CN115347994B - Method, device, medium, wireless access equipment and system for feeding back state in network - Google Patents
Method, device, medium, wireless access equipment and system for feeding back state in network Download PDFInfo
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- H04L47/283—Flow control; Congestion control in relation to timing considerations in response to processing delays, e.g. caused by jitter or round trip time [RTT]
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Abstract
The invention provides a method, a device, a medium, wireless access equipment and a system for feeding back a state in a network. An intra-network state feedback method is applied to wireless access equipment and comprises the following steps: performing delay estimation for each downlink data packet arriving at the wireless access device; calculating a delay delta between adjacent downlink data packets based on the estimated delay and maintaining a delay profile of ACK packets for uplink feedback based on the delay delta; when the ACK packet arrives at the wireless access device, the transmission of the ACK packet is delayed using an adaptive out-of-band feedback signal control mechanism. The invention solves the problems of weak network and network disconnection from the communication server end to the client end.
Description
Technical Field
The present invention relates to the field of network real-time communications technologies, and in particular, to a method, an apparatus, a medium, a wireless access device, and a system for feeding back a state in a network.
Background
Various Real-time communication services (Real-Time Communication, RTC) now have clear commercial prospects and great development potential due to their wide use in daily life. Common real-time communication services comprise video conferences, cloud games, virtual reality and the like, the common mode is that a server side sends real-time video frames to a client side, the real-time performance is an outstanding advantage, and the pictures can enhance interaction and experience, so that online communication of users is facilitated. At present, the real-time audio and video service has two important trends, namely that the user scale of various services is continuously increasing due to the low-delay requirement of users, and the business mode of the Internet network audio and video market is continuously expanding, so that a plurality of business modes including live broadcast, video cloud PaaS and video conference are opened up, and users with various requirements can be attracted.
For real-time communication traffic, real-time is both an advantage and a necessary requirement, i.e. it must maintain consistently low latency characteristics. In order to meet such demands, various technologies are proposed in academia and industry, such as congestion control technology, active queue management system and the like, and the RTT median of the current large-scale live broadcast platform is measured to be less than 100 milliseconds. Tail delay is now increasingly a key factor affecting overall quality of service, and in extreme cases users may face delays greater than 400 milliseconds, severely affecting the use experience. The tail delay is usually caused by network congestion, for example, a large number of users simultaneously access and interfere with each other to cause a sudden drop of available bandwidth, so that data packets are queued in large numbers, which represents relatively poor strength of the existing server against weak networks. The resolution of this problem is critical to improving customer satisfaction.
An increasingly common insight is that the network congestion phenomenon described above often occurs in the path of the backbone network to the user terminal, i.e. the last hop of the mobile end is the bottleneck of the whole end-to-end transmission. In fig. 1, the last hop represents the transmission from the wireless access device to the receiving client, and the transmission delay and queuing delay incurred on this hop are the main factors contributing to the rise in end-to-end delay and network congestion.
Based on the above analysis, in order to better make the real-time communication service resist the weak network, it is necessary to propose a feedback scheme of congestion state in the network, and by feeding back the congestion signal of the last hop to the transmitting end in advance, the transmitting end can adjust the bandwidth in time, adapt to the network change, and meet the demands of users.
Disclosure of Invention
The invention provides an intra-network state feedback method, device, medium, wireless access equipment and system for solving the problems of weak network and network disconnection from a communication server end to a client end.
In a first aspect, an embodiment of the present invention provides an in-network state feedback method, which is applied to a wireless access device, including:
performing delay estimation for each downlink data packet arriving at the wireless access device;
calculating a delay delta between adjacent downlink data packets based on the estimated delay and maintaining a delay profile of ACK packets for uplink feedback based on the delay delta;
when the ACK packet arrives at the wireless access device, the transmission of the ACK packet is delayed using an adaptive out-of-band feedback signal control mechanism.
In some implementations, the estimating the propagation delay for each downlink data packet arriving at the wireless access device includes:
measuring the current queue length and the dequeue rate;
calculating the queuing time of the downlink data packet in the current queue based on the current queue length and the dequeue rate;
acquiring the waiting time of the downlink data packet at the queue head at the moment;
the time interval during which the downlink data packet leaves the queue is measured, and the total delay of the downlink data packet is estimated, including the sum of the queuing time, the waiting time and the time interval.
In some implementations, the maintaining a delay profile of the ACK packet for uplink feedback based on the delay delta includes:
if the delay increment is positive, putting the delay increment into a sampling pool to update delay distribution;
and if the delay increment is negative, the absolute value of the delay increment is taken as a first token to be put into a token pool.
