WO2002041584A2

WO2002041584A2 - System and method for efficiently communicating data over multiple networks using various transmission schemes

Info

Publication number: WO2002041584A2
Application number: PCT/EP2001/013155
Authority: WO
Inventors: Chiu Y. Ngo
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2000-11-17
Filing date: 2001-11-12
Publication date: 2002-05-23
Also published as: CN1452825A; KR20020082209A; CN1197300C; JP2004514380A; EP1338121A2; WO2002041584A3

Abstract

A networking system and methods are disclosed that combine various subnets to improve the throughput and efficiency of various data transmission schemes such as automatic repeat request (ARQ) and layered source coding schemes. The networking system includes a network architecture that integrates the various subnets into an overlaid backbone network which can connect different data devices. The throughput and efficiency improvements are achieved by always using the most reliable subnet, i.e., transmission medium, available for paramount channels in the data transmission schemes, e.g., ARQ feedback channel or base layer channel.

Description

System and method for efficiently communicating data over multiple networks using various transmission schemes

Field of the Invention

This invention relates to a system and method for transmitting data over a network; more particularity, the invention relates to a networking architecture that improves the transmission reliability of data over various subnets in a home/business data network.

Background of the Invention

With an increase in the number of households and businesses having multi- digital consumer electronic (CE) equipment, there are greater demands for data networks that link two or more PCs and/or CE devices together. In its simplest form, data communication takes place between any two devices that are connected by some form of transmission medium. However, it is generally impracticable for such devices to be point-to-point connected. To connect all devices directly to each other would be expensive and bulky (in view of the number of connections required) for the home or business. Accordingly, multiple PCs and/or CE devices are generally connected via a network. Conventional communication networks typically include workstations, communication nodes and a communication network. The workstations may be computers, terminals, telephones, and other communication devices. Each of the workstations attach to respective communication nodes which are capable of transferring data between the workstations via the communication network. The communication network may be any conventional-type network such as switched (circuit- or packet-switched) and broadband (packet radio, satellite, bus-local and ring-local) networks.

The communication nodes use various communication protocols to allow for proper communication between the workstations via the communication network. Essentially, the protocols define the set of rules governing the exchange of data between the two workstations. The key functions of the protocol relate to syntax, semantics and timing. The communication may be direct (point-to-point) or indirect (via intervening active agents, e.g., the Internet).

One of the major functions of a home/business network is to distribute data throughout the building or region. This type of data networking concept allows multiple users to perform various useful tasks. Another function for such home/business networks relates to smart systems (e.g., home automation) which allows for control of various home/business functions. The popularity of smart energy modules (which control the building environment) and intelligent security systems are increasing. The conventional market for home/business networking is mainly PC-centric, e.g., PCs connected via a local area network (LAN). Using existing infrastructure and technologies, devices can be connected by various means, e.g., coaxial cable, plastic optical fiber (pof), power line, phone line, integrated service digital network (ISDN), and wireless (IR and RF). Coaxial cable and plastic optical fiber can provide reliable 10/100 Mbps Ethernet and 100Mbps 1394b connections. Other mediums such as phone lines, power lines and wireless can generally provide low to medium data-rate connections.

One major shortcoming related to the conventional home networks discussed above is that they rely on a single medium or technology for communication and interconnection. Moreover, in some cases, there may be multiple networks within a single building or residence. These multiple networks may essentially compete for the same bandwidth, e.g., radio frequencies. Even in the case where the multiple networks do not compete for the same bandwidth, there exists no integrated system for effectively managing and controlling (e.g., demand and allocation of bandwidth) such home/business network mediums. In U.S Patent Application 09/630,349, filed July 20, 2000, incorporated herein by reference, a network architecture is disclosed that integrates various subnets into an overlaid backbone network which can connect phone line network devices, power line network devices, radio frequency (RF) cordless devices, and devices clustered around internet protocols (IP), universal serial buses (USB) and PI 394, and distribute data efficiently and reliably over the subnets. The Applicant has found that such a network architecture provides numerous advantages that maybe used to solve various shortcomings in conventional data transmission strategies and coding schemes.

