Capacity Analysis for Compact MIMO Systems

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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“…1: the S-parameter (e.g. [12], [16], [20], [23]- [24]) and the more conventional Zparameter (e.g. [10], [11], [15], [18], [27]).…”

Section: A Mimo System Modelmentioning

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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“…11(a) the 3D graph of these quantities based on results in Figs. [8][9][10]. Each data point corresponds to a load impedance Z L .…”

Section: Relationship Between Output Correlation Received Power Amentioning

confidence: 99%

“…On the other hand, the so-called multiport conjugate match is able to retain both zero output correlation and 100% efficiency for any antenna separation [5], [9]. However, this ideal behaviour can only be achieved in a narrow frequency band, in the limit of small antenna separation, due to basic limitations in matching network [9], [10] .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On Closely Coupled Dipoles with Load Matching in a Random Field

Lau

Andersen

2006

2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications

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MIMO is a wireless communication technology that is growing in popularity due to its ability to deliver significant improvements over conventional systems. However, some applications require antennas to be closely spaced, which results in strong coupling among the antennas and performance degradation. Here we show that in a random field, load impedance can play an important role in the power, correlation and capacity performance of MIMO systems. While a good choice of load impedance can alleviate the loss of power and correlation performance, capacity performance is less sensitive to load variation. Moreover, the phase component of open circuit correlation has been found to have a significant influence on MIMO performance, indicating that important information is lost if it is neglected. A comparison between the performance metrics over different load impedances indicates that capacity depends largely on received power and not correlation.

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“…For the simulation and design of a MIMO system, precise knowledge about the channel matrix H is needed. Numerous MIMO channel models have been proposed to characterize the complicated propagation environments [9][10][11][12][13][14], such as statistical models and site-specific models based on ray tracing. The usual statistical channel models include the Rayleigh fading channel model for non-line-of-sight scenarios and the Rician fading channel model for line-of-sight scenarios.…”

Section: Introductionmentioning

confidence: 99%

Multi-Antenna Information Theory

Geyi¹

2007

PIER

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Abstract-It is well known that the performance of a wireless multiple-input and multiple-output (MIMO) system depends on the propagation channel. The propagation channel models can generally be divided into two different groups, the statistical models based on information theory and the site-specific models based on measurement or ray tracing. In this paper, a general procedure for predicting the MIMO channel model has been presented. Analytical expressions for the channel matrix elements in a general scattering environment have been derived from the statistical theory for a narrow-band electromagnetic field, and have been verified by numerical simulation and experiments. The limitations of information capacity of the MIMO wireless communication system imposed by the antennas have also been discussed, and analytical upper bounds on the information capacity in terms of the antenna parameters for multiple antenna system in free space have been obtained. Once the capacity of a MIMO system is specified, these upper bounds can serve as a criterion for estimating how many antennas are needed or how big the antenna must be to achieve the capacity.

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Capacity Analysis for Compact MIMO Systems

Cited by 25 publications

References 20 publications

Antenna Matching for Capacity Maximization in Compact MIMO Systems

Antenna Matching for Capacity Maximization in Compact MIMO Systems

On Closely Coupled Dipoles with Load Matching in a Random Field

Multi-Antenna Information Theory

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