Dr. Asif Gandhi of Alcatel-Lucent

ABSTRACT: This paper focuses on the impact of antenna down tilt for closely placed cells. The results show the need for small to no down tilt in coverage-limited scenarios, otherwise (for the case of close placement of cells), down tilt improves performance significantly. The most important conclusion of this study is that there is a large gain in downlink coverage and capacity due to down-tilting to the correct range of values; in fact, without the correct down tilt, all the gain in coverage due to the close placement of cells is lost. The simulations demonstrate that all in-building penetration advantage (up to 40 dB for the examples simulated in this paper) and up to 60% of the capacity can be lost if the tilts are off by 4° to 5° from the optimal for closely placed cells. In-building coverage is one of the challenges for current cellular systems, and it is shown that the same range of down tilt is optimal whether the users are in-building or on-street; hence the concern that down tilt will reduce in-building coverage is demonstrated as in-accurate for closely placed cells.

Another question that this paper addresses is: Are the down tilts which have been optimized for 3G systems also optimal for the 4G system? It is shown that the tilts that are optimal for 3G and voice systems are very good (if not optimal, at least near optimal) for the 4G LTE system. The simulations show that optimal down tilts can substantially reduce the number of basestations (and hence capital investment) needed from the point of view of capacity. Given the capacity constraints in 4G LTE systems, the study suggests that antenna design and down tilts must receive much more than nominal focus for urban areas.

Biography:

BIOGRAPHY: ASIF D. GANDHI is a distinguished member of technical staff in Alcatel-Lucent's Wireless Business Unit. His current focus is on CDMA/EVDO and OFDMA technologies, and he has been the customer technical prime for a Tier 1 customer since the last 2 years. He has led several cross-functional teams to solve complex technical problems in CDMA systems. He specialized expertise is in the area of RF performance, capacity, and coverage of wireless systems. He holds more than 15 U.S. patents and has several other patents pending, all in the area of wireless technologies. Several of these innovations have found their way into Alcatel-Lucent CDMA and UMTS products. Dr. Gandhi has published several journal and conference papers and numerous technical memorandums on the above topics, and is the author of a chapter in the book, “Handbook of CDMA System Design, Engineering and Optimization.” He received his bachelor of technology (B. Tech.) degree in electrical engineering from the Indian Institute of Technology (IIT), Mumbai, India, and an M.S. and Ph.D. in electrical and computer engineering from the University of Massachusetts, Amherst.

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Address:DMTS, Alcatel-Lucent, 600 Mountain Avenue, New Providence, NJ, United States, 07974

Dr. Asif Gandhi of Alcatel-Lucent

Biography:

Address:New Providence, NJ, United States