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Powerline Communications
The integration of Power Line Communication (PLC) is of interest to future broadband communication systems.
These communication systems will be mostly wireless but the use of non-dedicated wired infrastructure will help to reduce costs.
PLC uses the highly developed infrastructure of the electrical energy distribution network for data transmission.
So it is possible to enlarge the capacity of communication systems without additional wiring and additional costs for this wiring - for outdoor applications, for example to bridge the last mile, as well as indoor, for example to establish or enlarge LANs without new data cables.
To evaluate the potential of PLC an analysis of the channel capacity of the power line at higher frequencies is needed.
Measurements & Channel Capacity Evaluation
As a first step in this project a detailed analysis of the link level channel capacity of Indoor PLC channels is done at frequencies between 1 MHz and 30 MHz. This analysis is based on extensive measurements of the transfer function and the noise of these channels - for an office environment as well as for a home environment.
PLC enhanced WLAN
These measurements and evaluations are showing that a broadband use of PLC channels is possible. Therefore in this project the use of existing PLC devices in combination with 802.11 WLAN devices is investigated. The PLC network is used as a backhaul to connect the Access Points of a WLAN. This leads to a flexible extension of a WLAN without the need of a wired network (today typically Ethernet is used for this purpose).
Efficient Coding Scheme for PLC
Future broadband communication systems will be heterogeneous in several respects, for example relative to the used transmission channel but also relative to the complexity of the participant nodes.
For wireless communications using multiple antennas we developed in our group a new class of space-time block codes, the Linear Scalable Dispersion (LSD) codes. These codes meet the requirements of future communication systems. They are highly flexible and can be adapted to the particular requests of the transmission. As the next step in this project, a PLC application of these codes is investigated. They are used as a basis for a scalable and efficient PLC channel coding scheme.
The results show that this class of codes can be used as a generic coding scheme for heterogeneous networks. Alternatively, the PLC application can be considered as an example of the usage of the codes on a frequency selective channel with coloured noise. The applied linear block code optimally uses the diversity of the frequency selective channels in combination with OFDM. This leads to significant gains in performance in case of very frequency selective channels; for barely frequency selective channels or for an AWGN channel the performance is slightly better or not affected respectively. These performance results are verified using the measured PLC channels for realistic simulations.
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