Transmission Of Control Packets Research Articles

Opportunistic spectrum access for TDMA-based cognitive radio networks

In this paper, opportunistic spectrum access is proposed for TDMA-based cognitive radio networks. In TDMA-based networks, the time is divided into slots with fixed length one by one. If a primary user (PU) needs to transmit data, one or several slots will be used. Otherwise, the slots are idle and can be utilized by secondary users (SUs). When SUs want to use the licensed channel, they should sense the channel at the beginning period of each slot. Then SUs exchange their sensing results and make the same decision about the channel state (idle or used by PUs), which could reduce the probability of false sensing. The aforementioned duration is called spectrum sensing phase. When SUs decide there is an idle channel, they contend to use the channel at the rest time of the slot. The duration is called access phase. In this period, SUs contend the channel with backoff counters. When the remaining time is less than one data transmission duration, SUs cannot transmit data packets. Therefore, the remaining time is wasted. To solve this problem, SUs transmit control packets with small length in the remaining time instead. The SU who exchange control packets successfully reserves the channel and sends a data packet prior to other SUs in access phase of the next idle slot. Obviously, this reserved transmission is without collision. The independent spectrum sensing, channel state decision and control packets reservation influence the performance of SUs. The proposed scheme is formulated with all above factors. Simulations which consist with the numerical results show the proposed access scheme achieve higher throughput than the existed scheme without channel reservation.

A Time Slot Reservation in Modified TDMA-Based Ad Hoc Networks with Directional Antennas

In this paper, we study the bandwidth reservation issue in wireless ad hoc networks with directional antennas. Providing Quality of Service (QoS) support in the wireless ad hoc networks is one of the topics that have received a lot of attention in recent years. QoS provisioning is needed to support multimedia and real-time application in wireless networks. In the Time Division Multiple Accesses (TDMA) frame, the bandwidth is measured by the number of the data time slots. Control slots in the traditional TDMA frame can be used for transmission of the control packets, rather than the transmission of the data packets. We focus on the problem of how to make full use of slots to transmit data packets and do not affect control packets transmission. The purpose is to improve the time slot utilization rate. Based on our proposed modified TDMA frame, a novel time slot reservation algorithm is presented to achieve maximal available path bandwidth. Directional antennas allow transmission energy to be concentrated on a narrow range along a particular direction, which can significantly increase the data rate. The performance of our scheme is analyzed and implemented. Simulation results show that the proposed scheme performs better.

A tree-based address configuration for a MANET

This paper proposes an address configuration scheme for a MANET. In this paper, the tree-based architecture and the algorithm of constructing a MANET are presented. In this architecture, a proxy node can assign a unique address for neighbor new nodes, so the address configuration task is distributed around all proxy nodes. The transmission of control packets is controlled within one-hop scope, so the cost is reduced and the delay is shortened. Through this architecture, the address resources released by failed nodes can be automatically reclaimed for reuse, so a proxy node has always the sufficient address space for assignment. In order to ensure the uniqueness of a node’s address, the paper also proposes the MANET merging and partitioning algorithms. Finally, this paper evaluates the performance metrics of both the proposed scheme and the existing schemes, and the results show that the proposed scheme reduces the address configuration cost and shortens the address configuration delay.

S-MIM: a novel radio interface for efficient messaging services over satellite

This article presents a radio interface recently standardized by ETSI under the name of S-band Mobile Interactive Multimedia (S-MIM) and especially designed to provide ubiquitous messaging services over S-band GEO satellites using low-power terminals. Thanks to low terminal cost and high bandwidth efficiency, this standard allows the development of new satellite services, particularly for vehicular and machine-to machine applications. The S-MIM standard relies on a broadcasting radio interface such as DVB-SH or ETSI SDR in the forward link, and reuses 3GPP W-CDMA technology properly adapted to the scope in the return link. Thanks to the use of spread spectrum ALOHA, terminals can access the channel in a totally asynchronous manner. The use of a packet-optimized iterative successive interference cancellation (i- SIC) algorithm at the receiver allows exploiting the inherent power imbalance among terminals in order to boost the throughput with respect to conventional SSA systems. In addition, advanced packet transmission control techniques have been adopted to maximize the probability of successful packet reception in the challenging land mobile satellite channel. Finally, the S-MIM link layer provides efficient and reliable transport of IP datagrams over the forward and return link radio interfaces.

Power Control for Crossbar-Based Input-Queued Switches

We consider an N × N Input-Queued (IQ) switch with a crossbar-based switching fabric implemented on a single chip. The power consumption produced by the crossbar chip, due to the data transfer, grows as NR3, where R is the maximum bit rate. Thus, at increasing bit rate, power dissipation is becoming more and more challenging, limiting the crossbar scalability for high-performance switches. We propose to exploit Dynamic Voltage and Frequency Scaling (DVFS) techniques to control packet transmissions through each crosspoint of the switching fabric. Our power control operates independently of the packet scheduler and exploits the knowledge of a traffic matrix obtained by online measurements. We propose a family of control algorithms to reduce the power consumption. The algorithms are particularly efficient in nonoverloaded conditions. The actual potential of the proposed approach is also evaluated on a real design case synthesized on a 90 nm CMOS technology.

