In this paper, we put forward a proof of concept for sixth generation (6G) Terabit infrared (IR) laser-based indoor optical wireless networks. We propose a novel double-tier access point (AP) architecture based on anarray of arraysof vertical cavity surface emitting lasers (VCSELs) to provide a seamless grid-of-beam (GoB) coverage with multi-Gb/s per beam. We present systematic design and thorough analytical modeling of the AP architecture, which are then applied to downlink system modeling using non-imaging angle diversity receivers (ADRs). We propose static beam clustering with coordinated multi-beam joint transmission (CoMB-JT) for network interference management and devise various clustering strategies to address inter-beam interference (IBI) and inter-cluster interference (ICI). Non-orthogonal multiple access (NOMA) and orthogonal frequency division multiple access (OFDMA) schemes are also adopted to handle intra-cluster interference, and the resulting signal-to-interference-plus-noise ratio (SINR) and achievable data rate are derived. The network performance is studied in terms of spatial distributions and statistics of the downlink SINR and data rate through extensive computer simulations. The results demonstrate that data rates up to 15 Gb/s are achieved within the coverage area and a properly devised clustering strikes a balance between the sum rate and fairness depending on the number of users.

To achieve multi-Gb/s data rates in 6G optical wireless access networks based on narrow infrared (IR) laser beams, a high-speed receiver with two key specifications is needed: a sufficiently large aperture to collect the required optical power and a wide field-of-view (FOV) to avoid strict alignment issues. This paper puts forward the systematic design and optimisation of multi-tier non-imaging angle diversity receivers (ADRs) composed of compound parabolic concentrators (CPCs) coupled with photodiode (PD) arrays for laser-based optical wireless communication (OWC) links. Design tradeoffs include the gain-FOV tradeoff for each receiver element and the area-bandwidth tradeoff for each PD array. The rate maximisation is formulated as a non-convex optimisation problem under the constraints on the minimum required FOV and the overall ADR dimensions to find the optimum configuration of the receiver bandwidth and FOV, and a low-complexity optimal solution is proposed. The ADR performance is studied using computer simulations and insightful design guidelines are provided through various numerical examples. An efficient technique is also proposed to reduce the ADR dimensions based on CPC length truncation. It is shown that a compact ADR with a height of$\leq 0.5$cm and an effective area of$\leq 0.5$cm2 reaches a data rate of 12 Gb/s with a half-angle FOV of 30° over a 3 m link distance.

The demand for higher broadband speeds is ever increasing whereas the deployment of full fibre to the premises is slower than initially predicted and remains costly. Solutions exploiting the existing, ubiquitous, copper network and increasing its capacity would be highly beneficial in the near term. One approach is to use surface wave (SW) transmission mode to transmit signals over the existing copper cabling network. We present proof-of-concept experimental SW data transmission on twisted pair cables. A surface wave launcher for low GHz carrier frequency operation is designed and optimised. Experimentally, we demonstrate data rates in excess of 12 Gb/s in a 1.15-3.25 GHz band over a 6.1 m twisted pair cable with an average bit error rate of$2.25 \times 10 ^{-5}$, without coding or feedback implementation. Furthermore, higher frequency bands are tested with data rates up to 3.4 Gb/s displaying their potential for surface wave transmission. S-parameter measurements allow capacity estimations of SW data transmission on longer cable lengths using water-filling algorithms. Our calculations predict over 13 Gb/s capacity on a 100 m cable using a 3.5 GHz transmission bandwidth, this may be further extended by further increases to the bandwidth used for SW transmission.

In this paper, the performance of monostatic and bistatic passive ultra high frequency radio frequency identification (UHF RFID) systems under the effects of cascaded fading channels and interference is studied. The performance metric used is tag detection probability defined as the probability that the instantaneous received power is higher than the reader's sensitivity. A closed-form expression of the detection probability is derived using cascaded forward and backscatter fading channels and the reader antennas orientation relative to the tag. Furthermore, the performance of passive UHF RFID systems under reader-to-tag interference caused by both the desired RFID signal and multiple RFID interferers is analyzed, and the effect of constructive and destructive interferences is examined. In addition, the maximum reading range in ideal, multipath fading, and interfering environments is presented. To the best of our knowledge, this is the first work that provides a 3-D performance analysis of the passive UHF RFID systems under cascaded fading channels. The obtained results are very useful for the design and optimization of passive UHF RFID systems from an RF physical channel point of view.

In this paper the effect of partitioning arrays of transmitting antennas into spatially separated clusters on the condition number and capacity of MIMO wireless systems is examined using experimental channel measurements of an indoor MIMO-enabled distributed antenna system (DAS). It is first shown for a 3×2 MIMO system that distributing the transmit antennas into spatially separated clusters provides an improvement in channel conditioning (~1dB) and hence capacity, in line with previous findings. Next, a configuration with transmit antennas and 2 receive antennas is examined and it is found that when it is operated as a 6×2 MIMO system, it makes negligible difference to the conditioning of the channel whether the transmit antennas are grouped into 3 clusters of 2 antennas or 2 clusters of 3 antennas. The capacity varies by only a small amount (~%1) between the two clustering schemes, which can be accounted for by environment-specific signal-to-noise ratio (SNR) effects. It is then concluded that for the two typical indoor DAS scenarios tested here, if sufficient transmit diversity is provided (i.e. there are a relatively large number of transmit antennas compared to receive antennas), greater spatial distribution through increased clustering provides diminishing performance improvements. Given the typically lower installation cost of less distributed arrangements, they may then be a preferred option in commercial DAS deployments.

Airport terminals will increasingly require ubiquitous communications systems with high levels of computational power to provide the necessary intelligent automation to provide high quality services to passengers, stringent levels of safety and security that is as unobtrusive as possible, efficient processing of commercial goods and luggage, high quality information systems, airport transportation systems and appropriate support for in-house commercial ventures. These requirements will involve both fixed and mobile appliances, and hence an intelligent, adaptive, self-organizing and self-managing wired and wireless infrastructure will become an essential asset. This paper describes how The INtelligent Airport (TINA) project is therefore seeking to develop a new seamless wireless/wired ubiquitous infrastructure able to meet the above requirements. It will concentrate on how a passive RFID, using a radio over fiber-fed distributed antenna system can be used to provide location and tracking information on tagged assets over a wide area. By using the distributed antenna system, it is possible to suppress fading and nulls of the narrowband RFID channel and this allows the accuracy of RFID reads to be greatly improved and the area over which they can be read to be greatly increased. It also allows the use of the received signal strength indicator (RSSI) to provide a good measure of tag position.

The power consumption of radio over fiber fed distributed antenna networks is modeled. By optimization of the antenna unit RF output power, the power consumption is minimized. Optimized broadband multi-service and narrowband single service solutions are compared and it is shown that when more than 2 services are to be provided, the broadband multi-service system is more efficient.