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What is FEC and why is it used in wireless networks

What is FEC and why is it used in wireless networks
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mc87
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mc87
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jarrod_williamsCommented:
"Wireless channels are highly affected by unpredictable factors such as cochannel interference, adjacent channel interference, propagation path loss, shadowing and multipath fading. The unreliability of media degrades the transmission quality seriously. Forward error correction (FEC) schemes are frequently used in wireless environments to reduce the high bit error rate of the channel. In this paper, we propose an adaptive FEC scheme for multicast communication in wireless networks based on dynamic variation of coding parameters as a function of the channel bit error rate, desired QoS in terms of reliability, number of receivers and efficiency in terms of bandwidth use. Reed-Solomon erasure codes are used throughout this study because of their appropriate characteristics in terms of powerful coding and implementation simplicity. We make a numerical analysis of a set of Reed-Solomon erasure codes. The observations made throughout this numerical analysis are the basic principals of our adaptive FEC scheme. Numerical results show that our adaptive scheme provides the best trade-off between transmission overhead and guaranteed QoS"

Taken from:  http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=853639

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Kerem ERSOYPresidentCommented:
Hi,

FEC is simply Error Correction Code calculated and added to the transmitted data. Then the receiving end does the same calculation and compares the calculated value with received value and tries to understand if there is any error during transmission. FEC is more popular with Satellite transmission and also used in 802.1n and 802.3an ( 10 Gbit)

For more information :

http://en.wikipedia.org/wiki/Forward_error_correction

Cheers,
K.


 
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rfc1180Commented:
I think what is important to understand from FEC is that the physical layer of 802.11 is the air interface (open space), the radios transmit and recieve data via electromagnetic waves. The data bits are converted prior to sending the data via layer 1. There is so much information per transmission and becomes important to guard against data loss due to interference, typically co-channel interface. (Think of it has introducing redundancy in the binary information that is sent on the air interface). There is also multi-path fading to consider too, another reason for FEC. "Just think redundancy"

Billy
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