In some implementations, the delaying transmission of the ACK packet when the ACK packet arrives at the wireless access device using an adaptive out-of-band feedback signal control mechanism includes:
sampling a delay increment from the sampling pool when the ACK packet arrives at the wireless access device;
judging whether a token exists in the token pool;
preferentially consuming the tokens in the token pool under the condition that the tokens exist in the token pool, subtracting the consumed tokens on the basis of the delay increment of sampling, delaying the ACK packet on the basis of the delay increment remained after the tokens are consumed, and deleting the consumed tokens from the token pool;
in the absence of tokens in the token pool, the ACK packet is delayed based on the sample delay delta.
In some implementations, the delaying transmission of the ACK packet by the adaptive out-of-band feedback signal control mechanism when the ACK packet arrives at the wireless access device further includes:
if the delayed ACK packet violates the original transmission sequence of the transmission protocol, a second token is calculated and stored according to the calculation formula of the second token and is put into the token pool.
In some implementations, the delaying transmission of the ACK packet by the adaptive out-of-band feedback signal control mechanism when the ACK packet arrives at the wireless access device further includes:
outdated tokens in the token pool are updated and deleted periodically.
In some implementations, the second token is calculated as follows:
token＝arr j+1 +sample j+1 -arr j+2 -sample j+2
wherein token is the second token, arr j+2 And arr j+1 The arrival time of ACK packet j+2 and ACK packet j+1 are sample respectively j+2 And sample j+1 The delay increment for ACK packet j+2 and ACK packet j+1 sampled from the sample pool are respectively.
In a second aspect, an embodiment of the present invention provides an in-network status feedback device, including:
a delay estimation module, configured to perform delay estimation on each downlink data packet arriving at the wireless access device;
a delay profile maintenance module for calculating a delay delta between adjacent downlink data packets based on the estimated delay and maintaining a delay profile of an ACK packet for uplink feedback based on the delay delta;
and the feedback delay module is used for delaying the sending of the ACK packet by utilizing an adaptive out-of-band feedback signal control mechanism when the ACK packet arrives at the wireless access device.
In a third aspect, an embodiment of the present invention provides a computer-readable storage medium, where a computer program is stored, where the computer program, when executed by one or more processors, implements the method for in-network status feedback according to the first aspect.
In a fourth aspect, an embodiment of the present invention provides a wireless access device, including a memory and one or more processors, where the memory stores a computer program, and the computer program is executed by the one or more processors to implement the in-network state feedback method according to the first aspect.
In a fifth aspect, an embodiment of the present invention provides an audio/video real-time transmission system, including the wireless access device in the fourth aspect.
Compared with the prior art, one or more embodiments of the invention can bring at least the following advantages:
the invention predicts the delay of the last hop according to the information such as queuing and the like at the wireless access point, and feeds back the current network state to the transmitting end in advance, so that the transmitting end can sense that the network is congested and reduce the transmitting rate of the transmitting end to adapt to the change of the network in time, and a user is free from tolerating larger frame delay caused by unmatched bandwidth.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a related art RTC system architecture;
fig. 2 is a flowchart of an in-network status feedback method according to an embodiment of the present invention;
FIG. 3 is a flowchart of another method for in-network status feedback according to an embodiment of the present invention;
fig. 4 is a schematic diagram of an in-network status feedback device according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without making any inventive effort, are intended to be within the scope of the present invention.
The embodiment of the invention provides an intra-network state feedback method, device, medium, wireless access equipment and system, which are implemented on last hop wireless access equipment of an audio/video real-time transmission system and are used for solving the problems of weak network and network disconnection of the last hop network.
The scheme of the invention relates to three mutually coordinated aspects:
first, the feedback signal in the transmission protocol based on the out-of-band feedback is utilized to transmit the in-network state, so that the transmission rule is compatible: the transmission protocol based on out-of-band feedback, such as TCP, confirms that each data packet received by the client sends back an ACK packet, and after the sender receives the ACK packet, the sender automatically calculates network conditions such as RTT (Round-Trip Time), receiving rate, etc., and gives a reasonable sending rate decision, but the client does not have the capability of directly understanding a network feedback signal (such as available bandwidth), and no feedback packet exists in the connection. In view of this problem, the feedback mechanism design needs to be compatible with these existing transport protocols, so that modifications in the feedback mechanism regarding advanced feedback do not affect the implementation of the original transport mechanism and the feedback signal can be successfully identified by the sender. The method thus converts the predicted network conditions into signals that the sender can understand, creatively delays the reverse ACK packet to bring back the in-network state while the downlink data packet arrives, and simultaneously maintains the distribution about the in-network state to solve the problem of asynchronization of the data packet and the ACK packet, so that the continuously updated state distribution stored in the router will provide guidance to the transmission protocol and congestion control algorithm through feedback signals with the probability of closest real-time real network state.
