Method of sending feedback information in a fast automatic repeat request forming part of an overall wireless communication system

Abstract

A method of sending feedback information in a fast physical layer hybrid automatic repeat request (HARQ) for frequency division duplex communications that form an overall wireless communication system is described in which the received packets are acknowledged by transmitting feedback data to the sender, wherein the acknowledgement comprises the reservation of obtaining a plurality of slots in the uplink / downlink dedicated channel radio frame for the feedback data alone. It is also directed to the transmission of feedback data used in specified slots within each radio frame, wherein the first slot used is based upon the time offset between uplink and downlink channels, as well as based upon the time required for de-interleaving, de-ratematching, decoding and error checking. In an alternative embodiment, the method uses dedicated physical control channel (DPCCH) bits in at least some of the slots for transmitting such feedback data to the sender.

Description

TECHNICAL FIELD[0001]The present invention relates to sending feedback data to a sender of packets in a wireless communication system and in particular is directed to a new feedback channel for use in fast hybrid automatic repeat request.BACKGROUND OF THE INVENTION[0002]Fast hybrid automatic repeat request (HARQ) has been proposed as a vehicle to solve receiver memory problems which occur when soft combining schemes are used in wireless communications. The fast HARQ requires that an acknowledgement (or the so-called forward order) be transmitted within the next radio frame after the transmission of packet(s) in the forward direction. Hybrid ARQ (HARQ) is a link adaption technique used to improve the performance of wireless communications. In a Type 1 Hybrid ARQ, there is soft combining which is a type of repetition coding in which the retransmitted packet is combined with the initially transmitted packet. In Type 2 Hybrid ARQ, an incremental redundancy scheme is used. In both Type 1...

AI Technical Summary

Benefits of technology

[0008]Hybrid ARQ is a link adaption technique which is used to improve the performance of wireless communication systems and the Type 1 Hybrid ARQ with soft combining uses a type of repetition coding in which the retransmitted packet is combined with the initially transmitted packet. Type 2 Hybrid ARQ uses an incremental redundancy scheme and thus both in Type 1 and Type 2 Hybrid ARQ soft combining is utilized in the receiver and soft decisions values of the erroneous packets have to be stored in the receiver which of course, can lead to very high memory requirements at the receiver. It is thus clear that the amount of memory required for storing the soft decisions is proportional to the retransmission time interval.

[0009]For wireless communication system, the uplink and downlink radio frames have a probable time displacement between the uplink and downlink channels. For dedicated channels, the uplink and downlink frames are typically separated by 1,024 chips. The purpose of the fast feedback is to reduce the time interval for transmitting the feedback after receiving the packet. However, the receiver must typically de-interleave, de-ratematch, decode and error check the received packets after reception of the radio frame and all of these operations require time. Thus the fastest way to send acknowledgement is to stuff the feedback data in the next frame in the uplink direction so that the transmitter can retransmit the erroneous packets with a delays of only one transmission timing interval (TTI).

Problems solved by technology

Type 2 Hybrid ARQ uses an incremental redundancy scheme and thus both in Type 1 and Type 2 Hybrid ARQ soft combining is utilized in the receiver and soft decisions values of the erroneous packets have to be stored in the receiver which of course, can lead to very high memory requirements at the receiver.

However, the receiver must typically de-interleave, de-ratematch, decode and error check the received packets after reception of the radio frame and all of these operations require time.

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