Methods and apparatus of providing transmit diversity in a multiple access wireless communication system
First Claim
1. A communications method for use in a communications system including a first cell including a first base station and at least a first wireless terminal, the method comprising:
- operating the first base station to transmit signals on a plurality of different communications channels, each individual one of the plurality of different communications channels each having a physical characteristic which is detectable by said first wireless terminal, transmitting the signals on the plurality of different communications channels including periodically changing at least one signal transmission characteristic of a first communications channel in said plurality of communications channels to introduce an intentional variation into said first communications channel which results in a change in said physical characteristic corresponding to the first communications channel; and
selecting between said plurality of different communications channels for purposes of transmitting the signals to said first wireless terminal in response to feedback information received from said first wireless terminal indicating the one of the plurality of different communications channels which provides the best transmission channel conditions for transmissions to the first wireless terminal at a particular point in time,wherein said different communications channels consist of different portions of air link resource that is partitioned in at least one of time and frequency dimension.
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Accused Products
Abstract
Methods and apparatus for providing channel diversity to wireless terminals (WTs) in a manner that reduces the latency between the time a WT encounters satisfactory channel conditions are described. A plurality of communications channels with different physical characteristics are maintained in a cell by a base station (BS). Each WT monitors multiple channels and maintains multiple channel estimates at the same time so that rapid switching between channels is possible. Channel quality information is conveyed from each WT to the BS. The WT or BS selects a channel based on the measured channel quality. By supporting multiple channels and by introducing periodic variations into the channels in various embodiments, the time before a WT encounters a channel with good or acceptable channel conditions is minimized even if the WT does not change location. Multiple antennas are used at the BS to support numerous channels simultaneously, e.g., by controlling antenna patterns.
59 Citations
61 Claims
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1. A communications method for use in a communications system including a first cell including a first base station and at least a first wireless terminal, the method comprising:
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operating the first base station to transmit signals on a plurality of different communications channels, each individual one of the plurality of different communications channels each having a physical characteristic which is detectable by said first wireless terminal, transmitting the signals on the plurality of different communications channels including periodically changing at least one signal transmission characteristic of a first communications channel in said plurality of communications channels to introduce an intentional variation into said first communications channel which results in a change in said physical characteristic corresponding to the first communications channel; and selecting between said plurality of different communications channels for purposes of transmitting the signals to said first wireless terminal in response to feedback information received from said first wireless terminal indicating the one of the plurality of different communications channels which provides the best transmission channel conditions for transmissions to the first wireless terminal at a particular point in time, wherein said different communications channels consist of different portions of air link resource that is partitioned in at least one of time and frequency dimension. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A communications method for use in a communications system including a first cell including a first base station and at least a first wireless terminal, the method comprising:
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operating the first base station to transmit signals on a plurality of different communications channels, each individual one of the plurality of different communications channels each having a physical characteristic which is detectable by said first wireless terminal, transmitting the signals on the plurality of different communications channels including periodically changing at least one signal transmission characteristic of a first communications channel in said plurality of communications channels to introduce an intentional variation into said first communications channel which results in a change in said physical characteristic corresponding to the first communications channel; and selecting between said plurality of different communications channels for purposes of transmitting the signals to said first wireless terminal in response to feedback information received from said first wireless terminal indicating the one of the plurality of different communications channels which provides the best transmission channel conditions for transmissions to the first wireless terminal at a particular point in time, wherein said physical characteristic of one of said different communications channels is different from said physical characteristic of another one of said different communications channels.
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24. A communications method for use in a communications system including a first cell including a first base station and at least a first wireless terminal, the method comprising:
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operating the first base station to transmit signals on a plurality of different communications channels, each individual one of the plurality of different communications channels each having a physical characteristic which is detectable by said first wireless terminal, transmitting the signals on the plurality of different communications channels including periodically changing at least one signal transmission characteristic of a first communications channel in said plurality of communications channels to introduce an intentional variation into said first communications channel which results in a change in said physical characteristic corresponding to the first communications channel; and selecting between said plurality of different communications channels for purposes of transmitting the signals to said first wireless terminal in response to feedback information received from said first wireless terminal indicating the one of the plurality of different communications channels which provides the best transmission channel conditions for transmissions to the first wireless terminal at a particular point in time, wherein said step of periodically changing at least one signal transmission characteristic to introduce an intentional variation includes; introducing at least one of a periodic phase and periodic amplitude variation into said at least one of the different communications channels, the periodicity of the at least one variation being longer than the periodicity between the channel condition feedback information received from said first wireless terminal.
