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The two articles in this special section examine the Internet of Things (IoT) and Machine-type communications. IoT is about connecting devices and creating related applications to suit a business and economic need. One of its value propositions is automation. As the industry and academia understand the “plumbing” part of IoT and refine emerging business models such as ones based on software as a service (SaaS) and platform as a service (PaaS), the new developments increasingly focus on: Cross-domain interoperability; data analytics and the emergence of data marketplaces for IoT; and dealing with new application domains in a cost optimized manner, in particular ones that require low latency, high resiliency and availability, and so on., QC 20200427

METIS is the EU flagship 5G project with the objective of laying the foundation for 5G systems and building consensus prior to standardization. The METIS overall approach toward 5G builds on the evolution of existing technologies complemented by new radio concepts that are designed to meet the new and challenging requirements of use cases today¿s radio access networks cannot support. The integration of these new radio concepts, such as massive MIMO, ultra dense networks, moving networks, and device-to-device, ultra reliable, and massive machine communications, will allow 5G to support the expected increase in mobile data volume while broadening the range of application domains that mobile communications can support beyond 2020. In this article, we describe the scenarios identified for the purpose of driving the 5G research direction. Furthermore, we give initial directions for the technology components (e.g., link level components, multinode/multiantenna, multi-RAT, and multi-layer networks and spectrum handling) that will allow the fulfillment of the requirements of the identified 5G scenarios., QC 20150312

A novel scheme for data retransmission for wireless unicast communication is presented. The scheme is based on a transmitter and receiver structure and bit-level data processing using a combination of channel coding and network coding that allows retransmissions to contain the previously incorrectly received information and new information, both destined to the same receiver. Results show that, for the chosen forward error codes, up to 68.75% retransmission throughput gains are achieved compared to HARQ with Chase combining., QC 20120312. © 2011 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20111201

In Multiple Input Multiple Output (MIMO) communications, multiple antenna elements are employed both in the transmitter and the receiver, in order to obtain increased data rates or improved reliability compared to single-antenna transmission. In cellular systems, the Base Stations (BS) may operate in Single User (SU)-MIMO mode, i.e. to employ point-to-point transmission of data just for one multi-antenna User Equipment at a time. Alternatively, the BS can perform Multiuser (MU)-MIMO transmission, i.e. spatially multiplex data streams intended for different UEs that may be equipped with arbitrary numbers of antenna elements. The use of MU-MIMO mode offers potential system capacity gains especially when the BS employs a large antenna array. This chapter discusses various aspects of MIMO communications, with a special focus on the downlink direction of cellular systems. First, an overview of the fundamentals and existing techniques is given. Then, the MIMO related standards and standardization activities are described. Finally, some recent advances concerning MU-MIMO communications are addressed., QC 20120312

In a classical network, data streams originating from a source and intended to a desired destination are routed through intermediate nodes before reaching their final destination. By contrast, Network Coding (NC) manipulates at an intermediate node those data streams by combining the data from the streams before forwarding it to the destination. This paper describes the advances of NC in wireless communication for IMT-Advanced and beyond. A short overview of NC in wireless communications is given first. Afterward, the application of NC to broadcasting is described. Thereafter, NC methods in uplink wireless communications, such as User Grouping (UG) and Relay Selection (RS) are described. Further, the advantage of non-binary over binary network NC is shown in a multi-user multi-relay scenario. Finally the performance of NC is analyzed. In particular, in the uplink Multiple Access Relay Channel (MARC) scenario, the joint UG and RS methods lift the system capacity by 70%. The non-binary NC improves the SNR up to 4 dB. Finally the efficient broadcast method yields up to 22% overhead reduction compared to ARQ., QC 20111129

This chapter deals with Network Coding (NC) in general and with its application to wireless communication in particular. A short overview of Network Coding in wired and wireless communications is given in section 8.1. Section 8.2, NC describes methods in uplink wireless communications. In section 8.3 the advantage of nonbinary network codes over binary network codes is shown in a multiuser co-operative communication and multirelay scenarios. The application of Network Coding (NC) to broadcast scenarios is then described. Finally, NC trends in wireless communications are given in section 8.5., QC 20111201

