Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/12—Wireless traffic scheduling
  • H04W72/121—Wireless traffic scheduling for groups of terminals or users
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W52/00—Power management, e.g. Transmission Power Control [TPC] or power classes
  • H04W52/02—Power saving arrangements
  • H04W52/0209—Power saving arrangements in terminal devices
  • H04W52/0212—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is leader and terminal is follower
  • H04W52/0216—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is leader and terminal is follower using a pre-established activity schedule, e.g. traffic indication frame
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W52/00—Power management, e.g. Transmission Power Control [TPC] or power classes
  • H04W52/02—Power saving arrangements
  • H04W52/0209—Power saving arrangements in terminal devices
  • H04W52/0212—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is leader and terminal is follower
  • H04W52/0219—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is leader and terminal is follower where the power saving management affects multiple terminals
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
  • Y02D30/00—Reducing energy consumption in communication networks
  • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

• the present invention relates to a method and a device for the transmission of burst traffic.
• the present invention is particularly concerned with burst multiplexing in a Quality of Service (QoS) environment and burst transmission over radio LANs (WiFi / WiMAX). Therefore, it is useful to briefly review the underlying principles of QoS, traditional data multiplexing mechanisms as well as the IEEE 802.11 protocol.
• QoS Quality of Service
• WiFi / WiMAX radio LANs
• Fig. 1 is a block diagram of a simplified example of data transmission over a LAN having three host devices A, B and C;
• Fig. 2 is a block diagram of a conventional mechanism for time division multiplexing (TDM) of frames (from different applications) transmitted from device A to device B over the LAN shown in Fig. 1;
• Fig. 3 is a timing diagram of a transmission of Traffic Information Map (TIM) and Delivery Traffic Indication Message (DTIM) in an 802.11 LAN;
• Fig. 4 is a block diagram of the Traffic Information Map (TIM) shown in Fig. 3; and
• Fig. 5 is a flowchart of transmission of a LAN Association Request including three stations, two of which operate in power saving mode.
• QoS Quality of Service
• QoS refers to the probability that a network will fulfill a given traffic contract.
• the networks initially provided a network resource sharing service, in which competition for network resources is organized by "best" serving each stream as long as there is available capacity and rejecting excess traffic indiscriminately. Such a service is adequate as long as the load on the network is small in relation to its capacity and the applications using the network are not sensitive to delay variations.
• networks have had to provide high-speed, real-time services (eg, real-time audio / video transmission) in addition to traditional as for example messaging and file transfers.
• traffic flow is used throughout the rest of the Description to refer to data / messages that meet criteria related to the following characteristics:
• TCP Transmission Control Protocol
• UDP User Datagram Protocol
• a traffic flow might include:
• IP or TCP messages with "21" as the destination port and a given destination address
• IP or TCP messages that have a given destination IP address (subnet) address group
• class guarantees For a class warranty protocol, each packet entering the network is marked according to the class of traffic to which the packet belongs, and routers in the network classify and transmit the packets according to the service guarantees associated with the traffic classes.
• Traffic Smoothing attempts to format UDP and TCP traffic arriving irregularly into a flow of evenly spaced cells. This has the effect of smoothing peaks and valleys in a data transmission and reducing the load of network routers and their switching buffers as well as the jitter caused by long queues. Traffic smoothing is done by removing (where appropriate) excess datagrams in low priority traffic classes.
• the individual messages of a traffic flow are multiplexed on a transmission channel.
• 1 shows a simplified example of data transmission in a 10-LAN having three client devices A, B and C. If the ith frame of a message transmitted between a source device and a destination device designated by source. destination. i, then in the present example, at the times to, ti, t 2 and t 3 , the frames AB1, BC1, AB2 and BC2 are transmitted on the LAN 10.
• a frame is typically associated with a particular service provided by the network operator.
• Figure 2 shows a LAN in which four services are provided (Servicei, Service 2 , Services and Service 4 ), namely the services of email, telnet, streaming ⁇ streaming is a mode of transmission of contents , generally multimedia, on a network at a given bit rate, variable or fixed, less than or equal to the rate D of the network, so that these contents are displayed on the receivers as and when they are received) and FTP download .
• servicei the services of email, telnet
• streaming ⁇ streaming is a mode of transmission of contents , generally multimedia, on a network at a given bit rate, variable or fixed, less than or equal to the rate D of the network, so that these contents are displayed on the receivers as and when they are received
• FTP download FTP download
• the following examination will be limited to the multiplexing of frames transmitted between the device A and the device B.
