Capacity and Gain Analysis of a Reconfigurable MEMS Antenna

in Nordic Conference on Radio Science and Communications (RVK) (2008)

Feedback design in multiuser MIMO systems using quantization splitting and hybrid instantaneous/statistical channel information

in Proceedings ICT Mobile and Wireless Communications Summit (2008)

In the design of next generation multiuser communication systems, multiple antenna transmission is an essential part providing spatial multiplexing gain and allowing efficient use of resources. A major ... [more ▼]

In the design of next generation multiuser communication systems, multiple antenna transmission is an essential part providing spatial multiplexing gain and allowing efficient use of resources. A major limiting factor in the resource allocation is the amount of channel state information (CSI) available at the transmitter, particularly in multiuser systems where the feedback from each user terminal must be limited. To this effect we propose two independent approaches for an efficient representation of the channel in multiuser MIMO systems. In the first approach, channel quantization is considered where the total number of feedback bits is limited. A resource allocation scheme is proposed where the available rate is split between the scheduling phase, where all users feed back a coarse CSI quantization, and the precoding phase where the selected receivers refine their CSI. The optimum splitting of the available feedback rate provides a large increase in performance and even simple heuristic splitting gives a noticeable advantage. In the second approach, we exploit a combination of instantaneous and statistical channel information. For spatially correlated Rayleigh and Ricean channels, it is shown that the CSI to large extent can be represented by the channel norm when the long-term channel statistics are known. Within a minimum mean square error (MMSE) estimation framework, feedback of a few bits of the quantized channel norm is sufficient to perform efficient resource allocation and achieve performance close to that of full CSI. [less ▲]

Statistical Analysis and Optimal Design for Efficient Mobile Satellite Broadcast With Diversity

in IEEE Transactions on Vehicular Technology (2008), 57(2), 9861000

Correlation properties of large scale fading based on Indoor measurements

in IEEE Wireless Communications and Networking Conference (2007)

Statistical channel models are attractive for their simplicity but sometimes lack in precision. In to improve modelling accuracy, statistical model parameters, which are dependent on the environment, are ... [more ▼]

Statistical channel models are attractive for their simplicity but sometimes lack in precision. In to improve modelling accuracy, statistical model parameters, which are dependent on the environment, are extended to include spatial and temporal correlation. In outdoor scenarios these parameters are assumed constant over large areas of several wavelengths hence the name large scale parameters. This paper studies the large scale fading (LSF) and the applicability of bringing this previously used outdoor variable to the indoor case. The impacts of the model of the LSF on the outdoor system-performance have been studied and several relevant models have been proposed for outdoor cases. We present the intra-site autocorrelation as well as the inter-site cross correlation of the LSF for an indoor channel. The results are based on two separate measurement campaigns conducted at KTH, Stockholm and TUI, Ilmenau, using a single mobile station (MS) and multiple base stations (BSs) to investigate such models. We observe that the areas under which the LSF could be assumed constant are, in indoor scenarios, so small that it can be assumed independent from one local area to another. Furthermore, we find results that point towards the existence of inter-site correlation in some specific scenarios. [less ▲]

Full Diversity Detection in MIMO Systems with a Fixed-Complexity Sphere Decoder

in Proceedings IEEE International Conference on Acoustics, Speech, and Signal Processing (2007)

Occupant Classification Using Range Images

in IEEE Transactions on Vehicular Technology (2007), 56(2)(4), 19831993

On Downlink Beamforming with Indefinite Shaping Constraints

in IEEE Transactions on Signal Processing (2006), 54(9), 35663580

System Evaluation of Optimal Downlink Beamforming with Congestion Control in Wireless Communication

in IEEE Transactions on Wireless Communications (2006), 5(4), 743751

Array Interpolation and DOA MSE Reduction

in IEEE Transactions on Signal Processing (2005), 53(12), 44644471

MIMO Channel Capacity and Modeling Issues on a Measured Indoor Radio Channel at 5.8 GHz

in IEEE Transactions on Wireless Communications (2005), 4(3), 895903