Transmitter and method of transmitting and receiver and method of detecting OFDM signals

Abstract

A transmitter transmits payload data using Orthogonal Frequency Division Multiplexed (OFDM) symbols. The first OFDM symbol is a first type having a number of sub-carriers which is less than or equal to the number of sub-carriers of the one or more second OFDM symbols of a second type and a guard interval for the first OFDM symbol is selected in dependence upon the longest possible guard interval of the second OFDM symbol. Accordingly an OFDM communications system can be formed in which data is transmitted using a frame structure in which a guard interval is adapted to allow a mix of different types of OFDM symbols.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application claims priority to United Kingdom Application Number 1305799.7, filed 28 Mar. 2013, and European Patent Office Application Number 13170706.9 filed 5 Jun. 2013, the contents of which are incorporated herein by reference in their entirety.FIELD OF THE DISCLOSURE[0002]The present disclosure relates to transmitters and methods of transmitting payload data using Orthogonal Frequency Division Multiplexed (OFDM) symbols.BACKGROUND OF THE DISCLOSURE[0003]There are many examples of radio communication systems in which data is communicated using Orthogonal Frequency Division Multiplexing (OFDM). Systems which have been arranged to operate in accordance with Digital Video Broadcasting (DVB) standards for example, use OFDM. OFDM can be generally described as providing K narrow band sub-carriers (where K is an integer) which are modulated in parallel, each sub-carrier communicating a modulated data symbol such as Quadrature Amp...

AI Technical Summary

Benefits of technology

[0005]According to an aspect of the present disclosure there is provided a transmitter transmits payload data using Orthogonal Frequency Division Multiplexed (OFDM) symbols. The transmitter comprises a frame builder configured to receive the payload data to be transmitted and to receive signalling data for use in detecting and recovering the payload data at a receiver, and to form the payload data with the signalling data into frames for transmission. A modulator is configured to modulate a first OFDM symbol with the signalling data forming a part of each of the frames and to modulate one or more second OFDM symbols with the payload data to form one or more of the frames, and a transmission unit for transmitting the first and second OFDM symbols. The first OFDM symbol is a first type having a number of sub-carriers which is less than or equal to the number of sub-carriers of the one or more second OFDM symbols of a second type and a guard interval for ...

Problems solved by technology

However, there can also be a reduction in robustness in the sense that it may be more difficult for a receiver to recover data transmitted using a high number of sub-carriers compared to a smaller number of sub-carriers, because for a fixed transmission bandwidth, i...

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