Master of Science
Electrical and Computer Engineering
With everlasting increase of connectivity demand and high speed data communication, lots of progresses have been made to provide a sufficient quality of services (QoS). Several advanced technologies have been the cornerstone of this trend in academia as well as in industry. Nevertheless, there are some implementation challenges, which needs to be closely investigated. In this thesis, among all challenges, we elaborate on those related to number of radio frequency (RF) chains and resource scarcity.
The principle idea behind our proposed initial solution is to exploit the spatial domain as an additional degree of freedom. To be more specific, we benefit from spatial domain and antenna index in a multiple-input multiple-output (MIMO) system with dual-polarized (DP) antennas to convey the information. We develop a two-stage algorithm to groups the antennas which ends up to the optimum performance. Another advantage of this proposed algorithm is the complete complexity reduction of exhaustive search over the whole available space.
Moreover, due to the continuous growth of demands which results in spectrum scarcity, we investigate the extension of long term evolution (LTE) spectrum. Such a paradigm shift is realized to offload part of the data to unlicensed band, which has been initially dedicated to other standardizations such as wireless local area networks (WLAN). As both LTE and wireless fidelity (Wi-Fi) networks have been widely deployed with solid infrastructures, it is significantly important to make their coexistence viable with a cost-effective approach which inherently requires the minimum protocol modification. Thus, we take the advantage of spatially located multiple antennas of base station (BS) and access point (AP) for the sake of beamforming and interference reduction.
In addition to network coexistence, we approach the resource scarcity from the non-orthogonal multiple access (NOMA) point of view, where users share the frequency and time resources and are differentiated in power domain. In particular, we closely consider those users with limited number of RF chains. Similar to our first approach, we utilize spatial modulation (SM) in user end and after evaluating their performance, we propose to consider the capacity of SM NOMA to elaborate the impact of pairing on the achievable sum rate performance.
Zafari, Golara, "Performance Enhancement by Exploiting the Spatial Domain for Cost, Space and Spectrum Constraint 5G Communication" (2018). Electronic Thesis and Dissertation Repository. 5400.