US 2011/0299612 A1 · UNCONTROLLED SPATIAL MULTIPLE ACCESS IN WIRELESS NETWORKS

Abstract

An uncontrolled spatial multiple access system and method facilitating spatial multiple access for multiple devices in a wireless local-area network (WLAN). Embodiments of the system and method increase throughput of the wireless network by facilitating concurrent encoded frame transmission. Decoding of the quasi-overlapped frames is achieved using a chain decoding technique that takes data streams (or signals) containing the quasi-overlapping encoded frames and isolates each encoded frame so that the frame can be decoded. Quasi-overlapped frames means that the frames are overlapped in the body of the frame but not at the preamble (or headers) of the frames. Embodiments of the chain decoding also use interference nullifying and interference cancelation to enable concurrent quasi-overlapping transmission. A carrier counting multiple access technique of embodiments of the system and method allow wireless networks to retain their asynchronous nature while supporting spatial multiple access and maintain backwards compatibility with the IEEE 802.11 standard.

Claims20

Dependent claims

A method for transmitting and decoding multiple overlapped frames in a wireless network, comprising:

transmitting an encoded first frame from a first station on the wireless network;
transmitting an encoded second frame from a second station in the wireless network immediately after an end of a preamble of the encoded first frame has been transmitted such that the encoded first frame and the encoded second frame are quasi-overlapped;
receiving the encoded first frame and the encoded second frame at an access point on the wireless network;
and
using chain decoding to decode the overlapping encoded first frame and encoded second frame to obtain a decoded first frame and a decoded second frame.

2 more elements

A method for nullifying an encoded first frame transmitted wirelessly in a first signal containing a quasi-overlapping encoded first frame and encoded second frame, comprising:

initializing a linear filter representing an equalizer to obtain an initial modified fractional spaced equalizer, where the equalizer is a modified fractional spaced equalizer than works with oversampling;
updating the initial modified fractional spaced equalizer based on an averaged estimation of a gradient of the first signal to obtain an updated modified fractional spaced equalizer;
determining whether an iteration has converged;
if the iteration has converged, then defining the updated modified fractional spaced equalizer as the optimum modified fractional spaced equalizer;
and
using the optimum modified fractional spaced equalizer to nullify the encoded first frame and obtain the encoded second frame without interference from the encoded first frame.

3 more elements

A method for facilitating quasi-overlapping transmissions of an encoded first encoded frame and an encoded second frame in a wireless network, comprising:

determining that a wireless channel in the wireless network is idle;
having each station on the wireless network initialize its counter to zero;
using at least one contention technique to determine that a first station wins access to the idle wireless channel;
having the first station begin transmitting the encoded first frame immediately after winning access to the wireless channel;
having each station detect the transmission of a preamble of the encoded first frame and increasing each station's counter by one when this detection occurs;
causing stations other than the first station to pause for a fixed time duration that is longer than a length of the preamble;
continuously monitoring the wireless channel with the stations other than the first station;
using channel decoding to decode the media access control header of the encoded first frame;
and
having a second station transmit the encoded second frame immediately after transmission of the preamble of the encoded first frame such that the encoded first frame and the encoded second frame are quasi-overlapped.

7 more elements

Dependencies are inferred from the claim text.

Uncontrolled spatial multiple access in wireless networks

Life of this patent

Uncontrolled spatial multiple access in wireless networks

Life of this patent

Abstract

Claims20