CN102165781A

CN102165781A - Multisegment loss protection

Info

Publication number: CN102165781A
Application number: CN2009801373533A
Authority: CN
Inventors: T·J·拉雷尔; E·冈杜斯汉; M·J·索库普
Original assignee: Nortel Networks Ltd
Current assignee: Nortel Networks Ltd
Priority date: 2008-07-25
Filing date: 2009-06-01
Publication date: 2011-08-24
Also published as: KR20110036754A; WO2010010432A1; EP2308235A1; JP2012513689A

Abstract

A method for providing error correction of media packets. Service nodes associated with a core network segment use a first error correction process, and service nodes associated with an access network segment use a second error correction process. Service nodes associated with a local network segment may use a third error correction process. The present invention utilizes different error correction processes on different network segments as appropriate. Service nodes may receive indicators from monitoring agents that error correction is insufficient and, in response, a service node may increase an amount of error correction associated with a network segment. Media packets may be interleaved in a forward error correction (FEC) block in a manner that increases an amount of packet recovery.

Description

Multistage is lost protection

The application asks for protection the rights and interests that the sequence number of submitting on July 25th, 2008 is 61/083,710 U.S. Provisional Patent Application, by reference its disclosed full content is herein incorporated at this.

Technical field

The present invention relates generally to by segmented network packetized (packetized) video is provided, and the attribute that is particularly related to based on each network segment uses error correction procedure.

Background technology

Video such as television broadcasting or request program is delivered to the subscriber by the video distribution net with the packetized form more and more.Usually, digitized video at first is packaged into the Internet protocol packets stream by the sequential cells with digitized video and is transmitted to guard station (premises) from head end (headend) then by packetized, and described guard station is dwelling house or shopping centre for example.The packetized video has many advantages with respect to non-packetized video, comprises the ability of using emerging technology (for example switched digital video), compares previous possible technology distribution network bandwidth more efficiently.Yet the service supplier has been found that sending consistent packetized video flowing by the network that may cross over hundreds of miles reliably to the terminal use is a challenging suggestion.Each grouping must be passed by dissimilar device coupled a plurality of network segments together, and described dissimilar equipment can be operated in the different-energy territory such as light or electricity.Each grouping is faced with the potential destruction from cable cut (cable cut), equipment fault, transient noise and congested network node on the way.In case grouping arrives the guard station, destination, grouping just must be carried by local area network (LAN), described local area network (LAN) differs widely because of the guard station is different, and the service supplier may understand very less or controls limitedly for described local area network (LAN), and described local area network (LAN) may change according to terminal use's excitement in a period of time.Grouping finally is delivered to equipment such as set-top box or computer, shows on the monitor such as TV or liquid crystal display (LCD) computer screen being used for.

Video distribution Netcom often can be described to have three network segments: the core network section extends to regional Video service office from super head end; Access network section extends to the guard station from regional Video service office; And local network segment, it carries video packets in the guard station.Each network segment has different attributes and has brought the unique challenges relevant with sending of packetized video.The core network section is fiberoptical networking and may have massive band width normally.Access network section can be the xDSL network and may have very limited bandwidth.Local network segment in guard station can use the wired ethernet technology and have high robust, and the local network segment in the adjacent guard station can use wireless technology and have low robustness and the high sensitive to disturbing.

The service supplier has been found that the capital expenditure that is associated with the initial configuration of the local network that is used for the packetized Video service can be quite big.Similarly, the service supplier has been found that being used for of being associated with service call can be quite big in the local network debugging and the operating expenses of dealing with problems.Relate to the video quality at end user device place with the many problems that are associated to guard station delivery package video, this is because cable cutting, transient noise or the like may cause packet loss.The grouping error correcting technique, for example forward error correction (FEC) or automatic repetitive requests (ARQ) can be used to stop some situation of packet loss to influence video display quality.Using under the situation of FEC, FEC is provided to set-top box the guard station by the head end from the service supplier usually always, and the amount of employed FEC is subject to the network segment of bandwidth constraint maximum.Thereby although for example FEC may be enough to correct most of packet loss that may take place in the access section of network, FEC may be not enough to correct the packet loss that may take place in server section or this location.In addition, be corrected in the necessary FEC amount of the video quality problem that takes place in the local network segment in the guard station and may be not enough to be corrected in the video quality problem that takes place in the local network segment of another guard station.

ARQ may be useful when being used for access network section or local network segment, but it not be used in the core network section usually, and this is because implement ARQ in the core network section required processing and memory space to be arranged.Thereby the service supplier who implements ARQ may not provide any error correction for the core network section.Therefore, the service supplier to describe (loss profile) based on losing of particular network section will be useful with bandwidth for the heterogeneous networks section provides different error correction procedures.In addition, Network Provider is in response to about the feedback of the real time error state that is associated with network segment and dynamically to change the error correction procedure of using on network segment will be useful.

Summary of the invention

The present invention implements different error correction procedures in the different sections of the network that is coupled by service node, be sometimes referred to as the alleviation process of losing.The error correction mistake can comprise forward error correction (FEC), automatically repetitive requests (ARQ), Admission Control (CAC), any other is suitable for stoping or correcting suitable mechanism and any combination thereof of packet loss.The present invention is based on the bandwidth and the corresponding common or actual error type that runs into of network segment that are associated with corresponding network segment and implement suitable error correction procedure.Service node can receive grouping via first network segment, use first error correction procedure to recover the grouping of losing or destroying, and forwards the packet to via second network segment that use second error correction procedure is recovered to lose or the service node of the grouping that destroys.