A timely addition to the understanding of IMT-Advanced, this book places particular emphasis on the new areas which IMT-Advanced technologies rely on compared with their predecessors. These latest areas include Radio Resource Management, Carrier Aggregation, improved MIMO support and Relaying. Each technique is thoroughly described and illustrated before being surveyed in context of the LTE-Advanced standards. The book also presents state-of-the-art information on the different aspects of the work of standardization bodies (such as 3GPP and IEEE), making global links between them. Explores the latest research innovations to assess the future of the LTE standard. Covers the latest research techniques for beyond IMT-Advanced such as Coordinated multi-point systems (CoMP), Network Coding, Device-to-Device and Spectrum Sharing. Contains key information for researchers from academia and industry, engineers, regulators and decision makers working on LTE-Advanced and beyond., QC 20140225

QC 20140818

QC 20140818Chapter in book: ISBN 9781119993216

Globally, mobile communications are moving toward broadband communication systems to meet the challenges of significantly increasing data traffic such as that for mobile Internet applications. In order to meet this increasing traffic, the International Telecommunication Union - Radiocommunication Standardization Sector (ITU-R) initiated in 2000 the process toward the next generation of International Mobile Telecommunications systems, referred to as IMT-Advanced systems.

QC 20220211

We present a new space-time encoderbased on packet-level redundancy which can increase the space-time encoder rate beyond unity without compromising diversitygains. A complementary low-complexity decoding algorithmbased on maximum ratio combining and successive interferencecancelation is further proposed. A major merit of the decodingalgorithm is that it allows to adaptively tradeoff betweendiversity and multiplexing gains based on the estimated channelparameters at the receiver without requiring any channel stateinformation at the transmitter. System level simulation resultsgive insight into the advantages of the proposed scheme whencompared to its Alamouti and MIMO multiplexing based onsingle value decomposition counterparts., QC 20111128

WINNER is an ambitious research project aiming at identification, development, and assessment of key technologies for IMT-Advanced mobile communication systems. WINNER has devised an OFDMA-based system concept with excellent system-level performance for flexible deployments in a wide variety of operating conditions. The WINNER system provides a significant step forward from current 3G systems. Key innovations integrated into the system concept include flexible spectrum usage and relaying, adaptive advanced antenna schemes and pilot design, close to optimal link adaptation, hierarchical control signaling, and a highly flexible multiple access scheme. The end-to-end performance assessment results demonstrate that the WINNER concept meets the IMT-Advanced requirements.

QC 20111130

In this paper, distributed relay diversity systems are analyzed, modeled and evaluated in an Orthogonal Frequency Division Multiplexing (OFDM) based networks. The investigated distributed relay diversity schemes extend the ideas of a single hop transmit antenna schemes such as Cyclic Delay Diversity (CDD), Space Time Transmit Diversity (STTD), transmit Coherent Combining (CC) and Selection Diversity (SD) to distributed diversity systems. In contrast to the classical single hop system, the antennas in the distributed systems belongs to distributed relays instead of being co-located at the transmitter. The distributed relay diversity methods considered in this paper: Relay CDD (RCDD), Relay Alamouti (i.e.STTD), Relay CC (RCC) and Relay SD (RSD) are compared to the traditional 1-hop system. Analytical expressions for the received Signal to Interference Noise Ratio (SINR) are derived and used in a dynamic multi-cell multi-user simulator. Results show considerable SINR gains for both Round Robin and Max-SINR schedulers. The SINR gains translate into substantial cell throughput gains, up to 200%, compared to 1-hop systems. Despite its low complexity, the RCDD scheme has similar performance to that of other more sophisticated 2-hop schemes such as Relay Alamouti and Relay Coherent Combining. Marginally better results are observed for the Relay Selection Diversity scheme., QC 20111115