Secondly, the feedback signal is estimated by combining the current queue in the network and the transmission state of the wireless channel: since the in-network device is now the provider of feedback information, the receiving rate is predicted as the feedback signal from information such as the length of the queue, the sending rate, etc. that can be grasped at the access point. The wireless network state change frequency and amplitude are large, the wireless network state change frequency and amplitude are provided with independent packet sending modes, and state changes in transient state and steady state exist, so that the wireless network state is difficult to estimate and predict, the method decomposes queuing delay into long-term and short-term state quantities according to the transmission characteristics of a wireless channel, and predicts the overall queuing delay of a data packet together, and the method calculates corresponding delay (queuing time and waiting time) by using current queuing information in the two state quantities, wherein the two parts and the transmission delay form the overall delay together, and the estimation method is more accurate in constructing a feedback signal.
Third, adaptive out-of-band feedback signal control mechanism: for the original packet transmission sequence and packet loss state of the transmission protocol, for example, the transmission protocol itself based on TCP has a fixed sequence and different processing modes for the received ACK (Acknowledge character, acknowledgement character) packet, and the advanced feedback mechanism needs to correctly transmit the network feedback signal to the sender without damaging the original transmission state. Therefore, the method needs to adaptively adjust the action of the feedback signal transmission back end when facing different transmission states, maintains the transmission states without the phenomenon of protocol contradiction, and simultaneously modifies the advanced feedback mechanism to influence the original feedback result due to following the original transmission rules, so that the state distribution in the advanced feedback mechanism needs to be adaptively recovered and adjusted to adapt to the influence.
Example 1
The embodiment provides an intra-network state feedback method, which is applied to a last hop wireless access device (AP) of an audio/video real-time transmission system, and in practical application, the wireless access device may be a wireless router, a WiFi access point, or a cellular network base station, as shown in fig. 2, at least includes steps S101 to S103:
step S101, performing delay estimation for each downlink packet arriving at the wireless access device.
Aiming at the problem of available bandwidth reduction caused by network jitter and increased competing users possibly occurring in an access network, the method designs a queue-based hybrid delay estimation method, and the inherent technical idea is that the method decomposes queuing delay into different parts and introduces long-term and short-term estimators due to instability of a wireless link, measures average dequeue rate to calculate long-term queuing delay, and the residence time of a data packet in front of a queue (queue head) responds to short-term fluctuation, and besides queuing delay, the total delay of downlink data packets also comprises transmission delay. Meanwhile, by combining the three delays, more accurate estimation of the transmission delay of the last hop wireless route can be obtained.
Thus, in some implementations, as shown in fig. 3, the step S101 of performing delay estimation on each downlink packet arriving at the wireless access device may include the following sub-steps:
step S101a, measuring the current queue length and dequeue rate.
The measurement of the queue length qLen is performed when each packet arrives at the AP, and for the downlink transmission rate txRate (also the dequeue rate) from the AP to the client, the transmission rate is set to be a sliding average value of the transmission rates measured over a period of time, where the transmission rate is the transmission rate of a single stream in order to meet the practical situation, because there may be a case where multiple streams share the transmission rate in common in the AP.
Step S101b, calculating a queuing time qdelay=qlen/txRate of the downlink data packet in the current queue based on the current queue length and the dequeue rate.
To avoid bursty wireless network packet-sending rules, the queue length may be summed to the existing length minus the length of the queue that would dequeue immediately due to frame aggregation, meaning that this portion would not follow the general queuing rules.
Step S101c, obtaining the waiting time of the downlink data packet at the queue head at the time.
In some cases, the operation timing of acquiring the waiting time of the downlink data packet at the head of the queue at this time is implemented, that is, it is performed at a certain frequency, for example, checking the waiting time of the downlink data packet at the head of the queue every 5ms, specifically, checking whether the downlink data packet at the head of the queue has changed, if the head of the queue becomes a new downlink data packet, from this time to the new downlink data packet being sent from the wireless access device AP or from this time to the aggregate frame where this new downlink data packet is located being sent from the wireless access device AP, this elapsed time being the waiting time WaitTime at the head of the queue in this new downlink data packet, the WaitTime employed when the downlink data packet arrives being the waiting time of the packet at the head of the queue at this time.
Step S101d, measuring a time interval when the downlink data packet leaves the queue, and further estimating a total delay of the downlink data packet, including the queuing time, the waiting time and the time interval.
