Future Internet_**2010**, \(2\), 587-602; doi:10.3390/fi2040587  
_future internet_  
**ISSN 1999-5903**  
www.mdpi.com/journal/futureinternet  
_Article_  
**Look-Ahead Strategies Based on Store-Carry and Forward Relaying for Energy Efficient Cellular Communications**  
**[PERSON] \({}^{1,\star}\), [PERSON] \({}^{1}\) and [PERSON] \({}^{2}\)**  
\({}^{1}\) Centre for Telecommunications Research, King's College London, Strand WC2R 2 LS, London, UK;  
E-Mail: [EMAIL_ADDRESS]  
\({}^{2}\) Operational Research Group, London School of Economics, Houghton Street WC2A 2 AE, London, UK; E-Mail: [EMAIL_ADDRESS]  
\({}^{\star}\) Author to whom correspondence should be addressed; E-Mail: [EMAIL_ADDRESS];  
Tel. : +44 (0)20 7848 2889; Fax: +44 (0)20 7848 2664. _Received: 15 September 2010; in revised form: 25 October 2010 / Accepted: 2 November 2010 / Published: 4 November 2010_  
**Abstract:** With the increasing availability of Internet type services on mobile devices and the attractive flat rate all-you-can-eat billing system, cellular telecommunication networks are experiencing a tremendous growth in data usage demand. However, there are increasing concerns that current network deployment trends (including more efficient radio access techniques and increased spectrum allocation strategies), will be unable to support the increased Internet traffic in a sustainable way. The delay tolerant nature of mobile Internet traffic allows for a large degree of flexibility in optimizing network performance to meet different design objectives and it's a feature that has mostly gone unexplored by the research community. In this paper, we introduce a novel message forwarding mechanism in cellular networks that benefits from the inherent delay tolerance of Internet type services to provide flexible and adjustable forwarding strategies for efficient network operation while guaranteeing timely deliveries. By capitalizing on the elasticity of message delivery deadlines and the actual mobility of nodes inside the cell, considerable performance gains can be achieved by physically propagating information messages within the network. **Keywords:** energy-efficient communication; store-carry and forward relaying; multihop cellular networks; green networkingIntroduction  
Mobile network operators are currently experiencing an unprecedented increase in data traffic demand. Cisco forecasts that this demand will increase 66 times by year 2013 from the figures in 2008, exceeding the 2 exabytes per month data volume [1]. Already, North American operator AT&T comments a 5000% increase in data usage on its network over a three year period, with the growth showing no signs of decreasing in the near future. To cope with this demand surge, network operators have reside in four main solutions, namely: (1) increasingly smaller cell site deployments, (2) new\(-\)higher capacity\(-\)radio access technologies (RATs), (3) increased spectrum allocation and (4) network optimization. However, it is anticipated that such measures alone will not be able to keep up with the current data growth rates. For that reason, a significant volume of research work is currently looking into ways of improving the system efficiency so as to drive costs down while maintaining and improving the perceivable user experience. These efforts can be broadly taxonomized into the following two categories:  
1. Techniques; including more energy efficient hardware components, physical layer enhancements, energy-aware scheduling, better utilization of available spectrum via cognitive radio techniques and intelligent call admission control algorithms. 2. Architectures; including relay (mostly fixed) aided cellular networks, distributed antenna systems and co-existence of heterogenous mobile and wireless access networks. The work we present in this paper requires a new architectural framework for cellular networks that will allow a set of mechanisms for store carry and forward relaying to be enabled.