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Fractional frequency reuse (FFR) is an interference coordination technique well-suited to OFDMA based wireless networks wherein cells are partitioned into spatial regions with different frequency reuse factors. This work focuses on evaluating the two main types of FFR deployments: Strict FFR and Soft Frequency Reuse (SFR). Relevant metrics are discussed, including outage probability, network throughput,...
The paper analysed MAC protocol based on multiple-channel RMA by dividing transmission time of information packet into 1 & a. The paper adopts a joint-control strategy that detect with probability p1 in time 1, detect with probability p2 in time a. On this basis the paper brought forward a new RMA and wireless sensor networks MAC protocol. The paper resolves the throughput of the system, of the...
This paper proposes a new Random Channel Selection scheme with probabilistic backoff, called RCS, for a class of multi-channel MAC protocols in heavy loads WSNs to tackle the channel conflict problem. By adopting RCS, a node can reduce the probability of selecting a busy channel for data communication. Therefore, RCS can avoid data packet collision, and thus conserve more energy to extend the lifetime...
This paper concerns the performance evaluation of band-limited code-division multiple-access (CDMA) packet networks over Nakagami fading channels. New equations for packet success probabilities (PSP) are developed that can be used to efficiently compute the PSP of both slotted and unslotted CDMA networks for various Nakagami fading conditions, including Rayleigh fading. The packets may be uncoded...
Relaying is a well known technique to extend coverage and improve conditions for nodes in the outer coverage region. In this paper we propose a relaying scheme that exploits the spatial separation of relay and destination pairs to improve throughput by allowing simultaneous transmissions. The proposed scheme is a cross-layer optimization for two-hop relaying that uses position information to jointly...
In cognitive radio networks, secondary users can be coordinated to perform cooperative spectrum sensing to achieve higher detection accuracy. However, when the number of cooperative users increases, more overhead traffic of decision transmission introduced to network and throughput of cognitive radio network decreases. Furthermore, the performance of cooperative spectrum sensing is limited by the...
In this work, we establish a general framework for investigating statistical QoS provisioning in mobile ad hoc networks. Though the throughput and average delay in wireless ad hoc works have been has been intensively studied in the literature, statistical delay guarantee provisioning in large scale ad hoc networks has not received enough attention. A realtime application, e.g., interactive game and...
Efficient spectrum sensing ensures cognitive radio users opportunistically use the under-utilized frequency band without causing harmful interference to primary users. However, in practice, owing to the non-zero probability of the missed detection and false alarm of active primary transmission, a certain degree of performance degradation of the primary user is unavoidable. In this paper, we consider...
In this work, a new approach for dynamically allocating high priority probability and high priority slots in PR-ALOHA (Reserved ALOHA with Priority) was introduced. The Dynamic Slot Allocation (DSA) algorithm in PR-ALOHA is performed by dynamically allocating the number of high priority slots and high priority probability based on the available traffic. The performance of the system with DSA algorithm...
To handle the triple hidden terminal problems, this paper proposes OCO, an asynchronous multi-channel MAC protocol with opportunistic cooperation for wireless sensor networks. By adopting opportunistic cooperation, OCO effectively alleviates, if not eliminates, the triple hidden terminal problems. More importantly, OCO is fully distributed with no requirements of time synchronization or multi-radio...
The IETF Differentiated Service (DiffServ) architecture can allow for establishing a modern large scale network which guarantees the quality of service. In order to realize the multiple levels of packet drop precedence required for the Assured Forwarding (AF) framework of DiffServ, a multi-level RED algorithm is needed. RIO (RED with In/Out) is suitable for the AF scheme, and two major RIO variants...
Multicomputers have experienced a rapid development during the last decade. Multicomputers rely on an interconnection network among processors to support the message-passing mechanism. Therefore, the reliability of the interconnection network is very important for the reliability of the whole system. In this paper a new fault-tolerant routing algorithm, which is based on dimension order routing, is...
In this paper, an admission control (AC) scheme is proposed for handling multiclass Grade of Service (GoS) and Quality of Service (QoS) in Uplink Long Term Evolution (LTE) systems. GoS requirement in conjunction with QoS has been seldom taken into account in previous admission control and resource allocation algorithms for LTE uplink. We propose a novel algorithm for handling the priorities while...
The problem of optimizing the medium access probability in a multipacket-reception-capable network, when only inaccurate estimates of the offered traffic are known, is addressed. It is shown that a larger uncertainty in the traffic estimates must be compensated by a more conservative access policy. The analysis is verified by examples and simulation results.
WSN is an emerging technology which is deployed for monitoring and control applications. IEEE has introduced the 802.15.4 standard for a low rate, low power, low complexity and short range Wireless Personal Area Network (WPAN) in 2003. Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is defined as the basic access mechanism in the standard. It was noted that there is a problem of low...
A channel allocation mechanism for cognitive radios (CRs) with finite user population to enable maximum throughput and minimum forced termination probability for CR users (CUs) that are not capable of spectrum handover (SH) is presented. SH is an optimal scheme used by CUs to evacuate from time-slots that will be used by primary users (PUs) based on time-slot assignment (TA) information obtained in...
In this paper, performance enhancement technique using direct communication of a cellular system is analyzed. In this scheme, communication between two Mobile station (MS) within a cell is guaranteed by direct communication when base station (BS) of that cell is busy. Direct communication between two MS is established via base station and after that base station only monitors that connection using...
We study the layered transmission of a Gaussian source over multiple relays using superposition coding. First, we analyze the outage probability and performance in terms of average throughput and distortion for decode-and-forward protocols with single layer and superposed two-layer coding. For the superposition coding approach, we consider different power allocations to the base and enhancement layers...
In LTE-Advanced system, spectrum scarcity is an inevitable issue due to wider bandwidth requirement for downlink peak throughput up to 1Gbps. One of the solutions to this problem is that LTE-Advanced system can opportunistically use the spectrum of DVB system by using spectrum sensing and sharing method. But, the tradeoff problem between complexity and detection probability always exists in spectrum...
This paper addresses the problem of joint optimization of subchannel selection and spectrum sensing time for multiband cognitive radio networks. In particular, we construct a multiband spectrum sensing framework, and derive the probabilities of detection and false alarm taking the different subchannel gain into account. Furthermore, we formulate the multiband sensing as a two-parameter optimization...
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