This paper proposes the design of a symbol block interleaver in the time domain for the Single Carrier (SC) modulation. The interleaver scheme is intended to sufficiently improve the system performance during transmission of the high-order Quadrature Amplitude Modulation (QAM) constellations. Considered interleaver configurations are compared by the realized Signal-to-Noise Ratio (SNR) gains in two None-Line-of-Sight (NLoS) channel models: the Rayleigh model and the IEEE 802.11ad channel model. The proposed interleaver allows to achieve the SNR gain of up to 2.6 dB for 64-QAM while keeping low implementation complexity. This solution is already adopted by the IEEE 802.11ay standardization group. In addition, the interleaver design considers permutation of groups of symbols (rather than bits) that facilitates easy parallel hardware implementation.

This paper considers Universal Terrestrial Radio Access (UTRA) High Speed Packet Access (HSPA) Heterogeneous Networks (HetNet). A problem of the downlink-uplink (DL-UL) imbalance is explored which consists in serving the UL transmission by the strongest Node B in DL not being the strongest one in UL. This causes UL system capacity degradation as well as gives rise to potential problems with inter-cell interference control. The analysis performed in the paper demonstrated that the Soft Handover (SHO) mechanism available in HSPA and assuming simultaneous reception of the UL signal by a set of Nodes B, though not designed intentionally, can partially mitigate the DL-UL imbalance impact. However, some additional aspects of the problem remain such as the scheduling information reception reliability deterioration leading to inability to perform efficient UL scheduling. A novel method of the Enhanced Dedicated Channel (E-DCH) decoupling intended for comprehensive resolution of the DL-UL imbalance problems is proposed. The method consists in moving the UL serving cell functionality for users in SHO between a macro Node B and a Low Power Node (LPN) to the LPN, while keeping the DL serving cell functionality at the macro Node B. System level simulation results provided in the paper demonstrate that the E-DCH decoupling allows to compensate the negative impacts of the DL-UL imbalance in HSPA HetNet and achieve efficient system operation.

The stadium environment represents one of the tougher environments for cellular systems given the extreme density of users and the potential for a large amount of uplink traffic. This paper presents the design and evaluation of 2D antenna arrays employed with azimuth and elevation sectorization in the stadium environment to improve the 3GPP LTE mobile network performance. A typical stadium model is introduced and different deployment options for a 2D antenna array with multiple sector beams are considered. It is found that only 2 to 4 antenna sites are sufficient to provide effective stadium coverage with up to 44 parallel spatially multiplexed sectors by using the antenna arrays consisting of 10×16 (elevation × azimuth) cross-polarized antenna element pairs. For more efficient performance the beams of each antenna array should be oriented towards the nearest stadium stands under the antenna suspension point. Using the results of system-level simulations it is estimated that the spectral efficiency of the stadium deployment can be up to 1.5-1.8 bit/s/Hz/sec resulting in the overall throughput of up to 1.5 Gbit/s which should be sufficient to provide the connectivity for tens of thousands people attending the stadium events.

The latest 3GPP Rel-11 is characterized by a number of new features, where a few of them specifically address UE performance at the cell edge. In particular, uplink CLTD aims at reducing the UE transmission power, and/or improving the received SINR, by steering a transmission beam towards the base station based by sending appropriate feedback information. At the same time, the downlink Multiflow improves noticeably the cell edge performance as a UE receives simultaneously data from two neighboring cells. What remains unclear and is still under study, is the overall system behavior when these features are combined together. Furthermore, there is a special interest in providing the CLTD feedback from the so-called Multiflow assisting cell, which can mitigate the link imbalance and enable Multiflow operation for larger handover areas.

Modern evaluation methodologies for system level simulations of mobile radio networks (e.g., [1]) support modeling systems with multiple simultaneously operating base stations and mobile devices where accurate simulation of multi-user MIMO and other space-time signal processing techniques should be provided. To be able to predict realistic performance, such models introduce a number of channel parameters with complex auto- and cross-correlation properties. Particularly, such models include a set of large-scale parameters (tap delay spread, angular spreads of rays at the base station and mobile station sides, shadow fading, etc.) being cross-correlated as well as auto-correlated in the spatial domain (across the deployment area) with different correlation functions. This paper is devoted to a method for accurate generation of correlated channel parameters during a simulation based on filtering of the parameters defined in the nodes of a spatial grid. The proposed method combines formal mathematical exactness at least in the asymptotic case and a much lower computational complexity in comparison with existing solutions [2]. Method description, analytical derivation, implementation details and verification by numerical simulations for an exemplary deployment scenario are provided in the paper. The described method may be recommended for application in system level simulators for 3G and 4G mobile radio access networks such as WCDMA HSPA, IEEE 802.16m, LTE-A.

In this work, MIMO extensions to the existing HSUPA system are presented and evaluated. Three candidate MIMO enhancement architectures are proposed that differ with respect to the principles of code word mapping onto the two spatial streams for rank-2 transmission. The evaluation demonstrates MIMO throughput gains relative to SIMO ranging between 30% and 40%. The MIMO architecture with independent transmission of two code words over the two spatial channels is demonstrated to be the most effective because of its ability independently to adapt the data rate on each spatial channel to the instantaneous channel conditions. The gains are realized at high RoT (rise over thermal) values, indicating isolated small cells with low UE densities as the likely deployment scenario for HSUPA MIMO.

This paper presents a detailed analysis of the impact of power amplifier (PA) non-linearity on the performance of single carrier (SC) and OFDM systems in 60 GHz spectrum. The efficiency of the considered systems was analyzed by estimating values of the power amplifier output backoff needed to meet the requirements on the transmit spectrum mask (TSM) compliance and error vector magnitude (EVM). Different models of the PA including an experimentally measured model for the 60 GHz PA were considered. It was estimated that for many types of modulations and PA models, SC system can have up to 1.5 dB higher output power than OFDM system. However, for the experimental PA model accounting for amplitude modulation-phase modulation distortion in addition to amplitude modulation amplitude modulation distortion, the difference between the OFDM and SC output power levels was minimal, and OFDM even had approximately 1 dB better performance than SC for the BPSK modulation. A potential improvement in the transmit power due to application of digital predistortion techniques was estimated for both systems to be in the range from 1.5 to 3.4 dB.

This paper presents the results of an experimental investigation of 60 GHz wireless local area network (WLAN) systems in an office environment. The measurement setup with highly directional mechanically steerable antennas and 800 MHz bandwidth was developed and experiments were performed for conference room and cubicle environments. Measurement results demonstrate that the 60 GHz propagation channel is quasioptical in nature and received signal power is obtained through line of sight (LOS) and reflected signal paths of the first and second orders. The 60 GHz WLAN system prototype using steerable directional antennas with 18 dB gain was able to achieve about 30 dB baseband SNR for LOS transmission, about 15-20 dB for communications through the first-order reflected path, and 2-6 dB SNR when using second-order reflection for the office environments. The intra cluster statistical parameters of the propagation channel were evaluated and a statistical model for reflected clusters is proposed. Experimental results demonstrating strong polarization impact on the characteristics of the propagation channel are presented. Cross-polarization discrimination (XPD) of the propagation channel was estimated as approximately 20 dB for LOS transmission and 10-20 dB for NLOS reflected paths.

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.

The novel CORDIC-based architecture of the triangular systolic array for QRD of large size complex matrices is presented. The proposed architecture relies on QRD using a three angle complex rotation approach that provides significant reduction of latency (systolic operation time) and makes the QRD in such a way that the upper triangular matrix R has only real diagonal elements.