According to one embodiment of present invention, the monitoring agent in the one or more service node monitors the error state on the associated network section and communicates dynamically to revise type of error correction or the error correction amount that is used for the associated network section with upstream error correction controller (ECC).With the error correction procedure that two heterogeneous networks sections are associated can be different error correction procedures, and for example FEC and ARQ maybe can be to use identical type of error correction (for example FEC) but use the dissimilar error correction procedure of different error correction amounts.For example; the service node that is associated with the core network section can use a certain amount of FEC of the lost packets that is suitable for protecting first quantity that may lose on the core network section; and the service node that is associated with access network section can use and be suitable for protecting second and a certain amount of FEC of the lost packets of lesser amt; because compare the core network section, the bandwidth that access network section has may be obviously littler.

According to one embodiment of present invention, be suitable for protecting the FEC of the sufficient amount that may protect the relative a large amount of video packets that lose during the handover events (for example re-routing business around the optical cable of cut-out) at 50 milliseconds of (ms)-100ms on the core network section to divide into groups with the service node use that the core network section is associated.The service node that is associated with access network section use be suitable for protecting may the relatively small number amount that (for example being caused by transient noise) loses during the short duration pulse missing on the access network section (short duration impulse loss) video packets.The FEC grouping of using on access network section is the subclass of dividing into groups via the FEC that the core network section receives.The present invention realizes reusing not recomputate the required expense of FEC grouping at whole (tailor) FEC of particular network shed repair of FEC grouping.

After reading following detailed description of preferred embodiments in conjunction with the accompanying drawings, it will be understood to those of skill in the art that scope of the present invention and recognize the aspect that it is other.

Description of drawings

Be included in the specification and constitute wherein a part of accompanying drawing and explain that together with being used to the description of the principle of the invention has illustrated some aspects of the present invention.

Fig. 1 is the block diagram of switch type according to an embodiment of the invention Digital Media network.

Fig. 2 is the block diagram of guard station according to an embodiment of the invention.

Fig. 3 is the block diagram of the service node of enforcement error correction according to an embodiment of the invention.

Fig. 4 is the flow chart that the diagram headend service node place in switch type Digital Media network according to an embodiment of the invention implements the process of error correction.

Fig. 5 is the flow chart that illustrates according to one embodiment of present invention in the correction process at service node place.

Fig. 6 is the flow chart that illustrates according to another embodiment of the present invention in the correction process at service node place.

Fig. 7 is the block diagram of the service node of enforcement monitoring agent according to an embodiment of the invention.

Fig. 8 is that diagram is in response to the flow chart that changes error correction procedure about the losing the feedback of describing of change that be associated with network segment.

Fig. 9 is the block diagram of forward error correction according to an embodiment of the invention (FEC) piece.

Figure 10 is the block diagram of losing that illustrates from the continuous grouping of the FEC piece that transmits with the order that interweaves shown in Fig. 9.

Figure 11 is the block diagram of FEC piece according to another embodiment of the present invention.

Figure 12 is the block diagram of service node according to an embodiment of the invention.

Figure 13 is the block diagram of customer rs premise equipment according to an embodiment of the invention (CPE).

Embodiment

The following embodiment that sets forth represents to make those skilled in the art can put into practice necessary information of the present invention and has illustrated and puts into practice best mode of the present invention.When reading following description with reference to the accompanying drawings, it will be understood to those of skill in the art that design of the present invention and will recognize that the application of these designs of not illustrating especially at this.It should be understood that these designs and application fall in the scope of the disclosure and the accompanying claims.

Switch type Digital Media network allows to send streaming video at various channels or request program with the form of Media Stream, and the client can select to listen to or watch described channel or request program.Switch type Digital Media network can represent to be used for sending at public or private environment satellite, cable, internet protocol TV (IPTV) or the similar network of audio or video.Usually, the service supplier depends on large-scale hierarchical network, and its concentrated position from the aggregated media content sends and extends to customer rs premise by various go-betweens.Shown in Figure 1 an is exactly typical case but the switch type Digital Media network oversimplified.The concentrated position of aggregated media is present in the service node such as medium head end (MHE) 10 therein, and it is configured to by core network section 14 and access network section 16 the various Media Streams of corresponding channel are delivered to guard station 12.Access network section 16 provides to the wired or wireless access of guard station 12 and core network section 14 expressions various access network sections 16 to be connected to the main transmission network of MHE 10.

MHE 10 such as the super head end that is used for video can use various satellite antennas station (satellite dish farms), media server, encoder or the like usually, and its media content with corresponding channel offers MHE 10.Although for purpose of explanation MHE 10 is described as single entity, MHE 10 can comprise that many equipment to finish the required function of MHE 10, comprise Content Management, content encoding, video-on-demand service or the like is provided.MHE 10 polymerizations are from the media content of each provenance, distribute these media contents and in due course between suitably sending to guard station 12 on the channel.Notably, media content can be delivered to guard station 12 according to predefine dispatch list (schedule) or in response to client requests, as the video-on-demand service that is provided.Clearly media content can comprise ad content, and it is placed in the interior suitable groove (slot) of media content.In the switch type Digital Media network based on video or television, the ad content that is provided by MHE 10 normally is intended to be delivered to the client's of broad geographic area national advertisement.Illustrated the same of two MHE 10 as shown in fig. 1, switch type Digital Media network can have a plurality of MHE 10 for the purpose of redundancy.