• the traffic transmitted between the device A and the device B comprises n frames from each service.
• the traffic on the LAN will include:
• the output of the multiplexer 20 is:
• services may be given priority allowing the allocation of different percentages of bandwidth to individual services. For example, if the LAN provider in Figure 2 did not provide a service of FTP download and gave priority to the remaining services so that the email service is entitled to 50% of the bandwidth and that the telnet and streaming services are each entitled to 25% of the bandwidth; multiplexer would be:
• An 802.11 LAN is based on a Base Service Station (BSS) cellular architecture in which a BBS has at least two computers communicating with each other and each of the computers contains a Networking Interface (NIC) card.
• BSS Base Service Station
• NIC Networking Interface
• 802.11 LANs can be classified as ad hoc LAN or infrastructure LAN.
• the stations communicate directly with each other in a point-to-point manner without involving a central access point relay.
• AP Access Point
• the 802.11 protocol has two distinct layers of the wireless network model, namely the Media Access Layer (MAC) and the physical layer.
• the MAC defines two access methods, namely the Distributed Co-ordination Function (DCF) and the Point Co-ordination Function (PCF), and a number of functions including scanning, association, fragmentation, and energy saving to collectively manage the communication between stations.
• DCF Distributed Co-ordination Function
• PCF Point Co-ordination Function
• PCF Distributed Co-ordination Function
• the DCF does not employ a central control mechanism, but a Carrier Sensé Multiple Access with Collision Avoidance (CSMA / CA) distributed mechanism.
• CSMA Carrier Sensé Multiple Access with Collision Avoidance
• CA Carrier Sensé Multiple Access with Collision Avoidance
• PCF Point Co-ordination Function
• PCF is an access method that allows priority or delay sensitive packets to receive preferential treatment. More specifically, during the PCF, a point coordinator placed within an access point controls which stations can transmit at a given moment. Within a period of time called Contention Free Period (CFP), the point coordinator interrogates each station operating in PCF mode. During its turn, one and only one station may transmit frames for a specific period of time.
• CCP Contention Free Period
• the PCF divides the interval between two consecutive Beacon Frames (see below) into a Non-Contention Period and a Contention Period.
• a LAN can accommodate asynchronous transmissions (in which the stations do their own by using the CSMA) and synchronous transmissions (in which the stations attempt to be interrogated by the point coordinator before sending messages). frames).
• Scanning refers to the process by which a NIC searches for an Access Point.
• the scan is based on the detection of a periodically broadcast signal (or Beacon frame) (typically every 100 ms) by an access point.
• Beacon Frames contain the following information:
• Beacon__Interval ie the amount of time between beacon transmissions
• Time stamp [A time stamp is a time stamp for dating a message or event]
• C Service Set Identifier (SSID) (identifies the LAN so that a station can associate with a known LAN before data transmission); and
• Traffic Indication Map (d) Traffic Indication Map (TIM) (identifies which stations have data waiting for them in the Access Point buffer).
• a station Once a station has identified a Preferred Access Point, its NIC must associate (or establish a logical connection) with the Access Point.
• the association allows the access point to allocate resources for a NIC, and to synchronize with it.
• the station sends an Association Request frame to the Preferred Access Point.
• the Association Request frame carries information about the NIC and the SSID of the network it wishes to associate with.
• the Association Request frame further includes information indicating whether the station is operating in power saving mode.
• the Preferred Access Point Upon receipt of the Association Request frame, the Preferred Access Point, if it accepts the association request, reserves memory space and establishes an Association ID (AID) for the NIC of the station.
• AID 0 is reserved to indicate the presence of multicast / broadcast data waiting in an access point.
• the station's NIC is able to send frames to the access point. However, the station's NIC continues to scan for other Beacon frames from the access point to detect if the signal from the access point has become too weak to maintain communications. The NIC also uses the Timestamp from Beacon Frames to update its local clock and thereby maintain synchronization on the Access Point and other stations.
• the 802.11 standard includes a mechanism for fragmentation and re-assembly, which allows the frames to be fragmented into smaller pieces each of which has his own checksum. Once a channel has been acquired, the multiple fragments are sent consecutively in a sequence known as a "burst of fragments".
• the 802.11 power saving features allow a NIC to conserve battery power by switching to sleep mode when there is no need to send / receive data.
• the remainder of this description focuses on saving energy in an infrastructure network.