The transmission delay of a data packet is the time interval during which the data packet leaves the queue, because the transmission of the wireless channel is frame by frame, and the transmission is started only when the previous data frame arrives and the next data frame arrives. However, a data frame may include a plurality of data packets, the time interval cannot be measured according to the granularity of the data packets, or a plurality of time intervals of 0 continuous leaving queue appear, so the method aggregates the time intervals of leaving queue according to a certain time granularity, and estimates the transmission delay by counting the time intervals of leaving queue by using the aggregated data. By such a method, the downlink data packet transmission delay can be measured, and thus the total delay of the downlink data packet, including the sum of the queuing time, the waiting time and the transmission delay, can be estimated. The method estimates the total delay through the sum of the queuing time, the waiting time and the time interval, realizes the estimation of the mixed delay, and further can calculate the delay increment between adjacent downlink data packets based on the estimated total delay, namely the difference between the total delay between the adjacent downlink data packets.
Step S102, calculating a delay increment between adjacent downlink data packets based on the estimated delay, and maintaining a delay profile of the ACK packet for uplink feedback based on the delay increment.
In practice, TCP-based RTC systems have a variety of congestion control algorithms, which use them in different ways, although they all use ACK packets as a basis for out-of-band feedback. For example, BBR congestion control algorithms count the minimum RTT of ACK packets for rate adaptation, while Copa congestion control algorithms are sensitive to the delay of each ACK packet. To meet the requirements of different congestion control algorithms, the method faithfully provides an estimated delay at the finest granularity of each packet by delaying the ACK packets. The congestion control algorithm may then aggregate the fine-grained information and react in its own way. In the congestion control algorithm, when the downlink data packet decreases in available bandwidth or the interval between two adjacent data packets dequeued from the wireless access device AP increases due to the addition of competing data streams, the information representing network congestion needs to wait until two ACK data packets corresponding to the reverse direction are returned to the end with increased delay, the server end can perceive the delay and network condition and reduce the rate of sending data, and the advanced feedback mechanism shortens the control period, and when the downlink data packet arrives continuously, the transmission delay information is added directly to the reverse ACK packet which arrives before or arrives at the wireless access device AP in the wireless access device AP, and the sending of the ACK packets is delayed to reflect the increase of the queue length and the increase of the transmission delay. Congestion information is returned to the end directly following the last ACK without going through queuing and round trip time of the last hop.
The method utilizes the original acknowledgement mechanism of the transmission protocol to feed back the state in the network in advance by delaying the sending of the ACK packet, and does not produce redundant bandwidth consumption. In order to meet the requirements of different congestion control algorithms, the transmission delay estimation is provided with the finest granularity of each data packet, the estimated transmission delay and the distribution of the actual delay in transient state and steady state are unified, and the congestion control algorithms are rapidly guided by the closest real network conditions.
The network state is generally divided into a steady state and a transient state, and in order to ensure that the delay distribution maintained by the method and the delay operation on the ACK data packet do not affect the normal RTT estimation, the method respectively performs the following operations on the steady state and the transient state:
for steady state: in order to avoid that in the wireless access device AP the longer queuing delay causes the reverse ACK packet to continue to be sent with a delay, resulting in the congestion control algorithm exaggerating the true RTT and making an erroneous decision, the method does not directly add the absolute estimated transmission delay of the downlink data packet to the delay of the ACK packet. Instead, the delay delta, i.e. the delay difference between consecutive downlink data packets, is recorded. As the estimated transmission delay increases, the wireless access device AP records a series of delay increments and gradually increases the delay of the ACK packet. When the queue has been stably established, the delay increment will remain around zero, and the ACK packet for uplink feedback will not be affected by the extra delay;
for transients: directly utilizing the delay delta mechanism may not provide short-term delay fluctuations. The reason is that long-term delays are averaged and vary slowly, and non-zero delay increments generated by multiple downlink data packets can be carried in one ACK packet. In contrast, short-term delays vary from packet to packet. Not every delay increment may be carried in a separate ACK packet. The different simultaneity of the downlink data packet and the ACK packet for uplink feedback may cause multiple delay increments to accumulate into one ACK packet, which is not in line with the fact. Thus, the method does not directly superimpose the calculated delay increment of each data packet on the reverse ACK packet, but puts each delay increment as a possible sample into a sampling pool to be sampled by each reverse ACK packet (it should be clear that if the delay increment is positive, the ACK packet should be delayed, but if the delay increment is negative, the congestion relief is indicated, or only the data packet burst is encountered, and the delay of the ACK packet should be avoided), by which the distribution equivalence between the delay increment of the forward link and the delay of the reverse link ACK packet can be maintained, the distribution consistency between the actual delay and the predicted delay is optimized, and the two are matched accurately. The method further maintains a distribution of delay delta over the last period of time for updating the forward (link) data packet.
