The Transmission Control Protocol.

Multi-standard mobile terminals (MTs) are the trend of current and future mobile devices for taking advantage of heterogeneous integration of wireless access networks and providing ubiquitous connectivity and better quality of service. Holding multiple active interfaces, however, incurs significant power consumption burdens to MTs. This not only increases the carbon footprint of MTs but also makes the batteries of MTs deplete rapidly. Consequently, mobile users may have to relentlessly look for power outlets to charge their devices, which may threaten their true mobility freedom. To this end, in this article, we propose a promising approach based on coalition formation game and inter-terminal cooperation. Our innovative approach motivates MTs to cooperate, while addressing the issue of isolating selfish players. MTs assess radio channels and disseminate the acquired information as well as their available resources to sketch a global view of the radio environment. Based on this view, coalitions are formed whenever energy saving is foreseeable. Within a coalition, MTs pool their resources and perform their tasks cooperatively to maximize their energy efficiency. Simulation results validate that the proposed approach can effectively double the battery lifetimes of MTs, while successfully eliminating selfish players from cooperative groups.

Coalition formation game toward green mobile terminals in heterogeneous wireless networks

IEEE 802.11 WLANs are a very important technology to provide high speed wireless Internet access. Especially at airports, university campuses or in city centers, WLAN coverage is becoming ubiquitous leading to a deployment of hundreds or thousands of Access Points (AP). Managing and configuring such large WLAN deployments is a challenge. Current WLAN management protocols such as CAPWAP are hard to extend with new functionality. In this paper, we present CloudMAC, a novel architecture for enterprise or carrier grade WLAN systems. By partially offloading the MAC layer processing to virtual machines provided by cloud services and by integrating our architecture with OpenFlow, a software defined networking approach, we achieve a new level of flexibility and reconfigurability. In Cloud-MAC APs just forward MAC frames between virtual APs and IEEE 802.11 stations. The processing of MAC layer frames as well as the creation of management frames is handled at the virtual APs while the binding between the virtual APs and the physical APs is managed using OpenFlow. The testbed evaluation shows that CloudMAC achieves similar performance as normal WLANs, but allows novel services to be implemented easily in high level programming languages. The paper presents a case study which shows that dynamically switching off APs to save energy can be performed seamlessly with CloudMAC, while a traditional WLAN architecture causes large interruptions for users.

CloudMAC — An OpenFlow based architecture for 802.11 MAC layer processing in the cloud

This paper investigates advanced energy-efficient wireless systems in orthogonal frequency-division multiple access (OFDMA) downlink networks using coordinated multipoint (CoMP) transmissions between the base stations (BSs) in a heterogeneous network (HetNet), which is adopted by Third-Generation Partnership Project (3GPP) Long-Term Evolution (LTE)-Advanced to meet International Mobile Telecommunications-Advanced targets HetNet CoMP has received significant attention as a way of achieving spectral efficiency (SE) and energy efficiency (EE) Usually, in the literature, the total network power consumption is restricted to the sum of the power consumption of all BSs The significance of the power consumption of the backhaul links in wireless networks is normally omitted for its trivial effect with respect to that of the radio BSs For SE and EE analysis of HetNet CoMP, the energy and bandwidth consumption of the backhaul is considered, without which, the investigation remains incomplete However, SE and EE are design criteria in conflict with each other, and a careful study of their tradeoff is mandatory for designing future wireless communication systems The EE is measured as “throughput (bits) per joule,” whereas the power consumption model includes RF transmit (radiated), circuit, and backhaul power Furthermore, a nonideal backhaul model such as a microwave link is also investigated within intra-HetNet-CoMP (inside one cell), where an implementing fiber is not feasible An intercell interference (ICI) coordination method is also studied to mitigate ICI At the end, a novel resource allocation algorithm is proposed—modeled as an optimization problem—which takes into account the total power consumption, including radiated, circuit, and backhaul power, and the minimum required data rate to maximize EE Given an SE requirement, the EE optimization problem is formulated as a constrained optimization problem The considered optimization problem is transformed into a convex optimization problem by redefining the constraint using cubic inequality, which results in an efficient iterative resource allocation algorithm In each iteration, the transformed problem is solved by using dual decomposition with a projected gradient method Simulations results demonstrate how backhaul has a significant impact on total power consumption and the effectiveness of the studied schemes In addition, the results demonstrate that the proposed iterative resource allocation algorithm converges within a small number of iterations and illustrate the fundamental tradeoffs between SE and EE Our analytical results shed light on future “green” network planning in advanced OFDMA wireless systems like those envisioned for a fifth-generation (5G) system

Green HetNet CoMP: Energy Efficiency Analysis and Optimization

In this paper, we present a method for resource allocation for small cells that integrate licensed and unlicensed RF operations motivated by the widespread WiFi hotspots and the common inclusion of WiFi interface in most cellular terminals. Small cells have proven popular for cell coverage enhancement and traffic offloading from macrocells. We formulate an optimization problem that jointly allocates resources over both licensed and unlicensed bands with the goal of maximizing sum small cell user equipment (SUE) rate while achieving fairness among these user equipments and controlling inter-cell interference to neighboring macrocell users. The proposed solution further considers the quality of service (QoS) requirement of SUE traffics to be distributed over both licensed and unlicensed bands. We show the formulation of the proposed optimization problem as an efficient and low complexity linear programming. We further show that our problem formulation can be modified to maximize the revenue of mobile network operators. Our proposed solution achieves better performance than several existing solutions.