For example, automatic repeat request (ARQ) strategies have been used to control errors by means of retransmission on a two-way wireless communication link. Such ARQ systems can be classified into three categories: stop-and-wait, go-back-N, and selective repeat. However, all of these ARQ systems suffer from various inefficiencies.

In stop-and-wait ARQ, when a transmitter sends a data packet, it will stop and wait for an ACK/NACK from the receiver. This ARQ strategy is inefficiency because the channel is idle during the whole period. This inefficiency is particularly serious when the round-trip delay between the transmitter and the receiver is long compared to the transmission time of a message.

In a go-back-N ARQ system, when a receiver detects the presence of errors in a data packet, a negative acknowledgment (NACK) will be sent back to the transmitter. The transmitter will then stop sending new data packets and backs up to the data packet that is negatively acknowledged and re-sends that packet and the N-l succeeding data packets that were transmitted during the round-trip delay.

In selective repeat ARQ system, only the lost or corrupted data packets are resent and therefore, it gives the best performance in terms of throughput among the three, but has an increased requirement for buffers at the receiver. Buffers are needed to store those packets that are received out of sequence. In an environment where the error rate is high and the round-trip delay is long, the number of these re-sequencing buffers required may be considerable.

Another coding scheme that maybe improved is layered source coding. While layered source coding is one of the most effective schemes to provide error resilience in video transport systems, it still may suffer from some transmission inefficiencies based upon the transport prioritization method used. For example, in this scheme, video data information is decomposed into a number of layers, each represents different perceptually relevant components of the -video source. The base layer contains the essential information for the source and can be used to generate an output video signal with an acceptable quality. With the enhancement layers, a higher quality video signal can be obtained.

There are different ways of implementing layered coding. For example, in temporal domain layered coding, the base layer contains a bit stream with a lower frame rate and the enhancement layers contain incremental information to obtain an output with higher frame rates. In spatial domain layered coding, the base layer codes the sub-sampled version of the original video sequence and the enhancement layers contain additional information for obtaining higher spatial resolution at the decoder.

Generally, a different layer uses a different data stream and has distinctly different tolerances to channel errors. To combat channel errors, layered coding is usually combined with transport prioritization so that the base layer is delivered with a higher degree of error protection. If the base layer is lost, the data contained in the enhancement layers may be useless. Figure 1 illustrates a typical video system 10 with layered coding and transport prioritization. A layered source encoder 11 encodes input video data. A plurality of channels 12 carry the encoded data. A layered source decoder 13 decodes the encoded data.

Depending on the network, transport prioritization can be implemented differently. For example, in some wireless networks, unequal power control is used so that each layer coding sub-stream transport is sent with different levels of transmit power. However, this method of transport prioritization is not always possible or the most efficient.

There thus exists in the art a need for improved methods and systems for improving the efficiently of data transmission in home/business networks.

Summary of the Invention

The present invention provides a network architecture that integrates different subnets into an overlaid backbone network which can connect phone line network devices,

_* power line network devices, radio frequency (RF) cordless devices, and devices clustered around internet protocols (IP), universal serial and distributes data efficiently and reliably over the subnets. This network architecture is used to improve the throughput and efficiency of various data transmission schemes such as ARQ and layered source coding schemes. The improvements are based upon the selection of the most reliable transmission medium, i.e., subnet, available and use of that subnet for paramount channels in particular data transmission schemes.

One aspect of the present invention is directed to a method for assigning communication channels in a data network. The method includes the steps of receiving a connection request from a data device, determining whether the connection request will use a predetermined transmission scheme and selecting one of a plurality of subnets that has a predetermined reliability value that is greater than another of the subnets. The method also includes the step of assigning the selected subnet to be used by the predetermined transmission scheme to improve efficiency or reliability of data distribution over the network. One embodiment of the invention relates to assigning the selected subnet to be used as a base layer channel for a layered coding scheme Another embodiment of the invention relates to assigning the selected subnet to be used as a feedback channel for an ARQ scheme.

