Wireless communication method and apparatus for allocating training signals and information bits

Abstract

Techniques of channel correction and demodulation for orthogonal frequency division multiplexing (OFDM) systems are enhanced so that higher effective data rates and / or lower error rates can be achieved with a minimal processing load. Pilots are adaptively moved and / or removed, and their positions are changed, to enhance the channel estimation, decoding, and demodulation processes at the receiver. Reception is also enhanced by adding, removing, or changing the positions, of information-carrying data bits.

Description

Background technique [0001] Efficient demodulation of Orthogonal Frequency Division Multiplexed (OFDM) signals requires accurate and sufficient frequency characteristics of the time-frequency channel experienced by the signal. Once a channel is fully characterized, or equivalently, "estimated", the channel estimate can be used to maximize the effectiveness of the channel in optimally demodulating signals experiencing said channel. Typically, this process is called "channel equalization". [0002] In modern wireless communication systems, where OFDM is the modulation technique of choice, such as European Computer Manufacturers Association (ECMA)-368 Ultra Wideband (UWB) Personal Area Network (PAN) systems, channels are typically characterized by having two sets of signal to execute. The first signal is called the preamble, and its preamble signal synthesis is completely known to the receiver at all time and frequency samples comprising the preamble signal. The preamble is ty...

AI Technical Summary

Problems solved by technology

[0016] 1) lack of adaptive allocation of training signals within a group; and

[0017] 2) Lack of adaptive allocation of information bits in the internal time-frequency channel plane of the packet

Transmitters in current UWB OFDM systems cannot adaptively allocate information-carrying data bits within packets according to communication channel changes or desired conditions

[0020] However, it is known that even during relatively short periods of time spanning individual packets, UWB channels may suffer impairments on a time-varying basis over specific time-frequency slots

If such impairment occurs over a large area, e.g., over a significant part of the time-frequency plane, and in such a way as to impair the optimal use of previously allocated preambles and pilots, a substantial portion of the data, even when strong encryption using channel coding , may also be unrecoverable at the receiver

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