Resource Allocation and Inter-Cell Interference Management for Dual-Access Small Cells

Broadband wireless access becomes more and more important for current and future communication systems. The IEEE 802.16 (WiMAX) standard combines this technology with mesh multihop network topologies. These multihop networks can be deployed for high speed wide-area wireless networks. One key issue of mesh networking is the MAC (Medium Access Control) layer, which is used to share common channel resources (transmission opportunities) among wireless nodes. The scheduling and assignment of transmission opportunities can be realized in centralized or distributed manner. This paper analysis the IEEE 802.16 election based transmission timing (ebtt) mechanism for the coordinated distributed scheduling (C-DSCH). This mechanism is responsible for transmission timing of C-DSCH signaling messages. As the standard defines only a framework of the ebtt-mechanism this paper presents some extensions that are needed in order to guarantee a correct functionality. Furthermore, simulations using the network simulator ns2 show that the standard election mechanism does not perform well and causes a significant delay to data packets. This paper proposes new ideas to solve the problems and to reduce the packet delay.

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Transmission timing of signaling messages in IEEE 802.16 based Mesh Networks

This article presents an architecture to support IPTV services in an IMS-based NGN. The architecture extends the current IMS specification with the required functionality to meet additional requirements of IPTV services. The proposed architecture can be deployed by an IPTV provider over heterogeneous access networks (mobile, wireless, and fixed) as a part of standardized NGN solutions. After presenting an overview of the IPTV standardization activities in DVB, ITU-T, ETSI, ATIS, 3GPP, and OMA, this article focuses on the ETSI TISPAN IPTV standardization. IMS-based IPTV architectural functions and possible IPTV evolutionary steps are discussed, and then the article presents an implementation example.

IPTV Systems, Standards and Architectures: Part II - IPTV Services over IMS: Architecture and Standardization

This paper presents a novel architecture for providing converged IP-based TV (IPTV) services specified by ETSI TISPAN standardisation for IPTV in ongoing NGN release 2 specifications. The described IPTV architecture is based on utilisation of the IP Multimedia Subsystem concept used by NGN architectural framework and its adaptation to provide the IPTV specific functionalities and services. Using the foundation provided by the IMS based architecture, we propose a new functional architecture to enhance the functionalities and features needed for scalable converged networks, flexible media delivery and advanced IPTV service scenarios. The proposed architecture, leveraging on the FMC architecture that operators may deploy to provide IPTV service across different access networks in future deployments (mobile, wireless, fixed) has prototypically been implemented in the ScaleNet* demonstrator testbed. This paper analyses in detail the main principles for such a converged reference architecture. The paper also presents the IPTV service scenario prototype called Click-to-Multimedia which shows some basic features and advantages implemented on top of the presented architecture by prototyping demo applications as proof of concept reference.

IMS based IPTV services: architecture and implementation

Optimizing the operation of IEEE 802.11 networks requires to estimate the load of the wireless channel. The channel busy fraction, which is the fraction of time in which the wireless channel is sensed busy due to successful or unsuccessful transmissions, can be used as such indicator. It can be obtained from e.g. the IEEE 802.11k channel load report or hardware-specific interfaces. Previously, the channel busy fraction has been used as a metric for different purposes such as routing and admission control. However, a thorough evaluation of the relationship between the busy fraction and other important characteristics such as the collision probability and throughput is missing. In this paper, we present an analytical model to study the channel busy fraction in non-saturated IEEE 802.11 networks. We validate the model with measurements in a testbed. The predictions from the model match measurements well. Furthermore, we demonstrate how to apply the model to estimate the available link bandwidth. Using measurements obtained from a testbed operated at 6 Mbit/s, we show that the channel busy fraction allows an accurate prediction of the available bandwidth with an error smaller than 70 Kbit/s.

Theoretical and experimental analysis of the channel busy fraction in IEEE 802.11

To be able to serve the traffic demand in today's mobile networks, more than 123.000 base stations (BSs) have been deployed by the different network providers in Germany. These BSs are working 24/7 and are dimensioned to serve capacity demand during busy hours. Currently no mechanisms for a load adaptive network reconfiguration are implemented. As a result, much energy is wasted during times in which the capacity demand is low. This paper describes an adaptive, context-aware, and technology-comprehensive system architecture for power management in modern radio networks. The results presented are developed within the project Communicate Green (ComGreen). A major goal of ComGreen is the development of a testbed in order to investigate and demonstrate the main achievements of the project. The aim of this paper is twofold: First, it highlights the ComGreen concepts for power management in heterogeneous radio networks. Second, a detailed description of the testbed is provided.

Dmitry Sivchenko

Papers

Transmission timing of signaling messages in IEEE 802.16 based Mesh Networks

IPTV Systems, Standards and Architectures: Part II - IPTV Services over IMS: Architecture and Standardization

IMS based IPTV services: architecture and implementation

Theoretical and experimental analysis of the channel busy fraction in IEEE 802.11

Energy optimisation in heterogeneous multi-RAT networks