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25. A communications method for use in a communications system including a first cell including a first base station and at least a first wireless terminal, the method comprising:
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operating the first base station to transmit signals on a plurality of different communications channels, each individual one of the plurality of different communications channels each having a physical characteristic which is detectable by said first wireless terminal, transmitting the signals on the plurality of different communications channels including periodically changing at least one signal transmission characteristic of a first communications channel in said plurality of communications channels to introduce an intentional variation into said first communications channel which results in a change in said physical characteristic corresponding to the first communications channel; selecting between said plurality of different communications channels for purposes of transmitting the signals to said first wireless terminal in response to feedback information received from said first wireless terminal indicating the one of the plurality of different communications channels which provides the best transmission channel conditions for transmissions to the first wireless terminal at a particular point in time; and repeating said selecting step, wherein repeating said selecting step includes switching from a previously selected one of said plurality of different communications channels to another one of said plurality of different communications channels which has a better channel quality to said wireless terminal than said previously selected one of said plurality of different communications channels.
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26. A communications method for use in a communications system including a first cell including a first base station and at least a first wireless terminal, the method comprising:
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operating the first base station to transmit signals on a plurality of different communications channels, each individual one of the plurality of different communications channels each having a physical characteristic which is detectable by said first wireless terminal, transmitting the signals on the plurality of different communications channels including periodically changing at least one signal transmission characteristic of a first communications channel in said plurality of communications channels to introduce an intentional variation into said first communications channel which results in a change in said physical characteristic corresponding to the first communications channel; and selecting between said plurality of different communications channels for purposes of transmitting the signals to said first wireless terminal in response to feedback information received from said first wireless terminal indicating the one of the plurality of different communications channels which provides the best transmission channel conditions for transmissions to the first wireless terminal at a particular point in time, wherein said selecting between said plurality of different communications channels includes switching, and said switching occurs multiple times during an internet protocol communications session being conducted by said first wireless terminal with another terminal through said first base station without the internet protocol communications session being terminated and without the first wireless terminal changing its location within the first cell.
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27. A communications method for use in a communications system including a first cell including a first base station and at least a first wireless terminal, the method comprising:
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operating the first base station to transmit signals on a plurality of different communications channels, each individual one of the plurality of different communications channels each having a physical characteristic which is detectable by said first wireless terminal, transmitting the signals on the plurality of different communications channels including periodically changing at least one signal transmission characteristic of a first communications channel in said plurality of communications channels to introduce an intentional variation into said first communications channel which results in a change in said physical characteristic corresponding to the first communications channel; and selecting between said plurality of different communications channels for purposes of transmitting the signals to said first wireless terminal in response to feedback information received from said first wireless terminal indicating the one of the plurality of different communications channels which provides the best transmission channel conditions for transmissions to the first wireless terminal at a particular point in time, wherein said selecting between said plurality of different communications channels includes switching, and said switching is performed multiple times while said first wireless terminal remains at a fixed location within said first cell; and wherein the same carrier frequency is used to transmit the signals on said plurality of different communications channels, said transmitting signals including mixing baseband signals to passband signals having said carrier frequency prior to transmitting said signals on said plurality of different communications channels.
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28. A base station comprising:
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means for transmitting signals on a plurality of different communications channels, each individual one of the plurality of different communications channels each having a physical characteristic which is detectable by a first wireless terminal; means for periodically changing at least one signal transmission characteristic of a first communications channel in said plurality of communications channels to introduce an intentional variation into said first communications channel which results in a change in said physical characteristic corresponding to the first communications channel; means for selecting between said plurality of different communications channels for purposes of transmitting the signals to said first wireless terminal in response to feedback information received from said first wireless terminal indicating the one of the plurality of different communications channels which provides the best transmission channel conditions for transmissions to the first wireless terminal at a particular point in time; and means for scheduling information transmission to a plurality of wireless terminals on each of the plurality of different communications channels, said scheduling including assigning information transmission times to different wireless terminals which are to use the same one of the different communications channels. - View Dependent Claims (29)
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30. A communications method for use in a communications system including a first cell including a first base station and at least a first wireless terminal, the method comprising:
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operating the first base station to transmit signals on a plurality of different communications channels, wherein said plurality of different communications channels includes at least 3 different communications channels, said three different communications channels including a first communications channel, a second communications channel and a third communications channel, each individual one of the plurality of different communications channels each having a physical characteristic which is detectable by said first wireless terminal; selecting between said plurality of different communications channels for purposes of transmitting the signals to said first wireless terminal in response to feedback information received from said first wireless terminal indicating the one of the plurality of different communications channels which provides the best transmission channel conditions for transmissions to the first wireless terminal at a particular point in time; and changing at least one signal characteristic of each of said second and third communications channels on a periodic basis, wherein changing at least one signal characteristic of each of said second and third communications channels includes changing at least one transmission parameter used to control an antenna pattern, wherein transmitting signals on each of the plurality of different communications channels includes transmitting different information signals on each of the first, second and third communications channels to different wireless terminals, the different information signals being transmitted at the same time using different signal tones but the same carrier frequency.
