Abstract
In type II hybrid ARQ (HARQ) schemes, the uncoded information bits are transmitted first, while the error correction parity bits are sent upon request. Consequently, frequency diversity cannot be exploited during the first transmission. In this paper, we present the use of OFDM/TDM with MMSE-FDE and type II HARQ to increase throughput of OFDM due to frequency diversity gain.
Highlights
Packet services are dominant in future broadband wireless communications, where hybrid automatic repeat request (HARQ) is used for error control [1]
Type II HARQ sends only the error detection parity bits, while the error correction parity bits are retransmitted upon request if the decoder detects errors
We present the use of Orthogonal frequency division multiplexing (OFDM) combined with time division multiplexing (OFDM/TDM) using minimum mean square error frequency domain equalization (MMSE-FDE) [5] with type II HARQ to exploit the channel frequency selectivity
Summary
Packet services are dominant in future broadband wireless communications, where hybrid automatic repeat request (HARQ) is used for error control [1]. Orthogonal frequency division multiplexing (OFDM) is attractive due to its robustness against multipath channel, while a drawback is its high peak-to-average power ratio (PAPR) [2]. In type II HARQ-OFDM the uncoded packet is send first and neither coding nor frequency diversity gain is available. OFDM-based scheme (e.g., multicarrier CDMA) with type II HARQ [4] that efficiently exploits the channel frequency selectivity in the first transmission is preferable. We present the use of OFDM combined with time division multiplexing (OFDM/TDM) using minimum mean square error frequency domain equalization (MMSE-FDE) [5] with type II HARQ to exploit the channel frequency selectivity. In type II HARQ OFDM/TDM during the first uncoded transmission the channel frequency selectivity is exploited through MMSE-FDE to increase the throughput of conventional OFDM with a lower PAPR.
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