Pre-Rake Diversity Combining for UWB Systems in IEEE 802.15 UWB Multipath Channel

Shunsuke IMADA  Tomoaki OHTSUKI  

IEICE TRANSACTIONS on Communications   Vol.E88-B   No.5   pp.2193-2199
Publication Date: 2005/05/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.5.2193
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Wireless Communication Technologies
UWB,  Rake diversity combining,  Pre-Rake diversity combining,  

Full Text: PDF>>
Buy this Article

Since Ultra Wideband Impulse Radio (UWB-IR) system can resolve many paths and is thus rich in multipath diversity, the use of Rake diversity combining is very effective. In the Rake diversity combining, the bit error rate (BER) is improved with the increase of the number of fingers. The Pre-Rake diversity combining is known as another technique to achieve the performance equivalent to the Rake diversity combining without increasing the receiver complexity. In the Pre-Rake diversity combining, the transmitted signals are scaled and delayed according to the delay and strength of the multipath. In this paper, we propose Pre-Rake diversity combining techniques for UWB systems, All-Pre-Rake (A-Pre-Rake) diversity combining using perfect channel information, Selective-Pre-Rake (S-Pre-Rake) diversity combining using the information on the L strongest paths, and Partial-Pre-Rake (P-Pre-Rake) diversity combining using the information on the first L paths. From the results of our computer simulation for UWB-IR systems in IEEE 802.15 UWB multipath channel model, we show that the proposed Pre-Rake diversity combining techniques are effective for the UWB-IR systems to achieve good error rate performance, while keeping the complexity of the receiver low. We also show that the S-Pre-Rake diversity combining is effective to achieve good error rate performance with less channel information.