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The IEEE 802.16e standard has emerged as an exciting mobile wireless broadband technology that promises to deliver both high throughput and guaranteed quality of service (QoS). Call admission control (CAC) scheme serves as a great utility for WiMAX, which ensures that resources are not over committed and thereby, all existing connections enjoy guaranteed quality of service. Existing CAC schemes largely...
The base station in IEEE 802.16, or WiMAX, networks allocates contention-based time slots for the mobile stations to transmit their requests for additional bandwidth. Using a technique called subchannelization, multiple concurrent transmissions by mobile stations can be admitted by the base station during the same contention period. For transmission during this period, each station employs a contention-resolution...
HSDPA (High Speed Downlink Packet Access) is drawing great attention as the 3.5G technology capable of providing higher data rate packet switch services over Universal Mobile Telecommunication System (UMTS) to support broadband services like multimedia conferencing, VoIP, or high-speed internet access. The paper proposes the use of a Learning Vector Quantization (LVQ) Neural Network able to estimate...
In this paper, we compare communication schemes in scenarios of interest for underwater networks where multiple nodes collaborate towards the accomplishment of a target detection and tracking task. We consider two specific cases: in Scenario 1, a mobile Autonomous Underwater Vehicle (AUV) i) collects data from a set of fixed sensors deployed on the seafloor or ii) transmits data to the same nodes...
In recent years ICT technology is gaining importance to the railway environment, more specific in the networking on-board of trains. One of the first drivers was the “always connected” idea for mobile users, but in the mean time this idea has evolved beyond providing pure Internet access for passengers, to a better way of managing the trains in all aspects. This includes comfort services like passenger...
Current devices use a network selection policy that is mostly driven by the physical layer, choosing the point of attachment with the highest Received Signal Strength Indicator (RSSI). Unfortunately for 802.11 networks, RSSI is not a good indicator of actual network performance as it is normally the bandwidth to the Internet and not the wireless signal conditions which dictates the quality of service...
This paper proposes a heartbeat radio access protocol for a mobile ad-hoc network based on a random access protocol using a high-throughput and stable single-channel Q-ary free-access collision resolution algorithm. We provide an analytical derivation of the performance of this free-access collision resolution algorithm in the presence of feedback channel errors that may be present in the mobile radio...
The increase in multimedia usage places stringent requirements on wireless network performance in terms of lesser handoff delays. A VOIP client, for example, cannot tolerate a delay larger than 150 ms between the incoming voice packets to ensure a satisfactory interactive service to the user. Of the 150ms, only 50ms is allowed for handoff and the rest should accommodate the transmission delay of the...
Non-static transmission time interval (TTI) strategy is investigated in this paper, in order to improve the available potential performance of the enhanced uplink dedicated channel in universal telecommunication radio access low chip rate time division duplex system (UTRA LCR TDD). This strategy introduces a joint support of two kinds of TTI, 20ms and 5ms TTI. For 5ms TTI is competitive at end-to-end...
This paper explores a MAC (Medium Access Control) layer throughput with DCF (Distributed Coordination Function) protocol in the IEEE 802.11a/g-based mobile LAN. It is evaluated in both error-free and error-prone wireless channel with the maximum transmission rate of 54 Mbps, using theoretical analysis method. The DCF saturation throughput performance is analyzed by using the number of stations with...
IMT-Advanced system proposed by ITU-R for next generation mobile communications has the technical requirements of the performances of an improved broadcast, a multicast and a VoIP by supporting the transmission rates up to 100 Mbps for high mobility and 1 Gbps for low mobility. LTE-Advanced system is one of the leading candidates of IMT-Advanced systems and many telecommunications industries will...
In wireless multi-hop networks, when an end host would like to communicate with external wired hosts, data packets are to be transmitted at first to a gateway node which is connected to both a wireless multi-hop network and a wired network. When there are multiple candidate gateways to be connected, a wireless host should select one gateway as its own default gateway. One possible and simple way is...
This paper addresses the power allocation problem on relaying channels with user-cooperation for multi-user orthogonal frequency division multiplexing (OFDM) systems. The proposed problem is based on dual-mode mobile stations (MSs), where one interface is used to receive signals from a base station (BS) and the other is used to forward the signals to nearby MSs through out-of-band relaying. This dual-mode...
By development and the spread of a wireless technology,the mobile ad hoc network (Manet) that can be easily constructed only with mobile nodes is getting much attention.However, it is difficult to control the performance of the entire network appropriately, as a network consists of individual communication nodes operating autonomously and there is no device that controls the entire network. Recently,...
Consider a mobile network wherein nodes are confined to move and communicate in a given area. The network is assumed to be sparse, wherein a direct communication path from a source node via multiple hops to a destination node almost never exists. The nodes resort to storing, carrying, and forwarding packets when a contact occurs, as a means of communication. This paper investigates the question of...
The data rate of a point-to-point link can be substantially increased by using antenna arrays at both transmitter and receiver. Similar gains can be realized in the downlink of a cellular system with respect to the total cell throughput, if the base station serves multiple single-antenna mobiles simultaneously; however, the maximum rate of each individual user is relatively small then. In this paper,...
IEEE 802.16 wireless networks, known as WiMAX, employ a mechanism for guaranteed time allocation to mobile stations in order to meet the different quality of service requirements for service flows. The base station allocates contention-based time slots for the stations to transmit their requests for additional bandwidth. Each contention time slot can accommodate a single transmission if there is no...
Energy efficient communications in wireless communications is very important as mobile devices are battery- constrained. For mobile devices in a cellular system, uplink power consumption dominates the wireless power budget, due to the RF power requirements for reliable communications over long distances. Our previous work in this area demonstrated significant energy savings in uplink cellular OFDMA...
Traditionally, every mobile station (MS) riding in the mobile vehicle uses conventional connection to the base station (BS). However, in 802.16j mobile multihop relay (MMR) networks, one of the studied usage model is ldquocoverage on mobile vehiclerdquo. Therein, a relay station (RS) is mounted on a vehicle. The RS provides service to MSs riding on the vehicle by relaying their data to the mobile...
We consider a wireless collision channel, shared by a finite number of mobile users who transmit to a common base station. Each user wishes to optimize its individual network utility that incorporates a natural tradeoff between throughput and power. The channel quality of every user is affected by global and time-varying conditions at the base station, which are manifested to all users in the form...
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