Based on this, the above step S102 calculates a delay increment between adjacent downlink data packets based on the estimated delay, and maintains a delay profile of the ACK packet for uplink feedback based on the delay increment, and may further include the sub-steps of:
step S102a, calculating the delay increment between adjacent downlink data packets based on the estimated delay;
step S102b, maintaining a delay profile of the ACK packet for uplink feedback based on the delay delta;
if the delay increment is positive, putting the delay increment into a sampling pool to update delay distribution;
and if the delay increment is a negative number, the absolute value of the delay increment of the negative number is taken as a first token to be put into a token pool.
When the ACK packet arrives at the radio access device AP, the radio access device AP samples the delay delta from the sample pool and uses the delay delta obtained by the sampling to delay the transmission of the ACK packet, preferably randomly sampled from the sample pool. Under this mechanism, the wireless access device AP can simulate the delay profile of the fed back ACK packet even if burst packet arrival and departure occur. And the maintained delay distribution needs to be updated in a non-judging period, and the outdated delay increment sample in the sampling pool is deleted to truly simulate the network state in the latest period of time, so that the consistency of steady state and transient real delay and the delay distribution in the sampling pool is maintained.
Step S103, when the ACK packet arrives at the wireless access device, the transmission of the ACK packet is delayed by using the adaptive out-of-band feedback signal control mechanism.
Applying the delay delta to the uplink feedback ACK packets introduces additional challenges for ACK packet order preservation. For example, if ACK packet j+1 and ACK packet j+2 arrive at the same time and ACK packet j+2 is sampled with less delay than ACK packet j+1, the wireless access device may send ACK packet j+2 before ACK packet j+1, which results in confusion of the feedback ACK packet and the sender. However, directly limiting the transmission time of the ACK packet fed back to the ACK packet fed back before, for example, letting ACK packet j+2 wait until ACK packet j+1 has been transmitted, means that ACK packet j+2 is artificially delayed for a period of time, which may lead to overestimation of RTT and incorrect decision. The method thus generates a token to preserve the order of the ACK packets while also avoiding overestimation of RTT. When a subsequent ACK packet needs to wait for the transmission of a previous ACK packet, a second token is stored, where the second token is defined as follows:
token＝arr j+1 +sample j+1 -arr j+2 -sample j+2
wherein arr is j+2 And arr j+1 The arrival time of ACK packet j+2 and ACK packet j+1 are sample respectively j+2 And sample j+1 The delay increment of the ACK packet j+2 and the delay increment of the ACK packet j+1 sampled from the sampling pool are respectively stored in the token pool together with the first token generated when the delay increment is negative, and the first token and the second token can prevent the delay of the ACK packet, so that the next sampling is performedWhen a new delay increment is obtained, the consumption of the tokens in the token pool is tried first (the delay increment minus the token value), and then the processed delay increment value sample is used, and if, of course, the delay increment is reduced to 0 without consuming all the tokens in the token pool, the current ACK packet is not delayed, and the consumed tokens are deleted from the token pool. In this case, the average value of the actual transmission delay will remain the same as the estimated transmission delay, and the consistency of the actual transmission delay profile and the estimated transmission delay profile is also maintained.
To guarantee the transmission order and rules, the method performs an adaptive out-of-band feedback signal control mechanism. Thus, the step S103 mentioned above may further include the sub-steps of, when the ACK packet arrives at the wireless access device, using the adaptive out-of-band feedback signal control mechanism to delay transmission of the ACK packet:
step S103a, sampling delay increment from the sampling pool when the ACK packet arrives at the wireless access device;
step S103b, judging whether a token exists in the token pool; it should be appreciated that the token pool may have stored therein a first token and/or a second token.
Step S103c, preferentially consuming the tokens in the token pool under the condition that the tokens exist in the token pool, subtracting the consumed tokens on the basis of the delay increment of sampling, delaying the ACK packet on the basis of the residual delay increment, and deleting the consumed tokens from the token pool;
in step S103d, if there is no token in the token pool, the ACK packet is delayed based on the delay increment of the sampling.
In some implementations, when the ACK packet arrives at the wireless access device, step S103 may delay transmission of the ACK packet by using an adaptive out-of-band feedback signal control mechanism, and may further include:
step S103e, if the delayed ACK packet violates the original transmission sequence of the transmission protocol, a second token is calculated according to the calculation formula of the second token and stored into a token pool.
