International Journal of Sensors Wireless Communications and Control - Volume 1, Issue 1, 2011

It is a great pleasure to present the inaugural issue of International Journal of Sensors, Wireless Communications and Control. The idea to publish a journal on these areas is developed due to the emergence of high speed wireless network technologies such as fourth generation mobile broadband wireless, broadband fixed wireless access, and wireless local area networks, which allows a cluster of sensor, controller and plants to be linked together economically to form a wireless networked system. Wireless networked systems have raised and continue to raise fundamental challenges in the fields of science, engineering and industrial applications, hence, more up-to-the-minute modeling techniques, problem formulations and solutions are required. The journal will serve as a publishing platform for both the scientific results of the above mentioned issues as well as for other research articles, reviews and communications related to wireless networked systems. I would like to take this opportunity to thank Bentham Science Publishers for appointing me as Editor-in-Chief of the journal, and to acknowledge Ms. Sana Shakeel for her enthusiasm, dedication and continual support.

The current main digital broadcasting networks and standards include Digital Video Broadcasting Terrestrial (DVB-T), Handheld (DVB-H) and Digital Audio Broadcasting (DAB). DVB-T and DAB are key broadcast network technologies which are expected to complement other emerging technologies such as WiMAX and its derivatives in future 4G networks. Newer defined standards such as DVB-T2 and Next Generation Handheld DVB-NGH are also being developed and tested promising higher data rates and mobility support to allow new and improved services. The physical layer of all these technologies rely on Orthogonal Frequency Division Multiplexing (OFDM), which is a technique that distributes data over a large number of carriers spaced apart at precise frequencies providing frequency diversity. This special issue discusses the main optimisation techniques for the design and deployment of current and future Digital Broadcast networks that will minimise the complexity and power consumption of end user equipment and enhance the delivery of new broadband services. These techniques include the optimisation of current standards such as DVB-T and DVB-H, the use of On-channel Repeaters (OCR) to extend coverage and the development of new standards such as DVB-T2 and DVB-NGH. The main current network optimisation techniques include transmit diversity, low cost on-channel repeaters, multiple channel power amplification, receive diversity, efficient network modelling and planning tools and the definition of service scenarios that describe the future use of broadband services in terms of service type and reception conditions.

This paper discusses optimisation techniques for the design and deployment of future Digital Video Broadcast (DVB) networks that will minimise the complexity and power consumption of end user equipment and enhance the delivery of new broadband services. These techniques are investigated within the framework of the EC funded PLUTO (Physical Layer DVB Transmission Optimisation) project. The main network optimisation techniques include transmit diversity, low cost on-channel repeaters and multiple channel power amplification, receive diversity, efficient network modelling and planning tools and the definition of service scenarios that describe the future use of broadband services in terms of service type and reception conditions

This paper presents a field measurement campaign carried out by the IST PLUTO project to quantify the advantages that can be achieved practically if transmit delay diversity is applied to DVB-T/H systems. An extensive field trial was performed in Uxbridge (UK) to validate transmit diversity gain predictions obtained previously from theoretical modelling and laboratory measurements. DVB-T/H transmissions were performed in the 730 MHz frequency band. It is concluded that transmit delay diversity achieves significant improvement in the reception quality in difficult to reach areas without impacting the standard or increasing the complexity of receivers.

On-channel repeaters for Digital Video Broadcasting either Terrestrial or Handheld (DVB-T/T2/H/SH) are receiving increasing attention due to the advantages they can offer for Single Frequency Network (SFN) deployment and coverage. This article presents several issues and tradeoffs related to the design of such systems. These issues include echo cancellation and channel estimation for stable operation of the repeater, pre-distortion to improve amplifier linearity and Multiple Channel Power Amplification (MCPA) that allow multiple radio channels to use a single amplifier hence reducing the costs of the overall network deployment.

On-channel repeaters are able to receive and re-transmit a broadcast signal on the same frequency and thus can facilitate network expansion, particularly in an SFN, and network repair following the introduction of strong adjacentchannel transmissions. For effective operation, systems must incorporate excellent RF design and high-performance signal processing in order to remain stable and re-radiate a clean, decodable signal. This paper describes the operation of on-channel repeaters designed for DAB and DVB-T signals by BBC R&D, and goes on to outline a number of key techniques, including correlation compensation for controlling unwanted out-of-band products due to part-Nyquist signal occupancy and adaptive null-steering for pre-echo rejection in a DAB SFN. The former is now a field-proven technique whilst the latter is in development and awaiting a full engineering realisation.

Already DVB's first generation terrestrial broadcasting standard - DVB-T - enables the mobile reception of digital services. However, since the development of DVB-T in 1995 there have been significant improvements in the area of signal processing algorithms and semiconductor manufacturing. Hence, DVB initiated the development of a second generation terrestrial transmission standard that has been finalized 2008, i.e. DVB-T2. Using state-of-the-art algorithms this standard reaches the theoretical limits quite close and offers increased flexibility for all kinds of broadcast scenarios. A special focus was put on the performance in mobile reception. The use of an optimized forward error correction in addition to MIMO techniques offers reliable data transmission, also in difficult channels. This article will describe the key features of DVB-T2 enabling robust mobile reception, and in addition, will show simulation results in different mobile channels and reception scenarios.

The successor to the DVB-H broadcast handheld standard (DVB-NGH) is currently being defined by the DVBTM- H working group. A key feature which would distinguish the new standard from the old is the likely inclusion of cross-polar transmission and reception for increased capacity and robustness through twin-antenna MIMO schemes. To enable simulations of the various proposals to be carried out, a channel sounding campaign took place in July 2010 in Helsinki, Finland, focussing on cross-polar UHF transmission and reception. A number of practical designs for antennas suitable for a handheld terminal were included in the trial and all test data was obtained via these devices. Following the campaign, analysis of the data has produced a simple model for both outdoor and indoor scenarios of the antennainclusive 2-by-2 channel. This paper briefly describes the excitation signal and test arrangements before introducing the form of the channel model. Finally the actual parameters of the model which have resulted from the measurements are discussed and related to the likely observable behaviour of the NGH cross-polar signal

This paper investigates the impact of radio interference on the performance of an IEEE 802.15.4/ ZigBee communication link in an office environment. S-parameter measurements at frequencies around 2.405 GHz and with 3 MHz bandwidth, indicate level fluctuations of approximately 30 dB, caused by the propagation characteristics and multi-path fading within the room. Comparison between the fading characteristics of the room and the ZigBee packet error rate in the absence of interference indicates that errors occur when the path loss exceeds 55 dB, a level observed in less than 1% of scanned locations. Three types of interfering signals were generated within the room: band-limited additive white Gaussian noise (AWGN) centred at 2.405 GHz, a Bluetooth standard compliant signal and a WLAN (802.11.g) link. AWGN interference exceeding 15 dBm (total radiated power from the source causes the 802.15.4 link to suffer significant packet errors. The 802.15.4 link shows minimal observable packet loss in the presence of bursty Bluetooth. A study on coexistence between ZigBee and an actual IEEE 802.11g WLAN deployment shows that the degradation of the ZigBee link is approximately 50% and the net throughput of the WLAN link reduces by approximately 90%.