The media content of sending to one or more guard stations 12 can pass media center office (media hub office MHO) 18, and it is present in the core network section 14.Although do not need, single MHO 18 can be assigned to single city or metropolitan area.MHO 18 can visit the local media content, comprises local advertising, and it can be united with the media content that is provided by MHE 10 provides.Except local advertising was provided, local emergency warning message or content can be injected in the media content at MHO 18 places.MHE 10 and MHO 18 these two can provide various types of Code And Decode and transcoding (transcoding) to change coding, compression and the format that is associated with the media content of sending to customer rs premise 12 effectively.

The next service node that leads in the path of customer rs premise 12 can comprise media services office (MSO) 20, and it is present in the city or metropolitan area by MSO 20 services usually.In addition, MSO 20 can be dispersed throughout corresponding geographical position, for example is associated with one or more neighborhoods.In in these neighborhoods or corresponding region each, each MSO 20 can be associated with one or more access nodes (AN) 22, and it also can be called as couple in multiplexer.These access nodes 22 are all the wired or wireless connections between the various guard stations 12 of polymerization effectively.MSO 20 and access node 22 are associated with corresponding access network section 16 usually.The same as described, single access node 22 can be served the guard station 12 of any amount.Exemplary access network section 16 comprises digital subscribe lines (DSL), EPON (PON), Ethernet, cellular network, broadband wireless network (for example WiMAX network) or the like.Access node 22 can comprise digital subscriber line couple in multiplexer (DSLAM), optical line terminal (OLT), Ethernet modulator-demodulator, cellular basestation, WAP (wireless access point) or the like.It should be noted that if the distance between MSO 20 and the guard station 12 is enough little, then may not need access node 22 or not wish access node 22 service guard stations 12, and one or more guard station 12 can directly be served by MSO 20.

In case 12 inside in the guard station, media content just can be delivered to the equipment of arbitrary number, as shown in Figure 2.Notably, customer rs premise 12 can still not need to comprise residence gateway (PG) 24, residential gateway for example, described residence gateway provides the gateway function between access network section 16 and any customer rs premise equipment (CPE) 26, and described customer rs premise equipment is set-top box (STB), personal video recorder (PVR), personal computer (PC), phone or the like for example.PG 24 can be coupled to CPE 26 via local network segment 28, and described local network segment 28 can comprise one or more conversion equipments 30, for example router three 0A and Ethernet switch 30B.PG 24 can be used as autonomous device and implements maybe can be incorporated in another network components, for example cable or DSL modulator-demodulator.The communication link 34 that uses in local network segment 28 can comprise any traditional or dedicated network technology, comprise wireless such as WiFi, data by coaxial cable, the Ethernet by various physical mediums (for example 5 class cable or telephone wires) or the like, and each communication link 34 can have bandwidth and the robustness different with another communication link 34.It should be noted that Fig. 2 is used for illustrating that local network segment 28 can adopt various forms and can comprise various types of communication links 34, CPE 26 and conversion equipment 30.

The media packet of losing, destroying or postpone in any one in the

network segment

14,16,28 all can cause at the tangible audio or video in CPE 26 places unusual (aberration).In addition, each network segment has unique and different the losing of packet loss type that sign may or normally take place usually and describes on corresponding network segment.For example, owing to disturb the packet loss on the core network section 14 that causes rare relatively.Yet, may cause the type of the incident of the packet loss on the core network section 14, for example cable of Qie Duaning or network components fault may cause a large amount of relatively lost packets, and may influence all guard stations 12 by service supplier's service.By contrast, the typical case who is used for access network section 16 loses and describes to comprise more multifrequency question topic, burst noise or crosstalk for example, compare it with the caused lost packets of cutting off of cable and cause less lost packets, but compare the guard station 12 that its influence is less with the cable cut on the core network section 14.Challenging especially for the service supplier is local network segment 28, its difference because of guard station 12 is different, its each can comprise countless different conversion equipments 30, CPE 26 and communication link 34, and its configuration changes according to client's excitement in a period of time and not to service supplier's warning in advance.The end product of local network segment 28 variable and the dynamic (dynamic) that changes is that the service supplier bears very big expense and sets up media services that are used for guard station 12 and the media quality that keeps guard station 12 constantly.

Some service suppliers attempt reducing effect of lost packets by the mechanism of for example error correction and so on.Error correction is usually directed to trading off between bandwidth and the delay.Some error correcting techniques such as forward error correction (FEC) utilize additional bandwidth by comprise additional information among media packet, and described additional information can be used to the media packet of under the situation of the media packet of not waiting for retransmission of lost reconstructing lost or destruction.Other error correcting techniques such as automatic repetitive requests (ARQ) depend on the re-transmission of the media packet of losing or destroying, and this has reduced bandwidth cost but has increased delay and increased the storage demand of under the situation that needs retransmit medium being divided into groups.

Fig. 3 be according to an embodiment of the invention from MHE 10 to the guard station 12 the block diagrams of respective paths by switch type Digital Media network.In order to illustrate, some service node (for example MHO 18 in the core network section 14 or the access node 22 in the access network section 16) that can be used for one or more network segments omits from Fig. 3.Unusual in order to reduce or eliminate the video or the audio frequency that are associated with the media packet of losing or destroy, one or more error correction controllers (ECC) 36A-36D implements error correction procedure, for example MHE 10, MSO 20, PG 24 and CPE 26 at corresponding service node place.According to one embodiment of present invention, can be different in each corresponding service node place error correction procedure.For example, MHE 10 can use the FEC piece of specific big or small media packet and row and column FEC to divide into groups these two implements the FEC process to guarantee that MSO 20 can recover enough media packet under the situation that cable cut or similar incidents take place.The FEC process of even now may need very big bandwidth, but core network section 14 can comprise the fiberoptical networking with unnecessary bandwidth and therefore comprise the ability that realizes such FEC process.

