OFDM communication system and method
AssigneeNtt Docomo, Inc.
InventorsNoriyuki Maeda, Hiroyuki Atarashi, Mamoru Sawahashi
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Abstract
A transmitter used in a wireless communication system based on an orthogonal frequency division multiplexing (OFDM) scheme includes a determination unit that determines a spreading factor and an amplitude for a control channel based on at least one of signal quality information and interference information in data transmission. The transmitter also includes a multiplexing unit that multiplexes a data channel with the control channel having been code-spread based on the spreading factor and the amplitude. A modulator then modulates the multiplexed signal in the OFDM scheme for transmission as OFDM symbols.
Claims9
A wireless communication system employing an orthogonal frequency division multiplexing (OFDM) scheme, including a transmitter and a receiver, wherein the transmitter comprises:
- a determination unit configured to determine a spreading factor and an amplitude for a control channel based on at least one of signal quality information and interference information in data transmission;
- a multiplexing unit configured to multiplex a data channel with the control channel having been code-spread based on the spreading factor and the amplitude;
- and
- means for modulating the multiplexed signal in the OFDM scheme and transmitting the modulated signal as OFDM symbols;
- and wherein the receiver includes
- means for demodulating the OFDM symbols and despreading the demodulated symbols to extract the control channel.
A transmitter used in a wireless communication system based on an orthogonal frequency division multiplexing (OFDM) scheme, comprising:
- a determination unit configured to determine a spreading factor and an amplitude for a control channel based on at least one of signal quality information and interference information in data transmission;
- a multiplexing unit configured to multiplex a data channel with the control channel having been code-spread based on the spreading factor and the amplitude;
- and
- means for modulating the multiplexed signal in the OFDM scheme and transmitting the modulated signal as OFDM symbols.
A receiver used in a wireless communication system based on an orthogonal frequency division multiplexing (OFDM) scheme, comprising:
- a detection unit configured to detect a spreading factor and a channel type of a code-spread control channel from a received signal, the received signal being a data channel and the control channel multiplexed together;
- and
- control channel recovery means for recovering the control channel from the received signal based on the spreading factor and the channel type.
A wireless communication method based on an orthogonal frequency division multiplexing (OFDM) scheme comprising the steps of:
- determining a spreading factor and an amplitude for a control channel to be transmitted based on signal quality information and interference level in data transmission;
- multiplexing a data channel with a control channel having been code-spread using the determined spreading factor and amplitude;
- modulating the multiplexed signal in the OFDM scheme;
- transmitting the modulated signal;
- demodulating the transmitted signal in the OFDM scheme at a receiver;
- and
- despreading the demodulated signal to extract the control channel.
Dependencies are inferred from the claim text.