Network coding has recently attracted a lot of interest from the research community, mainly due to its simplicity of application and the large number of applications it can be suited for. Research in network coding started on wired networks, but the researchers soon came to realize that the inherent properties of the wireless medium render it a fertile ground for the application of network coding, and the resulting efforts mainly targeted bidirectional traffic scenarios. In this work, we focus on practical implementation issues for network coding when applied to uplink cellular traffic. We provide our own relaying scheme based on decode-and-forward relays and network coding, with a specially designed method of decoding at the receiver. We complement this method with user grouping in order to make better use of the application of network coding. We measure the SINR and capacity performances of our proposed scheme and compare them to the classical decode-and-forward algorithm in a system level simulator. We show that user grouping should complement a network coding solution in order to translate the decrease in the number of transmissions offered by network coding into capacity gains., QC 20111130

A discrete-time model of DS-CDMA signaling using multiple transmit and receive antennas employing linear transceiver filters is derived. For each link, connecting a base-station to a wireless mobile user, the downlink signal to interference plus noise ratio (SINR) after despreading is derived analytically, and as a by-product an exact closed-form solution of the orthogonality factor is obtained. The orthogonality factor is derived for any linear receiver structure that is implemented by a bank of correlators and for any linear combining techniques (such as MRC and MMSE), and for any number of transmit and/or receive antennas that utilize transmit (pre-RAKE) and receive (post-RAKE) filtering. The MIMO DS-CDMA model is derived using a filter representation, and is extended to a vector/matrix formulation that permits a systematic and efficient way of computing the SINR in a radio network simulator., QC 20110218

In this paper, the MIMO framework within WINNER for fourth generation radio systems is further developed and assessed for various deployment scenarios. The emphasis is on radio network system aspects of multi-antenna techniques where preferred configurations for three basic deployment scenarios are given. In the wide area scenario which aims to provide ubiquitous coverage for rural, suburban and urban areas, the scheme selection depends on the user density of spatially separated users. It ranges from grid of fixed beams (GoB) (TDMA based) in case of few users to SDMA with a fixed linear precoding codebook, and finally to adaptive beams with SDMA for highly dense system. In the metropolitan area scenario which is targeting system deployments in large urban environments, multi-user (MU) MIMO precoding performs very well for slow moving users. For higher velocities, per antenna rate control (PARC) or adaptive linear dispersion codes (LDCs) are better choices. In the local area scenario which is characterized by isolated sites, the combination of SDMA and spatial multiplexing achieved by MU-MIMO precoding provides high spectral efficiency., QC 20110712

A cooperative communication scheme referred to as relay cyclic delay diversity (RCDD) is presented in this paper. The scheme is based on a set of distributed relay nodes (RNs) with each node associated with a certain cyclic shift in order to generate artificially multi-path diversity and equivalently frequency diversity. RCDD is an open loop scheme and the user terminal (UT) only needs to estimate an effective channel from all the RNs and not the channel from each RN. The effective channel induced by RCDD is frequency selective and can be exploited by a maximum signal to interference noise ratio (SINR) scheduler which improves substantially the system throughput. The SINR of the RCDD is derived analytically and the performance of the method is evaluated in a dynamic multi-cell multi-user simulator. The results show considerable SINR gains that translate into substantial cell throughput gains compared to 1-hop systems., QC 20111004

A Fixed Beam (FB) system that uses a beam specific Secondary-Common PIlot CHannel (S-CPICH) as a phase reference for channel estimation and demodulation in WCDMA is evaluated in a dynamic radio network simulator. The impact of the angular spread on the DownLink (DL) system performance is analyzed. Furthermore, various scrambling code allocation strategies and an adaptive load-dependent power tuning algorithm of the common channels are proposed and evaluated. Extensive simulation results have verified that increasing the number of FB from 1 to 2 or 4 beams per sector in a typical urban radio channel yields significant DL capacity gains., QC 20110217