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31. A method of operating a wireless terminal in a communications system in which a base station transmits information using a plurality of communications channels, each communications channel having at least one different physical characteristic, the at least one different physical characteristic of one of the communications channels being intentionally varied by said base station over time, the method of operating the wireless terminal comprising:
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making a channel quality measurements of each of said communications channels; maintaining channel quality estimates for at least two of said communications channels at the same time; communicating channel quality feedback information to said base station indicative of which one of said plurality of different communications channels has the best quality for use in transmitting signals to said wireless terminal; and operating the wireless terminal to select which one of said plurality of communications channels should be used to transmit information to said wireless terminal as a function of the channel quality measurements, wherein said channel quality feedback information includes a channel identifier identifying the selected communications channel, wherein maintaining channel quality estimates for at least two of said communications channels at the same time includes; maintaining a first channel quality estimate for a first communications channel on which said wireless terminal reports to have good channel quality in said channel quality feedback information; and maintaining a second channel quality estimate for a second communications channel said wireless terminal does not report to have good channel quality in said channel quality feedback information.
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32. A method of operating a wireless terminal in a communications system in which a base station transmits information using a plurality of communications channels, each communications channel having at least one different physical characteristic, the at least one different physical characteristic of one of the communications channels being intentionally varied by said base station over time, the method of operating the wireless terminal comprising:
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making a channel quality measurements of each of said communications channels; maintaining channel quality estimates for at least two of said communications channels at the same time; communicating channel quality feedback information to said base station indicative of which one of said plurality of different communications channels has the best quality for use in transmitting signals to said wireless terminal, wherein maintaining channel quality estimates for at least two of said communications channels at the same time includes; maintaining a first channel estimate for a first communications channel; maintaining a second channel estimate for a second communications channel which is different from said first communications channel, the method further comprising; switching between using the first and second channel estimates in response to the first base station switching between said first and second channels in response to feedback information indicating a change in said first and second channels, said change corresponding to a variation intentionally introduced into said first and second channels by said base station. - View Dependent Claims (33)
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34. A wireless terminal for use in a communications system in which a base station transmits information using a plurality of communications channels, each communications channel having at least one different physical characteristic, the at least one different physical characteristic of one of the communications channels being intentionally varied by said base station over time, the wireless terminal comprising:
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means for making a channel quality measurements of each of said communications channels; memory including channel quality estimates for at least two of said communications channels at the same time; means for communicating channel quality feedback information to said base station indicative of which one of said plurality of different communications channels has the best quality for use in transmitting signals to said wireless terminal; and means for selecting which one of said plurality of communications channels should be used to transmit information to said wireless terminal as a function of the channel quality measurements; and wherein said channel quality feedback information communicated by said means for communicating includes a channel identifier identifying the selected communications channel. - View Dependent Claims (35)
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36. A transmission method for use in a device including multiple antennas, comprising:
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processing a first signal as a function of at least one coefficient in a first transmission control coefficient set corresponding to a first channel to produce a first processed signal having a first physical signal characteristic; transmitting the first processed signal from at least one of said multiple antennas; transmitting at least one other signal corresponding to the first signal, in parallel with the transmission of said first processed signal, from another one of said multiple antennas; processing a second signal as a function of at least one coefficient in a second transmission control coefficient set corresponding to a second channel to produce a second processed signal, said second processed signal having a second physical signal characteristic introduced by said processing which is different from said first physical signal characteristic; transmitting the second processed signal from at least one of said multiple antennas; transmitting at least one other signal corresponding to the second signal, in parallel with the transmission of said second processed signal, from another one of said multiple antennas; receiving channel condition feedback information from a wireless terminal at a first rate; and scheduling transmission of signals to said first wireless terminal as a function of said channel condition feedback information. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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48. A transmission method for use with a base station including a plurality of antennas which are used to transmit signals to multiple wireless terminals, the method comprising:
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maintaining a plurality of channels between said base station and at least one of said wireless terminals, said channels having different transmission characteristics; maintaining for each channel a transmission control coefficient set including at least one transmission control coefficient used to control at least one of said different transmission characteristics; receiving channel condition feedback information from at least one wireless terminals at a first rate; changing, at a second rate, the content of each set of transmission control coefficients over time to induce transmission variations into the signals transmitted using each of the maintained channels, and scheduling transmissions to individual wireless terminals using said channels as a function of received channel condition information. - View Dependent Claims (49, 50, 51, 52, 53, 54, 55)
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56. A base station comprising:
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multiple antennas; means for processing a first signal as a function of at least one coefficient in a first transmission control coefficient set corresponding to a first channel to produce a first processed signal having a first signal characteristic; means for transmitting the first processed signal using at least one of said multiple antennas; means for transmitting at least one other signal corresponding to the first signal, in parallel with the transmission of said first processed signal, from another one of said multiple antennas; means for processing a second signal as a function of at least one coefficient in a second transmission control coefficient set corresponding to a second channel to produce a second processed signal, said second processed signal having a signal characteristic introduced by said processing which is different from said first signal characteristic; means for transmitting the second processed signal from at least one of said multiple antennas; means for transmitting at least one other signal corresponding to the second signal, in parallel with the transmission of said first processed signal, from another one of said multiple antennas; a receiver for receiving channel condition feedback information from a wireless terminal at a first rate; transmission control means for modifying at least one coefficient in said first transmission control coefficient set, by an amount sufficient to induce a change in said feedback information, at a rate which is less than or equal to said first rate; and a scheduler for scheduling transmission of signals to wireless terminals as a function of said channel condition feedback information.
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57. A base station comprising:
a processor configured to control said base station to implement a method, the method comprising; transmitting signals on a plurality of different communications channels, each individual one of the plurality of different communications channels each having a physical characteristic which is detectable by a wireless terminal; periodically changing at least one signal transmission characteristic of a first communications channel in said plurality of communications channels to introduce an intentional variation into said first communications channel which results in a change in said physical characteristic corresponding to the first communications channel; and selecting between said plurality of different communications channels for purposes of transmitting the signals to said wireless terminal in response to feedback information received from said first wireless terminal indicating the one of the plurality of different communications channels which provides the best transmission channel conditions for transmissions to the wireless terminal at a particular point in time. - View Dependent Claims (58)
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59. A computer readable medium embodying machine executable instructions for controlling a base station to implement a method, the method comprising:
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transmitting signals on a plurality of different communications channels, each individual one of the plurality of different communications channels each having a physical characteristic which is detectable by a wireless terminal; periodically changing at least one signal transmission characteristic of a first communications channel in said plurality of communications channels to introduce an intentional variation into said first communications channel which results in a change in said physical characteristic corresponding to the first communications channel; and selecting between said plurality of different communications channels for purposes of transmitting the signals to said wireless terminal in response to feedback information received from said wireless terminal indicating the one of the plurality of different communications channels which provides the best transmission channel conditions for transmissions to the wireless terminal at a particular point in time. - View Dependent Claims (60)
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61. A base station comprising:
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a transmitter module for transmitting signals on a plurality of different communications channels, each individual one of the plurality of different communications channels each having a physical characteristic which is detectable by a wireless terminal; a control module for periodically change at least one signal transmission characteristic of a first communications channel in said plurality of communications channels to introduce an intentional variation into said first communications channel which results in a change in said physical characteristic corresponding to the first communications channel; and a selection module for selecting between said plurality of different communications channels for purposes of transmitting the signals to said wireless terminal in response to feedback information received from said wireless terminal indicating the one of the plurality of different communications channels which provides the best transmission channel conditions for transmissions to the wireless terminal at a particular point in time; and a scheduling module for scheduling information transmission to a plurality of wireless terminals on each of the plurality of different communications channels, said scheduling including assigning information transmission times to different wireless terminals which are to use the same one of the different communications channels, wherein said control module for periodically changing at least one signal transmission characteristic, includes a coefficient generator for generating sets of control coefficients used to control transmission characteristics of different communications channels in said plurality of communications channels, said control coefficients controlling the processing of signals to be transmitted on the different communications channels.
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Specification