Yet another aspect of the invention is directed to a data networking system including at least two controllers and at least one data device coupled to each of the controllers. The system also includes a plurality of subnets coupled to the controllers, each of the plurality of subnets having a predetermined reliability value. The controller is arranged to select one of a plurality of subnets that has a predetermined reliability value that is greater than another of the plurality of subnets, and to assign the selected one of the plurality of subnets to be used by a predetermined transmission scheme to improve efficiency or reliability of data distribution over the data networking system.

These and other embodiments and aspects of the present invention are exemplified in the following detailed disclosure.

Brief Description of Drawings The features and advantages of the present invention can be understood by reference to the detailed description of the preferred embodiments set forth below taken with the drawings, in which:

Fig. 1 is a conventional video transmission system;

Fig. 2 is a schematic block diagram of a preferred network architecture; Fig. 3. is a block diagram of an inter-subnet router;

Fig. 4 is a flow chart show various steps in an ARQ method in accordance with a preferred embodiment; and

Fig. 5 is a flow chart show various steps in a layered coding method in accordance with a preferred embodiment.

Detailed Description

Figure 2 illustrates a preferred network architecture used to practice the present invention. In Fig. 2, a home data network 100 is shown. Of course, it should be understood that the invention is not limited to home networks. The invention may also be applied to any environment that benefits from data networking such as business and educational facilities.

In this example, a residence 200 including a bedroom 201, a living room 202, and a study 203 is shown. Each room has a respective inter-subnet router 101 that connects various devices in the room to at least one of a plurality of subnets. This example includes a phone line subnet 102, a power line subnet 103, a wireless subnet 104, a coaxial subnet 105, a fiber subnet 106 and an external network 107. Each room also include various end-user devices (e.g., TV 110, video recorder 111, laptop 112, phone 113, NCR 114, facsimile 115, printer 116 and personal computer 117) which may transmit and/or receive data over the various subnets. Alternatively, all of the end-user deceives at this location may be coupled to a single router 101. The single router 101 then manages communication between the end-user devices and external devices located in a different building or location that also have access to the various subnets via an inter-subnet router.

Each router 101 maintains data related to the reliability of the plurality of subnets. Additional information and data may also be maintained to allocate subnet resources and facilitate connection admission control, as described in U.S. Application 09/630,359, filed July 20, 2000, incorporated herein by reference.

As shown in Table 1 below, each subnet has a different reliability index or rating. Each of these subnets is rated based on accepted performance criteria or standards. Some subnets are inherently more reliable to use then others.

Table 1: Reliability of subnets

Of course, it will be appreciated by one skilled in the art that other data structures can be defined to store and administer the connection data. The invention is not limited to a matrix-like table. In addition, each router 101 is not required to maintain such reliability data. One of the routers 101 may store such information. The other routers 101 access the information as needed. Such information may also be stored in an external device (e.g., a local or remote PC). The routers 101 then access the information from the external device as needed.

One embodiment of the present invention is based upon the realization that the efficiency of ARQ strategies highly depend upon the quality of the feedback channel. Therefore, wherever possible, the most reliable link should be used for this feedback channel. In this embodiment, the various subnets are selectively used to provide a reliable feedback link for ARQ schemes. In a preferred embodiment, this method is used to improve the reliability of the feedback channel and the efficiency of the ARQ strategies over the wireless subnet 104. A more reliable subnet is always chosen, if available, as a means for the feedback channel. This may be done by means of the inter-subnet router in the route-connection setup phase. For example, the forward route is via the wireless subnet and the reverse (or feedback) route is set to go through the phoneline subnet or the powerline subnet (each with a reliability value as defined in Table 1). This will improve the reliability of the feedback channel and thus, improve the efficiency of the ARQ mechanism for wireless communications.

In another embodiment, a transport prioritization based on a home network architecture discussed above utilized. As shown in Table 2 below, each subnet has different reliability index or value. By using different error resilience capabilities together with layered source coding, an efficient way of video transmission over a home network is provided.

