Ali Maiga

Very high bit rate power line communications for home networks

Power line communications (PLC) has become a viable local area network (LAN) solution for in-home networks. PLC systems can be used in a wide variety of applications requiring high data rate. Therefore, there is a need to achieve an extremely high bit rate. In this paper, the increase in current technology bandwidth up to 100 MHz is investigated. Furthermore, a fast computational resource allocation algorithm is also developed for linear precoded discrete multitone (LP-DMT), which enables reliable high bit rate under peak BER constraint. Simulations are run over PLC channels and it is highlighted that 1 Gbit/s transmission is achievable and it is also shown that peak BER constraint algorithms give better performance compared to classical peak SER constraint algorithms. In addition, the linear precoding technique brings significant bit rate gain.

Subcarrier, Bit and Time Slot Allocation for Multicast Precoded OFDM Systems

The conventional resource allocation method in multicast OFDM systems adapts the physical layer to the worst user link conditions. In this paper, we propose new subcarrier, bit and time slot allocation algorithms for multicast OFDM systems in indoor powerline communication (PLC) context. To increase the multicast bit rate, these algorithms jointly use linear precoded OFDM (LP-OFDM) modulation technique and the conventional multicast approach to exploit the channel frequency selectivity experienced by each user. The LP technique applied to OFDM systems has already proved its ability to significantly increase the system throughput in a PLC context. Here, different groups of multicast users according to their channel conditions are created and different ways of gathering users, leading to different modes, are analyzed. Simulations are run over indoor PLC channels and it is shown that the proposed modes combined with the LP-OFDM solution offer a significant bit rate gain compared to the conventional multicast approach. In addition, the interest of gathering multicast users into groups for multicast OFDM systems in PLC context is shown.

Increase in multicast OFDM data rate in PLC network using adaptive LP-OFDM

Linear precoding (LP) technique applied to OFDM systems has already proved its ability to significantly increase the system throughput in a powerline communication (PLC) context. In this paper, we propose resource allocation algorithms based on the LP technique to increase the multicast OFDM systems bit rate. The conventional multicast capacity is limited by the user which experiences the worst channel conditions. To increase the multicast bit rate, these proposed algorithms assign subcarriers and bits to different multicast users. Simulations are run over PLC channels and it is shown that the proposed solutions offer a bit rate gain up to 37% compared to the conventional multicast bit rate.

Electro magnetic compatibility for Power Line Communications

Within the ICT OMEGA project, a thorough study of the Electro Magnetic Compatibility (EMC) issues linked to Power Line Communications (PLC) has been conducted. In this paper, we present our investigations carried out in the context of a frequency bandwidth extension of PLC systems up to 100 MHz. The current status of EMC regulations for PLC is first recalled. An experimental study is then presented for the assessment of the effect of electromagnetic field radiation from an electrical network, in the 30 – 100 MHz band. Recommendations are given for the injected PSD levels to be used for future studies within the OMEGA project. From these results, the capacity of the PLC channel is evaluated in terms of outage probability. This analysis shows that an extended bandwidth up to 100 MHz provides capacities in excess of 1 Gbps, while satisfying the current emission limits. Finally, the possible countermeasures for the mitigation of EMC issues are discussed.

An efficient bit-loading algorithm with peak BER constraint for the band-extended PLC

Powerline communications (PLC) have become a viable local area network (LAN) solution for in-home networks. In order to achieve high bit rate over powerline, the current technology bandwidth is increased up to 100 MHz within the European project OMEGA. In this paper, an efficient bit-loading algorithm with peak BER constraint is proposed. This algorithm tries to maximize the overall data rate based on linear precoded discrete multitone (LP-DMT), which enables reliable high bit rate transmission. A fast computational algorithm with mean BER constraint is also proposed. Simulations are run over PLC channels and it is shown that peak BER constraint algorithm combined with linear precoding component gives better performance than mean BER constraint algorithm.

An efficient channel condition aware proportional fairness ressource allocation for powerline communications

Powerline communications (PLC) become a viable local area network (LAN) solution for in-home networks. We are witnessing a growing number of in-home devices and services using PLC systems. In this paper, the resource allocation problem with peak BER constraint is investigated in multiuser context. A new proportional fairness resource allocation algorithm which takes into account the channel conditions is proposed for the downlink. This algorithm is based on linear precoded OFDM (LP-OFDM) which enables reliable high bit rate transmission under peak BER constraint. The algorithm tries to maximize the overall throughput of the system under different users required bit rate constraints. Simulations are run over PLC channels and it is shown that proposed algorithms under peak BER constraint give better performance than classical proportional fairness algorithms. In addition, the linear precoding technique brings significant data rate gain and reduces the number of unsatisfied users.

Bit rate optimization with MMSE detector for multicast LP-OFDM systems

We propose a new resource allocation algorithm with minimum mean square error (MMSE) detector formulticast linear precoded orthogonal frequency divisionmultiplexing (LP-OFDM) systems. To increase the totalmulticast bit rate, this algorithm jointly uses the LP-OFDM modulation technique and an adaptation of the OFDM-basedmulticast approaches to exploit the transmission link diversities of users. The LP technique applied to multicast OFDM systems with zero forcing (ZF) detector has already proved its ability to increase the unirate multicast system bit rate in a power line communication (PLC) context. The new MMSE detector and the new related bit-loading algorithm are developed to enhance the ZF detector results. To improve both the bit rate and the fairness amongmulticast users, the utilization of the LP component inmultiratemulticast systems is then investigated. Simulations are run over indoor PLC channels, and it is shown that the proposed LP-based methods outperform the OFDM-based methods in terms of total bit rate and fairness index for both unirate and multirate multicast systems. Additionally, it is shown that the proposed bit-loading algorithm with MMSE detector outperforms the ZF detector and the OFDM-based receiver in terms of total multicast bit rate and fairness among users.