| 1. |
- Aydin, Osman, et al.
(författare)
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EU FP7 INFSO-ICT-317669 METIS, D 4.1 Summary on preliminary trade-off investigations and first set of potential network-level solutions
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- METIS WP4 covers research activities in network-level aspects of the advancement of wireless network technologies towards the year 2020 and beyond. The aim is to develop novel network-level technology concepts to address the challenges foreseen in future scenarios with regard to interference, traffic and mobility management issues. Moreover, another task of this work package is to propose functional enablers which can support the above potential solutions.This document provides* a report of the ongoing progress in WP4 regarding the research topics agreed upon in IR 4.1,* a high level description of the proposed concepts and approaches adopted by different partners.More specifically, the document describes, first set of potential network-level solutions and presents some first research results in order to position them with regards to the state of the art approaches. It also gives an overview of research activities to be considered later in WP4.
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| 2. |
- Li, Jingya, 1986, et al.
(författare)
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Optimal Design of Energy-Efficient HetNets: Joint Precoding and Load Balancing
- 2015
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Ingår i: IEEE International Conference on Communications. - : IEEE. - 1550-3607. - 9781467364324 ; 2015-September, s. 4664-4669
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Konferensbidrag (refereegranskat)abstract
- This paper considers the downlink of a heterogeneous network, where multiple base stations (BSs) can serve the users by non-coherent multiflow beamforming. We assume imperfect channel state information at both BSs and users. The objective is to jointly optimize the precoding, load balancing, and BS operation mode (active or sleep) for improving the energy efficiency of the network. The considered problem is to minimize the weighted total power consumption (both circuit power and dynamic transmit power), while satisfying per-user quality of service constraints and per-BS transmit power constraints. This problem is non-convex, but we prove that for each combination of BS modes, the considered problem has a hidden convexity structure. Thus, the global optimal solution is obtained by an exhaustive search over all possible BS mode combinations. Furthermore, by iterative convex approximations of the non-convex power consumption functions, a heuristic algorithm is proposed to obtain a local optimal solution with low complexity. Simulation results illustrate that our proposed algorithms significantly reduce the total power consumption, compared to the scheme where all BSs are continuously active. This implies that putting a BS into sleep mode by proper load balancing is an important solution for energy savings in heterogeneous networks.
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| 3. |
- Fallgren, Mikael, et al.
(författare)
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Multicast and Broadcast Enablers for High-Performing Cellular V2X Systems
- 2019
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Ingår i: IEEE Transactions on Broadcasting. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9316 .- 1557-9611. ; 65:2, s. 454-463
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on capabilities enabled by 5G connectivity in the cooperative, connected and autonomous cars, and elaborates on two technical enablers. One of the technical enablers consists of a beamformed broadcast/multicast technology that builds on adaptive and robust beam management techniques at the air interface. The other proposed technical component aims to improve the end-to-end architectural design of 5G networks to enable efficient broadcast and multicast transmissions for vehicle-to-anything services. Finally, the key results of multicast and broadcast technical components are described and ongoing and future areas of work and research are detailed.
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| 4. |
- Azimi-Abarghouyi, Seyed Mohammad, et al.
(författare)
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Integer-Forcing Message Recovering in Interference Channels
- 2018
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Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 67:5, s. 4124-4135
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a scheme referred to as integer-forcing message recovering (IFMR) to enable receivers to recover their desirable messages in interference channels. Compared to the state-of-the-art integer-forcing linear receiver (IFLR), our proposed IFMR approach needs to decode considerably less number of messages. In our method, each receiver recovers independent linear integer combinations of the desirable messages each from two independent equations. We propose an efficient polynomial-time algorithm to sequentially find the equations and integer combinations with maximum rates and analyze its complexity. We evaluate the performance of our scheme and compare the results with the minimum mean-square error linear receiver (MMSELR) and lattice-reduction-aided successive interference cancellation with signal-to-interference-plus-noise ratio maximizing preprocessing (LaR-aided SIC with SINR-Max), as well as the IFLR schemes. The results indicate that our IFMR scheme outperforms the MMSELR and LaR-aided SIC with SINR-Max schemes, in terms of achievable rate, considerably. Also, compared to the IFLR, the IFMR scheme achieves slightly less rates in moderate signal-to-noise ratios, with significantly less overall implementation complexity.
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| 5. |
- Di Taranto, Rocco, 1977, et al.
(författare)
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Location-aware Communications for 5G Networks
- 2014
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Ingår i: IEEE Signal Processing Magazine. - 1558-0792 .- 1053-5888. ; 31:6, s. 102-112
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Tidskriftsartikel (refereegranskat)abstract
- Fifth-generation (5G) networks will be the first generation to benefit from location information that is sufficiently precise to be leveraged in wireless network design and optimization. We argue that location information can aid in addressing several of the key challenges in 5G, complementary to existing and planned technological developments. These challenges include an increase in traffic and number of devices, robustness for mission-critical services, and a reduction in total energy consumption and latency. This article gives a broad overview of the growing research area of location-aware communications across different layers of the protocol stack. We highlight several promising trends, tradeoffs, and pitfalls.
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| 6. |
- Fang, Chao, 1991, et al.