• a station informs its access point if it is running in power saving mode or not by setting a power management bit in its association request frame. If a station indicates that it is operating in power saving mode, the Access Point will temporarily store any unicast, multicast, or broadcast traffic destined for it. If the station indicates that it is not operating in power saving mode, the access point will not keep unicast data for the station. However, if only one station on the LAN indicates that it is operating in power saving mode, the Access Point will temporarily store all multicast and broadcast frames (even frames destined for stations that do not do not operate in power save mode). When none of the stations is operating in power saving mode, the access point transmits unicast, multicast and broadcast frames as soon as possible to the relevant stations.
• a NIC When running in power saving mode, a NIC wakes up periodically (at intervals specified by a Listen_Interval field in the Station Association Request frame) to receive Beacon Frames from the Access Point and determine by examination of its Traffic Information Map (TIM) if the Access point to stored data for the station.
• TIM Traffic Information Map
• TIM There are two different types of TIM, namely a TIM and a Delivery Traffic Indication Message
• DTIM DTIM
• a TIM is transmitted with each Beacon Trame and indicates the presence of unicast data in the Access Point.
• a DTIM is transmitted less frequently (ie every DTIM period) and signals the imminent transmission of multicast / broadcast data stored temporarily in the access point.
• a DTIM is transmitted within a Beacon frame and immediately thereafter the broadcast / multicast frames waiting in the access point are transmitted to the relevant station (s).
• a TIM includes a DTIM account, a DTIM period, a bitmap control, and a partial virtual bitmap.
• the DTIM account and the DTIM period are used to inform the stations of the times when pending multicast frames will be sent.
• the DTIM account is an integer value decremented at each Beacon and represents the number of Beacon Frames (including the current Beacon Trame) that will be issued before multicast frames are sent (ie, a DTIM of 0 indicates that the current TIM is a DTIM).
• the DTIM period is the number of Beacon Frames between multicast frame transmissions (ie, if all TIMs are DTIMs, the DTIM period field will have a value of 1).
• Bit 0 of the bitmap control field contains the traffic flag bit associated with AID 0.
• AID 0 is reserved to indicate the presence of broadcast / multicast frames.
• bit 0 of the bitmap control field is set to 1 when one or more broadcast or multicast frames are waiting in the access point.
• the virtual partial bitmap is organized in 251 bytes (2,008 bits) where each bit indicates the presence of unicast traffic waiting in the access point for a specific station.
• the bit number N has a value of 0 if there is no unicast frame waiting for the station whose AID is N. Thus, if an access point has put unicast frames on hold for the station whose the AID is N, the bit number N in the virtual partial bitmap is 1.
• FIG. 5 shows an example in which three stations (STNi, STN 2 and STN 3 ) are associated with an access point 30.
• the STNi and STN 2 stations operate in energy saving mode and STN 3 does not operate in energy saving.
• the virtual partial bitmap in the next Beacon frame from the access point is filled as follows: 1 1 0.
• the station After the expiration of the Listen_Interval period specified in the Associate Request frame of a station, the station wakes up and receives the beacon frame transmitted by its associated access point. If the station detects that the bit corresponding to its AID is set in the TIM of the Beacon Frame, the station sends a PS-POLL frame to the attention of the Access Point to retrieve the unicast data stored therein. The station will remain in the awake state until it receives the response to its PS-POLL frame (or receive another
• Beacon frame indicating that the access point has no more data waiting for it). If a station is capable of receiving multicast and / or broadcast data, the station wakes up at each DTIM period to receive each DTIM and broadcast / multicast data transmitted immediately thereafter.
• a station wakes up and receives a Beacon Trace (containing a DTIM) at the beginning of each Period without Contention.
• a station detects that the bit corresponding to its AID is set in the DTIM (or in a subsequent TIM)
• the station will remain awake for the remainder of the Period without Contention or until it there is more additional traffic waiting in the Access Point. If there is still pending traffic in the Access Point at the end of the No Hold Period, the station may remain awake and transmit PS-POLL frames during the Hold Period to request delivery of the remaining frames.
• the present invention is directed to a method for transmitting traffic comprising the steps of classifying the traffic according to its IP address or DSCP field and transmitting the traffic in a multiplexed or multiplexed manner in a continuous multiplexed manner as a function of its classification.
• the present invention employs burst multiplexing to improve the energy saving functionality of receiving devices. More particularly, the present invention employs burst multiplexing in a QoS environment in which network traffic is classified and assigned priority levels according to the nature of the transported service. Depending on the classification, the traffic may be transmitted in a traditional multiplexed continuous or burst manner.