A fixed multi-beam system that uses the Primary- Common PIlot CHannel (P-CPICH) as a phase reference for channel estimation and demodulation in WCDMA is evaluated in a dynamic radio network simulator. The impact of the angular spread on the downlink system performance is analyzed. Furthermore, a scrambling code allocation strategy and an adaptive load-dependent power tuning algorithm for the P-CPICH are proposed. Extensive simulation studies are carried out to evaluate the capacity gains of 3 sector sites where each site is equipped with 1, 2 or 4 beams in a typical urban radio channel. Moreover an alternative antenna configuration consisting of 6 sector sites where each sector is equipped with 2 beams is evaluated., QC 20110217

In this paper, Simulated Annealing is used for designing a fixed multi-beam antenna array (AA) in a multi-user radio WCDMA system. The method can be used dynamically in a real system and/or in a radio planning tool. The proposed method is applied on a linear array by designing the Antenna Element (AE) pattern, the number of fixed beams, the AE spacing, and the AA transmit weights. The proposed method leads to a substantial BS power reduction which can be used to increase the system capacity or data throughput in a WCDMA system., QC 20110217

In this paper we consider relay communication as a way of increasing the diversity gain in fading wireless environments. The idea is to combine relay communication with delay diversity where each relay introduces a certain time delay to the signal before forwarding. The result is an increased frequency selectivity in the relay channel which can be exploited at the receiver. The obtained results show that, for single carrier signals with frequency domain equalization, considerable performance gain is obtained., QC 20110217

In this paper, single carrier frequency domain equalization with space time transmit diversity was implemented and evaluated in real-time using a DSP-based wireless MIMO test-bed. A new pilot structure for joint carrier frequency offset (CFO) and channel estimation is proposed and evaluated, to address the adverse inter-symbol interference and the severe CFO due to hardware impairments. The channel estimation method is done in the frequency domain using a non-parametric interpolation method. The new pilot scheme results in significant reduction of the required overhead signalling compared to previous schemes., QC 20110217

A comprehensive study is given of smart antennas for wide-band code-division multiple access (WCDMA). It analyzes, evaluates, and presents methods and ideas for the deployment of smart antennas in WCDMA third-generation wireless systems and for future generations. Three major implementations are evaluated and analyzed in a dynamic system simulator: higher order sectorization (HOS), fixed beams (FBs) with secondary common pilot channel (S-CPICH), and FBs with primary common pilot channel (P-CPICH) as a phase reference. The system modeling integrates antenna and wave propagation modeling to evaluate and design smart antennas in wireless communications. Furthermore, this paper analyzes the impact of angular spread of various antenna configurations, the interaction and impact of radio resource management as power tuning of the common channel, scrambling code (SCO) allocation technique, and soft and softer handover algorithm. Moreover, an SCO allocation strategy and an adaptive load-dependent power-tuning algorithm of the P-CPICH are proposed. Furthermore, a signal-to-(interference plus noise) ratio derivation is given. Extensive simulation studies are carried out to evaluate the capacity gains of HOS and FB. The 12-sector sites yield the best system downlink capacity gain compared to three-sector sites equipped with a single antenna, slightly more than three-sector sites equipped with four FBs each. The six-sector sites equipped with two FBs each reduce the gap between HOS and FB systems to 10%., QC 20111108

This paper analyzes higher order sectorization (HOS) in WCDMA. Sectorization is achieved by splitting the sites into smaller sectors using highly directional antennas. The impact of angular spread on the system throughput is evaluated using a dynamic radio network simulator. Increasing the number of sectors per site from 3 to 6 and 12 in a typical urban radio channel yields a downlink system capacity gain of 80% and 200% respectively. Simulations have shown that the increase in the ratio of users in soft and softer handover per sector is negligible and the impact of angular spread on the system performance of a 6 and 12 sector sites is minor and negligible for the 3 sector sites., QC 20111115