High-efficient Converged Digital Radio over Fibre (DRoF) Transmission and Processing for Indoor Both Cellular and IoT Services

© 2019 IEEE. Digital Radio over fibre (DRoF) transmission has long been considered as a promising solution for providing multiple wireless services over a single optical-wireless infrastructure for indoor and last-mile wireless coverage. However, with the increasing number of services and fast growing requirement of Internet of things (IoT), the existing technologies are not able to meet the demand of network convergence due to high capital expenditure (CAPEX) and operating expenditure (OPEX) in managing the vast amount of digitised data. In this paper, we demonstrate a compact multiservice hybrid fibre radio scheme for both downlink and uplink where a novel digital signal processing method and a novel fronthaul protocol are implemented with high bandwidth efficiency. The system uses pluggable modular RF frontend and digital cards so as to support the increasing services dynamically. Both RFID based IoT services and several cellular services from mobile network operators (MNOs) are converged onto a single <6Gbps optical link with high spectral efficiency, modulation accuracy and RF performance. The system is experimentally demonstrated and shows low EVM for all cellular services provided from China Unicom and high detection rate and localisation accuracy for the RFID service carried over 20km optical fibre link

Wireless communication, identification and sensing technologies enabling integrated logistics: a study in the harbor environment

In the last decade, integrated logistics has become an important challenge in the development of wireless communication, identification and sensing technology, due to the growing complexity of logistics processes and the increasing demand for adapting systems to new requirements. The advancement of wireless technology provides a wide range of options for the maritime container terminals. Electronic devices employed in container terminals reduce the manual effort, facilitating timely information flow and enhancing control and quality of service and decision made. In this paper, we examine the technology that can be used to support integration in harbor's logistics. In the literature, most systems have been developed to address specific needs of particular harbors, but a systematic study is missing. The purpose is to provide an overview to the reader about which technology of integrated logistics can be implemented and what remains to be addressed in the future

An overview of the CPRI specification and its application to C-RAN-based LTE scenarios

The CPRI specification has been introduced to enable the communication between radio equipment and radio equipment controllers, and is of particular interest for mobile operators willing to deploy their networks following the novel cloud radio access network approach. In such a case, CPRI provides an interface for the interconnection of remote radio heads with a baseband unit by means of the so-called fronthaul network. This article presents the CPRI specification, its concept, design, and interfaces, provides a use case for fronthaul dimensioning in a realistic LTE scenario, and proposes some interesting open research challenges in the next-generation 5G mobile network.The authors would like to acknowledge the support of projects CRAMnet (grant no. TEC2012-38362-C03-01) and EU H2020 5G-Crosshaul Project (grant no. 671598) to the development of this work.European Commissio

Multiservice Ethernet Digital Distributed Antenna Systems

Over 90% of wireless communications traffic occurs indoors and in-building wireless coverage is still one of the biggest obstacles for wireless users. As the growing demands on wireless capacity, coverage and connectivity have led to 4G and 5G standards, it has also become increasingly important to design and implement future-proof indoor wireless services in a cost effective manner. This thesis introduces a novel multi-service digital distributed antenna systems (DDAS) for indoor wireless coverage, which not only is able to transport multiple wireless carriers from different vendors and mobile operators, but also allows a converged architecture to integrate indoor wireless system with existing Ethernet infrastructures. The Cloud Radio Access Networks (C-RAN) has been suggested by major telecom vendors as the main architecture for last-mile coverage in 5G. However, the digital fronthaul interface defined in common public radio interface (CPRI), which is most widely adopted standard for C-RAN, requires very expensive infrastructures to be built due to the high data rate generated after digitisation. A solution has been introduced at the University of Cambridge previously to remove the digital redundancy by using a data compression technique which has shown 3-times higher transmission efficiency than CPRI. This thesis extends the concept to a more robust architecture allowing multiple wireless services to be transmitted simultaneously as well as being carried over standard Ethernet without losing the Quality of End-user Experience (QoE) and the Quality of Service (QoS) of in-building mobile network. A two-channel DDAS system with data compression algorithm is experimentally demonstrated, showing wide RF dynamic range for both 4G LTE service and 3G WCDMA service simultaneously carried over a single fibre-based infrastructure. The system leads to the design and implementation of full-service DDAS system allowing 14 channels (all 2/3/4G service from three major mobile operators) to be carried over single 10Gbps network. Typically, the system using CPRI will need over 30Gbps network to be installed for wireless coverage. Another key aspect covered in this thesis is the design and implementation of the multi-service DDAS over Ethernet (Eth-DDAS). Due to the stringent latency requirement in wireless services, mitigation of delays and errors in frame ordering has become a key challenge for putting DDAS over Ethernet. To overcome these problems, a special Eth-DDAS frame structure is proposed in this thesis. After digitisation, digital signal bearing RF information is packetised onto Ethernet-compatible frames with additional timestamps and sequence numbers before transported via fibre to the receiver. Three latency scenarios are tested with different payload sizes of the proposed frame structure and real-time RF performance is measured to prove the capability of implementation of such system in real-life using commercial off-the-shelf (COTS) ADC/DAC and FPGAs

