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We consider the problem of scheduling VMs (Virtual Machines) in a multi-server system motivated by cloud computing applications. VMs arrive dynamically over time and require various amounts of resources (e.g., CPU, Memory, Storage, etc.) for the duration of their service. When a VM arrives, it is queued and later served by one of the servers that has sufficient remaining capacity to serve it. The...
Carrier Sense Multiple Access (CSMA) protocols have been shown to reach the full capacity region for data communication in wireless networks, with polynomial complexity. However, current literature achieves the throughput optimality with an exponential delay scaling with the network size, even in a simplified scenario for transmission jobs with uniform sizes. Although CSMA protocols with order-optimal...
In dynamic cognitive radio networks (CRNs), unlicensed secondary users (SUs) opportunistically transmit in the spectrum holes left available by licensed primary users (PUs), without knowing in advance their presence on the channels. For SUs with multi-channel transmission capability, the process of selecting the channels to use by sequentially sensing the presence of PUs and evaluating the channel...
In dynamic cognitive radio networks (CRNs) secondary users (SUs) sense the spectrum bands to find temporal absence of primary users (PUs) and immediately transmit on the identified spectrum holes. SUs sequentially sense the channels, stopping when the available resources are expected to provide the best throughput performance. Following, the selected channels are exploited using multi-channel transmission...
The backpressure algorithm for dynamic network resource allocation achieves throughput optimality by making use of one-hop queue length differences. This elegant algorithm, on the other hand, does not yield good delay performance in general. We introduce a new class of enhanced dynamic backpressure algorithms which make use of a general queue-dependent bias function to exploit queue state information...
A prior layer-2 routing algorithm-D2ENDIST demonstrates advantages in throughput improvement, reroute period and failure recovery. Moreover, with the invention of software-defined networking (SDN), a revolutionary networking concept, dynamic routing protocols can embrace more flexible policy on per-flow basis. However, due to runtime complexity of dynamic routing, many issues on the practicality emerge...
Cognitive Radio Network (CRN) technology allows secondary users (SUs) to transmit data exploiting the wireless resources not utilized by licensed primary users (PUs). Channel exploration by SUs for finding transmission opportunities incurs non-negligible costs and is a key challenge in successful operation of CRN. In this paper, we investigate the joint effect of channel exploration order and stopping...
We design an adaptive modulation scheme to support opportunistic multicast scheduling in wireless networks. Whereas prior work optimizes capacity, we investigate the finite horizon problem where (once or repeatedly) a fixed number of packets has to be transmitted to a set of wireless receivers in the shortest amount of time — a common problem, e.g., for software updates or video multicast. In the...
In this paper, we propose techniques for clustering large-scale "streaming" graphs where the updates to a graph are given in form of a stream of vertex or edge additions and deletions. Our algorithm handles such updates in an online and incremental manner and it can be easily parallel zed. Several previous graph clustering algorithms fall short of handling massive and streaming graphs because...
Multicast traffic grooming is used to multiplex or groom multiple low bandwidth multicast connections into a high bandwidth wavelength channel or light-tree to increase the utilization of wavelength. However, multicast traffic grooming is NP-hard problem. Thus, we propose two heuristic algorithms with polynomial complexities, called Adjacent Node Component based Grooming for Throughput (ANCG-T) and...
The throughput of conventional multicast transmission in wireless systems is limited by the user with the worst channel quality in the multicast service group. The subcarrier allocation for multicast services in multicarrier systems is a feasible solution to overcome the capacity limitation by exploiting the frequency diversity among subcarriers. However, most of the current subcarrier allocation...
In this paper, we develop an efficient resource allocation algorithm for multiple-input multiple-output orthogonal frequency division multiple access (MIMO-OFDMA) networks that considers all OFDM symbols in the current frame. By recognizing the special structure of the optimization problem, we develop an efficient algorithm based on graph theory that has a complexity independent of the number of OFDM...
Achieving sufficient spatial capacity gain by having small cells requires careful treatment of inter-cell interference (ICI) management via BS power coordination coupled with user scheduling inside cells. Optimal algorithms have been known to be hard to implement due to high computation and signaling overheads. We propose joint pattern-based ICI management and user scheduling algorithms that are practically...
With the emergence of high bandwidth-delay product and heterogeneous wired / wireless networks, the standard TCP appears to be too conservative to offer reasonable performance. The use of parallel TCP connections has been suggested in such environments. We have demonstrated that, with the same level of aggressiveness, this approach can outperform the single-connection based approach. However, this...
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