Performance Evaluation of FIR Filter and Equalization for 802.11b WLAN

• Main Authors: Me-Ho Lu, 呂明和
• Other Authors: 歐陽彥杰
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/23960954040437562025

碩士 === 國立中興大學 === 電機工程學系 === 90 === Wireless Local Area Network communications become more and more popular part in communication area. Under the development from 802.11 to 802.11b and 802.11a to 802.11g, we find that products and technologies that meet the requirement for varies circumstances and varies distance for multi-rate transmission .In the IEEE standards, the purpose that adopting various kind of modulation such as Barker code CCK and OFDM is to reduce the bit error rate when signals is transferred through the channel. In wireless communication the ISI caused by multi-path effect that always is an important issue. ISI is also an important issue in 802.11b. we adopt the way of over-sampling ,our data spectrum must meet the radio spectrum requirement for band limited transmitter ,we adopted a couple of low pass filter pair —SQRT raised cosine filter in the transmitter and receiver design because of the characteristics of raised cosine filter, it can sampling at the point of zero ISI in the side-lobe spectrum. We adopt equalization to eliminate ISI problem in high data rated .The Algorithm using for our equalization, we adopt the adaptive LMS method because the transmitter preamble can used to be training sequence for our received data , and LMS is a popular and much easier realization algorithm. In the realization process, we find that the taps of the SQRT raised cosine Filter is fixed and the tap of the LMS equalizations is adaptive, and both of them have the same property to overcome the ISI effects. We address a new structure to merge both the raised cosine filter and the equalization in this thesis. Our new structure has the benefits of saving hardware complexity and fast convergence.