The second token is calculated as follows:
token＝arr j+1 +sample j+1 -arr j+2 -sample j+2
wherein token is the second token, arr j+2 And arr j+1 The arrival time of ACK packet j+2 and ACK packet j+1 are sample respectively j+2 And sample j+1 The delay increment for ACK packet j+2 and ACK packet j+1 sampled from the sample pool are respectively.
In some implementations, the first-in first-out principle is used when preferentially consuming tokens in the token pool, and the first-in stored tokens are preferentially consumed.
In some implementations, the delaying transmission of the ACK packet by the adaptive out-of-band feedback signal control mechanism when the ACK packet arrives at the wireless access device further includes:
step S103f, the outdated tokens in the token pool are updated and deleted regularly.
It should be noted that, the type of the feedback control signal is not limited in this embodiment, and the method is not limited by the type of the feedback control signal of the transmission protocol. For example, a control signal with transmission delay as a center (for example, a control method for adjusting a rate by RTT, packet interval, delay gradient, etc.) may be used, but the method may be conveniently extended to a case of other control signals (for example, packet loss, etc.).
In the method of the embodiment, feedback signals based on an out-of-band feedback transmission mechanism are established and maintained, feedback information is creatively transmitted implicitly aiming at the out-of-band feedback transmission protocol mechanism, and the challenge of compatibility of the existing transmission protocol is solved; the steady state and the instantaneous queue state of the router queue are utilized to accurately predict signals such as delay, speed and the like of a data packet in the last hop, so that the hybrid delay estimation based on the queue is realized; the self-adaptive out-of-band feedback frequency control mechanism is established, network state feedback is added on the returned data packet, and the original transmission sequence and state of the transmission protocol can be self-adaptively met, so that the original transmission is not influenced. The scheme is suitable for transmission protocols based on out-of-band feedback under various RTC systems such as TCP or QUIC.
Meanwhile, the method is easy to deploy in a large scale and compatible with the existing transmission protocol. On one hand, compared with the DCQCN which needs to generate a new message, the XCP and the RCP need to write estimation information into a self-defined transmission protocol, and ABC needs to modify some fields of the existing message. Therefore, the equipment of the sending end and the client end does not need to be forcedly modified (the selection of the client is difficult to control), the universality is improved, and the daily development and maintenance cost is saved, so that the practical deployment of the scheme is stronger.
On the other hand, compared with the scheme of FastACK which does not need to change a transmitting end, the method aims at improving delay performance. The main goal of fask ack is to improve the throughput of the wireless access device, rather than keep the delay low. Also in fastdack, the feedback signal is simply a time advanced by the transmission delay of the reverse ACK on the wireless channel, and its advanced feedback mechanism is insufficient to meet the low tail delay requirement compared to the present method. Such as whether queuing delay, which is important in the present method, is contained in the fastdack or in the control loop, may lead to situations where network congestion information cannot be brought back in time.
Finally, it should be noted that, for transmission protocols based on out-of-band feedback, such as TCP, the method is different from a scheme that needs to modify the content of the feedback packet to feed back in advance, in that the method is compatible with such transmission protocols, cannot create a new feedback packet to increase network load and cannot be identified by the transmitting end. Considering that the ACK packet itself cannot expand the message content, the method needs to use the time of reaching the sending end of the ACK packet to implicitly transfer the in-network state.
Example two
As shown in fig. 4, this embodiment provides an in-network status feedback device, including:
a delay estimation module 201, configured to perform delay estimation on each downlink data packet arriving at the wireless access device;
a delay profile maintenance module 202 for calculating a delay increment between adjacent downlink data packets based on the estimated delay and maintaining a delay profile of ACK packets for uplink feedback based on the delay increment;
the feedback delay module 203 is configured to delay transmission of the ACK packet by using an adaptive out-of-band feedback signal control mechanism when the ACK packet arrives at the wireless access device.
In some implementations, delay estimation for each downlink packet arriving at the wireless access device may include the sub-steps of:
measuring the current queue length and the dequeue rate;
calculating queuing time qDelay of the downlink data packet in the current queue based on the current queue length and the dequeue rate;
acquiring the waiting time of the downlink data packet at the queue head at the moment;
the time interval during which the downlink data packet leaves the queue is measured, and the total delay of the downlink data packet is estimated, including the sum of the queuing time, the waiting time and the time interval.
In some implementations, calculating a delay delta between adjacent downlink data packets based on the estimated delay and maintaining a delay profile of ACK packets for uplink feedback based on the delay delta may further include:
calculating a delay delta between adjacent downlink data packets based on the estimated delay;
maintaining a delay profile of ACK packets for uplink feedback based on the delay delta;
if the delay increment is positive, putting the delay increment into a sampling pool to update delay distribution;
and if the delay increment is a negative number, the absolute value of the delay increment of the negative number is taken as a first token to be put into a token pool.
