D13.2 Techniques and performance analysis on energy- and bandwidth-efficient communications and networking

Deliverable D13.2 del projecte europeu NEWCOM#The report presents the status of the research work of the various Joint Research Activities (JRA) in WP1.3 and the results that were developed up to the second year of the project. For each activity there is a description, an illustration of the adherence to and relevance with the identified fundamental open issues, a short presentation of the main results, and a roadmap for the future joint research. In the Annex, for each JRA, the main technical details on specific scientific activities are described in detail.Peer ReviewedPostprint (published version

Performance analysis of interference measurement methods for link adaptation in 5G New Radio

5G New Radio (NR) is coming faster than expected with early deployments which take place early 2019. It is more than a new mobile generation that offers higher data rates compared to previous generations, although it’s still the main driver. It will enable many new use cases and deployment scenarios that can be put into three main categories: enhanced mobile broad band (eMBB), ultra-reliable low latency communications (URLLC) and massive machine type communications (mMTC). 5G NR aims to further increase frequency resources utilization and efficiency. Cell edge users usually suffer from high levels of interference known as inter-cell interference. This phenomenon results in lower performance for the cell edge users and inefficient utilization of radio resources. Link adaptation techniques aim to increase cell edge performance by exploiting varying channel conditions and interference level at user equipment (UE). In this thesis channel state information (CSI) is studied as an essential part of link adaptation process. Channel quality indicator (CQI) is the main component of CSI reports from UE that gives recommendations about the next transmission modulation order and code rate. The accuracy of reported CQI depends on the accuracy of channel and interference measurements. In this thesis two different interference measurement methods based on two reference signals are studied: CSI interference measurement (CSI-IM) and non-zero power CSI reference signal (NZP CSI-RS). In this thesis performance with different configurable factors, different channel models and UE speeds are considered. Overall system overhead is also studied to give recommendation about the configuration of lower system overhead. Simulation results has shown that CSI-IM based interference measurement is more efficient compared to NZP CSI-RS method and operates well in different channel scenarios and different UE speed. While NZP CS-RS shows sensitivity to frequency selective channels and in higher user mobility cases. On the other hand, from overall system overhead perspective, CSI-IM based configuration is the best solution

Studies on 6-sector-site deployment in downlink LTE

Mobile data traffic is expected to increase massively in the following years. Consequently, service operators are induced to increase the capacity of their networks continually to attract more subscribers and maximize their revenues. At the same time, they want to minimize operational costs and capital expenditures. Among the alternatives that aim to increase the network capacity, higher order sectorization, and in particular a six sectorized configuration, is nowadays attracting a lot of attention for LTE macro-cell deployments since a higher number of sectors per site results in improved site capacity and coverage. A six sectorized configuration is attractive for both roll-out phase and growth phase of the network. In the roll-out phase, the radio access network is planned with 6-sector sites instead of 3-sector sites with the advantage that less sites are needed for the same capacity and coverage requirements. In the growth phase, the six sectorized configuration can be used to upgrade existing 3-sector sites where the traffic grows beyond the current sites' capabilities. Therefore, no additional expensive and time consuming contracts need to be signed for the locations of the new sites, while the existing sites are used more efficiently. However, although potentially a 6-sector site can offer a double capacity than a 3-sector site, several factors prevent the capacity from growing proportionately to the number of sectors. Consequently, there is an uncertainty on whether the capacity gain is high enough to justify the extra costs of the additional equipment and, more specifically, whether the 6-sector-site deployment is more economically attractive than a 3-sector-site deployment. The aim of this report is to solve this uncertainty. First, we present the main factors that affect the capacity gain. Next, we quantify the impact of these factors on the capacity gain in downlink LTE with the use of a system level simulator. Finally, we use the results of the simulation study as inputs for an economic study to access the reasons for a possible deployment of 6-sector sites instead of 3-sector sites for LTE

Hybrid Radio Resource Management with Limited Channel Feedback Information in Relay enhanced OFDMA Networks

In orthogonal frequency division multiple access based mobile networks buffer aided nontransparent in-band half duplex decode-and-forward relay nodes aim to improve coverage and capacity under fairness considerations. The existing centralized radio resource management and inter-cell interference coordination schemes can achieve this goals, although at the cost of a heavy signalling overhead. This cost is a critical issue, particularly for the frequency division duplex downlink transmission. On the other hand, the fully decentralized schemes often focus on different types of frequency reuse schemes with smaller amount of necessary feedback. Here, it is often overseen that in a practical deployment, the backhaul link quality is the bottleneck of the two-hop transmission, and the backhaul link is often modelled way too optimistically. Moreover, it is necessary to allocate radio resources to single hop mobile stations as well, which further limits the possible data rates of the relay-attached users. The research presented in this Thesis aims to improve the backhaul link quality in relay-assisted cellular networks under full consideration of practical constraints. In order to minimize the required channel feedback overhead this work proposes a hybrid radio resource management scheme consisting of three adapted procedures. The hybrid radio resource management scheme includes an adapted decentralized cell selection metric which improves the possibility to gain from the relays in the system for each user. A macro cell-centralized synchronous procedure is proposed, which is responsible to allocate the radio resources in each transmission time interval. Furthermore, an asynchronous network-centralized subband power allocation scheme with very limited feedback is proposed to maximize the wireless backhaul link quality with no losses for single-hop Mobile Station (MS)s. Comprehensive system level simulation results show stable fairness and improved throughput of the proposed hybrid radio resource management scheme. In addition possible energy savings for the shared channel are presented

Hybrid Radio Resource Management with Co-scheduling for Relay Extended OFDMA Networks

In orthogonal frequency division multiple access networks buffer aided non-transparent in-band half duplex decode and forward relay nodes aim to improve coverage and capacity under fairness considerations. Existing centralized radio resource management and inter cell interference coordination schemes achieve these goals at the cost of heavy signalling overhead. Especially for frequency division duplex downlink transmission this is an critical issue. Fully decentralized schemes often focus on different types of frequency reuse schemes with less amount of necessary feedback. Here, it is often overseen that in a practical deployment, the backhaul link quality is the bottleneck of the two hop transmission and needs to be taken into account. Moreover, it is often modelled way too optimistic and necessary co-scheduling with single hop UE further limits the possible data rate. In order to minimize the required overhead this work proposes a hybrid radio resource management (RRM) scheme. The RRM includes synchronous adapted two-hop proportional frequency selective resource scheduling as the decentralized part. Asynchronous subband power allocation scheme with very limited feedback is proposed to maximize the wireless backhaul link quality with no loss for single hop UE. Comprehensive system level simulation results show stable fairness and throughput when minimizing the required feedback and improvements for the backhaul links based on the centralized adapted power allocation including no losses in the overall system. In addition possible energy savings for the shared channel are presented when applying the proposed scheme