Pedestrians effects on indoor MIMO-OFDM channel capacity

Temporal variations caused by pedestrian movement can significantly affect the channel capacity of indoor MIMOOFDM wireless systems. This paper compares systematic measurements of MIMO-OFDM channel capacity in presence of pedestrians with predicted MIMO-OFDM channel capacity values using geometric optics-based ray tracing techniques. Capacity results are presented for a single room environment using 5.2 GHz with 2x2, 3x3 and 4x4 arrays as well as a 2.45 GHz narrowband 8x8 MIMO array. The analysis shows an increase of up to 2 b/s/Hz on instant channel capacity with up to 3 pedestrians. There is an increase of up to 1 b/s/Hz in the average capacity of the 4x4 MIMO-OFDM channel when the number of pedestrians goes from 1 to 3. Additionally, an increment of up to 2.5 b/s/Hz in MIMO-OFDM channel capacity was measured for a 4x4 array compared to a 2x2 array in presence of pedestrians. Channel capacity values derived from this analysis are important in terms of understanding the limitations and possibilities for MIMO-OFDM systems in indoor populated environments

Effect of pedestrian movement on MIMO-OFDM channel capacity in an indoor environment

Effects of pedestrian movement on multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) channel capacity have been investigated using experiment and simulation. The experiment was conducted at 5.2 GHz by a MIMO-OFDM packet transmission demonstrator using four transmitters and four receivers built in-house. Geometric optics based ray tracing technique was used to simulate the experimental scenarios. Changes in the channel capacity dynamic range have been analysed for different number of pedestrian (0-3) and antennas (2-4). Measurement and simulation results show that the dynamic range increases with the number of pedestrian and the number of antennas on the transmitter and receiver array

Four-element ultrawideband textile cross array for dual-spatial and dual-polarization diversity

The emergence of miniaturized flexible electronics enables on-duty first responders to collect biometrical and environmental data through multiple on-body sensors, integrated into their clothing. However, gathering these life-saving data would be useless if they cannot set up reliable, preferable high-data-rate, wireless communication links between the sensors and a remote base station. Therefore, we have developed a four-element ultrawideband textile cross array that combines dual-spatial and dual-polarization diversity and is easily deployable in a first responder's garment. The impedance bandwidth of the array equals 1.43 GHz, while mutual coupling between its elements remains below -25 dB. For a maximal bit error rate of 1e-4, the array realizes a diversity gain of 24.81 dB. When applying adaptive subcarrier modulation, the mean throughput per orthogonal frequency division multiplexing (OFDM) subcarrier increases by an extra bit/symbol when comparing fourth- to second-order diversity

A pattern reconfigurable U-slot antenna and its applications in MIMO systems

A new compact pattern reconfigurable U-slot antenna is presented. The antenna consists of a U-slot patch and eight shorting posts. Each edge of the square patch is connected to two shorting posts via PIN diodes. By switching between the different states of the PIN diodes, the proposed antenna can operate in either monopolar patch or normal patch mode in similar frequency ranges. Therefore, its radiation pattern can be switched between conical and boresight patterns electrically. In addition, the plane with the maximum power level of the conical pattern can be changed between two orthogonal planes. Owing to a novel design of the switch geometry, the antenna does not need dc bias lines. The measured overlapping impedance bandwidth of the two modes is 6.6% with a center (S/ 11/<frequency of 5.32 GHz. The measured radiation patterns agree well with simulated results. The antennas are incorporated in a 2×2 multiple-input-multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system to demonstrate the improvement in system capacity. In the real-time MIMO-OFDM channel measurement, it is shown that compared to omnidirectional antennas, the pattern reconfigurable antennas can enhance the system capacity, with 17% improvement in a line-of-sight (LOS) scenario and 12% in a non-LOS (NLOS) scenario at a signal-to-noise ratio (SNR) of 10 dB. © 2011 IEEE

Characteristics of MIMO-OFDM Channels in Indoor Environments

<p/> <p>We present the results of multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) channel measurements. The measurements were performed in indoor environments using four transmitters and four receivers with 40 MHz bandwidth at 5.25 GHz. Our measurements reveal two-dimensional small-scale fading, and correlation between MIMO subchannels. In the line-of-sight (LoS) case, the MIMO-OFDM channel capacity is found to be strongly dependent on the local scattering environment; and much less dependent in the non-LoS (NLoS) case. Also, MIMO channel capacity is found to be largely uncorrelated over 20 MHz in NLoS, while a strong correlation is found over 40 MHz in some LoS environments. The validity of the conventional Kronecker correlation channel model is tested, along with a recently proposed joint correlation model. The effects of varying antenna element spacing are also investigated, taking into account such effects as mutual coupling, radiation efficiency, and radiation pattern.</p

Research Article Characteristics of MIMO-OFDM Channels in Indoor Environments

We present the results of multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) channel measurements. The measurements were performed in indoor environments using four transmitters and four receivers with 40 MHz bandwidth at 5.25 GHz. Our measurements reveal two-dimensional small-scale fading, and correlation between MIMO subchannels. In the line-of-sight (LoS) case, the MIMO-OFDM channel capacity is found to be strongly dependent on the local scattering environment; and much less dependent in the non-LoS (NLoS) case. Also, MIMO channel capacity is found to be largely uncorrelated over 20 MHz in NLoS, while a strong correlation is found over 40 MHz in some LoS environments. The validity of the conventional Kronecker correlation channel model is tested, along with a recently proposed joint correlation model. The effects of varying antenna element spacing are also investigated, taking into account such effects as mutual coupling, radiation efficiency, and radiation pattern. Copyright © 2007 Hajime Suzuki et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1