The green ICT initiative: an IEEE-wide focus building upon ComSoc's leadership

This month's President's Page is devoted to the IEEE Green Information and Communications Technology (ICT) initiative. By its very nature, Green ICT is a theme, not only of interest but also offering numerous opportunities, for virtually every IEEE Society and Council. Through this initiative, ComSoc seeks an IEEE-wide outreach to achieve even greater recognition for IEEE's mission of advancing technology for humanity

Performance Evaluation of Multi-gigabit Indoor Visible Light Communication System

This paper presents a performance evaluation of a mobile multi-gigabit visible light communication (VLC) system in two different environments. The VLC channel characteristics and links were evaluated under the diverse situations of an empty room and a room with very strong shadowing effects resulting from mini cubicle offices. RGB laser diodes (LDs) were used to mitigate the low modulation bandwidth of conventional transmitters (light emitting diodes, LEDs) in the VLC system. In addition, an angle diversity receiver (ADR) was introduced to mitigate intersymbol- interference (ISI). Furthermore, a delay adaptation technique was used to further reduce the effect of ISI and multipath dispersion. The combination of delay adaptation and ADR (DAT ADR system) added a degree of freedom to the link design, which resulted in a VLC system that has the ability to provide high data rates (i.e. 5 Gbps) in the considered harsh indoor environment. Our proposed system used a simple on-off keying (OOK) modulation format and it was able to provide data rates of 5 Gbps and a bit-error-rate (BER) of 10-3 in the worst case scenario in the considered realistic indoor environment

High-Speed Indoor Visible Light Communication System Employing Laser Diodes and Angle Diversity Receivers

The two main challenges facing high data rate visible light communication (VLC) are the low modulation bandwidth of the current transmitters (i.e. light emitting diodes, LEDs) and the inter symbol interference (ISI) caused by multipath propagation. In this paper, we evaluate laser diodes (LDs) as a source of illumination and communication instead of LEDs for a VLC system in conjunction with an angle diversity receiver (ADR). The main advantage of using LDs is their high modulation bandwidth that enables communication at data rates of multi gigabits per second for VLC when using a suitable receiver, such as an ADR, which mitigates the ISI. Our proposed system uses simple on-off keying (OOK) modulation, and it is able to provide data rates of 5 Gbps and a bit-error-rate (BER) of 10-6 in the worst case scenario

Collaborative Adaptive Optical Wireless System in Realistic Indoor Environment

In this paper, we propose and evaluate a collaborative mobile optical wireless (OW) system that employs a collaborative adaptive beam clustering method (CABCM) in conjunction with an imaging receiver. Three cases involving two, three and five receivers are considered. A collaborative maximum ratio combining scheme is used to collaboratively distribute the transmit power among the diffusing spots. Our ultimate goal is to increase the received optical power and improve the signal-to-noise ratio (SNR) at each coexisting receiver when the system operates in a multiuser scenario under the constraints of background noise, multipath dispersion, mobility and shadowing typical in a real indoor environment. Our proposed system (collaborative adaptive beam clustering method) is evaluated at 30 Mbit/s to enable comparison with previous work, and is also assessed at higher bit rates: 2.5 Gbit/s and 5 Gbit/s. Simulation results show that the mobile CABCM system offers a significant performance improvement including a reduction in the background noise (BN) effect, a strong received power, reduction in delay spread, and improvement in the SNR over multiuser line strip multibeam system (LSMS). However, the performance degrades gradually with increase in the number of users

Optical wireless communication

Optical wireless communication has attracted significant interest recently in industry and academia. This special issue features a collection of inter-related papers with the intention to cover all necessary multidisciplinary challenges to realize optical wireless networks. We hope that this special issue will serve as a comprehensive reference and that it will be a resource which fosters many more new ideas for this rapidly emerging field

Antenna Beam Pattern Modulation with Lattice Reduction Aided Detection

This paper introduces a novel transmission design for antenna beam pattern modulation (ABPM) with a low complexity decoding method. The concept of ABPM was first presented with the optimal maximum likelihood (ML) decoding. However, an ML detector may not be viable for practical systems when the constellation size or the number of antennas is large such as in massive multiple input multiple output (MIMO) systems. Linear detectors, on the other hand, have lower complexity but inferior performance. In this paper, we present the antenna pattern selection with a lattice reduction (LR) aided linear detector for ABPM to reduce the detection complexity with the bit error rate (BER) performance approaching that of ML while conserving low complexity. Simulation results show that even with this suboptimal detection, performance gain is achieved by the proposed scheme compared to different spatial modulation techniques using ML detection. In addition, to validate the results, an upper bound expression for BER is provided for ABPM with ML detection

A Simple User Grouping and Pairing Scheme for Non-Orthogonal Multiple Access in VLC System

In this paper, a simple user grouping and pairing scheme is proposed for non-orthogonal multiple access (NOMA) and is applied for the downlink visible light communication (VLC) system. The proposed scheme is a mix of both NOMA and the conventional orthogonal multiple access (OMA) schemes. In the proposed scheme, every two users are paired using NOMA and all pairs are allocated with conventional OMA. The performance of the proposed scheme is compared to the performance of the conventional OMA in terms of the maximum sum rate. Simulation results show that the proposed scheme provides higher sum rate compared with the OMA scheme

LR based pre-coding aided spatial modulation with sub-optimal detection for V2X communications

In this manuscript, a novel transmit pre-coding matrix generation method and a linear decoding scheme are proposed for the generalised pre-coding aided spatial modulation (GPSM) system. The GPSM scheme proposed recently is a new multiple input multiple output (MIMO) transmission technique, which conveys information by activating a subset of receive antennas with the aid of transmit pre-coding. This scheme seems to be suitable in V2X since the base station only transmits data to certain users/vehicles. The proposed pre-coding matrix is based on the lattice reduction (LR) principle and provides significant performance improvement over the original pre-coding design in GPSM. Furthermore, as the GPSM in large-scale antenna systems, which is a trend in future communication systems, might be too complex to be implemented with the maximum likelihood (ML) detection, a linear decoding method is proposed to reduce the implementation complexity. Our studies show that the performance degradation caused by the linear detector can be compensated by the proposed LR based pre-coding. As a result, the LR based GPSM with linear detection is capable of achieving the comparable performance as that of the original GPSM scheme employing ML detection, while with significantly decreased detection complexity