time sends should held stationary, and this is even more important for real-time stream media protocol, because the sometimes fast and sometimes slow meeting in the process of giving out a contract for a project watches medium to cause bad influence to the user.Here we quote the standard that CoV (Coefficientof Variation) that TFRC author uses is used as weighing stationarity in its paper, and its computational methods are as follows:

$\mathrm{CoV}=\frac{\sqrt{\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(x_i-\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{x}_i)}^2}}{\left(\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{x}_i\right)}$

X wherein _iBe per number of data packets that 0.1 second, TFRC sent, what individual 0.1 second n refer to note down altogether.CoV is more little, shows that then the stationarity of transmission is good more.

The experimental situation of this experiment is identical with the experiment of Fig. 2 with method of operation.At first allow 8 TFRC connect the transmission data, the time is 5 minutes, and writes down its average CoV.Change TFRC Veno then into, transmit data again, the time still is 5 minutes, and writes down its CoV and comparing in TFRC.

Fig. 5 has provided the comparison to the stationarity of TCP transmission of TFRC Veno and TFRC agreement, and abscissa is represented the packet loss of wireless network, and from 0.0001 to 0.1, ordinate is represented the value of CoV.As can be seen from the figure, the value of the CoV of TFRC Veno and TFRC is basic identical, even also littler than the CoV of TFRC when packet loss is big at random, illustrates that the good transmission stationarity of TFRC is not sacrificed in the improvement of TFRC Veno.

Embodiment 5:TFRC Veno and the TFRC throughput under wireless network environment is accepted success rate, sends the comparison (Internet experiment) of stationarity

We build transmitting terminal and receiving terminal respectively in Hong Kong and Singapore, connect Internet at the receiving terminal of Singapore by wireless access network.We were at one day (9:00 10:00 of different periods, 11:0012:00,13:00 14:00,15:00 16:00,17:00 18:00,22:0023:00), simultaneously with 1 TFRC and 1 TFRC Veno transmission data, and note down its throughput, accept success rate (referring to that the bag of receiving accounts for the percentage of the bag of transmission) and CoV, and compare.This experiment repeats a week.Table 1 has provided wherein one day data.

Table 1 TFRC Veno and the TFRC throughput under wireless network environment is accepted success rate, sends the comparison (Internet experiment) of stationarity

As can be seen from Table 1, the throughput of TFRC Veno exceeds 30%--70% than TFRC most applications.And receiving on success rate and two indexs of CoV, then there is not any difference.This has illustrated TFRC Veno once more when improving the TFRC transmission performance, other advantages of not sacrificing TFRC.

Embodiment 6:TFRC Veno and TFRC the comparison (Internet experiment) under wireless network environment to the friendly of TCP transmission

Under the Internet experimental situation identical, done TFRC and TFRC Veno contrast to the friendly of TCP transmission with embodiment 5.We were at one day (10:30 11:30 of different periods, 13:3014:30,16:30 17:30,19:30 20:30,21:30 22:30), use the combination of 1 TFRC Veno+1 bar TCP Sack simultaneously, article 1, the combination of TFRC+1 bar TCP Sack, transmit data with the combination of 1 TCP Sack+1 bar TCP Sack, and note down the throughput of each connection, and compare.This experiment repeats a week.Table 2 has provided wherein one day data.

Table 2 TFRC Veno and TFRC the comparison (Internet experiment) under wireless network environment to the friendly of TCP transmission

As can be seen from Table 2, than the high 20%--50% of TFRC, and meanwhile, TCP Sack does not connect and does not reduce throughput because of the existence of TFRC or TFRC Veno the throughput of TFRC Veno most applications.This has illustrated that TFRC Veno and TFRC have the friendly of well TCP being transmitted.

Claims (3)

1. method that is applicable to the real time flow medium host-host protocol of wired and wireless network simultaneously is characterized in that following steps are arranged:

A. transmitting terminal sends the TFRC packet;

B. receiving terminal receives the TFRC packet, calculates packet loss p for the previous period simultaneously,

C. receiving terminal returns to transmitting terminal with the information of packet loss p by the ACK bag, receives that whenever b TFRC packet returns an ACK bag;

D. after transmitting terminal was received the ACK bag, TFRC calculated the transmission rate T that makes new advances according to following formula _Calc,

$T_{\mathrm{calc}}=\frac{S}{\mathrm{RTT}\sqrt{\frac{2b(1-\mathrm{\&gamma;})p}{1+\mathrm{\&gamma;}}}+3T_0\sqrt{\frac{b(1-{\mathrm{\&gamma;}}^2)p}{2}}p(1+32p^2)}$

In the formula: S is the size of the new packet of TFRC, and RTT is packet two-way time, and b is that receiving terminal receives that whenever 1 packet returns an ACK bag, and p is the packet loss that receiving terminal is beamed back, T ₀=4RTT, γ for the present invention to the resulting characteristic parameter of TCP Veno modeling,

E. transmitting terminal sends the TFRC packet according to new packet sending speed constantly at the next one.

2. the method that is applicable to the real time flow medium host-host protocol of wired and wireless network simultaneously according to claim 1 is characterized in that: packet loss $p=\frac{1}{\stackrel{\&OverBar;}{A}},$ The weighted average of the i-1 time packet loss of A wherein.

3. the method that is applicable to the real time flow medium host-host protocol of wired and wireless network simultaneously according to claim 1, it is characterized in that: the computing formula to the resulting characteristic parameter γ of TCP Veno modeling is

$\mathrm{\&gamma;}=\min ({\mathrm{\&theta;}}_1,{\mathrm{\&theta;}}_2+({\mathrm{\&theta;}}_1-{\mathrm{\&theta;}}_2)\&times;\frac{\mathrm{\&beta;}\&times;\mathrm{RTT}}{(\mathrm{RTT}-\mathrm{BaseRTT})\&times;W_{\max }})$

In the formula, θ ₁For TCP Veno is judging that packet loss is the speed that is reduced to during packet loss at random and the ratio of original speed, θ ₂The speed that is reduced to when judging that packet loss is congestion packet loss for TCP Veno and the ratio of original speed, BaseRTT is RTT minimum in the transmission course, W _Max=65535/S, S are the size of packet, and β is the constant that uses among the TCP Veno, gets 3 usually.

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