Packet configuring method and packet receiver

Abstract

A packet receiver is provided that accurately estimates a frequency offset and a channel impulse response even when a transmitted packet is detected with an erroneous timing in a communication mode (typified by the LAN (local Area Network)) where packets are asynchronously transmitted, and thus provides a training sequence which can demodulate the received packet. The training sequence 101 is formed of K sequences 100-1 to 100-K serially connected, each formed of the same N symbols. Even in a channel where a intersymbol interference occurs when such a training sequence is used, a received signal shifted by the time corresponding to N-symbols becomes the signal which is different by a phase difference caused by a frequency offset between the transmitter and the receiver. Thus, even if the head of a packet is detected with an erroneous timing, the frequency offset can be estimated.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to a packet configuring method and a packet receiver. Particularly, the present invention relates to a packet configuring method and a packet receiver, each for configuring a packet that contains training sequences in an asynchronous packet communication mode.[0002]FIG. 7 is a diagram illustrating a down-link control channel frame used for the conventional digital automobile telephone, described ETSI / GSM, “Recommendation GSM 05.02 Multiplexing and Multiple Access on the Radio Path”, version 3.3.0, 15, Apr., 1989. FIG. 7 shows an example of a 10-channel configuration being the head of a frame. This frame is formed of a frequency connection channel (FCCH) 1000, a synchronization channel (SCH) 1001 and a broadcast channel (BCCH) 1002. The slot forming SCH 1001 or BCCH 1002 is formed of the training portion 1011 and the data portions 1010 sandwiched by the training portion 1011. The frequency connection channel FCCH 1000 is ...

AI Technical Summary

Benefits of technology

The present invention provides a method and apparatus for accurately estimating the frequency offset and channel impulse of a received packet, even when the packet is erroneously detected in timing. This is achieved by using a training portion with repeated sequences, each formed of N symbols, to estimate the frequency offset and channel impulse response. The method and apparatus can be used in a communication mode where packets are asynchronously transmitted. The technical effects of the invention include improved accuracy in estimating the frequency offset and channel impulse, reduced training sequence length, and improved performance in detecting and compensating for errors in packet timing.

Problems solved by technology

In this case, the head of a packet cannot be already received accurately due to influences of noises or radio transmission path.

Hence, this method has the disadvantage in that the boundary between the sequence for frequency offset estimation and the sequence for channel impulse response estimation may not be recognized.

Moreover, the method has the disadvantage in that the length of a training sequence is prolonged using the sequence for frequency offset estimation and the sequence for channel impulse response estimation, whereby the transmission efficiency is degraded.

Images