FrA6- Physical Layer Optimisation

Friday, 21 June 2019, 8:30-10:30, Room 6


Session Chair: Jeongchang Kim (Korea Maritime and Ocean University, Korea)


Doubly Constrained Underlay Cognitive Radio System: Optimization and Analysis

Aniruddha Paturkar and Vibhuti Goel (BITS Pilani, Rajasthan, India); B. Sainath (BITS Pilani, India)
In this paper, we consider a doubly constrained underlay cognitive radio (CR) system. In it, a secondary user (SU) transmitter (Tx) is subject to average interference constraint, and spectral efficiency constraint. For the underlay system, we investigate both average energy efficiency and average spectral efficiency. Specifically, we develop an algorithm that determines the suboptimal operating point of transmit power with which the SU-Tx must operate for maximum energy efficiency. We derive an analytical expression for the fading-averaged spectral efficiency assuming Rayleigh fading with path loss and shadowing. To validate the analytical results, we simulate the model in two different platforms and investigate system performance. The analysis that we present are useful for constrained cognitive radio systems and networks.


Automatic Modulation Classification in the Presence of Interference

Pavlos Triantaris (Toshiba Research Europe Ltd., United Kingdom (Great Britain)); Evgeny Tsimbalo (Telecommunications Research Laboratory of Toshiba Research Europe Ltd., United Kingdom (Great Britain)); Woon Hau Chin (Toshiba Research Europe Limited, United Kingdom (Great Britain)); Deniz Gündüz (Imperial College London, United Kingdom (Great Britain))
A modulation recognition method based on a simple convolutional neural network (CNN) architecture is assessed through classification of synthetic baseband signals in the presence of a second known signal source. The complexity and adaptability of CNNs is leveraged so as to forgo statistical feature extraction procedures and efficiently classify based on raw signals or their modified forms. Experimentation for the optimisation of the model’s behaviour is carried out through an attempt to exploit the a priori information of the secondary source modulation scheme. Simulation results show that the proposed modifications demonstrate a positive effect upon general performance.


Optimal Reserved Resources to Ensure the Repetitions in Ultra-Reliable Low-Latency Communication Uplink Grant-free Transmission

Trung-Kien Le (EURECOM, France); Umer Salim (TCL, France); Florian Kaltenberger (Eurecom, France)
To meet the strict requirements of Ultra-Reliable Low-Latency Communication in the uplink, grant-free uplink transmission has been specified, allowing the UE to transmit data in a random-access fashion without first transmitting a scheduling request and then waiting for a uplink grant from the gNB. To further increase the reliability, these grant-free uplink transmissions can be repeated without waiting for HARQ feedback from the gNB. However, these repetitions have to happen within a certain interval to avoid a confusion in HARQ IDs of different HARQ processes. When a UE starts transmitting late in the interval, it, therefore, can not exploit all the possible repetitions and thus reliability and latency decrease. In this paper, a scheme based on reserved resources is proposed to ensure the number of repetitions in a specific period. The size of each reserved resource is optimized depending on its position so as to reduce resource consumption. The scheme evaluated by theoretical analysis and numerical results shows its benefits to system performance.


Reference Signal Design for Remote Interference Management in 5G New Radio

Elena Peralta (Tampere University of Technology, Finland); Mikko Mäenpää (Wireless System Engineering Finland Ltd., Finland); Toni A Levanen (Tampere University of Technology, Finland); Youngsoo Yuk (Nokia, Korea); Klaus Pedersen (Nokia – Bell Labs, Denmark); Sari Nielsen (Nokia, Finland); Mikko Valkama (Tampere University of Technology, Finland)
In time division duplexing based mobile networks, under certain atmospheric ducting conditions, the uplink reception may be interfered by the downlink transmissions of remote base-stations (BSs) located hundreds of kilometers away. This paper addresses such remote interference problem in 5G new radio (NR) macro deployment context. Specifically, two potential reference signal (RS) designs for remote interference management (RIM) are described, together with receiver detection processing framework, to efficiently detect the interference due to multiple remote aggressor base-stations at a victim BS. The first signal structure, denoted as the one OFDM symbol (1OS) based RIM-RS, is building on the channel state information reference signals (CSI-RS) of 5G NR. The second candidate is referred to as the two OFDM symbol (2OS) based RIM-RS design, and builds on the design principles of LTE RIM-RS. The considered RIM-RS solutions are extensively analyzed and compared, with different parameterizations, in several realistic interference scenarios. The obtained results show that the 2OS RS design provides better RIM performance in scenarios where the number of interfering BSs is small. However, when the number of interfering BSs increases, the 1OS RS design starts to outperform the 2OS based approach. Additionally, it is shown that the 1OS RIM-RS provides smaller overhead and can be frequency multiplexed with the physical downlink shared channel.


Two-Tier Cellular Networks: Enhanced Secondary Node Resource Allocation, Applied to LTE-A

Diogo Sequeira Martins (University of Lisbon – Instituto Superior Técnico & Vodafone Portugal, Portugal); Luis M. Correia (IST/INESC-ID – University of Lisbon & INESC, Portugal); Ahmed Alsohaily and Elvino Silveira Sousa (University of Toronto, Canada)
The ability to accommodate the contrasting requirements of extended coverage, enhanced capacity and reduced deployment costs has led to the adoption of Two-Tier connectivity structures, in which secondary nodes connect users’ terminals to base stations, as a promising design direction for contemporary cellular communications systems. This paper considers a Two-Tier Cellular Network employing fixed secondary nodes and introduces enhanced channel estimation and resource allocation procedures that exploit lower channel variation rates, along with the ability to use larger antenna arrays at these nodes to achieve substantial performance gains. Based on data measured from a live LTE-Advanced network, the expected average throughput gains when connecting a single secondary node varied between 10.2% and 65.0%. Furthermore, when emulating the deployment of five secondary nodes under the Round Robin, Best Channel Quality Index and Proportional Fair scheduling algorithms, one anticipates average throughput gains of 64.0%, 41.2% and 128.5%, respectively, while resource allocation fairness is expected to improve by 28.9%, 80.2% and 24.1%, respectively.


Ultra-reliable V2X Communication: On the Value of User Cooperation in the Sidelink

Malte Schellmann (Huawei Technologies German Research Center, Germany); Tapisha Soni (Huawei European Research Center & Germany, Germany)
The 5G system and its service for ultra-reliable low latency communication are considered key enablers for enhanced use cases of vehicular-to-anything (V2X) communications, paving the way towards automated and autonomous driving. Reliability in a wireless link can be improved substantially if a large degree of channel diversity can be exploited. The V2X sidelink can offer numerous independent communication links between a target car and its neighbours, and the diversity offered by these links can be made available by cooperative retransmission of data packets received from a prior multi-cast transmission. This paper elaborates on the value of user cooperation in the sidelink for attaining ultra-reliability in V2X communications by analyzing the reliability gains in dependence of the number of cooperating users and for considering an additional retransmission, if the latency budget allows. Analysis reveals that the attainable gains scale with up to one order of magnitude per cooperative user. If strong differences in the power per link due to path-loss effects are taken into account, gains are obviously degrading, though the degradation can be kept at a moderate level if an additional retransmission with appropriate user grouping is considered.