Robust Transmit Antenna Design for Performance Improvement of Cell-Edge Users: Approach of NOMA and Outage/Ergodic Capacity Analysis

• Published in: Sensors (Basel, Switzerland) Vol. 19; no. 22; p. 4907
• Main Authors: Do, Dinh-Thuan, Le, Chi-Bao, Lee, Byung Moo
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 10.11.2019; MDPI
• Subjects: Antenna design; Antennas; Closed form solutions; Communication; Energy efficiency; ergodic capacity; Ergodic processes; Exact solutions; non-orthogonal multiple access; Nonorthogonal multiple access; outage probability; Performance enhancement; Performance evaluation; Random variables; Receivers & amplifiers; Signal to noise ratio; transmit antenna selection; Transmitters; Wireless networks; wireless sensor network; Wireless sensor networks; transmit antenna selection; ergodic capacity; outage probability; non-orthogonal multiple access; wireless sensor network
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s19224907

In this investigation, a wireless sensor network using a non-orthogonal multiple access (NOMA) system is considered in two scenarios related to the number of serving access point/base stations, where two policies provide system performance improvement in two sensors (the near user and the far user). To improve performance efficiency, two robust transmit antenna strategies are designed related to the access point/base station (BS), namely (i) Transmit Antenna Selection (TAS) mode and (ii) two base station (TBS) approach to simultaneously serve NOMA users. First, the TAS scheme is implemented to provide suboptimal outage performance for such NOMA, in which BS equipped at least two antennas while NOMA users are equippeda single antenna. Secondly, the TBS scheme is conducted to enhance the outage performance, especially considering priority evaluation for the far user in user pairs. As an important result, such far users in two proposed schemes are studied by introducing the exact closed-form expression to examine outage behavior. Accordingly, the closed-form expressions regarding ergodic capacity can be further obtained. To corroborate the exactness of these metrics, Monte Carlo simulation is performed. In addition, the proposed schemes exhibit various performance evaluations accompanied by different related parameters such as power allocation factors, the number of transmit antenna, and transmit signal-to-noise ratio (SNR).