1,184 research outputs found
Millimeter Wave Cellular Networks: A MAC Layer Perspective
The millimeter wave (mmWave) frequency band is seen as a key enabler of
multi-gigabit wireless access in future cellular networks. In order to overcome
the propagation challenges, mmWave systems use a large number of antenna
elements both at the base station and at the user equipment, which lead to high
directivity gains, fully-directional communications, and possible noise-limited
operations. The fundamental differences between mmWave networks and traditional
ones challenge the classical design constraints, objectives, and available
degrees of freedom. This paper addresses the implications that highly
directional communication has on the design of an efficient medium access
control (MAC) layer. The paper discusses key MAC layer issues, such as
synchronization, random access, handover, channelization, interference
management, scheduling, and association. The paper provides an integrated view
on MAC layer issues for cellular networks, identifies new challenges and
tradeoffs, and provides novel insights and solution approaches.Comment: 21 pages, 9 figures, 2 tables, to appear in IEEE Transactions on
Communication
Control and data channel resource allocation in OFDMA heterogeneous networks
This paper investigates the downlink resource allocation problem in Orthogonal Frequency Division Multiple Access (OFDMA) Heterogeneous Networks (HetNets) consisting of macro cells and small cells sharing the same frequency band. Dense deployment of small cells overlaid by a macro layer is considered to be one of the most promising solutions for providing hotspot coverage in future 5G networks. The focus is to devise an optimised policy for small cells’ access to the shared spectrum, in terms of their transmissions, in order to keep small cell served users sum data rate at high levels while ensuring that certain level of quality of service (QoS) for the macro cell users in the vicinity of small cells is provided. Both data and control channel constraints are considered, to ensure that not only the macro cell users’ data rate demands are met, but also a certain level of Bit Error Rate (BER) is ensured for the control channel information. Control channel reliability is especially important as it holds key information to successfully decode the data channel. The problem is addressed by our proposed linear binary integer programming heuristic algorithm which maximises the small cells utility while ensuring the macro users imposed constraints. To further reduce the computational complexity, we propose a progressive interference aware low complexity heuristic solution. Discussion is also presented for the implementation possibility of our proposed algorithms in a practical network. The performance of both the proposed algorithms is compared with the conventional Reuse-1 scheme under different fading conditions and small cell loads. Results show a negligible drop in small cell performance for our proposed schemes, as a trade-off for ensuring all macro users data rate demands, while Reuse-1 scheme can even lead up to 40 % outage when control region of the small cells in heavily loaded
PROCESS FOR BREAKING DOWN THE LTE SIGNAL TO EXTRACT KEY INFORMATION
The increasingly important role of Long Term Evolution (LTE) has increased security concerns among the service
providers and end users and made security of the network even more indispensable. The main thrust of this thesis is to
investigate if the LTE signal can be broken down in a methodical way to obtain information that would otherwise be
private; e.g., the Global Positioning System (GPS) location of the user equipment/base station or identity (ID) of the
user. The study made use of signal simulators and software to analyze the LTE signal to develop a method to remove
noise, breakdown the LTE signal and extract desired information. From the simulation results, it was possible to
extract key information in the downlink like the Downlink Control Information (DCI), Cell-Radio Network
Temporary Identifier (C-RNTI) and physical Cell Identity (Cell-ID). This information can be modified to cause
service disruptions in the network within a reasonable amount of time and with modest computing resources.Defence Science and Technology Agency, SingaporeApproved for public release; distribution is unlimited
Efficient Scheduling Algorithms for Wireless Resource Allocation and Virtualization in Wireless Networks
The continuing growth in demand for better mobile broadband experiences has motivated rapid development of radio-access technologies to support high data rates and improve quality of service (QoS) and quality of experience (QoE) for mobile users. However, the modern radio-access technologies pose new challenges to mobile network operators (MNO) and wireless device designers such as reducing the total cost of ownership while supporting high data throughput per user, and extending battery life-per-charge of the mobile devices. In this thesis, a variety of optimization techniques aimed at providing innovative solutions for such challenges are explored.
The thesis is divided into two parts. In the first part, the challenge of extending battery life-per-charge is addressed. Optimal and suboptimal power-efficient schedulers that minimize the total transmit power and meet the QoS requirements of the users are presented. The second outlines the benefits and challenges of deploying wireless resource virtualization (WRV) concept as a promising solution for satisfying the growing demand for mobile data and reducing capital and operational costs. First, a WRV framework is proposed for single cell zone that is able to centralize and share the spectrum resources between multiple MNOs. Consequently, several WRV frameworks are proposed, which virtualize the spectrum resource of the entire network for cloud radio access network (C-RAN)- one of the front runners for the next generation network architecture.
The main contributions of this thesis are in designing optimal and suboptimal solutions for the aforementioned challenges. In most cases, the optimal solutions suffer from high complexity, and therefore low-complexity suboptimal solutions are provided for practical systems. The optimal solutions are used as benchmarks for evaluating the suboptimal solutions. The results prove that the proposed solutions effectively contribute in addressing the challenges caused by the demand for high data rates and power transmission in mobile networks
LTE Optimization and Resource Management in Wireless Heterogeneous Networks
Mobile communication technology is evolving with a great pace. The development of the Long Term Evolution (LTE) mobile system by 3GPP is one of the milestones in this direction. This work highlights a few areas in the LTE radio access network where the proposed innovative mechanisms can substantially improve overall LTE system performance. In order to further extend the capacity of LTE networks, an integration with the non-3GPP networks (e.g., WLAN, WiMAX etc.) is also proposed in this work. Moreover, it is discussed how bandwidth resources should be managed in such heterogeneous networks. The work has purposed a comprehensive system architecture as an overlay of the 3GPP defined SAE architecture, effective resource management mechanisms as well as a Linear Programming based analytical solution for the optimal network resource allocation problem. In addition, alternative computationally efficient heuristic based algorithms have also been designed to achieve near-optimal performance
Scalable RAN Virtualization in Multi-Tenant LTE-A Heterogeneous Networks (Extended version)
Cellular communications are evolving to facilitate the current and expected
increasing needs of Quality of Service (QoS), high data rates and diversity of
offered services. Towards this direction, Radio Access Network (RAN)
virtualization aims at providing solutions of mapping virtual network elements
onto radio resources of the existing physical network. This paper proposes the
Resources nEgotiation for NEtwork Virtualization (RENEV) algorithm, suitable
for application in Heterogeneous Networks (HetNets) in Long Term
Evolution-Advanced (LTE-A) environments, consisting of a macro evolved NodeB
(eNB) overlaid with small cells. By exploiting Radio Resource Management (RRM)
principles, RENEV achieves slicing and on demand delivery of resources.
Leveraging the multi-tenancy approach, radio resources are transferred in terms
of physical radio Resource Blocks (RBs) among multiple heterogeneous base
stations, interconnected via the X2 interface. The main target is to deal with
traffic variations in geographical dimension. All signaling design
considerations under the current Third Generation Partnership Project (3GPP)
LTE-A architecture are also investigated. Analytical studies and simulation
experiments are conducted to evaluate RENEV in terms of network's throughput as
well as its additional signaling overhead. Moreover we show that RENEV can be
applied independently on top of already proposed schemes for RAN virtualization
to improve their performance. The results indicate that significant merits are
achieved both from network's and users' perspective as well as that it is a
scalable solution for different number of small cells.Comment: 40 pages (including Appendices), Accepted for publication in the IEEE
Transactions on Vehicular Technolog
- …