Mikhail Shilov

Performance analysis of dynamic adjustment of TDD uplink-downlink configurations in outdoor picocell LTE networks

The dynamic adjustment of TDD UL-DL configurations to the instantaneous traffic conditions at small cells (e.g. Pico cells) in heterogeneous LTE networks can be used to further optimize the system performance. The dynamic adaptation of TDD configuration may result in opposite transmission directions in the neighboring cells and thus cause BS-BS and UE-UE inter-cell interference that may significantly affect the overall system performance. To avoid this problem all homogeneous Macro cell TDD deployments typically operate synchronously. However in heterogeneous networks low power small cells are rather isolated from each other in terms of mutual interference and thus can be considered as candidates for dynamic TDD adaptation. In this paper we investigate the possibility of using dynamic adjustments of TDD UL-DL configurations in application to outdoor Pico cell deployments. In particular, we show the feasibility of using opposite DL and UL transmission directions in neighboring Pico cells in terms of interference environment. Furthermore we evaluate the performance benefits from traffic adaptation in LTE TDD networks where cells can dynamically select TDD configuration and show that substantial gains in packet throughput performance may be achieved comparing to the traditional synchronous TDD networks.

Analysis of IEEE 802.16m and 3GPP LTE Release 10 technologies by Russian Evaluation Group for IMT-Advanced

The IMT-Advanced standardization process is executed by International Telecommunications Union Radiocommunication Sector (ITU-R) to define requirements to the next 4-th generation mobile communication systems and certify technologies meeting these requirements. This work presents results of the IEEE 802.16m and 3GPP LTE Release 10 technologies evaluation obtained by the Russian Evaluation Group (REG) as part of the ITU-R IMT-Advanced standardization process. The evaluation was done mainly by system level simulations and considered four mandatory test environments of IMT-Advanced: indoor, microcellular, base coverage urban and high speed. Cell spectral efficiency and cell-edge user spectral efficiency were evaluated for downlink and uplink transmissions. It was found out that performance of both IEEE and 3GPP technologies meets the IMT-Advanced requirements for all the considered evaluation scenarios. This conclusion was conveyed by the REG to ITU in the evaluation report submitted in June 2010.

Performance analysis of spatial reuse mode in millimeter-wave WPAN systems with multiple links

This paper presents the results of the spatial reuse mode performance analysis for millimeter-wave (mmWave) WPAN systems with steerable high-directional antennas. The practical approach to the spatial reuse problem solution is proposed and two spatial scheduling algorithms for spatial reuse mode implementation are presented. The system level simulations are used to estimate the performance of the proposed algorithms. It is demonstrated that the introduction of the spatial reuse mode for the indoor mmWave WPAN system with 8 parallel communication links will increase the overall mmWave WPAN system throughput in 3-5 times in comparison with conventional time division mode.

Feasibility Analysis of Dynamic Adjustment of TDD Configurations in Macro-Femto Heterogeneous LTE Networks

The dynamic adaptation of TDD configurations to traffic conditions at low power base stations (femtocells and picocells) in heterogeneous LTE networks can be used to optimize the system performance. For instance, a significant performance improvement can be achieved in DL and UL packet throughputs. However, in practical multi-cell deployments the TDD configuration adaptation may result in opposite transmission directions in the neighboring cells and thus cause new types of inter-cell interference such as BS-BS and UE-UE. These interference types are often called DL-UL cross interference and may significantly deteriorate the overall system performance. For this reason all homogeneous Macro cell TDD deployments typically operate synchronously (i.e. use same TDD configurations). However the recent advances in the field of heterogeneous networks have reopened the dynamic TDD problem since low power small cells are rather isolated from each other and thus can be considered as candidates for dynamic TDD adaptation. In this paper we provide a feasibility analysis of dynamic TDD configuration adjustment in application to Macro-Femto LTE TDD networks.