With MHE 10 contrasts, MSO 20 can be coupled to access network section 16, and described access network section 16 has very finite bandwidth, and for example xDSL communication path, and the unnecessary bandwidth that has is not enough to provide similar FEC block size and row and column FEC to divide into groups these two.Therefore MSO 20 can change the FEC block size and only generate row FEC grouping and implement the required amount of bandwidth of FEC with remarkable minimizing on access network section 16.Although different FEC block sizes and less FEC grouping have reduced the number of the media packet of losing that can be resumed, but the actual loss of considering access network section 16 is described (it is different from losing of core network section 14 and describes), so compromise enough reliabilities that provides.

PG 24 can be coupled to local network segment 28, and described local network segment 28 has high bandwidth communications link 34, but owing to the interference of wireless or other electronic equipments in the guard station 12 is lost by a large amount of media data packet.Therefore, PG 24 changes the FEC coding to be described to adapt to losing of being associated with local network segment 28 better, for example by change FEC block size and generation row and column FEC divide into groups these two so that CPE 26 can recover may be in a considerable amount of media packet of losing from the way of PG 24 to CPE 26.

Fig. 4 is the flow chart of the diagram correction process that can take place in MHE 10 according to an embodiment of the invention.MHE 10 receiving medias stream is for example from the broadcast TV channel (step 200) of broadcasting feed (feed).Media Stream can be the analog or digital form.If simulation, then MHE 10 can and be encoded into any appropriate format that is adapted to pass through digital switch type media network delivery of media, for example motion image expert group 2 (MPEG-2) or MPEG-4 with the Media Stream digitlization.If Media Stream is digitized, then MHE 10 can be transcoded into Media Stream desired bit rate or form (step 202).The Media Stream of coding is segmented into media segment (step 204) then.Segmentation can comprise any suitable grouping of digital media unit, and as skilled in the art to understand, can be based on employed digital coding and difference.For example, if coded format is MPEG-2, then media segment can comprise one or more transmission stream packets.For example, if coding is MPEG-4, then media segment can comprise one or more network abstraction layer unit.

Media segment is changed into suitable transmission grouping, for example real-time transport protocol (rtp) grouping (step 206) by package then.For purposes of illustration, suppose that the FEC error correction procedure will be used for core network section 14.Qi Wang a FEC error correction procedure is applied to media packet to generate a plurality of error correction packet (step 208) then.As is known to the person skilled in the art; the FEC error correction generally includes the two-dimensional block of the media packet that forms expectation size to be protected; or matrix; generate FEC grouping then, its can be used in such media packet in way, lose by network or situation about destroying under the one or more media packet of reconstruction.Suppose that MHE 10 is coupled to core network section 14, described core network section 14 is optical networking highway sections and has certain unnecessary bandwidth ability.Suppose that in addition core network segment 14 may be subjected to the influence of network components fault or cable cut frequently, described network components fault or cable cut may for example take place during away from 10 some miles construction of MHE new office building.The hypothesis MHE 10 or the network routed path that need 50 milliseconds (ms) to switch with the redundancy of the responsibility of bearing MHE 10 around the fault network parts or route is coupled to core network section 14 in addition, and during 50 ms time frames, for per second 2 megabits (Mbps) video data stream, 16 media packet of every channel as many as may be lost.Therefore, MHE 10 can select the FEC block size and generate enough FEC grouping can not upset by the MHE 10 in downstream under the situation that the medium on (disrupt) CPE 26 present with the recovery that realizes reaching 16 media packet so that in the media packet of losing between transfer period and recover.Media packet and FEC grouping are transmitted (step 210) by core network section 14 then.The FEC grouping can transmit with media packet in order mixedly, perhaps can transmit via individual channel or port.

Fig. 5 is the flow chart of the diagram correction process at MSO 20 places according to an embodiment of the invention.MSO 20 receives media packet and the FEC grouping (step 300) that sends from MHE 10.MSO 20 can use any media packet (step 302) of a FEC process to recover to lose owing to cable cut or other breaking-ups to media packet.Suppose that MSO 20 is coupled to access network section 16, described access network section 16 comprises xDSL communication link and limited bandwidth system.In addition, losing of access network section 16 describes mainly can comprise that each incident of losing causes the burst noise incident that is less than 5 lost packets usually.MSO 20 can use the two FEC block size different with the FEC block size that is used by MHE 10 to use the 2nd FEC process, and generate the FEC grouping still less that is generated than MHE 10 and only reach 5 lost packets (step 304) so that the FEC process is suitable for recovering each FEC piece, but for error correction packet, need less additional bandwidth.MSO 20 is then by grouping of access network section 16 transfer mediums and FEC grouping (step 306).

Fig. 6 is the flow chart in the correction process at MSO 20 places that illustrates according to another embodiment of the present invention.If at what Fig. 5 discussed, MSO 20 a plurality of media packet of reception and FEC grouping (step 400) and any grouping (step 402) of using FEC process and FEC packet recovery to lose.Yet, in this embodiment, suppose that MSO 20 is used in combination the ARQ error correction procedure with access network section 16.The ARQ process was stored in local memory device (step 404) with media packet in the transmission media packet at first before PG 24.The ARQ process is forwarded to media packet PG 24(step 406 then).If PG 24 confirms the reception of media packet, then the ARQ process can be removed or rewrite the media packet in (overwrite) local memory device.Otherwise the ARQ process will retransmit media packet up to receiving the confirmation from PG 24.Replacedly, the ARQ process can be used circular buffer, this circular buffer length be enough to cover common losing describe and respond from PG 24 to retransmitting the request of specific lost packets.In another embodiment, the ARQ process can implemented between MSO 20 and the CPE 26 rather than between MSO 20 and PG 24.

