Zero padding (ZP) of multicarrier transmissions has recently been proposed as an appealing alternative to the traditional cyclic prefix (CP) orthogonal frequency-division multiplexing (OFDM) to ensure symbol recovery regardless of the channel zero locations. In this paper, both systems are studied to delineate their relative merits in wireless systems where channel knowledge is not available at the transmitter. Two novel equalizers are developed for ZP-OFDM to tradeoff performance with implementation complexity. Both CP-OFDM and ZP-OFDM are then compared in terms of transmitter nonlinearities and required power backoff. Next, both systems are tested in terms of channel estimation and tracking capabilities. Simulations tailored to the realistic context of the standard for wireless local area network HIPERLAN/2 illustrate the pertinent tradeoffs.
Bibliographical noteFunding Information:
Paper approved by M. Chiani, the Editor for Wireless Communication of the IEEE Communications Society. Manuscript received September 6, 2000; revised March 15, 2001 and July 15, 2001. This work was supported in part by the National Science Foundation (NSF) under CCR Grant 98-05350 and in part by the NSF under Wireless Initiative Grant 99-79443. This paper was presented in part at the International Conference on Communications, New Orleans, LA, June 2000, and in part at the International Conference on Acoustic, Speech, and Signal Processing, Istanbul, Turkey, June 2000.
- Channel estimation
- Cyclic prefix
- IEEE 802.11a
- Orthogonal frequency-division multiplexing (OFDM)
- Zero padding