• the burst multiplexing method in a QoS environment can be performed by extending an hierarchical class mechanism such as ALTQ / HSFC to decide which multiplexing mechanisms should be used for the different classes of traffic.
• the burst multiplexing method can also be implemented in a DVB-H IPE, whose output data can be formatted in IP or MPEG-2 / MPE / IP transported in MPEG-2 or IP / UDP.
• the burst multiplexing method is applicable to unicast, multicast and broadcast data and is compatible with the IEEE 802.11 standard.
• the receiver When burst multiplexed unicast or multicast data is transmitted to an 802.11 receiver operating in power saving mode and it is desired to optimize the communication of battery power, the receiver should be set to wake up at intervals corresponding to the occurrence of bursts, and to stay awake for durations equal to the duration of the bursts of traffic.
• the burst multiplexing method is implemented by a specific device located on a network between a source device and a destination device.
• the burst multiplexing method can also be implemented in existing network devices such as servers, routers, and QoS devices.
• FIG. 6 is a block diagram of the burst multiplexing of LAN traffic. shown in Figure 1;
• Figure 7 is an example of a class tree diagram for burst multiplexed traffic.
• a burst multiplexing technique transmits messages in the form of bursts in which several consecutive messages concern the same traffic flow.
• Fig. 6 shows the output of a burst multiplexer used on the same type of traffic frames as previously described for the time division multiplexer (i.e. frames from the Servicei [email], Service 2 [telnet] , Services [streaming] and Servic ⁇ 4
• [FTP upload] transmitted between the device A and the device B).
• a first burst includes AB1.1, AB1.2, ... .AB1.10.
• the next burst includes AB2.1, AB2.2, ... .AB2.10 and the third and fourth bursts, respectively, include AB3.1, AB3.2, ... .AB3.10 and AB4.1, AB4.2, ... .AB4.10.
• the burst multiplexer After transmission of the last service burst, the burst multiplexer returns to the first service and transmits the next set of frames for the service (ie, the fifth burst from the burst multiplexer is AB1.11 , AB1.12, ... .AB1.20). The burst multiplexer then bursts the frames from the other services. Therefore, a cyclic process of multiplexing frames from different services is established, in which the repetition interval (T REP ) corresponds to the period ABlm, AB4.m + 9 (where m is any positive integer).
• the burst multiplexing technique can be implemented by associating different burst sizes with each traffic flow (i.e. a different value n which is fixed or variable over time) or by keeping n fixed in time but sending the frames from certain traffic streams more frequently and thereby allocating them more throughput.
• each user can claim a D / N rate regardless of the multiplexing (time-division or burst) method used on the channel.
• the burst multiplex method applies to the data transmission rate of a channel only when its rate D is greater than the average flow rate d of the traffic flow, typically of one or more orders of magnitude.
• the network interface card (NIC) of a burst multiplexed traffic listening station needs to be active only during periods in which bursts contain messages for the station. These activity periods alternate with periods of silence (in which the bursts contain messages for other stations) during which the receiver NIC can be turned off.
• each receiver only needs to listen to the channel for 10% of the time and can turn off its NIC for the remaining 90% of the time (actually a little less if the start and stop times interface are taken into account).
• each receiver should be constantly active and listen to the channel.
• the process of periodically deactivating a NIC provides a mechanism for increasing the lifespan of portable equipment batteries (eg computers Laptops (or Laptops), personal digital assistants (PDAs), cell phones incorporating a personal digital assistant (or smartphones)).
• portable equipment batteries eg computers Laptops (or Laptops), personal digital assistants (PDAs), cell phones incorporating a personal digital assistant (or smartphones)
• the WiFi interface will typically consume:
• the WiFi circuit With Time Division Multiplexing, the WiFi circuit will use approximately 260 mA to continuously receive the multiplexed traffic.
• the above energy savings can be achieved with burst multiplexing on Smartphone and PDA equipment because the power consumption of their radio circuitry is of the same order as that of the rest of the circuitry of these devices.
• the energy savings that can be achieved with a laptop will probably not be so significant, because a number of other components of the laptop have a much higher energy consumption than the radio circuitry.
• the power consumption of disks, video display units, processors, and so on. is typically 10 to 20 w. Therefore, the deactivation of circuitry Laptop radio during burst multiplexed traffic silences will produce a theoretical maximum increase in laptop battery life of approximately 5 to 10%.
