A comparison of bandwidth-efficient multiple access to other signal designs for correlated waveform multiple-access communications
نویسندگان
چکیده
There have been several recent papers in the literature that deal with the design of signature waveforms for use by the transmitters in uplink, single-cell, multiple-access communications. In particular, we consider the approach introduced in [1] and [2], where the signature waveforms are specifically designed for the centralized multiuser receiver at the base so that each transmitter can be guaranteed a preassigned quality-ofservice (QoS) requirement in terms of the received signal-to-interference ratio (SIR). The resulting strategy is called bandwidth-efficient multiple access (BEMA) [2]. When all users employ pulse amplitude modulation (PAM) and a common signaling rate, the key question in BEMA is how the waveforms must be designed to occupy as little bandwidth as possible and still meet the QoS objectives. For a strict measure of bandwidth, and for a given set of received powers, this question was addressed by the authors for the maximum SIR Decision-Feedback (MSIR-DF) receiver in [3]. A similar question was addressed in [4] where, for a sum constraint on the received powers, optimal signature signals and transmit powers were obtained for the linear MSIR receiver (without decision feedback). A somewhat different but related non-QoS approach proposes the design of signature signals that maximize the total capacity of the multiple-access channel under a spreading-gain constraint (cf. [5], [6]). This correspondence undertakes a comparison of the minimum bandwidth required (to achieve the QoS requirements) for the signals designed for the MSIR-DF receiver [3], for the linear MSIR receiver [4], and for sum-capacity maximization as in [6]. We show that the bandwidth required for multiuser receivers with decision feedback can be significantly less than that required for linear receivers or for sum-capacity maximization when the MSIR-DF receiver is used.
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ورودعنوان ژورنال:
- IEEE Trans. Information Theory
دوره 49 شماره
صفحات -
تاریخ انتشار 2003