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Ambient light elimination symbol-by-symbol detection method requiring no channel estimation in wireless optical communication

A wireless optical communication and channel estimation technology, applied in the field of ambient light elimination symbol-by-symbol detection, can solve problems such as system complexity increase, achieve the effect of simple algorithm, reduce system complexity and storage capacity

Active Publication Date: 2017-08-04
ZHEJIANG UNIVERSITY OF SCIENCE AND TECHNOLOGY
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The performance of signal block-by-block sequence detection is better than symbol-by-symbol detection, and the performance increases with the sequence length, but the system complexity also increases exponentially with the sequence length

Method used

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  • Ambient light elimination symbol-by-symbol detection method requiring no channel estimation in wireless optical communication
  • Ambient light elimination symbol-by-symbol detection method requiring no channel estimation in wireless optical communication
  • Ambient light elimination symbol-by-symbol detection method requiring no channel estimation in wireless optical communication

Examples

Experimental program
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example 1

[0035] Example 1 takes a wireless optical communication OOK system as an example to provide a symbol-by-symbol detection method for ambient light cancellation without channel estimation. The method forms a sequence of a discrete electrical signal received and sampled and previous decision signals in the observation window, and uses the generalized likelihood ratio measure and decision conditions to make a decision on a single signal at the current moment, that is, to detect symbol by symbol. The method includes the following steps:

[0036] (1) Establish a channel model: Determine the observation window length as L symbol periods according to the channel correlation time and system storage capacity, and the channel and ambient light status in the observation window remain unchanged. The signal in the observation window is expressed as follows: the sending sequence is x(k,L)=[x(k-L+1),...,x(k)], and the receiving sequence is y(k,L)=[y (k-L+1),...,y(k)], the noise sequence is n...

example 2

[0043]Example 2 In the wireless optical communication quaternary IM / DD system, the value changes of h(k) and B(k) within several observation window lengths are negligible, and the rest are the same as in Example 1. Only the difference between the example 2 method and the example 1 is detailed below:

[0044] (1) Establishing a channel model: It can be assumed that h(k)=h(k-1), B(k)=B(k-1). Therefore, the receiver estimates the channel state and ambient light at time k-1 as the estimated value at time k, that is, Example 2 uses figure 1 The solid and dashed lines.

[0045] (2) The transmitter first transmits L p Pilot symbols 3 known by the receiving end, where L p <L, after which data symbols unknown to the transmitter and receiver;

[0046] (3) In the decision sequence including initial pilot symbols, the receiving end selects modulation symbols 1 / 2 / 3, discarding all modulation symbols 0, that is, L 0 = 0, generate

[0047] (4) Judgment sequence based on accumulated...

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Abstract

The invention discloses an ambient light elimination symbol-by-symbol detection method requiring no channel estimation in wireless optical communication. In the case of channel estimation and ambient light estimation, the decision feedback symbol-by-symbol detection method can automatically eliminate the influence of ambient light, and channel estimation and ambient light estimation can be carried out based on decision feedback. The method is also applicable to the communication fields in which other channels contain additional invariable or slowly changing interference beside multiplication channel parameters. The method inherits the advantages of sequence detection performance improved with the sequence length, but the system complexity does not increase with the sequence length. In addition, the sequence is formed by a selective storage method, therefore the algorithm complexity and the necessary storage capacity can be further reduced, and the decision and estimation failure are avoided.

Description

technical field [0001] The invention is applicable to the field of wireless optical communication, and in particular relates to a symbol-by-symbol detection method for ambient light elimination without channel estimation in wireless optical communication. In the absence of channel estimation and ambient light estimation, the symbol-by-symbol detection method can automatically eliminate the influence of ambient light, and can perform channel estimation and ambient light estimation based on the detection results. This method is also applicable to other communication domains where other channels contain additive constant or slowly varying interferences in addition to multiplicative channel coefficients. Background technique [0002] Compared with traditional radio frequency and infrared communication, wireless optical communication has the advantages of high transmission power, no electromagnetic interference, and green energy saving. Wireless optical communication systems gen...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L25/02
CPCH04L25/0202
Inventor 宋天宇吴茗蔚丰明坤余作奔王中鹏周武杰翟治年
Owner ZHEJIANG UNIVERSITY OF SCIENCE AND TECHNOLOGY
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