• the above energy saving feature is not limited to WiFi interfaces. Indeed, all interfaces transmit radio (DVB-H, Bluetooth, DVB-S, WiMAX, Ultra Wide Band) or electric (Ethernet, ATM) can get the same benefits of energy savings due to gusts multiplexing .
• burst multiplexing is a increase in transmission delay.
• each traffic stream will be output for 100 ms every seconds. Therefore, the maximum transmission delay for a message will be 0.9 seconds (when a message frame from a service appears at the end of a burst for the service and it is necessary to wait until to the next burst for the service to receive the rest of the message), the minimum transmission delay being equal to the message switching time (when a message frame from a service arrives while the traffic from the service is processed by the multiplexer).
• the average transmission delay in the present example will therefore be approximately half a second.
• the length and variability of transmission delays in burst multiplexing will affect its utility to a greater or lesser extent depending on the nature of a service.
• services that are highly interactive eg Telnet, Reliable Datagram Protocol [RDP], Citrix, Secure Shell [SSH], web browsing
• Telnet Reliable Datagram Protocol
• SSH Secure Shell
• VoIP Voice over Internet Protocol
• non-interactive applications will be able to cope with varying increases in transmission delay while benefiting from the energy-saving benefits of burst multiplexing.
• IP / UDP applications in broadcast mode eg TV / IP broadcasting
• applications relying on a transport layer in connected mode TCP, Stream Control Transmission Protocol [SCTP ]
• streaming clients eg Mediaplayer, Realplayer, Quicktime
• streaming clients are designed to receive their traffic streams irregularly from the Internet and are therefore quite capable to support burst multiplexing.
• push mode accommodates burst multiplexing and has error detection / correction mechanisms that limit most, if not all, of the handshake and fax traffic.
• acknowledgment of a client to a server the transmission of acknowledgment messages contributing significantly to the energy consumption of a device, because the power consumption of a device increases when it transmits).
• POP Point of Presence
• STP Simple Mail Transfer Protocol
• FTP file transfer
• the degree of energy saving that can be achieved using burst multiplexing depends on the state in which a radio circuit is operated during the silence periods.
• the most useful energy saving modes are the sleep mode and the sleep mode.
• a radio circuit consumes between 1 and 8 times less energy than when it is operating in receive mode.
• sleep mode the energy consumption of the radio circuit is 20 to 60 times lower than that in reception mode. If we use the above example of the WiFi smartphone phone, increasing the lifetime of a receiver (ie 60% in operating the radio interface in sleep mode during periods of silence) would be 30% by operating the radio interface in idle mode during silence periods. Switching a radio circuit in idle mode requires no intervention in the software of a receiver. Therefore, it is possible to increase the life of a battery in a Smartphone device by approximately 30% by inserting a burst multiplexing function between a source and its receivers without modifying the receiver software.
• the receiver software in the case of sleep mode operation, the receiver software must be adapted to allow the receiver radio circuit to be switched to sleep mode during silence periods and in active mode when the LAN traffic contains bursts that are relevant to the receiver.
• Parameters that allow a receiver to recognize the beginning of silences and bursts that concern it are the duration of bursts, the duration of silences or the repetition period.
• Classical approaches to recognizing the beginning of silences and bursts relevant to a receiver use signaling protocol elements.
• the method of transmitting burst traffic is implemented in a specialized equipment (hereinafter referred to as the name "Traffic burster") located on the path between the source and destination devices.
• the method of transmitting burst traffic is implemented in an existing equipment (eg server, routers, traffic shapers [traffic shapers are devices allowing the control of the quantity and volume of stream traffic, sent over a network and the rate at which this traffic is sent] and WiFi or WiMAX Access Point and hereinafter referred to as "Existing Modified Device").
• Incorporating the Performance Enhanced Proxy (PEP) feature is a device used to improve the performance of Internet protocols such as TCP on network branches, where the original performance is affected based on the characteristics of the network. of a link or subnet on one of the branches]) in the Traffic burster or in the existing modified apparatus, the path between a destination device and a source device may be broken into two distinct connections known as Cl name and C2 in which Cl represents the connection between a server and the existing modified Traffic burster / 1 'equipment and C2 represents the connection between the modified Traffic burster / 1' existing equipment and a client station. Breaking the path between a source device and a client device makes it possible to independently set parameters for C1 and C2 (window sizes, congestion management and losses, acknowledgment traffic, compression) that are best suited to the medium used. This results in improved performance for lower power consumption.
