Experimental Evaluation of Layout Designs for 3 × 3 MIMO-Enabled Radio-Over-Fiber Distributed Antenna Systems

• Published in: IEEE transactions on vehicular technology 2014-02, Vol.63 (2), p.643-653
• Main Authors: GORDON, George S. D, CRISP, Michael J, PENTY, Richard V, WHITE, Ian H
• Format: Article
• Language: English
• Subjects: Antennas; Applied sciences; Broadband; Channels; Design engineering; Electrical engineering. Electrical power engineering; Electrical power engineering; Exact sciences and technology; Indoor; Information, signal and communications theory; Multiplexing; Optical fiber communications; Optical telecommunications; Power networks and lines; Radiocommunications; Signal and communications theory; Stations; Streams; Telecommunications; Telecommunications and information theory; Users connections and in door installation; Wireless networks
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2013.2276764

This paper experimentally demonstrates that, for two representative indoor distributed antenna system (DAS) scenarios, existing radio-over-fiber (RoF) DAS installations can enhance the capacity advantages of broadband 3 [Formula Omitted] 3 multiple-input-multiple-output (MIMO) radio services without requiring additional fibers or multiplexing schemes. This is true for both single- and multiple-user cases with a single base station and multiple base stations. First, a theoretical example is used to illustrate that there is a negligible improvement in signal-to-noise ratio (SNR) when using a MIMO DAS with all [Formula Omitted] spatial streams replicated at [Formula Omitted] RAUs, compared with a MIMO DAS with only one of the [Formula Omitted] streams replicated at each RAU for [Formula Omitted]. It is then experimentally confirmed that a 3 [Formula Omitted] 3 MIMO DAS offers improved capacity and throughput compared with a 3 [Formula Omitted] 3 MIMO collocated antenna system (CAS) for the single-user case in two typical indoor DAS scenarios, i.e., one with significant line-of-sight (LOS) propagation and the other with entirely non-line-of-sight (NLOS) propagation. The improvement in capacity is 3.2% and 4.1%, respectively. Then, experimental channel measurements confirm that there is a negligible capacity increase in the 3 [Formula Omitted] 3 configuration with three spatial streams per antenna unit over the 3 [Formula Omitted] 3 configuration with a single spatial stream per antenna unit. The former layout is observed to provide an increase of [Formula Omitted]1% in the median channel capacity in both the single- and multiple-user scenarios. With 20 users and three base stations, a MIMO DAS using the latter layout offers median aggregate capacities of 259 and 233 bit/s/Hz for the LOS and NLOS scenarios, respectively. It is concluded that DAS installations can further enhance the capacity offered to multiple users by multiple 3 [Formula Omitted] 3 MIMO-enabled base stations. Further, designing future DAS systems to support broadband 3 [Formula Omitted] 3 MIMO systems may not require significant upgrades to existing installations for small numbers of spatial streams.