(författare)
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Coordinated Hybrid Precoding for Energy-Efficient Millimeter Wave Systems
- 2018
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Ingår i: IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC. ; 2018-June
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Konferensbidrag (refereegranskat)abstract
- Hybrid precoding/combining architectures, which use fewer radio frequency (RF) chains than the number of antennas, have the potential to reduce energy consumption and provide high data rate for millimeter wave systems with large antenna arrays. In this paper, by allowing joint transmissions from multiple base stations (BSs), we jointly optimize over the hybrid precoders and the BSs sleep/active modes such that the total power consumption is minimized with per-user quality-of-service constraints. We present a decoupled hybrid beamforming scheme where the analog precoders are designed based on the equal gain transmission method and the digital precoders are found by solving a convex semidefinite problem. We define realistic models for the hardware power consumption and the channel’s blocking probabilities to compare the performance of our scheme with the fully-digital precoding scheme and to assess the value of BS cooperation. The simulation results show that our proposed method results in almost the same RF transmit power as the fully-digital precoding scheme while saving considerable hardware power due to the reduced number of RF chains and digital-to-analog converters. Moreover, the network densification is shown to further reduce the total power consumption through the optimal cooperative BS active/sleep mode selection.
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| 7. |
- Fang, Chao, 1991, et al.
(författare)
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Hybrid Precoding in Cooperative Millimeter Wave Networks
- 2021
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Ingår i: IEEE Transactions on Wireless Communications. - 1558-2248 .- 1536-1276. ; 20:8, s. 5373-5388
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we study the performance of cooperative millimeter wave (mmWave) networks with hybrid precoding architectures. Considering joint transmissions and BS silence strategy, we propose hybrid precoding algorithms which minimize the sum power consumption of the base stations (BSs), for both fully-and partially-connected hybrid precoding (FHP and PHP, respectively) schemes, for single-carrier and orthogonal frequency-division multiplexing systems. We reformulate the analog precoding part as an equal-gain transmission problem, which only depends on the channel information, and the digital precoding part as a relaxed convex semidefinite program subject to per-user quality-of-service constraints that gives the optimal sum power consumption in terms of the BS silence strategy. In order to reduce the complexity of the hybrid precoding algorithm with optimal BS silence strategy, we propose a sub-optimal hybrid precoding algorithm that iteratively put BSs with small power into the silent mode. The simulation results show that, depending on the parameter settings, the power consumption of the PHP may be dominated by the RF transmit power and it may result in a larger power consumption than the FHP. For the cases with 2 BSs and 4 users, implementation of the FHP and the PHP in cooperative networks reduces the required RF transmit power, compared to the case in a non-cooperative network, by 71% and 56%, respectively.
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| 8. |
- Krishnan, Rajet, 1982, et al.
(författare)
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Optimal and Approximate Methods for Detection of Uncoded Data with Carrier Phase Noise
- 2011
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Ingår i: IEEE Globecom 2011.
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Konferensbidrag (refereegranskat)abstract
- Previous results in the literature have shown that derivation of the optimum \textit{maximum-likelihood} (ML) receiver for \textit{symbol-by-symbol} (SBS) detection of an uncoded data sequence in the presence of \textit{random phase noise} is an intractable problem, since it involves the computation of the conditional \textit{probability distribution function} (PDF) of the phase noise process. In this paper, we seek to minimize \textit{symbol error probability} (SEP), which is achieved by SBS detection of the sequence based on all received signals. We show that the ML detector for this problem can be formulated as a weighted sum of central moments of the conditional PDF of phase noise. Given that the central moments of the conditional PDF of phase noise can be estimated, this new optimal structure is tractable with respect to the previously known optimal ML receiver. Furthermore, based on the new receiver structure, we propose a simple approximate method for SBS detection and investigate its scope and applicability. Simulation results demonstrate that SEP performance close to optimality can be obtained through the proposed method for scenarios of low phase noise variance and low \textit{signal-to-noise ratio} (SNR).
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| 9. |
- Lakshmana, Tilak Rajesh, 1980, et al.
(författare)
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Partial joint processing with efficient backhauling using particle swarm optimization
- 2012
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Ingår i: Eurasip Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1499 .- 1687-1472. ; 2012
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Tidskriftsartikel (refereegranskat)abstract
- In cellular communication systems with frequency reuse factor of one, user terminals(UT) at the cell-edge are prone to intercell interference. Joint processing is one of the coordinated multipoint transmission techniques proposed to mitigate this interference. In the case of centralized joint processing, the channel state information fed back by the users need to be available at the central coordination node for precoding. The precoding weights (with the user data) need to be available at the corresponding base stations to serve the UTs. These increase the backhaul traffic. In this article, partial joint processing (PJP) is considered as a general framework that allows reducing the amount of required feedback. However, it is difficult to achieve a corresponding reduction on the backhaul related to the precoding weights, when a linear zero forcing beamforming technique is used. In this work, particle swarm optimization is proposed as a tool to design the precoding weights under feedback and backhaul constraints related to PJP.The precoder obtained with the objective of weighted interference minimization allows some multiuser interference in the system, and it is shown to improve the sum rate by 66% compared to a conventional zero forcing approach, for those users experiencing low signal to interference plus noise ratio.
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| 10. |
- Mehrpouyan, Hani, 1981, et al.
(författare)
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A New Distributed Approach for Achieving Clock Synchronization in Heterogeneous Networks
- 2011
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Ingår i: IEEE Globecom 2011. - 1930-529X. - 9781424492688 ; , s. 5-
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Konferensbidrag (refereegranskat)abstract
- Heterogeneous networks have the potential to improve coverage, throughput, and energy efficiency of wireless networks through the use of specialized cellular structures, in particular femtocells and macrocells. However, to reduce interference between different cells, ensure smooth hand-offs from cell to cell, and achieve seamless operation the overall network needs to be synchronized. In this paper a new distributed clock synchronization scheme for heterogeneous networks is proposed that employs the clock drift information available at user-equipments (UEs) to achieve synchronization between non-interacting femtocells and macrocells. Simulation results show that the proposed scheme can significantly reduce the clock drift between macrocells and femtocells and result in timing synchronization throughout the network without introducing significant overhead.
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