In some implementations, utilizing the adaptive out-of-band feedback signal control mechanism to delay transmission of the ACK packet when the ACK packet arrives at the wireless access device may further include:
sampling a delay increment from the sampling pool when the ACK packet arrives at the wireless access device;
judging whether a token exists in the token pool; it should be appreciated that the token pool may have stored therein a first token and/or a second token.
Preferentially consuming the tokens in the token pool under the condition that the tokens exist in the token pool, subtracting the consumed tokens on the basis of the delay increment of sampling, delaying the ACK packet on the basis of the residual delay increment, and deleting the consumed tokens from the token pool; and
in the absence of tokens in the token pool, the ACK packet is delayed based on the sample delay delta.
In some implementations, when the ACK packet arrives at the wireless access device, the transmission of the ACK packet is delayed using an adaptive out-of-band feedback signal control mechanism, and may further include:
if the delayed ACK packet violates the original transmission sequence of the transmission protocol, a second token is calculated and stored according to the calculation formula of the second token and is put into the token pool.
The second token is calculated as follows:
token＝arr j+1 +sample j+1 -arr j+2 -sample j+2
wherein token is the second token, arr j+2 And arr j+1 The arrival time of ACK packet j+2 and ACK packet j+1 are sample respectively j+2 And sample j+1 The delay increment for ACK packet j+2 and ACK packet j+1 sampled from the sample pool are respectively.
In some implementations, the first-in first-out principle is used when preferentially consuming tokens in the token pool, and the first-in stored tokens are preferentially consumed.
In some implementations, the delaying transmission of the ACK packet by the adaptive out-of-band feedback signal control mechanism when the ACK packet arrives at the wireless access device further includes:
outdated tokens in the token pool are updated and deleted periodically.
It should be appreciated that the apparatus of this embodiment provides all of the benefits of the method embodiments.
It will be appreciated by those skilled in the art that the modules or steps described above may be implemented in a general purpose computing device, they may be concentrated on a single computing device, or distributed across a network of computing devices, or they may alternatively be implemented in program code executable by computing devices, such that they may be stored in a memory device for execution by the computing devices, or they may be separately fabricated into individual integrated circuit modules, or multiple modules or steps within them may be fabricated into a single integrated circuit module. The present invention is not limited to any defined combination of hardware and software.
Example III
The present embodiment provides a computer-readable storage medium having a computer program stored thereon, which when executed by one or more processors, implements the method as provided in the first embodiment.
In this embodiment, the storage medium may be implemented by any type of volatile or nonvolatile Memory device or combination thereof, such as a static random access Memory (Static Random Access Memory, SRAM for short), an electrically erasable programmable Read-Only Memory (Electrically Erasable Programmable Read-Only Memory, EPROM for short), a programmable Read-Only Memory (Programmable Read-Only Memory, PROM for short), a Read-Only Memory (ROM for short), a magnetic Memory, a flash Memory, a magnetic disk, or an optical disk. The details of the method are described in the first embodiment, and are not repeated here.
Example IV
The present embodiment provides a wireless access device comprising a memory and one or more processors, the memory having stored thereon a computer program which, when executed by the one or more processors, implements the method of the previous embodiments.
In this embodiment, the processor may be an application specific integrated circuit (Application Specific Integrated Circuit, abbreviated as ASIC), a digital signal processor (Digital Signal Processor, abbreviated as DSP), a digital signal processing device (Digital Signal Processing Device, abbreviated as DSPD), a programmable logic device (Programmable Logic Device, abbreviated as PLD), a field programmable gate array (Field Programmable Gate Array, abbreviated as FPGA), a controller, a microcontroller, a microprocessor, or other electronic component implementation for performing the method in the above embodiment. The method implemented when the computer program running on the processor is executed may refer to the specific embodiment of the method provided in the foregoing embodiment of the present invention, and will not be described herein.
In some implementations, the wireless access device may be a wireless router, a WiFi access point, or a cellular network base station, among others.
Example five
The embodiment provides an audio/video real-time transmission system, which comprises the wireless access device described in the foregoing embodiment.
In the several embodiments provided in the embodiments of the present invention, it should be understood that the disclosed system and method may be implemented in other manners. The system and method embodiments described above are merely illustrative.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
Although the embodiments of the present invention are described above, the embodiments are only used for facilitating understanding of the present invention, and are not intended to limit the present invention. Any person skilled in the art can make any modification and variation in form and detail without departing from the spirit and scope of the present disclosure, but the scope of the present disclosure is still subject to the scope of the appended claims.
