Transmitters, receivers and methods of transmitting and receiving

A method for transmitting Orthogonal Frequency Division Multiplexed (OFDM) symbols, wherein the OFDM symbols include a number of sub-carrier signals the number of sub carrier signals varying between at least some OFDM symbols some of the sub-carrier signals carrying data symbols and some of the sub-carrier signals carrying pilot symbols, the pilot symbols comprising scattered pilots symbols and continuous pilot symbols, the continuous pilot symbols being distributed across the sub-carrier signals in accordance with a continuous pilot symbol pattern and the scattered pilot symbols being distributed across the sub-carrier signals in accordance with a scattered pilot symbol pattern, the method comprising:

• generating pilot symbols, a number of the pilot symbols generated being different between at least some consecutive OFDM symbols;
• receiving a frequency domain data symbol stream and embedding the generated pilot symbols into the sub-carrier signals of the data symbol stream in accordance with the scattered pilot symbol pattern and the continuous pilot symbol pattern;
• generating, by circuitry, a time domain version of the symbol stream embedded with the pilot symbols, wherein the scattered pilot symbol pattern is one of a plurality of scattered pilot symbol patterns;
• and
• deriving the continuous pilot pattern from a stored master continuous pilot pattern based on the number of sub-carrier signals for an OFDM symbol, a number of the continuous pilot symbols embedded being different according to a magnitude of a bandwidth of the OFDM symbol.

A receiver configured to recover data from Orthogonal Frequency Division Multiplexed (OFDM) symbols, wherein the OFDM symbols include a number of sub-carrier signals the number of sub-carriers signals varying between at least some OFDM symbols, some of the sub-carrier signals carrying data symbols and some of the sub-carrier signals carrying pilot symbols, the pilot symbols comprising scattered pilots symbols and continuous pilot symbols, the continuous pilot symbols being distributed across the sub-carrier signals in accordance with a continuous pilot symbol pattern and the scattered pilot symbols being distributed across the sub-carrier signals in accordance with a scattered pilot symbol pattern, a number of pilots varying between at least some OFDM symbols the receiver comprising:

• a demodulator configured to detect a signal representing the OFDM symbols, and to generate a sampled digital version of the OFDM symbols in a time domain,
• a Fourier transform processor configured to receive the time domain digital version of the OFDM symbols and to form a frequency domain version of the OFDM symbols, from which the pilot symbol bearing sub-carriers and the data symbol bearing sub-carriers can be recovered, and
• a detector configured to recover the data symbols from the data bearing sub-carrier signals of the OFDM symbols and to recover the pilot symbols from the pilot bearing sub-carrier signals of the OFDM symbols in accordance with the scattered pilot symbol pattern and the continuous pilot symbol pattern,
• wherein the scattered pilot symbol pattern is one of a plurality of scattered pilot symbol patterns, and
• the detector comprises a memory configured to store a master continuous pilot pattern and a processor configured to detect a number of sub-carrier signals and to derive the continuous pilot pattern from the master continuous pilot pattern based on the number of sub-carrier signals for an OFDM symbol, a number of continuous pilots detected being a modified number according to a magnitude of a bandwidth of the OFDM symbol.

A method for receiving and recovering data from Orthogonal Frequency Division Multiplexed (OFDM) symbols, wherein the OFDM symbols include a number of sub-carrier signals, the number of sub-carrier signals varying between at least some OFDM symbols, some of the sub-carrier signals carrying data symbols and some of the sub-carrier signals carrying pilot symbols, the pilot symbols comprising scattered pilots symbols and continuous pilot symbols, the continuous pilot symbols being distributed across the sub-carrier signals in accordance with a continuous pilot symbol pattern and the scattered pilot symbols being distributed across the sub-carrier signals in accordance with a scattered pilot signal symbol pattern, a number of the pilot symbols being different between at least some consecutive OFDM symbols, the method comprising:

• detecting a signal representing the OFDM symbols;
• generating a sampled digital version of the OFDM symbols in a time domain;
• receiving the time domain digital version of the OFDM symbols and forming a frequency domain version of the OFDM symbols, from which the pilot symbol bearing sub-carrier signals and the data symbol bearing sub-carrier signals can be recovered;
• recovering the data symbols from the data bearing sub-carrier signals of the OFDM symbols;
• recovering, by circuitry, the pilot symbols from the pilot bearing sub-carrier signals of the OFDM symbols in accordance with the scattered pilot symbol pattern and the continuous pilot symbol pattern, wherein the scattered pilot symbol pattern is one of a plurality of scattered pilot symbol patterns and the continuous pilot pattern is independent of the scattered pilot symbol pattern;
• detecting a number of sub-carrier signals;
• and
• deriving the continuous pilot pattern from a stored master continuous pilot pattern based on the number of sub-carrier signals for an OFDM symbol, a number of the continuous pilot symbols detected being a modified number according to the magnitude of a bandwidth of the OFDM symbol.