Efficient frequency division duplex communication system with interleaved format and timing adjustment control
First Claim
1. A method of duplex communication, comprising the steps oftransmitting, over a first frequency band of a plurality of frequency bands, a control pulse preamble from a user station to a base station,receiving, during a first preamble interval, said control pulse preamble at said base station,transmitting, over a second frequency band of said plurality of frequency bands and during a base message interval following said first preamble interval, a base-to-user message from said base station to said user station,receiving said base-to-user message at said user station,transmitting, over said first frequency band, a user-to-base message from said user station to said base station, andreceiving, during a user message interval following said base message interval, said user-to-base message at said base station.
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Accused Products
Abstract
A system for efficient time division duplex communication between a base station and a plurality of user stations over multiple frequency bands whereby guard time overhead is reduced through use of an interleaved frame structure and active adjustment of reverse link transmission timing as a function of round trip propagation time. A time frame is divided into a plurality of time slots. A user station transmits a preamble over a user frequency band. The base station receives the preamble and transmits, in a given time slot, a forward link message over a base frequency band to a user station. The user station responds with a reverse link message over the user frequency band in a subsequent time slot. While the base station is transmitting to a first user station over the base frequency band, it receives messages from another user station over the user frequency band, using the time slot differential between forward and reverse link messages for round trip propagation. The base station may, based on a measured propagation delay, command the user station to adjust its reverse link transmission timing so as to allow for reduced guard times. The base station may also instruct the user station to adjust its power, or may perform antenna selection in a multi-antenna system, in response to receiving the preamble from the first user station. Base and user time slots may be offset to increase the amount of available propagation delay time for round trip messaging, and avoid simultaneous transmission and reception by a user station.
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Citations
54 Claims
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1. A method of duplex communication, comprising the steps of
transmitting, over a first frequency band of a plurality of frequency bands, a control pulse preamble from a user station to a base station, receiving, during a first preamble interval, said control pulse preamble at said base station, transmitting, over a second frequency band of said plurality of frequency bands and during a base message interval following said first preamble interval, a base-to-user message from said base station to said user station, receiving said base-to-user message at said user station, transmitting, over said first frequency band, a user-to-base message from said user station to said base station, and receiving, during a user message interval following said base message interval, said user-to-base message at said base station.
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10. A method of multiple access, wireless communication, comprising the steps of
transmitting, during a first time slot and over a base transmission frequency band, a first base-to-user message from a base station to a first user station, receiving said first base-to-user message at said first user station, transmitting, over a user transmission frequency band, a control pulse preamble from a second user station to said base station, receiving, during said first time slot, said control pulse preamble at said base station, measuring at said base station a received signal strength indication for said control pulse preamble, transmitting, during a second time slot and over said base transmission frequency band, a second base-to-user message from said base station to said second user station, said second base-to-user message comprising a power adjustment command directed to said second user station, receiving said second base-to-user message at said second user station, transmitting, over said user transmission frequency band, a user-to-base message from said first user station to said base station, and receiving, during said second time slot, said user-to-base message at said base station.
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21. A frame structure for multiple access, wireless communication, comprising
a plurality of time frames, and a plurality of time slots in each of said time frames, each of said time slots comprising a base interval, during which either a base-to-user message may be transmitted over a first frequency band by a base station to a first user station in established communication with said base station during said time slot, or a general polling message may be transmitted over said first frequency band, said general polling message indicating the availability of said time slot, a user interval, during which either a user-to-base message may be received over a second frequency band at said base station from a second user station in established communication with said base station, or a reply message may be received over said second frequency band at said base station from a third user station seeking to establish communication with said base station, and a preamble interval following said user interval, during which a control pulse preamble may be received over said second frequency band from a fourth user station in established communication with said base station, whereby said base station may after receiving said control pulse preamble respond to said fourth user station in a following time slot.
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28. An interleaved air interface frame structure for carrying out time division multiplexed communication, comprising
a plurality of time frames during each of which a base station may transmit over a first designated frequency band of a plurality of frequency bands and user stations may transmit over a second designated frequency band of said plurality of frequency bands, and a plurality of time slots in each of said time frames, said time slots having a base station portion corresponding to said first designated frequency band and a user station portion corresponding to said second designated frequency band, wherein said base station portion comprises a base message interval, during which said base station transmits a first base-to-user message to a first user station in response to having received a first control pulse preamble from said first user station over said first designated frequency band in an immediately preceding time slot, and a base preamble interval, during which said base station transmits at least one preamble burst directed to a second user station in established communication with said base station, whereby said second user station responds to said at least one preamble burst in a following time slot, and wherein said user station portion comprises a user message interval, during which a third user station transmits a user-to-base message over said first designated frequency band in response to having received a second base-to-user message over said second designated frequency band in an immediately preceding time slot, and a control pulse preamble interval, during which a fourth user station transmits a control pulse preamble to said base station over said first designated frequency band, whereby said base station responds to said control pulse preamble in said following time slot.
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33. An interleaved frequency division duplex frame structure for multiple access, wireless communication, comprising
a plurality of time frames, and a plurality of time slots in each of said time frames, said time slots each comprising a base station portion and a user station portion, wherein a duplex pairing consists of a first base station portion in a first time slot and a first user station portion in a second time slot subsequent to said first time slot, whereby a base station transmits over a first designated frequency band a base-to-user message during said first base station portion, and said base station receives over a second designated frequency band a user-to-base message from a user station during said first user station portion, and wherein for each time slot said user station portion is offset by a predetermined amount of time from said base station portion so that said user station portion and said base station portion partially overlap.
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43. A frame structure for wireless communication, comprising
a plurality of time frames, and a plurality of time slots for each time frame, each time slot comprising a base transmission interval during which a base station may transmit over a first designated frequency band a base-to-user message to a first one of a plurality of user stations in established communication with said base station, and a user transmission interval during which said base station may receive a user-to-base message over a second designated frequency band from a second one of said user stations, wherein the start of said user transmission interval in each time slot is offset by a predetermined amount of time relative to the start of said base transmission interval, and wherein a portion of said user transmission interval overlaps a portion of said base station interval.
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48. A method of wireless communication, comprising the steps of
transmitting, during a first time interval and over a base transmission frequency band, a first base-to-user message from a base station to a first user station, receiving said first base-to-user message at said first user station, transmitting, over a user transmission frequency band distinct from said base transmission frequency band, a control pulse preamble from a second user station which is already in established communication with said base station to said base station, receiving, during a second time interval, said control pulse preamble at said base station, transmitting, during a third time interval following said second time interval and over said base transmission frequency band, a second base-to-user message from said base station to said second user station, receiving said second base-to-user message at said second user station, transmitting, over said user transmission frequency band, a user-to-base message from said first user station to said base station, and receiving, during a fourth time interval substantially overlapping with said third time interval, said user-to-base message at said base station.
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54. A method of wireless duplex communication, comprising the steps of
transmitting, over a first frequency band of a plurality of frequency bands, a control pulse from a user station to a base station in established communication with said user station, receiving at said user station, over a second frequency band of said plurality of frequency bands, a base-to-user message from said base station, said base-to-user message being transmitted by said base station in response to receiving said control pulse, and transmitting, over said first frequency band and after receiving said base-to-user message, a user-to-base message from said user station to said base station.
Specification