16 research outputs found
Performance Analysis of Network-Assisted Two-Hop D2D Communications
Network-assisted single-hop device-to-device (D2D) communication can increase
the spectral and energy efficiency of cellular networks by taking advantage of
the proximity, reuse, and hop gains when radio resources are properly managed
between the cellular and D2D layers. In this paper we argue that D2D technology
can be used to further increase the spectral and energy efficiency if the key
D2D radio resource management algorithms are suitably extended to support
network assisted multi-hop D2D communications. Specifically, we propose a
novel, distributed utility maximizing D2D power control (PC) scheme that is
able to balance spectral and energy efficiency while taking into account mode
selection and resource allocation constraints that are important in the
integrated cellular-D2D environment. Our analysis and numerical results
indicate that multi-hop D2D communications combined with the proposed PC scheme
can be useful not only for harvesting the potential gains previously identified
in the literature, but also for extending the coverage of cellular networks.Comment: 6 pages and 7 figure
VOD STREAMING WITH A NETWORK CODING EQUIVALENT CONTENT DISTRIBUTION SCHEME
Although random access operations are desirable for on-demand video streaming in peer-to-peer systems, they are difficult to efficiently achieve due to the asynchronous interactive behaviors of users and the dynamic nature of peers. In this paper, we propose a network coding equivalent content distribution (NCECD) scheme to efficiently handle interactive videoon- demand (VoD) operations in peer-to-peer systems. In NCECD, videos are divided into segments that are then further divided into blocks. These blocks are encoded into independent blocks that are distributed to different peers for local storage. With NCECD, a new client only needs to connect to a sufficient number of parent peers to be able to view the whole video and rarely needs to find new parents when performing random access operations. In most existing methods, a new client must search for parent peers containing specific segments; however, NCECD uses the properties of network coding to cache equivalent content in peers, so that one can pick any parent without additional searches. Experimental results show that the proposed scheme achieves low startup and jump searching delays and requires fewer server resources. In addition, we present the analysis of system parameters to achieve reasonable block loss rates for the proposed scheme
GREENET - An Early Stage Training Network in Enabling Technologies for Green Radio
International audienceIn this paper, we describe GREENET (an early stage training network in enabling technologies for green radio), which is a new project recently funded by the European Commission under the auspices of the 2010 Marie Curie People Programme. Through the recruitment and personalized training of 17 Early Stage Researchers (ESRs), in GREENET we are committed to the development of new disruptive technologies to address all aspects of energy efficiency in wireless networks, from the user devices to the core network infrastructure, along with the ways the devices and equipment interact with one another. Novel techniques at the physical, link, and network layers to reduce the energy consumption and carbon footprint of 4G devices will be investigated, such as Spatial Modulation (SM) for Multiple-Input-Multiple-Output (MIMO) systems, Cooperative Automatic Repeat reQuest (C-ARQ) protocols, and Network Coding (NC) for lossy networks. Furthermore, cooperation and cognition paradigms will be exploited as additional assets to improve the energy efficiency of wireless networks with the challenging but indispensable constraint of optimizing the system capacity without degrading the user's Quality-of-Service (QoS)
Multi-radio cooperative ARQ in wireless cellular networks: a MAC layer perspective
Multi-Radio Cooperative Automatic Retransmission Request (MCARQ)
schemes are introduced in this paper within the context of hybrid networks
which combine long-range and short-range communications. Since the number of
wireless devices is incessantly increasing, it is frequently possible to establish a
spontaneous cooperative cluster in the close proximity of any wireless device.
These devices forming the cluster are connected to both a cellular-based network
such as WiMAX, 3G, or LTE and a short-range network based on technologies
such as WLAN, Zigbee, Bluetooh, or UWB, among other possibilities. The main
idea behind the proposed MC-ARQ scheme is that, upon transmission error
through the cellular interface, retransmission can be requested to the wireless grid
surrounding the destination device using the short-range interface instead of the
primary cellular link. Therefore, besides the cooperative diversity attained with CARQ
schemes, the traffic load in the cellular interface is reduced benefiting thus a
high number of users and reducing both energy consumption and interference.
The Persistent Relay Carrier Sensing Medium Access (PRCSMA) protocol is
presented as an example of solution for the MAC layer in this emerging new topic.Postprint (published version
Joint Spectrum and Power Allocation for D2D Communications Underlaying Cellular Networks
This paper addresses the joint spectrum sharing and power allocation problem for device-to-device (D2D) communications underlaying a cellular network (CN). In the context of orthogonal frequency-division multiple-access systems, with the uplink resources shared with D2D links, both centralized and decentralized methods are proposed. Assuming global channel state information (CSI), the resource allocation problem is first formulated as a nonconvex optimization problem, which is solved using convex approximation techniques. We prove that the approximation method converges to a suboptimal solution and is often very close to the global optimal solution. On the other hand, by exploiting the decentralized network structure with only local CSI at each node, the Stackelberg game model is then adopted to devise a distributed resource allocation scheme. In this game-theoretic model, the base station (BS), which is modeled as the leader, coordinates the interference from the D2D transmission to the cellular users (CUs) by pricing the interference. Subsequently, the D2D pairs, as followers, compete for the spectrum in a noncooperative fashion. Sufficient conditions for the existence of the Nash equilibrium (NE) and the uniqueness of the solution are presented, and an iterative algorithm is proposed to solve the problem. In addition, the signaling overhead is compared between the centralized and decentralized schemes. Finally, numerical results are presented to verify the proposed schemes. It is shown that the distributed scheme is effective for the resource allocation and could protect the CUs with limited signaling overhead