混合自動重複請求(HARQ)可以定義爲高速率正向糾錯編碼和ARQ誤差控制的結合。在一般標準ARQ中，有各種類型的冗餘位可以添加到必須傳輸的數據中。這是在錯誤檢測代碼的幫助下完成的，其中可能包括循環冗餘檢查(CRC)。對於混合ARQ，轉發的數據也與正向糾錯碼一起編碼(Chockalingam et al, 1999)。而且，奇偶校驗位要麼與消息一起立即發送，要麼在請求時傳輸。因此，HARQ在無線系統中具有更好的性能。
The present times has witnessed a huge growth in the internet. There has been a high interest of the people in a number of portable computing devices. This has led to the creation of the large demand for the high speed wireless systems related to packet based data services in the future. As a result of the downlink, there is a requirement of high throughput. In the future systems, there will be dominant type of traffic. The backbone of the internet is something which is based on the internet protocol. Thus, there should be an increase in the development of the packet transmission related schemes in order to develop the future air interface which are beyond the 3G mobile radio based systems.
Forward Error Correction may be defined as the technique which is used in wireless systems for the purpose of control of errors during the processes related to the transmission of data over the unreliable or noisy channels which are related to communication. One of the primary ideas in the same is to sensor the encoding in a redundant manner in such a way that it uses an error correcting code. FEC processing is something which may applicable to the digital bit stream. In addition to this, it can also be used for the purpose of demodulation of the carrier which is digitally modulated data. The information which is related to FEC information can be added to those storage devices that have the ability to enable easy recovery of the corrupted data.
Hybrid Automatic Repeat Request (HARQ) may be defined as the combination of high rate forward error correcting coding and ARQ error control. In case of the general standard ARQ, there are various types of redundant bits which may be added to the data which has to be transmitted. This is done with the help of an error detecting code which may include the cyclic redundancy check (CRC). In case of the Hybrid ARQ the data which is forwarded is also encoded along with the forward error correction code (Chockalingam et al, 1999). Also, the parity bits are sending either immediately with the message or they are transmitted on the request. Because of this, there is a better performance of HARQ in wireless systems.
In this research paper, the discussion will focus on the comparison of the two different methods which has been implemented in case of wireless communication, Forward Error Correction (FEC) and HARQ (Hybrid ARQ). Different aspects related to the both will be discussed and analyzed. In addition to this, several rationales related to the design of the same will also be discussed.