Methods and apparatus for signal transmission and reception in a broadband communication system
First Claim
1. A communication method for a mobile station operating in accordance with a time frame structure that includes a plurality of frames, each frame containing a plurality of subframes, each subframe containing a plurality of time slots, each time slot containing a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols, the method comprising:
- receiving from a base station information about availability of a random access channel;
transmitting a random access signal over the random access channel within an uplink frequency band, whereinthe random access signal contains a code sequence associated with a chip rate, the code sequence designated to the base station and the chip rate being a fraction of a system sampling rate; and
the random access signal has a time duration longer than multiple of the OFDM symbols;
receiving an acknowledgement to the random access signal from the base station, the acknowledgement carrying an identifier associated with the mobile station; and
transmitting an OFDM signal over a control channel at the system sampling rate and within the uplink frequency band.
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Accused Products
Abstract
In a broadband wireless communication system, a spread spectrum signal is intentionally overlapped with an OFDM signal, in a time domain, a frequency domain, or both. The OFDM signal, which inherently has a high spectral efficiency, is used for carrying broadband data or control information. The spread spectrum signal, which is designed to have a high spread gain for overcoming severe interference, is used for facilitating system functions such as initial random access, channel probing, or short messaging. Methods and techniques are devised to ensure that the mutual interference between the overlapped signals is minimized to have insignificant impact on either signal and that both signals are detectable with expected performance by a receiver.
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Citations
20 Claims
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1. A communication method for a mobile station operating in accordance with a time frame structure that includes a plurality of frames, each frame containing a plurality of subframes, each subframe containing a plurality of time slots, each time slot containing a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols, the method comprising:
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receiving from a base station information about availability of a random access channel; transmitting a random access signal over the random access channel within an uplink frequency band, wherein the random access signal contains a code sequence associated with a chip rate, the code sequence designated to the base station and the chip rate being a fraction of a system sampling rate; and the random access signal has a time duration longer than multiple of the OFDM symbols; receiving an acknowledgement to the random access signal from the base station, the acknowledgement carrying an identifier associated with the mobile station; and transmitting an OFDM signal over a control channel at the system sampling rate and within the uplink frequency band. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A mobile station operating in accordance with a time frame structure that includes a plurality of frames, each frame containing a plurality of subframes, each subframe containing a plurality of time slots, each time slot containing a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols, the mobile station comprising:
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a receiver configured to receive from a base station information about availability of a random access channel; a transmitter configured to transmit a random access signal over the random access channel within an uplink frequency band, wherein the random access signal contains a code sequence associated with a chip rate, the code sequence designated to the base station and the chip rate being a fraction of a system sampling rate; and the random access signal has a time duration longer than multiple of the OFDM symbols; a receiver configured to receive an acknowledgement to the random access signal from the base station, the acknowledgement carrying an identifier associated with the mobile station; and a transmitter configured to transmit an OFDM signal over a control channel at the system sampling rate and within the uplink frequency band. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification