Wednesday, January 19, 2011

Turbo Code Applications 2

Terrestrial telephony: 
 
    Turbo codes are suited for down-to-earth applications such as terrestrial telephony. Satellite technology provides global coverage and service. UMTS is being standardized to ensure an efficient and effective interaction between satellite and terrestrial networks. 

    An important third generation cellular standard is cdma2000, which is standardized by the third generation partnership project (3GPP). As in UMTS (Universal Mobile Telephone Service), cdma2000 systems use turbo codes for forward error correction (FEC). While the turbo codes used by these two systems are very similar, the differences lie in the interleaving algorithm, the range of allowable input size and the rate of constituent RSC encoders. 

Oceanographic Data-Link: 
 
    This data-link is based on the Remote Environmental Data-Link (REDL) design. ViaSat is a company offering satellite networking products. ViaSat offers a modem with turbo encoding and decoding. It is reported that turbo coding increases the throughput and decreases the bandwidth requirement.

Image processing: 
 
     Embedded image codes are very sensitive to channel noise because a single bit error can lead to irreversible loss of synchronization between the encoder and the decoder. Turbo codes are used for forward error correction in robust image transmission. Turbo codes are suited in protecting visual signals, since these signals are typically represented by a large amount of data even after compression. 

WLAN (Wireless LAN) : 
 
     Turbo codes can increase the performance of a WLAN over traditional convolutional coding techniques. Using turbo codes, an 802.11a system can be configured for high performance. The resulting benefits to the WLAN system are that it requires less power, or it can transmit over a greater coverage area. Turbo code solution is used to reduce power and boost performance in the transmit portion of mobile devices in a wireless local area network (WLAN). 

OFDM: 
 
     The principles of orthogonal frequency division multiplexing (OFDM) modulation have been around for several decades. The FEC block of an OFDM system can be realizes by either a block-based coding scheme (Reed-Solomon) or turbo codes. 

XDSL modems: 
 
      Turbo codes present a new and very powerful error control technique which allows communication very close to the channel capacity. Turbo codes have outperformed all previously known coding schemes regardless of the targeted channel. Standards based on turbo codes have been defined. 

These applications indicate that turbo codes can play a vital role in many of the communications systems which are being designed. Low power, memory efficient implementation of turbo codes is thus an important research area.

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