• C1 and C2 window sizes, congestion management and losses, acknowledgment traffic, compression
• Traffic arriving at Rate d in the Traffic burster will have to be delayed to be transmitted on the multiplex channel at a higher rate D.
• the Traffic burster (and the existing device modified) stores the traffic in its buffers and waits until it is able to transmit the traffic on the multiplex channel.
• the delays caused by this process vary according to the duration of the bursts, the number of traffic flows being processed and the traffic arrival time in the Traffic burster.
• bursty traffic is multiplexed and forwarded by an extension to the Alternate Queuing mechanism (ALTQ).
• ALTQ Alternate Queuing mechanism
• bursty traffic is multiplexed and transmitted by a DVB-H IPE mechanism.
• the extension to the ALTQ mechanism includes burst transmission of certain classes and traditional time division multiplexing of other classes, in which all traffic classes are handled by the algorithm.
• Hierarchical Fair Service Curve (HFSC) Hierarchical Fair Service Curve
• Burst traffic classes also have an attribute indicating that they are bursty classes and another attribute indicating the duration of BD bursts.
• a leaf corresponding to a burst traffic class must have at least one brother in the class tree for the burst transmission model to work effectively.
• Figure 7 shows a class tree in which a root class 50 has an available bandwidth of 10 Mbs.
• the root 50 has three daughter classes, namely engineering 52, marketing 54 and administration 56.
• the root bandwidth is shared between the child classes, the engineering class 52, the marketing class 54 and the administration class 56 having a width allocated band of 5 Mbs, 2 Mbs and 3 Mbs respectively.
• the engineering class 52 has three daughter classes, namely IP / TV 58, mail 60 and download 62.
• the engineering class 52 and its three daughter classes (IP / TV 58, mail 60 and download 62) form a subtree STi.
• the classes within the STi subtree are bursty traffic classes.
• the bandwidth of the engineering class 52 is shared between its daughter classes, the class IP / TV 58, mail 60 and the download class 62 having an allocated bandwidth of 2 Mbs, 1 Mbs and 2 Mbs respectively.
• the administration class 56 also has two child classes X and Y. Thus, the administration class 56 and its two child classes X and Y form an ST 2 subtree.
• each class of traffic ia the permission to transmit bursts of maximum duration BDj at the speed given by the bandwidth currently allocated to his father.
• Each of the sister classes in a subtree are transmitted cyclically with a calculated frequency so that each class obtains its average allocated bandwidth BWj.
• a first class of bursty traffic (Bi) has no traffic (or has less traffic than its allowed quota to transmit within a given burst duration BDi, the traffic class will stop transmitting even if it has not consumed all of its allocated gust duration, however, the next burst class (B 2 ) will not be permitted to transmit until the end of the burst duration allocated to the first class of traffic.
• bursts (Bi) (ie, if Bi had enough traffic to fill its allocated bursts duration BDi), and the excess bandwidth (from the class whose transmission was prematurely terminated) is given the father class of the subtree in bursts.
• the parent class can (in turn) return the excess bandwidth to its father (eg the engineering class 52 can return excess bandwidth from from class IP / TV 58 to root class 50) or keep the bandwidth in excess for itself, thus allowing its own bursts to be performed at a higher bandwidth.
• the parent class eg engineering class 52
• its parent class also known as the "grandfather class”
• the grandfather class can route the excess bandwidth to another of its child classes (eg the class administration 56) which can in turn redistribute the excess bandwidth to its daughter classes (eg class X or Y).
• the parent class may not give the excess bandwidth to one or more of its child classes (ie, the engineering class 52 may not not redistribute the excess bandwidth from the real-time class 58 to the interactive or download classes 60, 62).
• the above organizational rules are provided for illustrative purposes only and that systems with subtree gusty trees or even trees mixing normal and burst subtrees are also possible. .
• Traffic classification ie, assigning traffic to queues based on an address and a DSCP field
• traffic conditioning ie assigning a DSCP field according to addresses and ports source / destination
• the Traffic classification can be performed using information provided by an Electronic Service Guide (which describes all multicast streams of sessions using for example Session Description Protocol (SDP) and Announcements for example Session Announcement Protocol (SAP)) for automatically allocate all the elementary streams of a session to the same burst class, this burst class having been chosen from all bursty classes having sufficient bandwidth.
• SDP Session Description Protocol
• SAP Session Announcement Protocol
• the Traffic burster takes IP streams as input and outputs some of these IP streams as bursts over an ordinary network interface (eg ethernet, ATM, WiFi WiMax etc.). On this output interface the IP datagrams are encapsulated in level 2 frames of the interface.