Although the bandwidth that ARQ need be littler than FEC error correction procedure under the situation that packet loss does not take place, ARQ can introduce and retransmit the very big delay that is associated.In addition, ARQ may be not suitable in some network segments, wherein after big packet loss event, may overwhelm the ability that sends service node service repeat requests, or wherein required processing and the memory space of medium grouping needs too much resource to the request that retransmits.For example, because a considerable amount of media packet are sent out by core network section 14, and a large amount of repeat requests need be serviced under the situation of packet loss event (for example cable cut), so the ARQ error correction procedure may not be suitable error correction procedure for core network section 14.

With reference now to Fig. 7,, the block diagram of service node shown in Figure 3 is shown.One or more service nodes, for example MSO 20, PG 24 and CPE 26 can comprise the monitoring agent (MA) 38 of the corresponding network segment that can the monitor service node be coupled to, and losing of determining to be associated with the particular network section described.MA 38 upstream ECC 36 provides information or request dynamically to change the error correction procedure be used to recover the grouping of losing on the corresponding network section.Be applicable to the monitoring agent description to some extent in the U.S. Patent Application Serial Number of submitting on December 20th, 2,007 11/961,879 among the present invention, by reference its disclosure be herein incorporated.

Fig. 8 is the diagram flow chart that is used to change the process of the error control process on the network segment according to an embodiment of the invention.In order to illustrate, will Fig. 8 be discussed in conjunction with Fig. 7.Suppose that PG 24 uses a FEC process, fix under the situation that losing of special time local network segment 28 describe giving that this process provides enough the error correction that recovers the lost data packet that sent by PG 24 for CPE 26.The incident of describing of losing of local network segment 28 has taken place to change in hypothesis in addition.For example, suppose that the client has reconfigured conversion equipment 30 in the mode that abandons grouping that increases on the local network segment 28, or will the big electronic equipment such as microwave oven move to and approach communication link 34, and cause the increase of instantaneous packet loss by the electromagnetic field that microwave oven generates.Therefore, newly losing of given local network segment 28 described, and PG 24 and CPE 26 employed FEC processes may be given the lost packets that is not enough to compensate bigger quantity now.MA 38C determines that losing of local network segment 28 describe to change (step 500).For example, MA 38C can determine in a considerable amount of transmission, and the FEC grouping is not enough to all groupings of recovering to lose.MA 38C is the ECC 36C that for example is associated with PG 24 of ECC 36(upstream) error control messages is provided, notice ECC 36C: existing error correction procedure is not enough (step 502).Error control messages can be the request to the FEC that accelerates grouping, and the data of describing are lost in identification, or can inform that the new error correction procedure of the error protection that need be used to provide increase presents any other message of quality to keep suitable medium to PG 24.

Suppose that the communication link 34 between PG 24 and the CPE 26 has enough bandwidth (step 504), in response to receiving error control messages, ECC 36C can initiate different error control processes to the follow-up media packet that receives, and this process provides and surpassed the additional error correction that ECC 36C before provided.Suppose a plurality of media packet (step 506) that are sent to CPE 26 that PG 24 receives from MSO 20 via access network section 16.ECC 36C comes media packet is carried out error correction (step 178) according to the error correction procedure that is associated with network segment 16.Before the error control messages that receives from CPE 26, ECC 36C may provide the media packet of specific FEC block size and have enough FEC groupings to realize reaching the recovery of 5 continuous lost packets.The FEC grouping that ECC 36C changes the FEC block size now and generates bigger quantity from media packet is to realize recovering to reach 10 continuous lost packets (step 510) by CPE 26.PG 24 uses new FEC block size and the FEC that accelerates to divide into groups a plurality of media packet are sent to CPE 26(step 512).This process can be repeated until that the rank of the error control processing that ECC 36C provides is enough to provide suitable medium to present quality at CPE 26 places.It should be noted that the error control modification does not relate to any additional treatments of upstream service node or any additional bandwidth of upstream network section 14 or 16.The problem in the video transmission it should be noted that is in addition automatically monitored under the situation of the manual intervention that does not have service supplier employee and is corrected, and has eliminated the call center that is associated and the support cost of making house calls thus.

According to one embodiment of present invention, service node can be implemented a FEC error correction procedure to first network segment, and second network segment is implemented the 2nd FEC error correction procedure and needn't be regenerated the FEC grouping that receives via first network segment.The bandwidth that the invention enables processing node to reduce easily to be used to correction process and not consumption of natural resource recomputate new FEC grouping.The present invention uses as therefore these two all is herein incorporated at the standard SMPTE 2002-1 of SMPTE (SMPTE) and SMPTE 2022-1() described in Pro-MPEG forum code of practice (COP) #3 FEC process.Pro-MPEG FEC comprises the FEC matrix that generation has a plurality of row, is called " L " dimension of matrix, and has a plurality of row, is called " D " dimension of matrix.Now the dimension of FEC matrix will be described with reference to D dimension (line number) then also with reference to L dimension (columns) at first.For example, have 5 row and 10 capable FEC matrixes will be called as 10(L at this) x 5 (D) FEC matrix.Error correction is that the form with FEC grouping provides, and described FEC grouping is based on that media packet in the specific row or column of FEC matrix obtains.Be generated to correct the FEC that loses with the particular row associated packet and be grouped in this and will be called as capable FEC grouping.Be generated to correct the FEC that loses with the particular column associated packet and be grouped in this and will be called as row FEC grouping.Can dividing into groups by generation row and column FEC, these two provides big relatively error correction amount.Can divide into groups to provide less error correction amount by only generating row FEC.As skilled in the art to understand, the size of FEC matrix, and the use of row and column FEC grouping is the expectation error correction amount and the trading off between the amount of bandwidth of utilizing.Ratio higher between FEC grouping and media packet has increased the possibility of error correction, but has similarly increased transfer medium grouping and the required bandwidth of FEC grouping.Phrase " FEC matrix " will be used in reference to corresponding matrix for media packet at this.Phrase " FEC piece " this will be used in reference to generation corresponding FEC matrix and the FEC that generates based on the FEC matrix divide into groups these two.