In this embodiment, transport prioritization is performed using the different subnets supported by the inter-subnet router. The base layer is delivered through the highest reliable subnet available at the time, and the enhancement layers are transported through other subnets with decreasing order of reliabilities. Higher reliability subnets are given preference when available.

An example of mapping the layered coding to PHY modes is depicted in Table 2. Of course, it will be appreciated that other methods of mapping the coded layers to the subnets can be used. These other method, for example, may depend on the number of coded layers and the availability of subnets from one router to another. Table 2:

An important feature of this embodiment is the realization of a transport prioritization method that is based on different subnets provided by the inter-subnet routers in a home network. A wireless video system may make use of layered coding and different subnets supported by the home network by mapping the base layer to the highest reliable subnet and the enhancement layers to other sub nets with decreasing order of reliabilities.

FIG. 3 shows the internal architecture of the router 101. The router 101 includes one or more data connections 322, one or more input/output connections 324, a processor 325, a memory 326, and an internal clock 328. The data connections 322 represent interfaces for the various subnets 102 through 106. As discussed above, data connections 322 may alternatively represent one or more data connections from the subnets 102 through 106 and or from the external network 107, e.g., a global computer communications network such as the Internet, a wide area network, a metropolitan area network, a local area network, a terrestrial broadcast system, a cable network, a satellite network, a wireless network, or a telephone network, as well as portions or combinations of these and other types of networks. The input/output connections 324 represent interfaces (e.g., hardwired, wireless, inferred, video, analog or digital) for the various end-user devices (e.g., items 110 through 117 shown in Fig. 2). The data connections 322, input/output connections 324, processor 325, memory 326 and clock 328 communicate over a communication medium 327. The communication medium 327 may represent, e.g., a bus, a communication network, one or more internal connections of a circuit, circuit card or other device, as well as portions and combinations of these and other communication media. It should be understood that the particular configuration of the router 101 as shown in FIG. 3 is by way of example only. Those skilled in the art will recognize that the invention can be implemented using a wide variety of alternative system configurations. Figure 4 shows a flow chart depicting the selection and control of ARQ connections between end-user devices via the various subnets. In step S10, an end-user device requests a connection to one or more other end-user devices. The router 101 to which the particular end- user device is coupled to then processes the request. The request comprises commands and interface protocols routines which are interpreted by the router 101. The following are two examples of type of connections that may be requested:

TV 101 requests video data from the NCR 114 or the video 111; Laptop 112 requests access to the phone 113 (e.g., wireless) or the external network 107 (e.g., to gain access to Internet).

In step Sll, the router 101 determines whether a ARQ connection is to be used. The most reliable subnet is then determined based upon the data such as in Table 1, in S12. This subnet is then dynamically assigned as the ARQ or feedback channel in S13. One or more predetermined subnets may also be assigned as the ARQ or feedback channel in advance during a system step-up phase. These predetermined subnets may also be prioritized to determine their order of use should one predetermined subnet not be available at a particular time. Figure 5 shows a flow chart depicting transport prioritization control when using layered coding between end-user devices via the various subnets. Step S10 is the same as described above. In step S14, the router 101 determines whether a layered coding type connection is to be used. The most reliable subnet is then determined based upon the data such as in Table 1, in S15. This subnet is then dynamically assigned as the base layer in S16. The various enhancement layers are then assigned subnets based upon the available subnets in descending order of reliability.

Alternatively, one or more predetermined subnets may also be assigned for the base and enhancement layers in advance during a system step-up phase, e.g., as shown in Table 2 above. These predetermined subnets may also be prioritized to determine their order of use should one predetermined subnet not be available at a particular time.

As shown in Figs. 4 and 5, if ARQ or layered coding is not used, other types of processing may be performed in S17.

It will be appreciated that the present invention is also application to other data transmission schemes and applications. In particular, any such scheme that can be improved by assignment of higher reliability channels for more critical functions.

