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Public safety communication systems are currently evolving due to emergence of long term evolution (LTE) as a mature solution to replace the legacy ones while providing new services. However, LTE is initially designed for commercial cellular network and needs to be furthermore evolved to tackle the substantial requirements of public safety use cases. For instance, opportunistic deployments require modifications to enable the autonomous operation and meshing of moving base stations while satisfying heterogeneous frequency band availability. In this article, we present a novel radio access network infrastructure architecture that enables multi-hop LTE mesh networking for nomadic and autonomous base stations via in-band self-backhauling. Furthermore, we investigate the coordination and orchestration functionality within the proposed architecture and propose a hierarchical resource scheduling algorithm in order to efficiently meet quality of service (QoS) requirements for real-time traffic while maximizing the throughput for elastic flows. To demonstrate the feasibility and reliability of our proposed architecture, we implement the corresponding self-backhauling air-interface based on OpenAirInterface platform and compare it with the legacy LTE air-interface. Finally, we evaluate the efficiency and adaptability of our proposed resource scheduling algorithm in various network topology and heterogeneous traffic flows with QoS requirements.

Commoditization and virtualization of wireless networks are changing the economics of mobile networks to help network providers, e.g. Mobile Network Operator (MNO), Mobile Virtual Network Operator (MVNO), move from proprietary and bespoke hardware and software platforms towards an open, cost-effective, and flexible cellular ecosystem. In addition, rich and innovative local services can be efficiently materialized through cloudification by leveraging the existing infrastructure. In this work, we present a Radio Access Network as a Service (RANaaS), in which a Cloudified Centralized Radio Access Network (C-RAN) is delivered as a service. RANaaS describes the service life-cycle of an on-demand, elastic, and pay as you go RAN instantiated on top of the cloud infrastructure. Due to short deadlines in many examples of RAN, the fluctuations of processing time, introduced by the virtualization framework, have a deep impact on the C-RAN performance. While in typical cloud environments, the deadlines of processing time cannot be guaranteed, the cloudification of C-RAN, in which signal processing runs on general purpose processors inside Virtual Machines (VMs), is a challenging subject. We describe an example of real-time cloudified LTE network deployment using the OpenAirInterface (OAI) LTE implementation and OpenStack running on commodity hardware. We also show the flexibility and performance of the platform developed. Finally, we draw general conclusions on the RANaaS provisioning problem in future 5G networks.

Long-term evolution (LTE) is becoming the technology reference for 4G cellular networks, as it is increasingly adopted by all major operators all over the world. Currently, LTE is rising to the challenge of addressing several issues (e.g. cellular networks’ capacity crunch, ultra-high bandwidth, ultra-low latency, massive numbers of connections, super-fast mobility, diverse-spectrum access) that speed up the pace toward 5G. Moreover, LTE is expected to be an important part of the 5G solution for future networks and also plays an essential role in advancing public safety (PS) communications. In the United States, LTE has been chosen as the next appropriate communication technology to support PS, and it is likely to be the same in the European Union. Moreover, several vendors (e.g. Ericsson, Nokia-Alcatel, Huawei, Cisco) are now starting to propose LTE-based PS solutions and some of them have been put to real experimentation in the field.

In this work, we present novel Architectural Design Patterns towards open, cloud-based 5G communications. We provide a brief classification of technologies that cannot be ignored in the design process of 5G systems and illustrate how a new technological added value can be created, when current methodologies, design paradigms, as well as design patterns and their extensions are properly exploited in efficient Radio Access Network (RAN) architectures. We believe that in many cases, the required technology is already there; nevertheless the correct approach has to be worked out and placed within an appropriate context, especially in the case of the integration of complex RAN systems. The enhancements in RF optimization, the progress in cloud computing, Software Defined Networks (SDN) and Network Function Virtualization (NFV), new design concepts such as Network Slicing have to become part of the RAN design methodology. Diverse architectural concepts should break existing stereotypes to pave the way towards the true 5G system integration.

In this paper, we provide a revolutionary vision of 5G networks, in which SDN technologies are used for the programmability of the wireless network, and where a NFV-ready network store is provided to Mobile Network Operators (MNO), Enterprises, and Over-The-Top (OTT) third parties. The proposed network serves as a digital distribution platform of programmable Virtualized Network Functions (VNFs) that enables 5G application use-cases. Currently existing application stores, such as Apple's App Store for iOS applications, Google's Play Store for Android, or Ubuntu's Software Center, deliver applications to user specific software platforms. Our vision is to provide a digital marketplace, gathering 5G enabling Network Applications and Network Functions, written to run on top of commodity cloud infrastructures, connected to remote radio heads (RRH). The 5G Network Store will be the same to the network provider as the application store is currently to a software platform.

It has been recognized that effective communications and the ability to share various media are keys to a successful operation in public safety and military applications. LTE (Long Term Evolution) is becoming the most widely deployed broadband communication technology making it the technology of choice for public safety to replace TETRA and similar networks. However, LTE is a cellular network by design in that it has planned and fixed antenna locations, and is connected to a common packet core network. Even though the LTE self-organized operation makes the planning, configuration, management, optimization and healing of the network simpler and faster, LTE networks are not well-suited for the moving cell, particularly to establish the backhaul link among the base stations. In this paper we present a novel concept of enhanced evolved Node B (e2NB) to enable meshing of the neighboring e2NBs and maintain the LTE-compliant communication service with the legacy terminals reusing the LTE air interface while moving. We evaluate the performance of the e2NB in terms of backhaul link performance and end-to-end communication using the OpenAirInterface (OAI) LTE implementation. Emulation results demonstrate the feasibility of the proposed approach to build a self-organized mesh network over LTE/LTE-A. They also show that LTE quality-of-service requirements can be maintained in multi-hop networks subject to resource allocation across multiple e2NBs.

LTE is deployed in most countries and continuously evolving to match new user requirements. While it is expected to support 5G deployments for outdoor and long range communications, it will also be used for Public Safety services in major countries. Among those, new scenarios call for wider networks on the move relying on self-backhauling. In this article we argue that the LTE relay interface (Un) is an efficient candidate to enable multi-hop LTE mesh networks. We first study the Un interface and highlight its main properties. We then analyze and compare out-band LTE-Uu, in-band LTE-Uu with full duplex radios and in-band Un interface to mesh LTE base stations. We perform link-level emulations to assess the performance of the Un interface subject to different conditions. Finally, we compare the achievable throughput of self-backhauled LTE mesh network using either Un or LTE-Uu through a system-level simulation.

Reliable service provisioning is crucial to the public safety (PS) communications especially when network outage happens. Isolated E-UTRAN operation, introduced in LTE Release 13, is able to host separate core network functions at the base stations (BSs) to provide limited set of services to the users. However, a significant issue remains to be solved is to coordinate among BSs to create an autonomous network and enhance service availability and reliability. In this paper, an in-band LTE self-backhauling operation leveraging the relay interface is proposed to create an autonomous mesh network of BSs. This calls for an efficient resource allocation for multiple unplanned backhaul links between BSs. To this end, we present a cross-layer scheduling problem for in-band self-backhauled LTE network, and provide a interference-aware hierarchical resource allocation algorithm that is able to meet specific quality of service (QoS) requirements for real-time traffic while adapting to the workload of other types of traffic, through efficient leverage of FDD capabilities and network frequency re-use. Finally, a thorough evaluation on our proposed approach is realized via extensive simulations on different network topologies and diverse traffic flows, and the results demonstrate our work effectiveness utilization of available resources to satisfy QoS requirements.