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Optimal Cluster Partitioning for Wireless Sensor Networks with Cooperative MISO SchemeKatayama, Masaaki, Yamazato, Takaya, Huang, Zheng January 2010 (has links)
No description available.
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QoS Over Multihop Wireless NetworksSaxena, Tarun 04 1900 (has links)
The aim of this work is to understand the requirements behind Quality of Service (QoS) for Multihop Wireless Networks and evaluate the performance of different such strategies. This work starts by establishing the basis for requirement of QoS and evaluates different approaches for providing QoS. Bandwidth is selected as the most important resource amongst the resources identified for ensuring QoS. The problem is modeled as an optimization problem that tries to maximize the amount of bandwidth available in the system while providing bounds over the bandwidth available over a route. Other QoS parameters are bound by hard limits and are not involved in the optimization problem.
The existence of spatial reuse rules has been established through simulations for a TCP based network. This establishes that the reuse rules are independent of the MAC and network layer protocols used. This idea is used in designing the simulations for strategies that use controlled spatial reuse and give known bounds for QoS. Simulations take the network and a set of connections to generate the best possible schedule that guarantees bandwidth to individual connections and maximizes the total number of slots used in the entire system. The total number of slots used is a measure of the bandwidth in use. The set of graphs and connections is generated by a random graph and connection generator and the data set is large enough to average the results.
There are two different approaches used for scheduling the connections. The first approach uses graph coloring and provides a simpler implementation in terms of network deployments. Second approach uses on-demand slot allocation. The approaches are compared for their pros and cons.
The first approach uses graph coloring to allocate fixed number of slots to each link. This makes an equivalent of a wired network with fixed bandwidth over each link. This network is simpler to operate and analyze at the cost of one time expense of graph coloring. The assumption here is that the network is static or has low mobility.
The on demand approach is more flexible in terms of slot assignment and is adaptable to the changing traffic patterns. The cons are that connection establishment is more expensive in terms of bandwidth required and is more complicated and difficult to analyze. The advantages include low initial network establishment cost and accommodation of mobility.
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OPTIMIZING DATA FRESHNESS IN INFORMATION UPDATE SYSTEMSBedewy, Ahmed M. 30 September 2021 (has links)
No description available.
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Performance evaluation and protocol design of fixed-rate and rateless coded relaying networksNikjah, Reza 06 1900 (has links)
The importance of cooperative relaying communication in substituting for, or complementing,
multiantenna systems is described, and a brief literature review is presented.
Amplify-and-forward (AF) and decode-and-forward (DF) relaying are investigated and
compared for a dual-hop relay channel. The optimal strategy, source and relay optimal
power allocation, and maximum cooperative gain are determined for the relay channel. It
is shown that while DF relaying is preferable to AF relaying for strong source-relay links,
AF relaying leads to more gain for strong source-destination or relay-destination links.
Superimposed and selection AF relaying are investigated for multirelay, dual-hop relaying.
Selection AF relaying is shown to be globally strictly outage suboptimal. A necessary
condition for the selection AF outage optimality, and an upper bound on the probability of
this optimality are obtained. A near-optimal power allocation scheme is derived for superimposed
AF relaying.
The maximum instantaneous rates, outage probabilities, and average capacities of multirelay,
dual-hop relaying schemes are obtained for superimposed, selection, and orthogonal
DF relaying, each with parallel channel cooperation (PCC) or repetition-based cooperation
(RC). It is observed that the PCC over RC gain can be as much as 4 dB for the outage
probabilities and 8.5 dB for the average capacities. Increasing the number of relays deteriorates
the capacity performance of orthogonal relaying, but improves the performances of
the other schemes.
The application of rateless codes to DF relaying networks is studied by investigating
three single-relay protocols, one of which is new, and three novel, low complexity multirelay
protocols for dual-hop networks. The maximum rate and minimum energy per bit and
per symbol are derived for the single-relay protocols under a peak power and an average
power constraint. The long-term average rate and energy per bit, and relay-to-source usage
ratio (RSUR), a new performance measure, are evaluated for the single-relay and multirelay
protocols. The new single-relay protocol is the most energy efficient single-relay scheme
in most cases. All the multirelay protocols exhibit near-optimal rate performances, but are
vastly different in the RSUR.
Several future research directions for fixed-rate and rateless coded cooperative systems,
and frameworks for comparing these systems, are suggested. / Communications
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Performance evaluation and protocol design of fixed-rate and rateless coded relaying networksNikjah, Reza Unknown Date
No description available.
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