Since the invention of wireless telegraphy by Marconi in 1897, wireless technology has not only been enhanced, but also has become an essential part of our everyday lives. In years, wireless technology has been expanded more and more. The first wireless mobile phone invented around 1980. In wireless networking, IEEE 802.11 also known as WiFi was the first standard released in 1997, but IEEE 802.11b-1999 is known as the first wireless networking standard that was widely accepted. IEEE 802.15 also known as PAN was created in 2003 and IEEE 802.16 also known as WiMax is the latest standard for mobile and fixed wireless communication approved in 2004. Unlike its short range predecessors, 802.11 and 802.15, WiMax has longer range up to 50 km. The most popular implementation of the IEEE 802.16 standard is the “Mobile Wireless MAN” technically proposed by the IEEE 802.16e-2005 amendment. WiMax uses broadband communication methods like orthogonal frequency division multiplexing and it has significant advantages such as high data rates in addition to long range of operability. The receiver design of WiMax involves many challenges because of wireless channel nature. Implementation problems lower WiMax performance. WiMax standard has several blocks in physical layer. Forward Error Correction block (FEC) is one of the most important blocks of physical layer for WiMax. FEC block includes a randomizer and a viterbi decoder. Viterbi decoder has significant delay and uses large memory blocks. Various methods in the literature are available for implementation of viterbi decoder. In this thesis, important blocks in WiMax PHY with their functions are explained. Then, after a survey of different problems in implementation of WiMax FEC block, different methods for design and implementation of viterbi decoder are studied. Afterwards, different methods for implementation of viterbi such as Register Exchange (RE), Trace Back (TB) and Hybrid methods are compared, and for clarification of differences between these methods, advantages and disadvantages of them are highlighted. Parameters used for comparison are memory usage, delay, processing speed and power. RE method has high processing speed and low delay, but it uses large memory blocks. Unlike RE method, TB method has lower processing speed and higher delay but it has low memory usage. There is a tradeoff between memory usage and delay, so Hybrid methods try to gather advantages of both RE and TB methods. Here, we use a modified RE (MRE) method as an optimal method for design and implementation of FEC that has low delay and low memory usage, and we proposed a new hardware combined of MRE method with a Keywords: IEEE 802.16, FEC, Implementation, Viterbi Decoder