In a preferred embodiment, these steps are implemented by computer readable code (e.g., software programs) executed by the processor 325. The code may be stored in the memory 326 or read/downloaded from a memory medium such as a CD-ROM or floppy disk. In other embodiments, hardware circuitry may be used in place of, or in combination with, software instructions to implement the invention.

While the present invention has been described above in terms of specific embodiments, it is to be understood that the invention is not intended to be confined or limited to the embodiments disclosed herein. On the contrary, the present invention is intended to cover various structures and modifications thereof included within the spirit and scope of the appended claims.

Claims

CLAIMS:

1. A method for assigning communication channels (12) in a data network (10), the method comprising the steps of: receiving (S10) a connection request from a data device; determining (Sll, S14) whether the connection request will use a predetermined transmission scheme; selecting one of a plurality of subnets (102-106) that has a predetermined reliability value that is greater than another of the plurality of subnets; and assigning ,(S 13, S16) the selected one of the plurality of subnets to be used by the predetermined transmission scheme to improve efficiency or reliability of data distribution over the network.

2. The method according to Claim 1, wherein the predetermined transmission scheme is either an ARQ or layered coding scheme.

3. The method according to Claim 2, wherein the plurality of subnets (102-106) including one or more of the following a phone line subnet (106), power line subnet (103), a wireless subnet (104), a coaxial subnets (105), and a fiber subnet (106).

4. The method according to Claim 3, wherein the data device comprises a computer (117), a display device (110), a video device (111), a consumer electronic device (114) or a voice communication device (113).

5. The method according to Claim 4, wherein the selected one of the plurality of subnets is assigned to be used as a feedback channel (S13)for the ARQ scheme.

6. The method according to Claim 5, further comprising the step of using another of the plurality of subnets for transmitting data that is different from the selected one of the plurality of subnets.

7. The method according to Claim 6, wherein the another of the plurality of subnets is the wireless subnet (114).

8. The method according to Claim 1, wherein the step of selecting the one of the plurality of subnets is dynamically performed in accordance with predetermined reliability data for each the plurality of subnets.

9. The method according to Claim 1, wherein the step of selecting the one of the plurality of subnets is performed in accordance with a predetermined subnet prioritization set-up.

10. The method according to Claim 4, wherein the selected one of the plurality of subnets is assigned to be used as a base layer channel for the layered coding scheme (11).

11. The method according to Claim 10, further comprising the step of assigning another one of the plurality of subnets that is different from the selected one of the plurality of subnets to be used for an enhancement layer channel for the layered coding scheme.

12. A memory medium (326)including code for assigning channels in a data network,, the code comprising: code to receive a connection request from a data device; code to determine whether the connection request will use a predetermined transmission scheme, the predetermined transmission scheme comprising at least an ARQ or a layered coding scheme; code to select one of a plurality of subnets that has a predetermined reliability value that is greater than another of the plurality of subnets; and code to assign the selected one of the plurality of subnets to be used by the predetermined transmission scheme to improve efficiency or reliability of data distribution over the data network.

13. The memory medium (326) according to Claim 12, wherein the selected one of the plurality of subnets is assigned to be used as an ARQ feedback channel for the ARQ scheme.

14. The memory medium (326) according to Claim 13, wherein the selected one of the plurality of subnets is assigned to be used as a base layer channel for the layered coding scheme.

15. A data networking system (100) comprising: at least two controllers (101); at least one data device (110) coupled to each of the controllers; a plurality of subnets (102-166) coupled to the controllers (101), each of the plurality of subnets having a predetermined reliability value, wherein the controller (101) is arranged to select one of a plurality of subnets that has a predetermined reliability value that is greater than another of the plurality of subnets, and to assign the selected one of the plurality of subnets to be used by a predetermined transmission scheme to improve efficiency or reliability of data distribution over the data networking system.

16. The system (100) according to Claim 15, wherein the selected one of the plurality of subnets is assigned to be used as a feedback channel for an ARQ scheme.

17. The system (100) according to Claim 15, wherein the selected one of the plurality of subnets is assigned to be used as a base layer channel for a layered coding scheme (11).