Controlled superposition coding in multi-user communication systems
First Claim
1. A communications method for use in a communications system including a base station and a plurality of wireless terminals, a different communications channel existing between each wireless terminal in said plurality of wireless terminals and said base station, the communications channel existing between each particular wireless terminal and the base station having a quality which is the channel quality for the particular wireless terminal, the method comprising:
- operating the base station to;
i) maintain a set of channel condition information indicating the channel quality of each of said plurality of wireless terminals;
ii) examine the set of channel condition information to identify wireless terminals having channel conditions which differ from one another by at least a pre-selected minimum amount; and
iii) assign a communications channel segment to be used to communicate superimposed signals corresponding to at least two different wireless terminals identified as having channel conditions which differ by at least said pre-selected minimum amount.
3 Assignments
0 Petitions
Accused Products
Abstract
Methods of using superposition coding in a communications systems, e.g., a multi-user communications system. Superpostion coding in accordance with the invention occurs in the case of an uplink by transmissions of different wireless terminals transmitting using the same communications resource, e.g., simultaneously transmitting using the same frequencies. The signals combine in the communications channel resulting in one transmission being superimposed on the other transmission. The device, e.g., base station, receiving the superimposed signals uses superposition decoding techniques to recover both signals. To obtain the benefit of the superposition, assignments of channel segments to multiple wireless terminals is controlled by the base station and/or transmission power levels are controlled by on or more wireless terminals sharing the same uplink communications resource, e.g., time slot, to make sure that the received signals from the different devices will have different received power levels making superposition decoding possible.
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Citations
30 Claims
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1. A communications method for use in a communications system including a base station and a plurality of wireless terminals, a different communications channel existing between each wireless terminal in said plurality of wireless terminals and said base station, the communications channel existing between each particular wireless terminal and the base station having a quality which is the channel quality for the particular wireless terminal, the method comprising:
operating the base station to;
i) maintain a set of channel condition information indicating the channel quality of each of said plurality of wireless terminals;
ii) examine the set of channel condition information to identify wireless terminals having channel conditions which differ from one another by at least a pre-selected minimum amount; and
iii) assign a communications channel segment to be used to communicate superimposed signals corresponding to at least two different wireless terminals identified as having channel conditions which differ by at least said pre-selected minimum amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 19, 20, 21, 22)
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11. A base station for use in a communications system including a plurality of wireless terminals, a different communications channel existing between each wireless terminal in said plurality of wireless terminals and said base station, the communications channel existing between each particular wireless terminal and the base station having a quality which is the channel quality for the particular wireless terminal, the base station comprising:
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a set of channel condition information indicating the channel quality of each of said plurality of wireless terminals;
means for examining the set of channel condition information to identify wireless terminals having channel conditions which differ from one another by a pre-selected minimum amount; and
means for assigning a communications channel segment to be used to communicate superimposed signals corresponding to a least two different wireless terminals identified as having channel conditions which differ by at least said pre-selected minimum amount. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A communications method for use in a communications system including a base station and a plurality of wireless terminals, a different communications channel existing between each wireless terminal in said plurality of wireless terminals and said base station, the communications channel existing between each particular wireless terminal and the base station having a quality which is the channel quality for the particular wireless terminal, the method comprising:
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operating a first wireless terminal having a first channel quality to transmit a first portion of a superimposed communications signal to said base station; and
operating a second wireless terminal having a second channel quality to transmit a second portion of said superimposed communications signal to said base station, the first and second channel qualities being different by at least a first pre-selected amount, said first and second signal portions combining in the air during transmission to the base station to form said superimposed communications signal. - View Dependent Claims (18)
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23. A wireless terminal including:
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a receiver for receiving a superimposed assignment signal including a first signal portion and a second signal portion one of said signal portions being intended for said wireless terminals with the other one of said signal portions being intended for another wireless terminal, the first signal portion being received with at a lower power level than said second signal portion;
a superposition decoder for decoding said first and second signal portions;
means for determining from information included in one of said first and second signal portions which portion is intended for said wireless terminal; and
a transmitter for transmitting signals in uplink communications channel segments to which received superimposed assignment signals intended for said wireless terminal correspond. - View Dependent Claims (24, 25)
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26. A communications method for use in a communications system including a base station and a plurality of wireless terminals, a different communications channel existing between each wireless terminal in said plurality of wireless terminals and said base station, the communications channel existing between each particular wireless terminal and the base station having a quality which is the communications channel quality for the particular wireless terminal, signals transmitted from the wireless terminals to the base station combining during transmission between, the method comprising:
operating the base station to;
assign an uplink communications channel segment to be used simultaneously by a first and second device;
receive a composite signal from said uplink communications channel segment, said composite signal including a first signal transmitted by said first device and a second signal transmitted by said second device; and
perform a superposition decoding operation on the received composite signal to decode the first and second signals included in said composite signal. - View Dependent Claims (27, 28, 29, 30)
Specification