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This work analyzes the downstream impediments of centralized local access networks with LAN capability and proposes an efficient downstream scheme over a distributed upstream control plane, where OLT is relieved from the burden of upstream control function and inter-ONU communication.
There are real challenges in both the IEEE 802.11 wireless local area network (WLAN) protocol and the medium access control (MAC)-functions providing the required quality-of-service, high throughput and minimum latencies. The IEEE 802.11 layer supports both the distributed coordination function (DCF) and the enhanced DCF (EDCF). The different access categories (AC) within the EDCF can enhance the...
Due to the rapid and independent developments of systems, heterogeneity has become a common feature of current networks. In order to harmonize two different networks and close the gap between their technologies, we need to develop a good mechanism for network selection, and access that best satisfy user requirements. Many public areas (collages, airports, hotels...etc) have different systems for providing...
We study a multiple-access system with a primary user (PU) and a secondary user (SU) utilizing the same frequency band and communicating with a common receiver. Both users transmit with a fixed transmission rate by employing a channel inversion power control scheme. The SU transmits with a certain probability that depends on the sensing outcome, its queue length and whether it has a new packet arrival...
Scheduling is a fundamental component in resource (bandwidth and power) management in NG wireless networks and plays the main role in providing QoS requirements such as delay, throughput and packet loss for different classes of service in 802.16d networks. In this paper we propose a novel scheduling algorithm Strict Priority Based Adaptive modulation and Coding (SP_AMC_Based) that can grantee QoS...
Several centralized algorithms have been proposed for upstream bandwidth-allocation in passive optical networks (PONs); making the optical line terminal (OLT) in the central office the intelligent device that arbitrates time-division access to the shared upstream channel. When the distance between the OLT and optical network units (ONUs) is extended from 20 km to beyond 100 km, as suggested by next...
Mobile ad-hoc networks (MANETs) are dynamic in nature. Links between nodes may constantly change due to mobility. The performance of the transmission control protocol (TCP) degrades in such an environment mainly due to its inability to differentiate between congestion and link failures which are frequent in MANETs. Several TCP variants were proposed to adapt TCP to a mobile environment. In addition,...
In this paper, two estimators are proposed for calculating fine timing and channel impulse response (CIR) of a CD-OFDM based communication system. The proposed low complexity algorithms are designed to operate with asynchronous nodes having independent timing and carrier frequency offsets. These algorithms fully exploit the specially designed structure of time domain preamble used for cooperative...
In order to successfully resolve the network infrastructure's problems the network provider has to improve the service quality. However in traditional ways, maintaining and improving of the service quality are generally determined in terms of quality of service criteria, not in terms of satisfaction and perception to the end-user. The latter is represented by Quality of Experience (QoE) that becomes...
Various ad-hoc routing protocols have been proposed for wireless networks with dense distribution of wireless nodes. For support of multihop transmission in sparse wireless networks, some DTN (delay-tolerant network) routing have been proposed. However, it is difficult to get better tradeoff between communication overhead and reachability of data messages in DTN routing. This paper proposes a novel...
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