SDN-Based Routing for Backhauling in Ultra-Dense Networks

Abstract

Ultra-Dense Network (UDN) deployment is considered a key element to achieve the requested capacity in future fifth-generation (5G) mobile networks. Backhaul networks in UDNs are formed by heterogeneous links with multi-hop connections and must handle massive traffic. Backhauling in future 5G networks may represent the capacity bottleneck. Therefore, there is the need for efficient and flexible routing schemes able to handle the dynamism of the traffic load in capacity-limited networks. Toward this goal, the emerging Software-Defined Network (SDN) paradigm provides an efficient solution, transferring the routing operation from the data plane switches to a central controller, thus achieving more flexibility, efficiency, and faster convergence time in comparison to conventional networks. This paper proposes and investigates an SDN-approach for an efficient routing in a capacity-limited backhaul network that carries data and control traffic of a heterogeneous UDN. The routing algorithm is centralized in the SDN controller and two different types of traffic flow are considered: data and control plane coordination traffic. The goal is to reduce or even to avoid the amount of traffic that the backhaul network is not able to support, distributing in a fair way the eventual lack of bandwidth among different access points. Simulation results show that with the considered approach the performance significantly improves, especially when there is an excess of traffic load in the network. Moreover, thanks to the SDN-based design, the network can reconfigure the traffic routing depending on the changing conditions.

A Multi-Layer Multi-Timescale Network Utility Maximization Framework for the SDN-Based LayBack Architecture Enabling Wireless Backhaul Resource Sharing

“…The SDN paradigm with a control plane that is separate from the data plane and with a centralized SDN controller has spurred significant research interest in wireless networks [13][14][15]. An extensive set of studies have developed SDN-based architectures for the backhaul of wireless network traffic [16][17][18]. Given the complexity of the backhaul, most of this work has considered layered or tiered architectures [12,[19][20][21][22][23][24], whereby intermediate gateway nodes perform various protocol related functions [25][26][27][28].…”

Backhaul-Aware Dimensioning and Planning of Millimeter-Wave Small Cell Networks

“…However, because of the higher frequencies, these bands are prone to atmospheric effects or rain fade, which can attenuate the signal and limit its range. Thus, the wireless option presents more challenging issues to face, such as the directional LOS design [22], the self-BH [23][24][25] or the multi-hop BH [26][27][28]. The in-band self-BH problem is aimed at finding the optimal BH and access time resource partition, combined with the user association and the beam alignment.…”

“…This issue, together with the optimization of energy consumption, is addressed in [27], where the base stations in light-load condition are turned off to minimize power consumption. Both works [27,28] employ Software-Defined Networks (SDN) technology for dynamic construction of mesh networks in order to handle the variations of the traffic load. The multi-hop BH in multi-operator scenarios is addressed in [29], where a matching theory-based algorithm is developed considering both wireless channel characteristics and economic factors.…”