| 1. |
- Barros da Silva Jr., José Mairton, 1990-, et al.
(författare)
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Low Resolution Phase Shifters Suffice for Full-Duplex mmWave Communications
- 2019
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Ingår i: 2019 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS). - : IEEE. - 9781728123738
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Konferensbidrag (refereegranskat)abstract
- Full-duplex base-stations with half-duplex nodes, allowing simultaneous uplink and downlink from different nodes, have the potential to double the spectrum efficiency without adding additional complexity at mobile nodes. Hybrid beam forming is commonly used in millimeter wave systems for its implementation efficiency. An important element of hybrid beam-forming is quantized phase shifters. In this paper, we ask if low-resolution phase shifters suffice for beamforming-based full-duplex millimeter wave systems. We formulate the problem of joint design for both self-interference suppression and downlink beamforming as an optimization problem, which we solve using penalty dual decomposition to obtain a near-optimal solution. Numerical results indicate that low-resolution phase shifters can perform close to systems that use infinite phase shifter resolution, and that even a single quantization bit outperforms half-duplex transmissions in both low and high residual self-interference scenarios.
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| 2. |
- Dao, Van-Lan, et al.
(författare)
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Reliability and Fairness for UAV Communication Based on Non-Orthogonal Multiple Access
- 2019
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Ingår i: 2019 IEEE International Conference on Communications Workshops (ICC Workshops). - 9781728123738
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Konferensbidrag (refereegranskat)abstract
- Recently, communication using unmanned aerial vehicles (UAVs) as relay nodes has been considered beneficial for a number of applications. Moreover, non-orthogonal multiple access (NOMA) with users being assigned different signal power levels while sharing the same time-frequency domain has been found effective to enhance spectrum utilization and provide predictable access to the channel. Thus, in this paper we consider an UAV communication system with NOMA and propose a solution to find the optimal values for the user’s power allocation coefficients (PACs) needed to achieve the required levels of communication reliability. We present a closed-form expression for the PAC of each user and also propose an algorithm for finding the optimal altitude of the UAV required to satisfy the fairness condition for all users. Finally, we provide numerical examples and compare the results for three types of communication environments.
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| 3. |
- Tang, Siyang, et al.
(författare)
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Performance Analysis for MmWave MIMO-SCMA systems Using Lens Antenna Array
- 2019
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Ingår i: 2019 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS). - : IEEE. - 9781728123738
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Konferensbidrag (refereegranskat)abstract
- The recent concept of beamspace multiple input multiple output (MEMO) can significantly reduce the number of required radio frequency (RE) chains in millimeter wave (mmWave) massive MEMO systems without obvious performance loss. However, the number of supported users cannot be larger than the number of RF chains in hybrid MEMO architectures. To break this fundamental limit, we introduce the concept of sparse code multiple access (SCMA) with beamspace MEMO, then a useful upper bound on the average symbol error probability is obtained through the union bound. The bound is tight in beamspace nunWave MEMO-SCMA systems for high SNR regions. The analytical result is compared with simulations, and the results confirm the effectiveness of the analysis for mmWave MEMO-SCMA channels.
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