Cause the incident of lost packets, for example cable cut on the core network section 14 or the impulsive noise on the access network section 16 cause a series of continuous packet loss usually, rather than spread all over a plurality of random packet of the FEC piece of grouping.Divide into groups to be generated to be used for error correction if just list FEC, then can recover the continuous grouping of losing that quantity equal L from the FEC piece, the continuous grouping of assumed lost is the only lost packets in the FEC piece.These two is generated and is used for error correction if row and column FEC divides into groups, and then can recover the continuous grouping of losing that quantity equals L+1 from the FEC piece, supposes that once more those groupings are the only lost packets in the FEC piece.

The present invention is with the interweave transmission of FEC piece of media packet and FEC grouping of the mode that increases the number of consecutive packets that can recover under the situation that does not need to generate additional FEC grouping.The present invention also realizes the suitable subclass (proper subset) of FEC grouping is reused for the follow-up error correction on second network segment and does not need to regenerate the FEC grouping, even the FEC block size is changed.

Fig. 9 is the block diagram that the exemplary FEC piece 50 of a plurality of media packet 52 and FEC grouping 54 is shown with 5x10 FEC matrix according to one embodiment of present invention.For purposes of illustration, media packet 52 and FEC the grouping 54 these two this can be called jointly the grouping 52,54.It should be noted for L and the D that defines the FEC matrix ties up, only consider media packet 52.In this specific FEC piece 50, as shown in row 56A-56F and row 58A-58K, there are 50

media packet

52 and 16 FEC groupings 54.It should be noted that if send 50 media packet 52 required original rates under the situation without any FEC grouping 54 are per second 2 megabits (Mb/s), then sending the divide into groups bandwidth of 54 required increases of 50

media packet

52 and 16 additional FEC is 2.64 Mb/s, the error correction bandwidth cost of this expression 32%.

In

traditional FEC piece

50,16 FEC grouping 54 is enough to correct 6(L(5)+1) the continuous packet loss of individual media packet 52.Notice in Fig. 9, two numerals of each

grouping

52,54 carrying, leftmost numeral separates with the rightmost numeral by "/".For each media packet 52, leftmost numeral media packet 52 by continuous decoding to be used on CPE 26 showing the grouping serial number of the order that is adopted.For each FEC grouping 54, leftmost numeral FEC grouping 54 will mix the continuous order that adopted with the media packet 52 of continuous ordering usually.Each FEC grouping 54 of locating at the end (row 56F) of every row of FEC piece 50 can be used to correct or recover to be present in and FEC grouping 54 any media packet 52 of going together mutually, as long as other media packet 52 in this row are not lost and maybe can be used row FEC grouping 54 and rebuilt.Each FEC grouping 54 of locating at the end (row 58K) of every row of FEC piece 50 can be used to correct and be present in divide into groups any single medium grouping 52 of 54 same column with FEC, maybe can not use capable FEC to divide into groups 54 and rebuilt as long as other media packet 52 in these row are lost.

The rightmost numeral transmitted in packets order that interweaves according to an embodiment of the invention in each grouping 52,54.By interleaved

packet

52,54 before passing through the transmission of network segment, the number of the continuous media packet 52 that the present invention can recover divides into groups to be increased to L+D+1=16 continuous grouping continuously from L+1=6.It should be noted that in the FEC piece 50 shown in Fig. 9, recover the ability of 16 continuous lost packets and represent to increase by 167% with respect to traditional FEC piece 50.The order that interweaves of grouping 52,54 according to an embodiment of the invention is as follows.Interweave first media packet the 52, the 54th in the order, the media packet 52 at be expert at 58A and row 56A place.Interweave next one grouping the 52, the 54th in the order, the media packet 52 at be expert at 58B and row 56B place.The grouping of the 3rd in the order the 52, the 54th that interweaves, the media packet 52 at be expert at 58C and row 56C place.This process is proceeded along diagonal path 60 to be placed with the order that interweaves up to the FEC grouping 54 at row 58F and row 56F place.At this moment, because row 56F is last row in the FEC piece 50, so the next column in the order that interweaves is first row, row 56A.Yet, because row 58F is not the last column in the FEC piece 50, so the next line in the order that interweaves is row 58G.Therefore, the next media packet the 52, the 54th in the order that interweaves, the media packet 52 at row 58G and row 56A place.This process is proceeded along diagonal path 62 to be placed with the order that interweaves up to the FEC grouping 54 at row 58K and row 56E place.At this moment, because row 58K is the last column in the FEC piece 50, so the next line in the order that interweaves is first row, row 58A.Yet because row 56E is not last row in the FEC piece 50, the next column in the order that interweaves is row 56F.Therefore, the next media packet the 52, the 54th in the order that interweaves is by the FEC grouping 54 at capable 58A shown in the diagonal path 64 and row 56F place.Should be noted that row 56F is last row in the FEC piece 50, the next media packet the 52, the 54th in the order that therefore interweaves, the media packet 52 at row 58B and row 56A place.This process is proceeded in all

groupings

52,54 are all interweaving order with the same way as shown in the diagonal path 66-90.

