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OFDM communication apparatus and OFDM communication method

A communication device and a technology for multiplexing signals, which are applied in multiplexing communication, orthogonal multiplexing systems, code division multiplexing systems, etc. rate characteristics, demodulation signal error rate characteristics deterioration, etc.

Inactive Publication Date: 2003-02-12
III HLDG 12 LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in this case, the error rate characteristic of the demodulated signal in the receiver device deteriorates
[0012] As described above, in the existing OFDM method using multicast, multiple receiving devices that have received errors in the received signal in units of bursts transmit a burst in units of signals including a retransmission request signal in the same frame. Therefore, there is a problem that it is difficult to improve the transmission efficiency of information signals and improve the error rate characteristics of demodulated signals

Method used

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  • OFDM communication apparatus and OFDM communication method
  • OFDM communication apparatus and OFDM communication method
  • OFDM communication apparatus and OFDM communication method

Examples

Experimental program
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Embodiment 1

[0049] In this embodiment, retransmission control in the OFDM scheme will be described. First, the outline of this embodiment will be described. The source device transmits a specific signal in burst units (hereinafter referred to as 'multicast burst') to a plurality of receiver devices. Specifically, the source device sequentially transmits group-specific multicast bursts to a set of receiver devices (hereinafter referred to as "group") that receive the same multicast burst. That is, for example, the source device transmits multicast burst 1 to group 1 (receiver device 1 to receiver device 10) at time t1, and transmits burst 1 to group 2 (receiver device 11 to receiver device 20) at time t2. Burst 2 for multicast.

[0050] When an error occurs in the demodulated signal of a multicast burst, all receiver devices simultaneously transmit a burst-unit signal including a retransmission request signal (hereinafter referred to as "retransmission request signal") to the transmitter...

Embodiment 2

[0115] In this example, refer to Figure 9 The following will be described: In Embodiment 1, the retransmission request of the above-mentioned predetermined multicast burst is identified by using a signal obtained by equal-gain synthesis of signals transmitted by a specific subcarrier in the predetermined multicast burst . Figure 9 is a block diagram showing the configuration of an OFDM communication apparatus according to Embodiment 2 of the present invention. again, yes Figure 9 In and embodiment 1 ( Figure 5 ) with the same structure as Figure 5 The same reference numerals are given to the structures in , and detailed descriptions are omitted.

[0116] The OFDM communication device of this embodiment has the following configuration: In the OFDM communication device of Embodiment 1, a DIV synthesis unit 801 is provided instead of the DIV selection unit 412 .

[0117] In the following, the operation of the OFDM communication device with the above structure will be de...

Embodiment 3

[0130] In this embodiment, the following case will be described: In Embodiment 1, the above-mentioned predetermined multicast burst is identified using a signal obtained by performing maximum-ratio combination of signals transmitted by a specific subcarrier in a predetermined multicast burst. Burst retransmission requests.

[0131] The configuration of the OFDM communication device of this embodiment is the same as that of the OFDM communication device of Embodiment 1 except for the DIV synthesis unit 801, so detailed descriptions are omitted.

[0132] Hereinafter, the operation of the OFDM communication device with the above-mentioned structure will be described focusing only on the aspects different from the first embodiment. Hereinafter, for simplicity of description, it is assumed that the receiver device receives only one multicast burst (here, multicast burst 1) transmitted from the source device. Furthermore, the sending end device and each receiving end device include...

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Abstract

An OFDM communication apparatus and an OFDM communication method that realize both an improvement in efficiency of transmitting information signals and an improvement in error rate characteristic of demodulated signals in OFDM systems using multicast. The OFDM communication apparatus comprises receiver means for receiving an OFDM signal transmitted to a plurality of OFDM communication apparatuses; detector means for detecting errors, if included in the received OFDM signal; generator means for superimposing, if the received OFDM signal includes any errors, a retransmission request signal on a predetermined subcarrier to thereby generate a retransmission request OFDM signal; and transmitter means for transmitting the generated retransmission request OFDM signal in a timing predetermined in common to all the foregoing plurality of OFDM communication apparatuses.

Description

technical field [0001] The present invention relates to an OFDM (Orthogonal Frequency Division Multiplexing; Orthogonal Frequency Division Multiplexing) communication device (hereinafter referred to as an "OFDM communication device"), and particularly relates to performing retransmission control (in a receiver device related to a predetermined transmission signal) If an error occurs in the demodulated signal, an OFDM communication device that retransmits the above-mentioned transmission signal to the control of the receiving end device). Background technique [0002] With regard to retransmission control in the conventional OFDM system, a case where a transmitting-side device performs retransmission to a receiving-side device will be described as an example. First, the transmitting-side apparatus performs IFFT (inverse Fourier transform) using the information signal of the receiving-side apparatus, etc., to generate an OFDM signal obtained by superimpo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L1/16H04B1/707H04B7/24H04J11/00H04J13/00H04L1/18H04L27/26H04W4/06H04W28/04H04W72/04
CPCH04L2001/0093H04L1/18H04L1/1692H04L2001/125H04L27/2601H04L5/0021H04L27/2649H04L5/0053H04L27/26134
Inventor 须藤浩章
Owner III HLDG 12 LLC
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