The millimeter wave (mmWave) bands offer the possibility of orders of magnitude greater throughput for fifth-generation (5G) cellular systems. However, since mmWave signals are highly susceptible to blockage, channel quality on any one mmWave link can be extremely intermittent. This paper implements a novel dual connectivity protocol that enables mobile user equipment devices to maintain physical layer connections to 4G and 5G cells simultaneously. A novel uplink control signaling system combined with a local coordinator enables rapid path switching in the event of failures on any one link. This paper provides the first comprehensive end-to-end evaluation of handover mechanisms in mmWave cellular systems. The simulation framework includes detailed measurement-based channel models to realistically capture spatial dynamics of blocking events, as well as the full details of Medium Access Control, Radio Link Control, and transport protocols. Compared with conventional handover mechanisms, this paper reveals significant benefits of the proposed method under several metrics.
Dual connectivity to different types of cells (e.g., macro and pico cells) has been proposed in Release @math of Long Term Evolution-Advanced (LTE-A) @cite_1 and in @cite_32 . However, these systems were designed for conventional sub-6 GHz frequencies, and the directionality and variability of the channels typical of mmWave frequencies were not addressed. Some other previous works, such as @cite_3 , consider only the bands under @math GHz for the control channel of 5G networks, to provide robustness against blockage and a wider coverage range, but this solution could not provide the high capacities that can be obtained when exploiting mmWave frequencies. The potential of combining legacy and mmWave technologies in outdoor scenarios has also been investigated in @cite_13 , highlighting the significant benefits that a mmWave network achieves with flexible, dynamic support from LTE technologies. Articles @cite_11 @cite_16 propose a multi-connectivity framework as a solution for mobility-related link failures and throughput degradation of cell-edge users, enabling increased reliability with different levels of mobility.
@cite_1 @cite_32 @cite_3 @cite_16 @cite_13 @cite_11
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Recently, a new network architecture with split control-plane and user-plane has been proposed and gained a lot of momentum in the standardisation of Long Term Evolution (LTE) Release 12. In this new network architecture, the control-plane, which transmits system information and handles user connectivity, and the user-plane, which manages user data, are split and no longer transmitted necessarily by the same network node. This dual connectivity confers a large flexibility to the system, and allows for a more energy efficient operation and enhanced mobility management. In this paper, we present a detailed description of our dual connectivity framework based on the latest LTE-Advanced enhancements, in which macrocell-assisted (MA) small cells use different channel state information-reference signals (CSI-RS) to differentiate among each other and allow User Equipment (UE) to take adequate measurements for cell (re)selection. Taking into account the limited number of available CSI-RSs, we study the assignment problem of CSI-RSs to MA small cells, analyse CSI-RS collision and confusion issues and present simulation results to demonstrate the flexibility of the proposed network architecture. Ultra-high reliable communication and improved capacity are some of the major requirements of the 5th generation (5G) mobile and wireless networks. Achieving the aforementioned requirements necessitates avoiding radio link failures and the service interruption that occurs during the failures and their re-establishment procedures. Moreover, the latency associated with packet forwarding in classical handover procedures should be resolved. This paper proposes a multi-connectivity concept for a cloud radio access network as a solution for mobility related link failures and throughput degradation of cell-edge users. The concept relies on the fact that the transmissions from co-operating cells are co-ordinated for both data and control signals. Latency incurred due to classical handover procedures will be inherently resolved in the proposed multi-connectivity scheme. Simulation results are shown for a stand alone ultra dense small cells that use the same carrier frequency. It is shown that the number of mobility failures can considerably be decreased without a loss in the throughput performance gain of cell-edge users. 5G is expected to provide a unified platform where a number of different frequency bands and technologies are strategically integrated and combined. In this paper we investigate the potential of combining micro-wave (microWave) and millimeter-wave (mmWave) technologies in outdoor scenarios. We first envision the design and architecture of a novel 5G microWave mmWave Heterogeneous Network (HetNet) where the mmWave backhaul is integrated. Next, we discuss a Service-Driven Dynamic Resource Radio Management system for the proposed architecture and propose a Multi-Layer Dynamic Transmission Scheme, which enables cooperation between different network slices, increasing the degrees of freedom of the overall system. Finally, we present a preliminary analytical and experimental study of the performance of the proposed 5G microWave mmWave HetNet, highlighting the significant benefits that a mmWave network achieves with flexible, dynamic support from microWave technologies. The 5th generation of mobile networks is envisioned to unify different access types under one system in order to enable efficient and performant operations. We propose a radio network architecture for tight integration of multiple radio access technologies supporting traffic steering, link selection, and aggregation of traffic flows from and to different sources. This enables the radio network architecture to support better throughput, and increased reliability with different levels of mobility. Specifically, we propose a common user plane and control plane across different radio technologies utilizing similar principles, such that the joint operation of radio technologies can be optimized.