Bernhard Raaf

Effect of Relaying on Coverage in 3GPP LTE-Advanced

Current broadband wireless networks are characterized by large cell sizes. Yet, even in advanced networks that will be built using 3 GPP Long Term Evolution (LTE), also referred to as 3GPP LTE-Advanced, or mobile WiMAX radio interface, users on the cell edge will face relatively low signal-to-interference-plus-noise-ratio (SINR). An attractive solution for this problem is provided by multihop technologies. In this paper we consider the feasibility of Decode and Forward (DF) Relay Nodes (RNs) from 3GPP LTE-Advanced perspective. We propose a novel evaluation methodology that can be used to find a relation of RN transmission power, ratio between number of Base Stations (BSs) and RNs, and performance of the system. Evaluation of DF relays in 3GPP LTE-Advanced framework indicates a good performance gain.

Business Impact of Relay Deployment for Coverage Extension in 3GPP LTE-Advanced

Relays are expected to be a cost efficient way to fulfill requirements on high data rate coverage in next generation cellular networks, like LTE-Advanced. This paper presents a cost model and the respective analysis used for investigating the impact of relaying on cost savings for operators. The approach consists of defining the service level that next generation cellular networks should provide and deriving deployments of eNBs and RNs (or equivalently iso- performance scenarios) that fulfill these requirements. Iso- performance scenarios are therefore obtained by means of simulations and compared in the cost model.

LTE-Advanced: The path towards gigabit/s in wireless mobile communications

This paper addresses the performance targets and the technology components being studied by 3GPP for LTE-Advanced. LTE-Advanced is the next major step in the evolution of UTRAN Long Term Evolution (LTE) release 8, currently being finalized by 3GPP. The high level targets of LTE-Advanced are to meet or exceed the IMT-Advanced requirements set by ITU-R and furthermore, meet any additional operator requirements. This for instance includes the target of supporting more than one gigabit/s data rates, higher cell throughput and lower cost per bit. The technology components being identified as part of the LTE-Advanced Study Item include component carrier aggregation to enable up to 100MHz bandwidth, advanced MIMO options up to 8×8 in DL and 4×4 in UL, coordinated multiple point transmission and reception (CoMP), relay nodes (RN) and autonomous component carrier selection (ACCS) for uncoordinated femto cell deployment.

On the coverage extension and capacity enhancement of inband relay deployments in LTE-advanced networks

Decode-and-forward relaying is a promising enhancement to existing radio access networks and is currently being standardized in 3GPP to be part of the LTE-Advanced release 10. Two inband operation modes of relay nodes are to be supported, namely Type 1 and Type 1b. Relay nodes promise to offer considerable gain for system capacity or coverage depending on the deployment prioritization. However, the performance of relays, as any other radio access point, significantly depends on the propagation characteristics of the deployment environment. Hence, in this paper, we investigate the performance of Type 1 and Type 1b inband relaying within the LTE-Advanced framework in different propagation scenarios in terms of both coverage extension capabilities and capacity enhancements. A comparison between Type 1 and Type 1b relay nodes is as well presented to study the effect of the relaying overhead on the system performance in inband relay node deployments. System level simulations show that Type 1 and Type 1b inband relay deployments offer low to very high gains depending on the deployment environment. As well, it is shown that the effect of the relaying overhead is minimal on coverage extension whereas it is more evident on system throughput.

Dynamic relaying in 3GPP LTE-advanced networks

Relaying is one of the proposed technologies for LTE-Advanced networks. In order to enable a flexible and reliable relaying support, the currently adopted architectural structure of LTE networks has to be modified. In this paper, we extend the LTE architecture to enable dynamic relaying, while maintaining backward compatibility with LTE Release 8 user equipments, and without limiting the flexibility and reliability expected from relaying. With dynamic relaying, relays can be associated with base stations on a need basis rather than in a fixed manner which is based only on initial radio planning. Proposals are also given on how to further improve a relay enhanced LTE network by enabling multiple interfaces between the relay nodes and their controlling base stations, which can possibly be based on technologies different from LTE, so that load balancing can be realized. This load balancing can be either between different base stations or even between different networks.

Future Mobile Communication Networks: Challenges in the Design and Operation

This article highlights particular challenges inherent in the design and operation of future mobile communications systems This paper also discusses the various degrees of freedom involved, and points out which design paradigms appear most promising and which major fields of future research remain.

Handover Framework for Relay Enhanced LTE Networks

Relaying is one of the proposed technologies for future releases of UTRAN long term evolution (LTE) networks. Introducing relaying is expected to increase the coverage and capacity of LTE networks. In order to enable relaying, the architecture, protocol and radio resource management procedures of LTE, such as handover, have to be modified. A user can be handed over not only between two base stations, but also between relays and base stations, and between two relays. With the introduction of relaying, there is a need for a new procedure to hand over a relay and all its associated users to another base station, allowing a flexible and dynamic relay deployment. In this paper, we extend the LTE release 8 handover mechanisms so that it can accommodate these new handover functionalities in a flexible manner.

B4G local area: High level requirements and system design

A next generation Beyond 4G (B4G) radio access technology is expected to become available around 2020 in order to cope with the exponential increase of mobile data traffic. In this paper, research motivations and high level requirements for a B4G local area concept are discussed. Our suggestions on the design of the B4G system as well as on the choice of its key technology components are also presented.

Comparison of Relay and Pico eNB Deployments in LTE-Advanced

Relaying is one of the most important novel elements in 3GPP LTE-Advanced study item. It promises to offer significant gain for system capacity or coverage depending on the deployment prioritization. In this paper, we investigate the feasibility of relay node deployments in terms of system throughput and cell coverage area extension as compared to pico node deployments and traditional homogeneous single-hop macro cells. Relay backhaul link overhead is taken into consideration as a limiting factor in a relay deployment; nevertheless, results show that its effect on coverage extension is in most cases negligible. While the effect of relay backhaul overhead is small in coverage limited scenarios, the limitations on throughput due to relaying are evident, in particular, for 500m ISD scenarios. This study also demonstrates that both relay and pico node deployments outperform clearly traditional macro cell deployment in terms of coverage and network capacity.

Vision for Beyond 4G broadband radio systems

Mobile communication systems have evolved over the past decades and each new generation brought new experience to the users enabled by technology innovations, while keeping some well established principles from previous generations. This trend continued up to LTE (Long Term Evolution) Advanced, the predominant 4th generation system which has just been standardized in 3GPP and is being rolled out soon. How will this trend continue to future systems which will be deployed in some 10 years from now which will be advanced enough to be called “Beyond 4G” (B4G)? This article presents how such B4G systems will look like and some key technologies they will rely on including versatile numerology, massive virtual MIMO from many base stations, both centralized and distributed architectures using fiber optics as backbone, advanced interference mitigation, cognitive self organization, and wideband RF radios.