High Capacity Fiber-Connected Wireless MIMO Communication

There will be more and more users while beyond-5G (B5G) and 6G bring more wireless applications. Current cellular communication networks assign specific serving boundaries for each radio, which becomes a limitation when too many users work with one radio simultaneously. By physically distributing radios. user’s service can be more uniform. Radio-over-fiber is a promising enabling technology for distributed antenna systems.To have several tens of Gbit/s data rate, we need to apply millimeter-wave (mm-wave) frequency band in radio-over-fiber (RoF). However, mm-wave signals have weak penetration and high propagation loss. Hence, beamforming and/or multiple-input-multiple-output (MIMO) technology become necessary for mm-wave RoF to overcome those drawbacks.This thesis introduces an automatic distributed MIMO (D-MIMO) testbed with a statistical MIMO capacity analysis for an indoor use case. Raytracing-based simulations also predicts the indoor case to make a comparison. The statistical MIMO capacity analysis shows that D-MIMO has a higher and more uniform capacity than co-located MIMO (C-MIMO) in measurements and simulations.Next, a mm-wave sigma-delta-over-fiber (SDoF) link architecture is proposed for MIMO applications. In the implementation of this link, a QSFP28 fiber link connects a central unit with a remote radio unit with four bandpass sigma-delta-modulation (BPSDM) bitstreams. The remote radio unit generates four mm-wave signals from four BPSDM signals and feeds a linear array antenna. The measurement characterizes the remote radio head at each stage and concludes that this proposed link can reach 800 Msym/s data rate with -0.5 dBm output bandpower.Furthermore, the proposed link is demonstrated with digital beamforming and multi-user MIMO (MU-MIMO) functionalities. The digital beamforming function reaches 700 Msym/s with -25 dB error vector magnitude (EVM) results by improving the received bandpower in comparison to (single-input-single-output) SISO results. The MU-MIMO function serves two independent users at 500 Msym/s symbol rate and satisfies 3GPP requirements at 1 m over-the-air distance.In conclusion, this thesis proves that D-MIMO has a higher and more uniform capacity than C-MIMO by statistical analysis from measurements and simulations. The proposed novel mm-wave SDoF link can pave the way for future D-MIMO applications

Massive MIMO for Internet of Things (IoT) Connectivity

Massive MIMO is considered to be one of the key technologies in the emerging 5G systems, but also a concept applicable to other wireless systems. Exploiting the large number of degrees of freedom (DoFs) of massive MIMO essential for achieving high spectral efficiency, high data rates and extreme spatial multiplexing of densely distributed users. On the one hand, the benefits of applying massive MIMO for broadband communication are well known and there has been a large body of research on designing communication schemes to support high rates. On the other hand, using massive MIMO for Internet-of-Things (IoT) is still a developing topic, as IoT connectivity has requirements and constraints that are significantly different from the broadband connections. In this paper we investigate the applicability of massive MIMO to IoT connectivity. Specifically, we treat the two generic types of IoT connections envisioned in 5G: massive machine-type communication (mMTC) and ultra-reliable low-latency communication (URLLC). This paper fills this important gap by identifying the opportunities and challenges in exploiting massive MIMO for IoT connectivity. We provide insights into the trade-offs that emerge when massive MIMO is applied to mMTC or URLLC and present a number of suitable communication schemes. The discussion continues to the questions of network slicing of the wireless resources and the use of massive MIMO to simultaneously support IoT connections with very heterogeneous requirements. The main conclusion is that massive MIMO can bring benefits to the scenarios with IoT connectivity, but it requires tight integration of the physical-layer techniques with the protocol design.Comment: Submitted for publicatio

Near-Instantaneously Adaptive HSDPA-Style OFDM Versus MC-CDMA Transceivers for WIFI, WIMAX, and Next-Generation Cellular Systems