Millimetre-Wave Fibre-Wireless Technologies for 5G Mobile Fronthaul

The unprecedented growth in mobile data traffic, driven primarily by bandwidth rich applications and high definition video is accelerating the development of fifth generation (5G) mobile network. As mobile access network evolves towards centralisation, mobile fronthaul (MFH) architecture becomes essential in providing high capacity, ubiquitous and yet affordable services to subscribers. In order to meet the demand for high data rates in the access, Millimetre-wave (mmWave) has been highlighted as an essential technology in the development of 5G-new radio (5G-NR). In the present MFH architecture which is typically based on common public radio interface (CPRI) protocol, baseband signals are digitised before fibre transmission, featuring high overhead data and stringent synchronisation requirements. A direct application of mmWave 5G-NR to CPRI digital MFH, where signal bandwidth is expected to be up to 1GHz will be challenging, due to the increased complexity of the digitising interface and huge overhead data that will be required for such bandwidth. Alternatively, radio over fibre (RoF) technique can be employed in the transportation of mmWave wireless signals via the MFH link, thereby avoiding the expensive digitisation interface and excessive overhead associated with its implementation. Additionally, mmWave carrier can be realised with the aid of photonic components employed in the RoF link, further reducing the system complexity. However, noise and nonlinearities inherent to analog transmission presents implementation challenges, limiting the system dynamic range. Therefore, it is important to investigate the effects of these impairments in RoF based MFH architecture. This thesis presents extensive research on the impact of noise and nonlinearities on 5G candidate waveforms, in mmWave 5G fibre wireless MFH. Besides orthogonal frequency division multiplexing (OFDM), another radio access technology (RAT) that has received significant attention is filter bank multicarrier (FBMC), particularly due to its high spectral containment and excellent performance in asynchronous transmission. Hence, FBMC waveform is adopted in this work to study the impact of noise and nonlinearities on the mmWave fibre-wireless MFH architecture. Since OFDM is widely deployed and it has been adopted for 5G-NR, the performance of OFDM and FBMC based 5G mmWave RAT in fibre wireless MFH architecture is compared for several implementations and transmission scenarios. To this extent, an end to end transmission testbed is designed and implemented using industry standard VPI Transmission Maker® to investigate five mmWave upconversion techniques. Simulation results show that the impact of noise is higher in FBMC when the signal to-noise (SNR) is low, however, FBMC exhibits better performance compared to OFDM as the SNR improved. More importantly, an evaluation of the contribution of each noise component to the overall system SNR is carried out. It is observed in the investigation that noise contribution from the optical carriers employed in the heterodyne upconversion of intermediate frequency (IF) signals to mmWave frequency dominate the system noise. An adaptive modulation technique is employed to optimise the system throughput based on the received SNR. The throughput of FBMC based system reduced significantly compared to OFDM, due to laser phase noise and chromatic dispersion (CD). Additionally, it is shown that by employing frequency domain averaging technique to enhance the channel estimation (CE), the throughput of FBMC is significantly increased and consequently, a comparable performance is obtained for both waveforms. Furthermore, several coexistence scenarios for multi service transmission are studied, considering OFDM and FBMC based RATs to evaluate the impact inter band interference (IBI), due to power amplifier (PA) nonlinearity on the system performance. The low out of band (OOB) emission in FBMC plays an important role in minimising IBI to adjacent services. Therefore, FBMC requires less guardband in coexistence with multiple services in 5G fibre-wireless MFH. Conversely, OFDM introduced significant OOB to adjacent services requiring large guardband in multi-service coexistence transmission scenario. Finally, a novel transmission scheme is proposed and investigated to simultaneously generate multiple mmWave signals using laser heterodyning mmWave upconversion technique. With appropriate IF and optical frequency plan, several mmWave signals can be realised. Simulation results demonstrate successful simultaneous realisation of 28GHz, 38GHz, and 60GHz mmWave signals