Mythri Hunukumbure

Efficient Multielement Ray Tracing With Site-Specific Comparisons Using Measured MIMO Channel Data

In this paper, an advanced site-specific image-based ray-tracing model is developed that enables multielement outdoor propagation analysis to be performed in dense urban environments. Sophisticated optimization techniques, such as preprocessing the environment database using object partitioning, visibility determination, diffraction image tree precalculation, and parallel processing are used to improve run-time efficiency. Wideband and multiple-input-multiple-output (MIMO) site-specific predictions (including derived parameters such as theoretic capacity and eigenstructure) are compared with outdoor site-specific measurements at 1.92 GHz. Results show strong levels of agreement, with a mean path-loss error of 2 dB and a mean normalized-capacity error of 1.5 b/s/Hz. Physical-layer packet-error rate (PER) results are generated and compared for a range of MIMO-orthogonal frequency-division-multiplexing (OFDM) schemes using measured and predicted multielement channel data. A mean Eb/N 0 error (compared to PER results from measured channel data) of 4 and 1 dB is observed for spatial-multiplexing and space-time block-code schemes, respectively. Results indicate that the ray-tracing model successfully predicts key channel parameters (including MIMO channel structure) and thus enable the accurate prediction of PER and service coverage for emerging MIMO-OFDM networks such as 802.11n and 802.16e

MIMO Channel Measurements and Analysis with Prototype User Devices in a 2GHz Urban Cell

This paper describes an outdoor MIMO measurement campaign conducted in the 2 GHz band employing a sounding bandwidth of 20 MHz. The study aimed to compare the MIMO performance of two prototype devices with a reference dipole antenna module. The results obtained reveal a systematic blocking of one of the PDA antenna ports with the users thumb alongside a significant reduction in the available MIMO channel capacity. The laptop MIMO enabled device was found to offer good MIMO capacity enhancement, matching the performance achieved with the dipole antennas

5G systems: The mmMAGIC project perspective on use cases and challenges between 6–100 GHz

mmMAGIC (Millimetre-Wave Based Mobile Radio Access Network for Fifth Generation Integrated Communications) is an EU funded 5G-PPP project, whose overall objective is to design and pre-develop a mobile radio access technology (RAT) operating in the 6–100 GHz range, capable of impacting standards and other relevant fora. The focus of the project is on extreme Mobile Broadband, which is expected to drive the 5G requirements for massive increase in capacity and data-rates. This paper elaborates on some 5G key research areas such as: identification of the most compelling use-cases and Key Performance Indicators (KPIs) for future 5G systems, advantages and challenges of millimeter-wave (mmWave) technologies, channel measurements and channel modeling, network architecture; and the design of a new mobile radio interface including multi-node and multi-antenna transceiver architecture.

The Effect of Computation and Feedback Delay on the Capacity of Multiuser MIMO Systems in a Small Outdoor Cell

This paper examines how the capacity of three multiuser multiple-input multiple-output (MIMO) algorithms is affected by a delay in computing and feeding back the transmit (and receive) weighting matrices used by the algorithms. Iterative schemes determining transmit weights that achieve the system-wide Nash equilibrium (NE) or block-diagonalization (BD) of the overall system channel matrix are compared as is a scheme applying successive diagonalization (SD) among users. The NE is found to be far the most robust to out-of-date channel information, whilst SD is found to suffer badly at even the shortest delay considered here (about 0.9 ms); BDs losses vary over a wide range depending on the delay. For the two iterative algorithms we also examine the tradeoff between better convergence and less delay. In both cases, the loss in capacity for weaker convergence is very small, and so it is desirable to minimize the delay and thus the capacity loss caused by it

Down-link beamforming effects on the code orthogonality in UTRA-FDD systems

A novel approach in quantifying code orthogonality factor for UTRA-FDD systems is extended in this paper to include the impact of down-link beamforming. The effects of fixed beamforming on code orthogonality is analysed through the aid of real channel data taken from urban cellular environments. The results show a significant overall improvement in code orthogonality with beamforming, especially in the case of an urban large cell.

Millimeter Wave LOS Coverage Enhancements with Coordinated High-Rise Access Points

Millimetre wave (mm-wave) communication is considered as one of the most important enablers for the fifth generation communication (5G) system to support data rate of Gbps and above. In some scenarios, it is crucial to maintain a line of sight (LOS) link for users enjoying 5G immersive experiences and thus requiring very high data rate. In this paper, we investigate the LOS probability in mm-wave systems. In particular, we study the impact of access point (AP) and blockage height on the LOS probability and propose a solution to effectively enhance the LOS coverage by using high-rise APs on top of low-rise APs normally installed on street furniture, e.g., lamp poles. Two deployment options are explored: 1) irregular deployment and 2) regular deployment, where LOS probability is derived for both cases. Simulation results show that the impact of AP height on LOS probability is significant and using coordinated high-rise APs jointly deployed with low-rise APs will substantially improve the LOS probability.