Hybrid Optical MODI

7/31/2019 Hybrid Optical MODI

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Prsented

By

REVATHIBANU


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Introduction

Project objectives and motivations

Communication System

Structured Redundancy

Forward Error Correction Turbo decoding

Abstract

Existing System

Existing System Disadvantage

Proposed System Proposed System Advantages

Block Diagram And explanation

Application

Conclusion


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TURBO codes have received considerable attention in providing

reliable communication links.

They find applications in 3rd Generation, digital video broadcasting

return channel via satellite (DVB-RCS), IEEE 802.16 and other

communication standards Simulations of turbo codes to evaluate their error performance in the

high signal-to-noise ratio (SNR) region is highly time consuming.

The performance of turbo codes over fully interleaved and

exponentially correlated Rayleigh fading channels has been

investigated in


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Motivation

Can we have error free communication as much as possible.

Objectives

Studying channel coding

Understanding channel capacity

Ways to increase data rate

Provide reliable communication link


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Structural modular approach

Various components

Of defined functions

Channel

Coding

Source

Coding

ModulationFormatting

Digitization

MultiplexingAccess

techniques

send

receive


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Channelencoder

Input word

k-bit

Output word

n-bit

Redundancy = (n-k)

Code rate = k/n

codewordCode sequence


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Turbo coded data transmission over a hybrid channel, consisting

of parallel free space optical (FSO) and radio frequency (RF)

links, is considered, and analytical bit error performance results

are derived.

In this paper, we are going to develop BER analysis of turbocodes for hybrid FSO/RF channels using the transfer function

bounding technique.

Random and specific codeword bit selection for Transmission

through the RF link are considered.

Joint optimization of puncturing and RF bit selection patterns

also one of the major conept in this application


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First, BER analysis for a turbo coded system that transmitsrandomly selected codeword bits through the RF link is derived

Second, we present a procedure to analyze BER performance inhybrid channels when specific codeword bits are selected for

transmission through the RF link Finally, we present a novel technique to jointly optimize

puncturing and RF bit selection patterns.


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Considering the word length in mind we go for this hybrid technique

which be implemented either FSO or RF channels.

FSO links have large unlicensed bandwidths but they are more

affected by various atmospheric factors, including scattering,

absorption, and atmospheric turbulence. Due to limited RF bandwidths, most of the data are transmitted

through the dominant FSO link, leaving out only a small fraction to

be carried by the RF link.


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Disadvantages

- Photonic NW is a complex system ( a large number of

different functions must cooperate for a network such as

transmission

Routing and Switching

Control and management

Intractable problem (NP-Complete).

Therefore, assumptions and heuristics are used to reduce the

process complexity.


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Parallel FSO/RF hybrid channels have been analyzed in using low

density parity check (LDPC) codes.

In performance of convolution codes has been studied for hybrid

channels, and code design and power assignment criteria are

investigated. Our proposed approach utilizes a weight-two input sequence

algorithm to reduce the search space.

The proposed method can also be used for designing codes in other

hybrid channels


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Advantages

Solve the electronic equipment bottleneck

Exploit the existing network Support services such as connection on demand

Improves bandwidth (BW) efficiency and source utilization of the network.


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INTER

LEAVER

PUNT

URINGENCODER 1ENCODE 2

RF LINK

OPTICAL

LINK

SNR

VALUE

SNR

VALUE

COMPA

RISION


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In Section II, we present the hybrid channel model. In Section III, a BER analysis for the hybrid channel when

randomly selected codeword bits are transmitted throughthe RF link is presented

. Section IV describes BER analysis when specific codewordbits are transmitted through the RF link.

Section V presents our idea of joint optimization ofpuncturing and RF bit selection patterns

In Section VI, numerical results showing significant

benefits from the turbo coded transmission through thehybrid channel are presented.

Section VII concludes our study.


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are used extensively in 3G and 4G mobile telephony standards MILITARY AND LAW ENFORCEMENT

Can be used to improve the interface in systems that employ multiple trellis-based algorithms.

Applications include Telephones

Internet LANs - local area networks CATV - for video, voice and Internet connections Utilities - management of power grid

Security - closed-circuit TV and intrusion sensors Military - everywhere!

Multimedia systems require varying quality of service. QoS Latency

Low latency for voice, teleconferencing

Bit/frame error rate (BER, FER) Low BER for data transmission.

Mobile 3G systems In use in Japan UMTS NTT DoCoMo

Turbo codes : pictures/video/mail Convolutional codes : voice
http://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/4Ghttp://en.wikipedia.org/wiki/4Ghttp://en.wikipedia.org/wiki/3G


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Mature, stable, well established and implemented

In this paper, we develop BER analysis of turbo codes for

hybrid FSO/RF channels using the transfer functionbounding technique.

Random and specific codeword bit selection for

transmission through the RF link are considered.

The exact trade-offs that can be obtained between the

optical and RF link SNR values for maintaining a certainerror probability are described.

Joint optimization of puncturing and RF bit selectionpatterns is proposed

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Hybrid Optical MODI