Apparatus and method for transmitting and receiving a RACH signal in SC-FDMA system
View Patent ↗Embodiments of the present invention may provide an apparatus and a method for transmitting and receiving a random access channel (RACH) in a single carrier-frequency division multiple access (SC-FDMA) system. A frequency domain RACH signal may be mapped to a localized sub-frequency band of an entire frequency band available to the SC-FDMA system. A guard band including at least one sub carrier may be allocated between the RACH signal band and other channel signal bands. A guard time may be allocated between the RACH signal and other channel signals in the time domain. The RACH signal may include a short message including information related to a mobile station. The RACH signal may be detected in a frequency based method, a time based method or a sliding matched filter based method. Receiver complexity can be decreased if the RACH signal includes a CAZAC code sequence for a preamble. In such a case, a receive delay may be simply calculated and then adjusted more accurately.
1. An apparatus for transmitting a random access channel (RACH) signal to a base station in a single carrier-frequency division multiple access (SC-FDMA) system, comprising:
a code generator to generate a code sequence for at least one preamble of the RACH signal;
a first converting unit to convert the code sequence into a frequency domain code sequence;
a mapping unit to map the frequency domain code sequence of the RACH signal to a portion of sub carriers, which are continuous and locally located in an entire frequency band available to the SC-FDMA system, and to allocate a guard band including at least one sub carrier between the frequency domain code sequence and other channel signal bands;
a second converting unit to convert the sub carriers to a time domain sequence to be transmitted;
a cyclic prefix (CP) inserting unit to insert a CP within the time domain sequence; and
a transmitting unit to transmit the time domain sequence.
2. The apparatus of claim 1 , wherein the code sequence includes a Constant Amplitude Zero Autocorrelation waveform (CAZAC) sequence.
3. An apparatus for receiving a random access channel (RACH) signal including at least one preamble from a mobile station in a single carrier-frequency division multiple access (SC-FDMA) system, comprising:
a receiver to receive a signal from the mobile station;
an extracting unit to extract an RACH signal from the received signal;
a converting unit to convert the extracted RACH signal into a frequency domain sequence;
a de-mapping unit to extract sub carriers mapped to the RACH signal from the frequency domain sequence, the extracted sub carriers including the at least one preamble having a code sequence and being a portion of sub carriers, which are continuous and locally located in an entire frequency band available to the SC-FDMA system.
4. The apparatus of claim 3 , wherein the code sequence includes a Constant Amplitude Zero Autocorrelation waveform (CAZAC) sequence.
5. A method of transmitting a random access channel (RACH) signal to a base station in a single carrier-frequency division multiple access (SC-FDMA) system, the method comprising:
generating a code sequence for at least one preamble of a RACH signal;
converting the code sequence into a frequency domain code sequence;
mapping the frequency domain code sequence of the RACH signal to a portion of sub carriers available to the SC-FDMA system;
allocating a guard band between the frequency domain code sequence and other channel signal bands;
converting the sub carriers to a time domain sequence to be transmitted;
inserting a cyclic prefix (CP) within the time domain sequence; and
transmitting the time domain sequence.
6. The method of claim 5 , wherein the code sequence includes a Constant Amplitude Zero Autocorrelation waveform (CAZAC) sequence.
7. A method of receiving a random access channel (RACH) signal including at least one preamble from a mobile station in a single carrier-frequency division multiple access (SC-FDMA) system, comprising:
receiving a signal from the mobile station;
extracting an RACH signal from the received signal;
converting the extracted RACH signal into a frequency domain sequence; and
extracting sub carriers mapped to the RACH signal from the frequency domain sequence, the extracted sub carriers including at least one preamble having a code sequence and being a portion of sub carriers, which are continuous and locally located in an entire frequency band available to the SC-FDMA system.
8. The method of claim 7 , wherein the code sequence includes a Constant Amplitude Zero Autocorrelation waveform (CAZAC) sequence.