• an ordinary network interface eg ethernet, ATM, WiFi WiMax etc.
• the Traffic burster feature can be hosted in a regular IP DVB-H Encapsulator.
• the output of the encapsulator rather than (or in addition) being sent in MPEG-2 on an Asynchronous Serial Interface (ASI), is sent in MPEG-2 over IP on an ordinary network output interface.
• ASI Asynchronous Serial Interface
• These outputs are not limited to burst IP datagrams, but may include all MPEG-2 transport packets used to carry PSI / SI tables, FEC, and possibly Megaframe Packets Initialization. (MIP).
• MIP Megaframe Packets Initialization.
• a MIP is an MPEG-2 packet used in a Single Frequency Network (SFN) context, containing a time stamp indicating the time (modulo 1 s) at which the following MPEG-2 transport packets will be delivered by all modulators.
• SFN Single Frequency Network
• a time stamp indicating the time (modulo 1 s) at which the following MPEG-2 transport packets will be delivered by all modulators.
• the Traffic burster when hosted in an IPE Encapsulator, transmits on its regular network output interface:
• MPEG-2 packets can be encapsulated in UDP / IP / MACx (where MACx is the MAC protocol of the ordinary output interface) to be delivered by an ordinary IP network.
• Output IP streams directed to the ordinary network interface can also be sent in MACx IP (ie without MPEG-2 encapsulation).
• MACx IP ie without MPEG-2 encapsulation
• no information about MPEG-2 signaling, FEC, or MIP is sent over the regular network interface.
• no Signaling information on the duration, frequency and timing of gusts will only be sent to the receivers.
• this output mode has the advantage of using the standard IP stack of the receiver.
• the output data is encapsulated (the IP streams of the output data being encapsulated in IP, MPE, MPEG-2, UDP, IP and the PSI / SI tables, FEC and MIP being encapsulated in sections
• the above signaling information will be sent to the receivers (ie in the PSI / SI tables).
• the burst duration is indicated in the IF tables and the burst timing in the least significant bits of the MPE address.
• time stamps in MIPs and MPEs are inaccurate due to delays imposed by the network and the energy saving mode of operation (described in the next section) of access. This inaccuracy causes the parameters in the signaling information to have values lower than their actual values.
• a receiver operating in energy saving mode should receive traffic while saving its batteries.
• the energy saving that can be achieved by means of such receivers is not optimal because the receivers wake up prematurely.
• the loss associated with the above signaling inaccuracy being estimated at approximately 10%.
• One of the disadvantages of MPEG-2 / MPE / IP encapsulation is the need to write an MPEG-2 / MPE stack in the receiver and integrate it into the system either in the kernel (MPEG-2, Ethernet ), or in userland (MPEG-2 / MPE / IP in IP) with feedback of the traffic in the IP stack of the receiver.
• the 802.11 power saving mode transmits unicast traffic to a destination device without taking into account that some services may accommodate more delays than others.
• network administrators will configure the maximum delay based on the maximum time that highly interactive applications can tolerate, and DTIM periods of 1 to 3 are usually recommended.
• burst multiplexing is not incompatible with 802.11.
• the station will therefore have to know the duration of bursts either by configuration or learning
• the energy saving that can be achieved by burst transmission will be reduced because inter-burst periods are expected to be significantly greater than the DTIM intervals.
• the energy saving mode of operation transmits multicast and broadcast traffic immediately after each DTIM and reports the presence of multicast and broadcast traffic in the TIM (AID 0). Therefore, each station associated with an Access Point will have to receive all multicast / broadcast traffic transmitted in order to receive the traffic of interest.
• burst transmission of multicast traffic is not provided for in the 802.11 standard, although the process itself is not incompatible with 802.11.
• multicast traffic is transmitted in bursts using a standard Access Point, which adds a maximum delay of DTIM * Beacon_Interval ms to the multicast traffic.
• the TIMs sent at each DTIM interval will have their AID 0 set to 1 to indicate the presence of multicast traffic, even if the multicast traffic following a DTIM will take the form of a burst of traffic.
• the station will therefore have to know the duration of the bursts and the inter-bursts period, either by configuration or by learning (see below). If the station opts for a standard configuration (wakes up all DTIM intervals), the energy saving that can be achieved by gust transmission will be reduced by the fact that inter-burst periods are expected are significantly higher than the DTIM intervals.
• the station will be able to receive broadcast and multicast traffic that is sent continuously.
• the efficiency of the 802.11 energy saving mode when there is significant multicast activity on a LAN is improved by providing more accurate information on the various multicast groups having traffic waiting at a given moment.
• This can be achieved by extending to the multicast groups the notion of association (as currently used for unicast traffic).
• the IDA expansion process uses a table (ie, Table d r Association Multicast) making the correspondence between AID: (a) multicast groups; or
• an Access Point when receiving Internet Group Management Protocol (IGMP) (for IPv4) or Multicast Listener Discovery (MLD / IPv6) activity indicating that at least one station wants to join a multicast group, an Access Point consults the Multicast Association Table to find an entry for the multicast group or the pair (S, G). If the Multicast Association Table does not include an entry for the multicast group or the (S, G) pair, an unused AID is allocated to the multicast group (or to the (S, G) pair) and a new entry is created in the Multicast Association Table.
• IGMP Internet Group Management Protocol
• MLD / IPv6 activity indicating that at least one station wants to join a multicast group
• an Access Point consults the Multicast Association Table to find an entry for the multicast group or the pair (S, G). If the Multicast Association Table does not include an entry for the multicast group or the (S, G) pair, an unused AID is allocated to the multicast group (or to the (S, G) pair) and a new entry
• the Access Point transmits a modified Association Frame indicating the selected AID to the relevant multicast devices.
• the modified Association Frame has the same format as a standard Association frame but instead of being passed in response to an Association_Request, it is transmitted according to an IGMP / MLD multicast activity.
• the modified Association Frame uses the point address access (as the source address) and the MAC address derived from the IP multicast address (for example according to RFC 1188). This allows the modified Association Frame to be received by all stations that are members of the relevant multicast group.
• the Access Point When at least one of the stations associated with an Access Point is operating in power-saving mode, the Access Point stores datagrams for the various multicast / pair groups (S, G) identified in the Multicast Association Table. until the next DTIM, and updates the TIM with the AID of multicast groups on hold.
• the access point transmits a TIM and multicast datagrams stored in ascending order of AID in a manner similar to that of unicast data (i.e. in response to PS-POLL messages from the manifesting station). an interest for the multicast group).
• the IGMP queriers function is to make it possible to know which multicast groups are expected by the connected machines
• This function is usually hosted in a multicast router and consists of sending IGMP messages "querier garlic groups" at regular intervals, with the result that only one receiver is responsible for securing the transfer of multicast traffic.
• the station If the station is operating in energy saving mode with traditional continuous multiplexing, it will receive all TIMs (including those announcing traffic that is not relevant to it) and will be able to determine from them whether it is There is relevant multicast traffic waiting in the access point without having to decode all the multicast traffic at each DTIM interval.
• a station When operating in burst multiplexed power saving mode, a station can receive unicast and multicast traffic using traditional or advanced AID mechanisms. However, in order to obtain satisfactory behavior, it is necessary to set the Listen_Interval of the station to a value lower than the Inter-Burst Interval.
• Conventional approaches that allow a receiver to recognize the beginning of silent and burst periods relevant to it use protocol elements (eg, encapsulation, HCV-H, MPEG-2 / MPE / IP) or configuration options.
• An eighth embodiment uses a self-learning mechanism to automatically and adaptively determine the burst duration, the silence duration (burst repeat interval).
• the self-learning mechanism uses a Period Assessment Module (EP) and a Quality Assessment Module (QE).
• EP Period Assessment Module
• QE Quality Assessment Module
• the EP module attempts to locate bursts over a sufficient period of time (i.e., a time period of approximately 10 to 15 s). This evaluation can be performed by continuous listening of traffic and counting. This implies that the terminal must be switched to CAM mode (Constantly Awake mode) during these periods. In this case, the EP module can be located in the user space.
• Period evaluation can also be performed by analyzing TIMs to determine the frequency of unicast and multicast information availability. This method is less accurate because a TIM only provides information about the presence or absence of traffic, without giving any indication as to the amount of traffic. However, this method is preferable from the point of view of energy saving, because even during the sampling periods, a station operates in energy saving mode. It should be noted that this method must be implemented in the radio interface driver.
• the Quality Assessment (QE) module periodically analyzes parameters such as RTP frame sequencing and the progression of TCP or SCTP sequence numbers.
• the EQ module uses this information to diagnose failures related to frame loss.
• the period evaluation module is started when the system is initialized. After which, the EP module is launched:

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