After the service node (for example MSO 20) in downstream receives the

grouping

52,54 that interweaves, MSO 20 with by with Fig. 9 in the

grouping

52,54 that interweaves of the represented continuous order arrangement of each

grouping

52,54 leftmost numeral that are associated.Suppose during FEC piece 50 is transferred to MSO 20, cable cut to take place, and during being transformed into reserve MHE 10, a plurality of

continuous groupings

52,54 are lost.

To be the FEC piece 50 shown in Fig. 9 received by MSO 20 and with the block diagram after the continuous sequencing Figure 10.Have the media packet that grouping 52,54 expression of " X " is lost.Should be noted that 16

media packet

52,54 are lost owing to cable cut.Should be noted that in addition the

grouping

52,54 of losing is not by continuous order, because they are transmitted with the order that interweaves in Figure 10.Because the order of transmission of

interleaved packet

52,54 of the present invention, so each in 16 lost

packets

52,54 can be resumed.For purpose clearly, although the recovery of lost packets has been discussed, each lost packets will be discerned by the numeral that corresponding lost packets had among Figure 10.In the lost

packets

5,42,43,50,57 and 64 each can be at first by the corresponding FEC grouping 54 in the associated row, and perhaps the grouping 42 of losing by the existing packet reconstruction from row 58G under the situation of lost packets 42 recovers.

5 and 42 before be resumed because divide into groups, and the grouping 35 and 12 of losing next can be as not being present in grouping only being arranged and be resumed among corresponding row 56E and the 56F.Because the grouping of losing 35 before had been resumed, the grouping 34 of losing then can as be not present among the capable 58F only having the grouping and be resumed.Because the grouping of losing 26 will be not to be present in row grouping only to be arranged among the 56D after the grouping 34 of losing is resumed, the grouping 26 of losing can be resumed then.The grouping 27,21,20,14,13 and 7 of losing is restored in the same way.

Figure 11 is the block diagram of FEC piece 92 according to another embodiment of the present invention.Suppose that MSO 20 receives the FEC piece 50 shown in Figure 10, and recover the grouping that all are lost.In addition, suppose that access network section 16 does not have enough bandwidth and bears 32% expense, these two will need 32% expense wherein to comprise row and column FEC grouping 54 in FEC piece 50.In addition, it is 5 or continuous grouping still less that losing of supposing to be associated with access network section 16 describes to indicate average packet loss continuously.According to one embodiment of present invention, MSO 20 can delete (prune) or abandon capable FEC grouping 54 from FEC piece 50, and reuses row FEC grouping 54 and create the FEC piece 92 shown in Figure 11.Should be noted that according to the loss that is associated with access network section 16 and describe that 5 row FEC groupings 54 will be enough to recover the lost packets of common quantity.It should be noted that row FEC grouping 54 does not need to regenerate from the FEC matrix, but be reused, thereby reduced the processing time and reduced visible artefacts (artifact) on the CPE 26 that may cause by processing delay.

With reference to Figure 12, provide the block representation of service node 94.Service node 94 is general controlled entities that the function of MSO 20, MHE 10, MHO 18 or PG 24 can be provided.Especially, service node 94 can comprise control system 96, and described control system 96 has enough memories 98 to be used for necessary software 100 and data 102 to promote aforesaid operation.Except the function that entire equipment is provided, software 100 can provide MA 38 and EEC 36, and this depends on configuration.In addition, control system 96 can be associated with one or more communication interfaces 104 to promote the necessary communication of operation.Service node 94 can be that independent entity maybe can be the part of the another part such as switch, router etc.

With reference to Figure 13, illustrate the block representation of CPE 26.CPE 26 can comprise control system 106, and described control system 106 has enough memories 108 to be used for necessary software 110 and data 112 to operate as described above.Equally, software 110 can provide the function of CPE 26 usually, and the function of MA 38 and EEC 36, and this depends on configuration.Control system 106 can be associated to promote aforesaid communication with one or more communication interfaces 114.In addition, control system 106 can be associated with user interface 116 provides streaming video and receives information from the client can listen the form that maybe can see with the mutual of client and to the client with promotion.

One of ordinary skill in the art would recognize that improvement and correction to the preferred embodiment of the present invention.Improvement that all are such and correction all are considered to fall within the scope of this disclosed design and claims.

Claims

1. one kind is used for sending the method for a plurality of media packet from head end to customer rs premise equipment by Video service office and residential gateway at the switched digital video network, and described method comprises:

Receive more than first video packets in Video service office;

Use first error correction procedure to provide first error correction to more than first video packets;

Send more than second video packets that comprises more than first video packets to residential gateway via the switched digital video network; And

Use second error correction procedure to provide second error correction to more than second video packets at the residential gateway place, wherein first error correction procedure is different from second error correction procedure.

2. method according to claim 1, wherein more than second video packets also comprises a plurality of video packets of recovering by first error correction procedure.

3. method according to claim 1 also comprise receiving more than first forward error correction (FEC) grouping that is associated with more than first video packets, and wherein first error correction procedure is used more than first FEC to divide into groups to provide first error correction.

4. method according to claim 3 also comprise to residential gateway sending more than second the FEC grouping that is associated with more than second video packets, and wherein second error correction procedure is used more than second FEC to divide into groups to provide second error correction.

5. method according to claim 4, wherein more than second subclass that the FEC grouping is more than first FEC grouping.

