Report itu-r m. 2038 Technology trends
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- 8 Conclusions
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7 Implementation issuesThe introduction of MIMO techniques into wireless communication systems introduces a number of implementation challenges. At the BS the greatest impact is likely to be in the increased RF and cabling requirements due to the increased number of transmit/receive antenna elements until more integrated antenna, receiver, transmitter structures are developed. The greatest challenges, however, lie within the terminal where the size, power and cost constraints must be overcome. Research initiatives must address the viability of terminals employing MIMO or diversity techniques, with particular emphasis being placed on maximizing the performance of the terminal antenna system in realistic macrocellular deployment scenarios and within the restricted form factors of future terminals such as laptops, PDAs and handsets. Key challenges will include the design of antennas with low correlation within such a confined space and good performance in realistic indoor and outdoor nomadic and mobile propagation environments and the difficulties of minimizing interactions between different functions within the terminal (EMC). Diverse terminal antennas have already been investigated for various form factors, including picocell base units [Smith et al., 1997 and 1999] and fixed wireless access terminals [Kitchener and Smith, 1998]. In the first two cases the antennas are purely internal to a standard housing, while in the third the terminal form factor was adapted to enable best antenna performance. Both of these approaches are options for future implementations of diverse/MIMO terminal antennas. In the context of a free-standing terminal, e.g. a laptop, an important aspect is whether the terminal antenna elements are flat on a table (e.g. in the base unit) or vertically oriented (in the display), and making the design robust against several deployments is part of the challenge [Smith et al., 1997 and 1999]. A key element in the development of MIMO antenna systems is optimization of the design to work in the MIMO propagation channels of the target deployment scenarios. The MIMO propagation channel is a current study area in both 3GPP and 3GPP2 standards organizations, with a series of submissions from various companies. Also, the COST 259 5 research project team has used various propagation measurement results to arrive at an outdoors-to-outdoors channel model, and COST 273 6 aims to extend this work, with subgroup activities including MIMO systems, handset antennas, channel measurements and channel modelling. It is expected that ongoing research by the industry will yield results in the following areas: – MIMO propagation channel models for macro-, micro-, and picocellular deployment scenarios which are sufficiently detailed to allow theoretical evaluation of MIMO/diversity terminal antenna configurations. – Generic antenna system designs for laptops, PDAs, stand-alone units, and handsets.
– Designing efficient signal processing algorithms and associated coding schemes which achieve much of the capacity gains allowed by the theory, but which can be implemented with much lower levels of processing power [Ariyavisitakul, 2001]. There are clearly substantial implementation issues to be solved before MIMO techniques can used to increase the capacity of mobile communication networks. However, it is useful to consider the complexity of achieving high data rates within the same channel bandwidth using conventional high order modulation schemes. For a MIMO link using [4,4] antennas and 4 state modulation the equivalent single channel link would need to use a 256-point modulation constellation for the same symbol rate. With a not unreasonable 16-point modulation on the [4,4] MIMO system it would be necessary to implement a somewhat unrealistic 4 096 point modulation on the single high-speed channel.
CATREUX, S., DRIESSEN, P. F. and GREENSTEIN, L. J. [August 2001] Attainable Throughput of an Interference-Limited Multiple-Input Multiple-Output (MIMO) Cellular System. IEEE Trans. Comm., Vol. 49, 8, p. 1307-1311. FOSCHINI, G. J. [Autumn 1996] Layered Space-Time Architecture for Wireless Communications in a Fading Environment When Using Multi-Element Antennas. Bell Labs Tech. J. p. 41 59. FOSCHINI, G. J. and GANS, M. J. [1998] On Limits of Wireless Communications in a Fading Environment when Using Multiple Antennas. Wireless Personal Comm., 6, p. 315-335. FOSCHINI, G. J., GOLDEN, G. D., VALENZUELA, R. A. and WOLNIANSKY, P. W. [November 1999] Simplified processing for high spectral efficiency wireless communication employing multi-element arrays. IEEE J. Selected Areas in Comm., Vol. 17, p. 1841-1851. KITCHENER, D. and SMITH, M. S. [24 February 1998] Low cost antennas for mobile communications. Proc. IEE Colloquium 1998/206 on «Low cost antenna technology». RALEIGH, G. G. and CIOFFI, J. M. [March 1998] Spatio-Temporal Coding for Wireless Communications. IEEE Trans. Comm., Vol. 46, 3, p. 357-366. SHAFI, M. and SMITH, P. J. [January 2002] MIMO Capacity in Rician Fading Channels and its Relationship to the K Factor. IEEE Trans. Lett. Comm. SMITH, M. S., BUSH, A. K., GWYNN, P. G. and AMOS, S. V. [September 1999] Microcell and Picocell base station internal antennas. Proc. WCNC 99, p. 708, New Orleans, United States of America. SMITH, M. S., KITCHENER, D. K., DALLEY, J. E. J. and THOMAS, R. R. [April 1997] Low cost diversity antennas for low power wireless base stations. Proc. ICAP 97, p. 1.445, Edinburgh, United Kingdom. SMITH, P. J. and SHAFI, M. [August 2001] On a Gaussian Approximation to the Capacity of Wireless MIMO Systems. IEEE Trans. Comm. SMITH, P. J. and SHAFI, M. [2002a] Water Filling Methods for MIMO Systems. Proc. of 3rd AusCTW, (4-5 February) Canberra, Australia. SMITH, P. J. and SHAFI, M. [2002b] On a Gaussian Approximation to the Capacity of Wireless MIMO Systems. Conference Proc., ICC 2002, (April 2002). New York, United States of America. TELATAR, E. I. [November 1999] Capacity of Multi-Antenna Gaussian Channels. Euro Trans. Telecom. Vol. 10, p. 585-595. Directory: dms pub -> itu-r -> opb -> rep rep -> Report itu-r m. 2243 (11/2011) rep -> Report itu-r bt. 2053-2 (11/2009) L rep -> Report itu-r sa. 2312-0 (09/2014) rep -> Report itu-r rep -> Report itu-r sm. 2179 (09/2010) Short-range radiocommunication devices measurements rep -> Report itu-r rep -> Report itu-r rs. 2194 (10/2010) rep -> Report itu-r rs. 2165 (09/2009) rep -> Rep. Itu-r bs. 2104 Download 490.99 Kb. Share with your friends:
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