Claims (9)
1. An intra-network state feedback method, which is applied to wireless access equipment, comprises the following steps:
performing delay estimation for each downlink data packet arriving at the wireless access device;
calculating a delay delta between adjacent downlink data packets based on the estimated delay and maintaining a delay profile of ACK packets for uplink feedback based on the delay delta; the maintaining a delay profile of the ACK packet for uplink feedback based on the delay delta includes: if the delay increment is positive, putting the delay increment into a sampling pool to update delay distribution; if the delay increment is a negative number, the absolute value of the delay increment is taken as a first token to be put into a token pool;
when the ACK packet arrives at the wireless access device, the transmission of the ACK packet is delayed by utilizing an adaptive out-of-band feedback signal control mechanism; the method for delaying the sending of the ACK packet by utilizing the self-adaptive out-of-band feedback signal control mechanism when the ACK packet arrives at the wireless access device comprises the following steps: sampling a delay increment from the sampling pool when the ACK packet arrives at the wireless access device; judging whether a token exists in the token pool; preferentially consuming the tokens in the token pool under the condition that the tokens exist in the token pool, subtracting the consumed tokens on the basis of the delay increment of sampling, delaying the ACK packet on the basis of the delay increment remained after the tokens are consumed, and deleting the consumed tokens from the token pool; in the absence of tokens in the token pool, the ACK packet is delayed based on the sample delay delta.
2. The in-network state feedback method of claim 1, wherein said delay estimation of each downlink packet arriving at the wireless access device comprises:
measuring the current queue length and the dequeue rate;
calculating the queuing time of the downlink data packet in the current queue based on the current queue length and the dequeue rate;
acquiring the waiting time of the downlink data packet at the queue head at the moment;
the time interval during which the downlink data packet leaves the queue is measured, and the total delay of the downlink data packet is estimated, including the sum of the queuing time, the waiting time and the time interval.
3. The in-network status feedback method of claim 1, wherein the delaying the transmission of the ACK packet by the adaptive out-of-band feedback signal control mechanism when the ACK packet arrives at the wireless access device, further comprises:
if the delayed ACK packet violates the original transmission sequence of the transmission protocol, a second token is calculated and stored according to the calculation formula of the second token and is put into the token pool.
4. The in-network status feedback method of claim 3, wherein the delaying the transmission of the ACK packet by the adaptive out-of-band feedback signal control mechanism when the ACK packet arrives at the wireless access device, further comprises:
outdated tokens in the token pool are updated and deleted periodically.
5. The in-network state feedback method of claim 3, wherein the second token is calculated as follows:
token＝arr j+1 +sample j+1 -arr j+2 -sample j+2
wherein token is the second token, arr j+2 And arr j+1 The arrival time of ACK packet j+2 and ACK packet j+1 are sample respectively j+2 And sample j+1 The delay increment for ACK packet j+2 and ACK packet j+1 sampled from the sample pool are respectively.
6. An in-network status feedback device, comprising:
a delay estimation module, configured to perform delay estimation on each downlink data packet arriving at the wireless access device;
a delay profile maintenance module for calculating a delay delta between adjacent downlink data packets based on the estimated delay and maintaining a delay profile of an ACK packet for uplink feedback based on the delay delta; the maintaining a delay profile of the ACK packet for uplink feedback based on the delay delta includes: if the delay increment is positive, putting the delay increment into a sampling pool to update delay distribution; if the delay increment is a negative number, the absolute value of the delay increment is taken as a first token to be put into a token pool;
the feedback delay module is used for delaying the sending of the ACK packet by utilizing an adaptive out-of-band feedback signal control mechanism when the ACK packet arrives at the wireless access equipment; the method for delaying the sending of the ACK packet by utilizing the self-adaptive out-of-band feedback signal control mechanism when the ACK packet arrives at the wireless access device comprises the following steps: sampling a delay increment from the sampling pool when the ACK packet arrives at the wireless access device; judging whether a token exists in the token pool; preferentially consuming the tokens in the token pool under the condition that the tokens exist in the token pool, subtracting the consumed tokens on the basis of the delay increment of sampling, delaying the ACK packet on the basis of the delay increment remained after the tokens are consumed, and deleting the consumed tokens from the token pool; in the absence of tokens in the token pool, the ACK packet is delayed based on the sample delay delta.
7. A computer readable storage medium, wherein the storage medium has stored thereon a computer program which, when executed by one or more processors, implements the in-network state feedback method of any of claims 1 to 5.
8. A wireless access device comprising a memory and one or more processors, the memory having stored thereon a computer program which, when executed by the one or more processors, implements the in-network state feedback method of any of claims 1 to 5.
9. An audio/video real-time transmission system comprising the wireless access device of claim 8.
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