Apparatus and method for coded orthogonal frequency- division multiplexing

An orthogonal component and encoding technology, applied in the direction of multi-frequency code system, payload distribution, forward error control, etc., can solve the problem of low encoding rate and achieve the effect of improving SNR

Active Publication Date: 2010-05-05
BRITISH BROADCASTING CORP
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  • Abstract
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Problems solved by technology

However, it has been realized that, because of high coding rates, the acceptable proportion of erasure information due to channel selectivity is lower than conventionally used FECs (which, because of their relatively weak work with lower encoding rates)

Method used

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  • Apparatus and method for coded orthogonal frequency- division multiplexing
  • Apparatus and method for coded orthogonal frequency- division multiplexing
  • Apparatus and method for coded orthogonal frequency- division multiplexing

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Embodiment Construction

[0020] Now, preferred embodiments of the present invention will be described by way of example. figure 1 is a diagram of a COFDM transmitter 2 according to the invention. First, the multiplexer 4 receives data streams from a number of different data sources and combines these data streams into a single data stream for transmission. Next, the data stream output from the multiplexer is passed to a scrambler 6, which transforms the input data stream into a pseudo-random form, for example using a pseudo-random number generator or a transformation function. This is used to obtain a more uniform energy distribution on the energy spectrum, because the spectrum of the signal no longer depends only on the data, and long 0s or long 1s appearing in the data are broken up.

[0021] The data is then passed to a Forward Error Correction Coding (FEC) unit 8 where redundant data bits are added to the data so that the transmitted form of the data is more robust against errors and nulls. Subs...

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Abstract

A COFDM transmission scheme is provided that offers improved resilience to noise or deleterious effects in the transmission path. The scheme transmits two copies of the data on different symbols or carriers, if one version of the data is lost, the receiver can attempt demodulation of the surviving version. Furthermore, by using a different PAM mapping to encode each copy of the data, signal to noise performance and data rates are equivalent to conventional Quadrature Amplitude Modulation schemes, but with an improvement in SNR when transmission conditions are poor.

Description

technical field [0001] The invention relates to a method and a device for coding orthogonal frequency division multiplexing. Background technique [0002] Coded Orthogonal Frequency Division Multiplexing (COFDM) is used as the core of various broadcasting standards. In broadcasting, although one common version of the signal is usually transmitted, environmental effects on the transmission path mean that each receiver will receive a signal that has essentially been transmitted over a different channel. It is thus important that the broadcast system is able to handle a wide range of possible channels and that each receiver is individually able to compensate for the effects of the particular channel it receives. An important advantage of broadcasting is the way in which COFDM can overcome frequency or time selective channels, which exhibit characteristics that vary with time or frequency and affect the quality of transmission channel. [0003] One aspect of COFDM is the use ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26H04L27/34H04L1/00
CPCH04L1/0071H04L1/08H04L27/2602H04L27/34H04L5/0044H04L27/02H04L27/2647H04L27/3405H04L27/2626
Inventor J·H·斯托特
Owner BRITISH BROADCASTING CORP
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