Complete user datagram protocol (CUDP) for wireless multimedia packet networks using improved packet level forward error correction (FEC) coding

Abstract

A complete User Datagram Protocol (CUDP) is disclosed that reduces packet loss. Channel frame error information is used with a packet level forward error correction (FEC) coding technique to accommodate wireless multimedia traffic. Each packet, as well as the channel frame error information, is forwarded to a given application. The CUDP protocol further assists the FEC decoding process by forwarding the locations of corrupted frames to the FEC decoder. Maximal Distance Separable (MDS) codes can be applied to a group of packets, to achieve additional robustness. An MDS decoder utilizes the frame error information to recognize the erasures within each packet. The error information can be represented as a set of LTU error indicators associated with each packet (for FEC decoders requiring an erasure indicator). The error indicators point to the starting and ending location of the erroneous data. The error information can also be represented as a reformatted packet (for FEC decoders Recognizing Erasures). The frame (LTU) error information from the lower layers is incorporated in the packet payload. An FEC encoder is also disclosed that encodes multimedia packets utilizing a packet-coding scheme, such as a Vertical Packet Coding (VPC) scheme or a Long Vertical Packet Coding (LVPC) scheme.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a divisional application of U.S. patent application Ser. No. 09 / 668,242, filed on Sep. 22, 2000 and is related to U.S. patent application Ser. No. 09 / 668,243 entitled “Radio Link Protocol (RLP) / Point-to-Point Protocol (PPP) Design for Wireless Multimedia Packet Networks that Passes Corrupted Data and Error Location Information Among OSI Layers,” assigned to the assignee of the present invention and incorporated by reference herein.FIELD OF THE INVENTION [0002] The present invention relates generally to wireless packet networks, and more particularly, to methods and apparatus for reducing lost or corrupted packets in such wireless packet networks. BACKGROUND OF THE INVENTION [0003] It is inevitable that future wireless services will support Internet Protocol (IP)-based multimedia applications. For example, current and emerging wireless networks allow (i) a user to download information from the Internet using a wireless...

AI Technical Summary

Benefits of technology

[0009] We have recognized that the above-described shortcomings of the UDP protocol may be overcome by a revised UDP protocol, referred to herein as the complete User Datagram Protocol (CUDP), that reduces unnecessary packet discarding.

[0010] More specifically, we have developed the CUDP that includes new packet handling procedures and reduces unnecessary packet discarding. The disclosed CUDP protocol utilizes channel frame error information obtained from the physical and link layers to assist the packet level error recovery. In addition, the CUDP supports packet level FEC coding in order to reduce information loss.

[0011] The present invention forwards each packet, as well as the channel frame error information, to a given application. In particular, the disclosed CUDP protocol further assists the packet level FEC decoding process by forwarding the locations of corrupted frames to the FEC decoder. A transmitter in accordance with the present invention optionally applies FEC techniques employing Maximal Distance Separable (MDS) codes to a group of packets, to achieve robustness against packet loss within the Internet and against packet error over wireless channels. At the receiver, the CUDP protocol forwards the frame error information, as well as the packet data, to the application layer. An MDS decoder utilizes the frame error information to recognize the erasures within each packet.

Problems solved by technology

Network congestion on the Internet leads to packet loss and degraded quality.

Wireless packet networks encounter packet losses between a base station and a mobile receiver as a result of channel errors and network congestion.

Furthermore, such packet losses can be random or bursty, depending on the environment, rate-of-motion and network loading.

Therefore, it has been recognized that use of the UDP protocol in a wireless network will cause considerable packet losses, and as a result, poor audio / video quality and increased power consumption.

The inefficiency of the UDP protocol in wireless networks arises from the discarding of a packet containing only a small portion of corrupted data.

However, the UDP protocol yields high packet loss rates even under low and medium physical layer data losses.

Therefore, the (n−k) value employed by the FEC encoder should be sufficiently large to effectively reduce the packet loss, which implies increased overhead and less efficiency.

On the other hand, in a wireless network employing the UDP Lite protocol, which performs a checksum based on the packet header, so that only corrupted packet headers result in packet loss, the FEC decoder may receive perfect or corrupted packets, and performs both error and erasure correction.

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