Adaptive antennas for GSM and TDMA systems

Anderson, S.; Hagerman, Bo; Dam, Henrik; Forssen, U.; Karlsson, Jonas; Kronestedt, Fredric; Mazur, S.; Molnar, K.J.

doi:10.1109/98.772980

Cited by 48 publications

(21 citation statements)

References 15 publications

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“…However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. INTRODUCTION Although multiple antenna technology has been around for over half a century, its usage has been limited to physically large systems such as ground based radar systems and cellular base stations [1], [2]. One critical barrier to its implementation in compact systems is the problem of high signal correlation among antennas that are packed into a small (in wavelength units) spatial volume.…”

mentioning

confidence: 99%

Antenna Matching for Capacity Maximization in Compact MIMO Systems

Lau

Andersen

Molisch

et al. 2006

2006 3rd International Symposium on Wireless Communication Systems

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Abstract-As MIMO technology slowly matures, it is finding its way into more wireless applications. However, some important applications, including mobile communications, require compact implementations. One important challenge in miniaturizing MIMO systems for compact terminals is to overcome capacity performance degradation resulting from mutual coupling among closely separated antennas. In this contribution, we begin with a review of the state-of-the-art, with particular emphasis on impedance matching and its impact on capacity. Whereas it has been shown that a multiport extension of the conjugate match is optimum in a reference environment with uniform 3D angular power spectrum, its bandwidth is severely reduced by decreasing antenna separation. On the other hand, noncoupled, individual port matching is inherently simpler to implement and broader in bandwidth, but offers a smaller capacity. Here, we demonstrate that mean capacity can be easily maximized with respect to individual port matching in a given random field. The extent of capacity gains provided by the optimized matching network over existing individual port matching networks strongly depends on the propagation environment.

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mentioning

confidence: 99%

Antenna Matching for Capacity Maximization in Compact MIMO Systems

Lau

Andersen

Molisch

et al. 2006

2006 3rd International Symposium on Wireless Communication Systems

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“…Finally, some concluding remarks are summarized in Section 4. [4]. The aim in an adaptive antenna array system is to replace the conventional sector antenna by two or more closely spaced antenna elements.…”

Section: Introductionmentioning

confidence: 99%

“…Under some assumptions, for example a uniform linear array where the antenna elements are separated by a half wavelength, there is a one-toone correspondence between a certain direction-of-arrival (DOA) of an incoming wave front and the phase shift of the signals at the output of the antenna elements. Thus, appropriately shifting the signals prior to transmission (or reception), an adaptive antenna system is capable of steering the radiated energy toward (or from) the desired user, while at the same time minimize the interference to other users [4].…”

Section: Introductionmentioning

confidence: 99%

System Performance of Transmit Diversity Methods and a Two Fixed-Beam System in WCDMA

Osseiran

Logothetis

2004

Wireless Pers Commun

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Downlink transmit diversity modes for WCDMA together with a two fixed-beam antenna array system are compared relative to the single antenna sectorized system in a radio network simulator. The transmit diversity methods investigated are: space-time transmit diversity and closed-loop mode I transmit diversity. Frequency selective (COST 259) and flat fading channels are considered and their impact to speech-only and data-only services is evaluated. A third service, which highlights the system performance of the various advanced antennas, is also investigated.The results in this investigation point out that the diversity gain in flat fading channels is substantial. In frequencyselective fading, the benefits of fixed beam systems is encouraging, whereas transmit diversity methods (especially Space-Time Transmit Diversity) is unsatisfactory.

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“…For mobile communications, the first step to apply this technology was taken at the introduction of diversity reception at base stations. This was later followed by the so-called smart antennas or adaptive antennas, which relies on array beamforming techniques to achieve system performance improvements [1]. Both these techniques are only implemented at the base station side, since the complexity was considered to be too high for mobile terminals, and the improved performance was already "good enough" at the time.…”

Section: Introductionmentioning

confidence: 99%

Unleashing multiple antenna systems in compact terminal devices

Lau

Andersen

2009

2009 IEEE International Workshop on Antenna Technology

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ABSTRACT:The effective use of multiple antenna systems in compact terminal devices is plagued by the problems of mutual coupling and spatial correlation. Consequently, increasing the number of antennas per unit volume results in rapidly diminishing returns after an upper limit is reached. We review recent advances on this topic of closely coupled antennas, including several existing techniques that may be used to push the boundary further, such that closely spaced antennas can still give good performance. A new approach of decoupling closely spaced antennas is also introduced.

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Adaptive antennas for GSM and TDMA systems

Cited by 48 publications

References 15 publications

Antenna Matching for Capacity Maximization in Compact MIMO Systems

Antenna Matching for Capacity Maximization in Compact MIMO Systems

System Performance of Transmit Diversity Methods and a Two Fixed-Beam System in WCDMA

Unleashing multiple antenna systems in compact terminal devices

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