Burts-by-burst (BbB) adaptive high-speed downlink packet access (HSDPA) style multicarrier systems are reviewed, identifying their most critical design aspects. These systems exhibit numerous attractive features, rendering them eminently eligible for employment in next-generation wireless systems. It is argued that BbB-adaptive or symbol-by-symbol adaptive orthogonal frequency division multiplex (OFDM) modems counteract the near instantaneous channel quality variations and hence attain an increased throughput or robustness in comparison to their fixed-mode counterparts. Although they act quite differently, various diversity techniques, such as Rake receivers and space-time block coding (STBC) are also capable of mitigating the channel quality variations in their effort to reduce the bit error ratio (BER), provided that the individual antenna elements experience independent fading. By contrast, in the presence of correlated fading imposed by shadowing or time-variant multiuser interference, the benefits of space-time coding erode and it is unrealistic to expect that a fixed-mode space-time coded system remains capable of maintaining a near-constant BER

Performance Evaluation of 24GHz Spectrum Indoor Wireless Radio Links

Wireless communication systems are susceptible to propagation impairments such as scattering, interference, multipath fading, and delay spread. Furthermore, unlike wired networks in which signals propagate in a confined media characterised by high quality system performance and high data rates up to 10Gbps, wireless signals propagate through the air and are as a result prone to security attacks. As WLANs are becoming vital tools to meet the demand for wireless internet services, it becomes imperative to study novel approaches for achieving good access and high data rate transmission. The conventional WLAN network standards by IEEE802.11 family are characterised by maximum data rate of 54Mbps. This is below the required bandwidth for channel intensive applications such as multimedia services, uncompressed video streaming, fast file uploads and downloads. Also, the numerous subscribers competing for seamless wireless internet connection has overcrowded the network channels in microwave bands, resulting in poor performance and degradation of the entire WLAN networks. As much as 1Gbps and higher data rates communication are attractive for several application described above, this technological goal can only be realised by engaging millimetre wave (MMW) spectrum. The Spectrum bands at 24GHz, 28GHz, 38GHz and 60GHz are currently being focused on to support shorter-range, high-speed communication systems. These bands are capable of the Gb/s throughput as required by bandwidth intensive and multimedia consumer-oriented applications . The potentials of 24GHz spectrum for gigabits data rate delivery performance in real time applications was investigated in this work

Multiuser Parallel Transmission with 1-tap Time Domain Beamforming by Millimeter Wave Massive Antenna Arrays

This paper investigates the feasibility of multiuser parallel transmission by sub-array beamforming using millimeter wave bands in which the Line-of-Sight (LoS) dominant channel environment is expected. Focusing on high beamforming gain provided by the massive antenna array, each sub-array conducts first eigenmode transmission and thus one stream is allocated per user without null steering. This paper also proposes 1-tap time domain beamforming (TDBF) as the same weight is applied to all frequency components. It reduces computation complexity as well as suppressing the effect of additive noise on weight derivation. Computer simulation results show that increasing the subarray spacing stably improves signal-to-interference power ratio (SIR) performance and that the proposed 1-tap TDBF can match the performance of the frequency domain first eigenmode transmission as a rigorous solution

Space-time coding techniques with bit-interleaved coded modulations for MIMO block-fading channels

The space-time bit-interleaved coded modulation (ST-BICM) is an efficient technique to obtain high diversity and coding gain on a block-fading MIMO channel. Its maximum-likelihood (ML) performance is computed under ideal interleaving conditions, which enables a global optimization taking into account channel coding. Thanks to a diversity upperbound derived from the Singleton bound, an appropriate choice of the time dimension of the space-time coding is possible, which maximizes diversity while minimizing complexity. Based on the analysis, an optimized interleaver and a set of linear precoders, called dispersive nucleo algebraic (DNA) precoders are proposed. The proposed precoders have good performance with respect to the state of the art and exist for any number of transmit antennas and any time dimension. With turbo codes, they exhibit a frame error rate which does not increase with frame length.Comment: Submitted to IEEE Trans. on Information Theory, Submission: January 2006 - First review: June 200

Advanced Wireless LAN

The past two decades have witnessed starling advances in wireless LAN technologies that were stimulated by its increasing popularity in the home due to ease of installation, and in commercial complexes offering wireless access to their customers. This book presents some of the latest development status of wireless LAN, covering the topics on physical layer, MAC layer, QoS and systems. It provides an opportunity for both practitioners and researchers to explore the problems that arise in the rapidly developed technologies in wireless LAN