2,790 research outputs found
Low Power Analog-to-Digital Conversion in Millimeter Wave Systems: Impact of Resolution and Bandwidth on Performance
The wide bandwidth and large number of antennas used in millimeter wave
systems put a heavy burden on the power consumption at the receiver. In this
paper, using an additive quantization noise model, the effect of analog-digital
conversion (ADC) resolution and bandwidth on the achievable rate is
investigated for a multi-antenna system under a receiver power constraint. Two
receiver architectures, analog and digital combining, are compared in terms of
performance. Results demonstrate that: (i) For both analog and digital
combining, there is a maximum bandwidth beyond which the achievable rate
decreases; (ii) Depending on the operating regime of the system, analog
combiner may have higher rate but digital combining uses less bandwidth when
only ADC power consumption is considered, (iii) digital combining may have
higher rate when power consumption of all the components in the receiver
front-end are taken into account.Comment: 8 pages, 6 figures, in Proc. of IEEE Information Theory and
Applications Workshop, Feb. 201
Code designs for MIMO broadcast channels
Recent information-theoretic results show the optimality of dirty-paper coding (DPC) in achieving the full capacity region of the Gaussian multiple-input multiple-output (MIMO) broadcast channel (BC). This paper presents a DPC based code design for BCs. We consider the case in which there is an individual rate/signal-to-interference-plus-noise ratio (SINR) constraint for each user. For a fixed transmitter power, we choose the linear transmit precoding matrix such that the SINRs at users are uniformly maximized, thus ensuring the best bit-error rate performance. We start with Cover's simplest two-user Gaussian BC and present a coding scheme that operates 1.44 dB from the boundary of the capacity region at the rate of one bit per real sample (b/s) for each user. We then extend the coding strategy to a two-user MIMO Gaussian BC with two transmit antennas at the base-station and develop the first limit-approaching code design using nested turbo codes for DPC. At the rate of 1 b/s for each user, our design operates 1.48 dB from the capacity region boundary. We also consider the performance of our scheme over a slow fading BC. For two transmit antennas, simulation results indicate a performance loss of only 1.4 dB, 1.64 dB and 1.99 dB from the theoretical limit in terms of the total transmission power for the two, three and four user case, respectively
- …