Pontus Wallentin

Device-to-Device Communications for National Security and Public Safety

Device-to-device (D2D) communications have been proposed as an underlay to long-term evolution (LTE) networks as a means of harvesting the proximity, reuse, and hop gains. However, D2D communications can also serve as a technology component for providing public protection and disaster relief (PPDR) and national security and public safety (NSPS) services. In the United States, for example, spectrum has been reserved in the 700-MHz band for an LTE-based public safety network. The key requirement for the evolving broadband PPDR and NSPS services capable systems is to provide access to cellular services when the infrastructure is available and to efficiently support local services even if a subset or all of the network nodes become dysfunctional due to public disaster or emergency situations. This paper reviews some of the key requirements, technology challenges, and solution approaches that must be in place in order to enable LTE networks and, in particular, D2D communications, to meet PPDR and NSPS-related requirements. In particular, we propose a clustering-procedure-based approach to the design of a system that integrates cellular and ad hoc operation modes depending on the availability of infrastructure nodes. System simulations demonstrate the viability of the proposed design. The proposed scheme is currently considered as a technology component of the evolving 5G concept developed by the European 5G research project METIS.

Radio resource management distribution in a beyond 3G multi-radio access architecture

Efficient employment of multiple radio access technologies is expected to be an important property of beyond 3G networks. This will put high demands on radio resource management support, both within and in-between radio access technologies. In this paper we discuss how to distribute radio resource management in a multi-radio access network, and identify three main distribution strategies: network centralized, network distributed and finally the option of having multi-access radio resource management located in the terminal. A combination of network distributed and terminal based radio resource management appears to be the best choice for dynamic multi-access radio resource management in most scenarios. Further, relations towards user plane functions are discussed and modeled, and the functionality is mapped to nodes and interfaces of a beyond 3G reference radio access network architecture.

Tight Integration of New 5G Air Interface and LTE to Fulfill 5G Requirements

Integration of new radio technologies to legacy ones has always been an important feature in any wireless communication generation shift and it is envisioned that for the transition to 5G this will be even more critical. Different 5G research projects have acknowledged the demand for a new air interface that will be designed to operate in higher frequency bands (compared to the ones currently allocated to LTE) where propagation is more challenging and coverage is spotty. This paper proposes a radio access network (RAN) architecture that realizes a tight integration of this new air interface with LTE to enable cross-air interface optimizations such as common resource management, faster mobility and simultaneous multi-connectivity features. The tight integration also aims at leveraging both the better coverage of LTE and the higher capacity of the higher frequency bands. In order to realize this integration, a common protocol layer (also called integration layer) lying on the top of lower layer protocols specified per air interface is proposed. The paper analyzes the alternatives for this integration layer, having the LTE protocol stack specified by 3GPP as a reference model. A recommendation is issued and, based on that, potential multi-connectivity features are presented.

A generic link layer in a beyond 3G multi-radio access architecture

A major aspect of beyond 3G networks is the efficient integration of multiple radio access technologies in a common network. One advantage of this multi-radio access integration will be an increased radio resource efficiency, e.g., due to a larger trunking gain and reduced radio cost per link. One realization of the multi-radio access integration is based on a generic link layer, which provides generic data processing for a multitude of radio access technologies. The generic link layer enables fast and lossless access selection. The functional architecture of the generic link layer is discussed, including the separation of radio dependent and radio independent functions. Furthermore, the relationship of the generic link layer to (multi-) radio resource management functions and radio specific transmission functions is presented and an example of access selection is described. Finally, we present how the generic link layer is included into a beyond 3G network architecture.