6. method according to claim 5 also comprises:

The indication that the FEC that is lazy weight about more than second FEC grouping in the reception of Video service office divides into groups;

Receive more than the 3rd video packets in Video service office;

Use first error correction procedure to provide first error correction to more than the 3rd video packets;

Send more than the 4th video packets that comprises more than the 3rd video packets to residential gateway via the switched digital video network; And

In response to described indication, send more than the 3rd the FEC grouping that is associated with more than the 4th video packets via the switched digital video network to residential gateway, and wherein more than the 4th FEC grouping comprises that the FEC than more than second the bigger quantity of FEC grouping divides into groups.

7. method according to claim 1, wherein first error correction procedure is to use forward error correction (FEC) error correction procedure of more than first row FEC grouping and more than first row FEC grouping, and wherein second error correction procedure is only to use the FEC error correction procedure of more than second row FEC grouping.

8. method according to claim 7, wherein more than second row FEC grouping comprises more than first row FEC grouping.

9. method according to claim 1, wherein first error correction procedure is forward error correction (FEC) error correction procedure, and wherein second error correction procedure is automatic repetitive requests (ARQ) error correction procedure.

10. method according to claim 1, wherein first error correction procedure is based on losing that the network segment that is coupled to Video service office is associated and describes to select.

11. method that is used for sending more than first video packets by network with core network section and access network section, described core network section is coupled to the access network section with first service node, and described access network section is coupled to the local network segment with second service node, and described method comprises:

Generate more than first forward error correction (FEC) grouping based on more than first video packets;

Send more than first video packets and more than first FEC grouping to first service node;

From more than first FEC grouping, remove more than second FEC grouping to form more than the 3rd FEC grouping; And

Send more than first video packets and more than the 3rd FEC grouping to second service node, wherein the core network section has first bandwidth greater than second bandwidth of access network section.

12. method according to claim 11 also comprises:

Receive the indication that comprises the FEC grouping of not enough FEC amount about more than the 3rd FEC grouping from second service node;

Receive more than second video packets;

Send more than the 3rd video packets to second service node; And

In response to described indication, send more than the 4th the FEC grouping that is associated with more than the 3rd video packets to second service node, described more than the 4th FEC grouping comprises the FEC amount of packets greater than the FEC grouping of not enough FEC amount.

13. method according to claim 11 also comprises:

At the first service node place, the indication that the FEC that reception is a lazy weight about more than the 3rd FEC grouping divides into groups; And

In response to described indication, send more than the 4th FEC grouping to second service node, and wherein said more than the 4th FEC grouping comprises the FEC grouping than more than the 3rd the bigger quantity of FEC grouping.

14. a method that is used for providing by two network segments with different bandwidth error correction comprises:

At the first service node place, reception comprises more than first packet of more than first video packets and more than first forward error correction (FEC) grouping, in described more than first packet each has the associated sequence number that identifies the continuous order that is associated with more than first packet, and wherein more than first packet is received at the first service node place with the order that interweaves; And

Send more than second packet that comprises more than first video packets and more than second FEC grouping to second service node, described more than second FEC grouping comprises the suitable subclass of more than first FEC grouping, described more than second packet be based on more than first video packets and more than second FEC grouping in each sequence number that is associated be sent out with continuous order.

15. a service node comprises:

Import first interface, be suitable for communicating with first network segment;

Output interface is suitable for communicating with second network segment; And

Control system, be coupled to input first interface and output interface and be suitable for:

More than first error correction packet that receives more than first video packets and be associated via first network segment with more than first video packets;

Use more than first error correction packet to provide first error correction to more than first video packets;

Generate more than second error correction packet based on more than first video packets; And

Send more than second video packets that comprises more than first video packets and more than second error correction packet to second service node.

16. service node according to claim 15, wherein more than second video packets also comprises the video packets of a plurality of recoveries that recovered by first error correction.

17. service node according to claim 15, wherein more than second the suitable subclass that error correction packet is more than first error correction packet.

18. service node according to claim 17, wherein more than first error correction packet comprises a plurality of capable error correction packet and a plurality of row error correction packet, and wherein more than second error correction packet is made up of a plurality of row error correction packet.

19. service node according to claim 15, wherein said control system also is suitable for:

Reception is the indication of the error correction packet of lazy weight about more than second error correction packet;

Receive more than the 3rd video packets and more than the 3rd error correction packet;

Send more than the 4th video packets that comprises more than the 3rd video packets to second service node; And

In response to described indication, send more than the 4th error correction packet that is associated with more than the 4th video packets to second service node, and wherein said more than the 4th error correction packet comprises the error correction packet than the bigger quantity of error correction packet of lazy weight.

20. service node according to claim 15, wherein first error correction is based on that losing of being associated with first network segment describe to select.

21. method that is used for sending a plurality of media packet at the switched digital video network, described switched digital video network has via first network segment and is coupled to first service node of second service node and is coupled to second service node of the 3rd service node via second network segment, and described method comprises:

At the second service node place, receive more than first video packets from first service node via first network segment;

Use first error correction procedure to provide first error correction at the second service node place to more than first video packets;

Send more than second video packets that comprises more than first video packets to the 3rd service node via second network segment; And

Use second error correction procedure to provide second error correction to more than second video packets at the 3rd service node place, wherein first error correction procedure is different from second error correction procedure.

22. method according to claim 21 also comprise receiving more than first forward error correction (FEC) grouping that is associated with more than first video packets, and wherein first error correction procedure is used more than first FEC to divide into groups to provide first error correction.

23. method according to claim 22 also comprise to the 3rd service node sending more than second the FEC grouping that is associated with more than second video packets, and wherein second error correction procedure is used more than second FEC to divide into groups to provide second error correction.