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This paper studies user-centric cluster scheme in cloud radio access network (Cloud-RAN), where distributed Radio Remote Heads (RRHs) are connected to a centralized Based Band Units (BBUs) pool and all baseband processing is performed via high-bandwidth low-latency backhaul network. In user-centric cluster scheme, BBU schedules multiple RRHs for each user to form the serving cluster, and then BBU...
Energy efficient routers (EERs) are promising devices to achieve green communications for ISP to save energy and cost. However, deploying this kind of routers may introduce severe accumulated packet delay, especially for high-end optical routers. In this paper, we present three contributions to solve the above issue with dynamically balancing QoS and the energy consumption, while preserve the real...
Cloud Radio Access Network (C-RAN) offers an evolution in base stations architecture. The base station is broken down into a Base Band Unit (BBU) and a Remote Radio Head (RRH). While BBUs are pooled in a single geographical point, RRHs are distributed across multiple sites. In conventional architectures, a one-to-one logical mapping exists between BBUs and RRHs. One BBU is assigned to one RRH, so...
Rapid growth and demand for computational power by scientific, business and web-applications has led to the creation of large-scale datacenters consuming enormous amounts of power. Improving the efficiency of datacenters, with a focus on power consumption and carbon emission, is a topical theme on which we are witnessing an increasing amount of academic and industrial research. The objective of this...
This paper investigates dynamic topology management functionalities in the flexible deployment of a hybrid aerial-terrestrial cognitive cellular network for public safety in unexpected or temporary events. An evolutionary roll out and roll back of the network architecture in the disaster relief scenario is proposed under the assistant of topology management algorithm, in order to manage the number,...
As the scale of cloud data centers becomes larger and larger, the energy consumption of data centers also grows rapidly. Dynamic consolidation of Virtual Machines (VMs) presents a significant opportunity to save energy by turning off idle or under-utilized Physical Machines (PMs) in data centers. In this paper, we present a multi-agent based architecture for performing dynamic VM consolidation task...
Driven by global warming suppression and depletion of fossil fuel resource, micro-grid (MG) especially the one with renewable sources such as solar photovoltaic (PV) and wind generations (WG) are getting attention in power systems. Nevertheless, due to the unpredictability and fluctuation of the energy generated by renewable energy resources, it is hard to adapt to the change of the consumers' electricity...
General-purpose computing on GPUs (GPGPU computing) is becoming widely adopted; however, some GPGPU applications fail to fully utilize GPU resources. In these cases, spatial multitasking better exploits the parallelism offered by GPUs by partitioning the GPU resources among simultaneously-running applications. When one or more such applications have quality-of-service (QoS) requirements, enough resources...
Given the significant energy consumption in operating base stations (BSs), improving their energy efficiency is an important problem in cellular networks. To this end, this paper proposes a novel framework, called DCR (dynamic cell reconfiguration) that dynamically adjust the set of active BSs and user association according to user traffic demand for energy conservation. In order to overcome prohibitive...
The thermal-aware service rate assignment problem is a major challenge in cyber-physical systems. This problem is complex because of the severe temperature changes in uncertain physical environments and variable power consumption for each application, and these two effects might cause the system to overheat. This study proposes a dynamic-programming based service rate assignment with a feedback control...
Wireless sensor networks may support heterogeneous applications ranging from classical environmental monitoring, to more demanding integrated surveillance systems based on multimedia traffic. To this extent, we argue that the specific MAC layer solutions must be flexible enough to provide differentiated services based on the context of the specific WSN. In this work, we leverage the SPARE MAC protocol...
According to several studies, the power consumption of the Internet accounts for up to 10% of the worldwide energy consumption, and several initiatives are being put into place to reduce the power consumption of the ICT sector in general. To this goal, we propose a novel approach to switch off network nodes and links while still guaranteeing full connectivity and maximum link utilization. After showing...
U-APSD is the power save procedure defined in IEEE802.11e to improve the QoS performance of multimedia applications. U-APSD is specially suited for bi-directional traffic streams. But in some scenario without synchronized uplink and downlink traffic, defects in U-APSD procedure will result in some problems. In order to address this issue, this paper develops a low power implementation scheme of U-APSD...
This paper investigates effects of pilot assisted channel estimation on dynamic resource allocation in a multiuser orthogonal frequency division multiplexing (OFDM) system. The channel estimation is done in each OFDM symbol through least-squared error (LSE) or minimum mean-squared error (MMSE) algorithm. The performance of each of these algorithms is evaluated through computer simulations. The maximal...
We investigate a power-controlled transmission scheme for streaming media traffic over wireless links. The server (source) transmits encoded media packets to a client (user) over a fluctuating wireless channel. The client stores received packets into a fixed-size buffer and plays them out at a constant rate. Due to random channel interference, the source needs to adapt its transmission power and rate...
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