Abstract
We propose a flexible transmission scheme which easily allows to switch between cyclic-prefixed single-carrier (CP-SC) and cyclic-prefixed multicarrier (CP-MC) transmissions. This scheme takes advantage of the best characteristic of each scheme, namely, the low peak-to-average power ratio (PAPR) of the CP-SC scheme and the robustness to channel selectivity of the CP-MC scheme. Moreover, we derive the optimum power allocation for the CP-SC transmission considering a zero-forcing (ZF) and a minimum mean-square error (MMSE) receiver. By taking the PAPR into account, we are able to make a better analysis of the overall system and the results show the advantage of the CP-SC-MMSE scheme for flat and mild selective channels due to their low PAPR and that the CP-MC scheme is more advantageous for a narrow range of channels with severe selectivity.
Highlights
Orthogonal frequency division multiplexing (OFDM) is already used in digital radio (DAB), digital television (DVB), wireless local area networks (e.g., IEEE 802.11a/g and HIPERLAN/2), broadband wireless access (e.g., IEEE 802.16), digital subscriber lines (DSL) and certain ultra wide band (UWB) systems (e.g., MBOA)
Building on our previous work [16], we propose a power allocation approach to cyclic-prefixed single-carrier (CP-SC) transmission, when a linear zero-forcing (ZF) or a minimum mean-square error (MMSE) receiver is used
The use of the MMSE criterion is justified by the fact that minimizing the mean-square error (MSE) leads to the maximization of the decision signal-to-noise ratio (SNR), which is inversely proportional to the bit error rate (BER)
Summary
Orthogonal frequency division multiplexing (OFDM) is already used in digital radio (DAB), digital television (DVB), wireless local area networks (e.g., IEEE 802.11a/g and HIPERLAN/2), broadband wireless access (e.g., IEEE 802.16), digital subscriber lines (DSL) and certain ultra wide band (UWB) systems (e.g., MBOA). OFDM results in simple transmitters and receivers, enabling simple equalization schemes, it has some drawbacks, among which we can cite high peak-to-average power ratio (PAPR), sensitivity to carrier frequency offset, and the fact that it does not exploit the channel diversity [3] as the more important ones. We consider that the transmitter has partial channel state information (CSI), in terms of the signal-to-noise ratio (SNR) of each subchannel In this scenario, it is well known that for OFDM it is possible to allocate power and bits across the subchannels in order to maximize the rate [13]. For some simulated channels, the optimum point for switching from one scheme to the other in order to remain optimal in terms of the peak transmission power needed for a given transmit rate For both strategies, we derive the optimal power allocation to maximize capacity, given a mean transmit power level. We always index matrix and vectors entries starting from 1
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