SCTP Tunneling: Flow Aggregation and Burst Transmission to Save Energy for Multiple TCP Flows over a WLAN

SUMMARY To raise the energy efficiency of wireless clients, it is important to sleep in idle periods. When multiple network applications are running concurrently on a single wireless client, packets of each application are sent and received independently, but multiplexed at MAC-level. This uncoordinated behavior makes it difficult to control of sleep timing. In addition, frequent state transitions between active and sleep modes consume non-negligible energy. In this paper, we propose a transport-layer approach that resolves this problem and so reduces energy consumed by multiple TCP flows on a wireless LAN (WLAN) client. The proposed method, called SCTP tunneling, has two key features: flow aggregation and burst transmission. It aggregates multiple TCP flows into a single SCTP association between a wireless client and an access point to control packet transmission and reception timing. Furthermore, to improve the sleep efficiency, SCTP tunneling reduces the number of state transitions by handling multiple packets in a bursty fashion. In this study, we construct a mathematical model of the energy consumed by SCTP tunneling to assess its energy efficiency. Through numerical examples, we show that the proposed method can reduce energy consumption by up to 69%.

Mobility Prediction based Routing in Mobile Adhoc Network using Hidden Markov Model

Dynamic network topology of Mobile Ad hoc networks (MANETs) which is a consequence of node mobility, make routing a denoting challenge and routes are subject to recurrent disconnections. In such a context, it is important to limit interruptions caused by the node mobility. This paper presents exploiting the concept of routing through predicting the mobility of nodes and therefore reducing the overhead by eliminating transmissions of control packets which are required otherwise for route reconstruction. Also, former awareness of patterns of mobile nodes can be used to suitably allocate resources and upgrade the quality of service (QOS) experienced by mobile devices. This paper proposes Hidden Markov Model (HMM) approach for predicting the mobility of nodes to reduce the overhead head of routing for route discovery.

An Energy-Efficient MAC Protocol Employing Dynamic Threshold for Wireless Sensor Networks

Energy efficiency is a critical issue for sensor network since the network lifetime depends on efficient management of the energy resource of sensor nodes. Particularly, designing energy efficient MAC protocol has a significant influence on the performance of wireless sensor network with regards to the energy. The existing MAC protocols developed for sensor network try to avoid energy waste during idle listening time by controlling the duty cycle of the transmission period. Since the traffic conditions are diverse, they may not always display improvements in energy consumption. In this paper we propose a new energy efficient MAC protocol called dynamic threshold MAC (DT-MAC), which employs a dynamic threshold for the buffer of each sensor node to maximize the energy efficiency regardless of specific network traffic condition. Here the packets are stored in the buffer, and then transmitted when the number of packets in the buffer exceeds the threshold dynamically decided according to the number of hops of the node from the source in the path of packet forwarding. The simulation results using OMNnet++ show that DT-MAC enables significant improvement in energy consumption compared to the existing MAC protocols. The proposed DT-MAC protocol also reduces the number of transmissions of control packets.

Modulation level allocation for MGS streaming over a multihop wireless channel

This article introduces a method for efficiently transmitting medium grain scalable video packets over a transmission path consisting of multiple wireless links. Medium grain scalability provides bit rate adaptation according to the available bit rate by dropping a number of video packets in the compressed bit stream. In other words, rate-distortion control can be achieved by means of packet transmission control. The available bit rate and the spectral efficiency are determined by the bandwidth and the modulation level, respectively. Accordingly, the number of packets available for transmission is affected by the modulation level of the packets. However, if we consider modulation levels with higher spectral efficiency in order to increase the number of packets and reduce the expected video distortion, the packet error rate of the transmitted packets can also be increased because the spectrally efficient modulation levels are sensitive to channel noise. This is another reason for the increment in expected video distortion, because the erroneous received packets cannot be used for video reconstruction. Therefore, this article considers the minimization of expected video distortion by the optimization of two factors--packet extraction for transmission and modulation level allocation for the extracted packets. Packet extraction is optimized for the path between the source and destination nodes, whereas the modulation level for each extracted packet is optimized for each link along the transmission path.

Integrated Synthesis of Control and Bandwidth Scheduling on Networked Control Systems

Many Networked Control Systems (NCS) comprise several control loops that are closed over a network of computation nodes. In those systems, periodic, sporadic and non-periodic packets share the network bandwidth, complex timing behavior and communication lead to delay and jitter, which both degrade the control performance. That is to say the performance of NCS is determined not only by control algorithms, but also by the quality of serves (QoS) of network. Therefore, the network QoS must be considered during the controller synthesis. Also, the control performance should be taken into account during system scheduling. In this paper, a control–scheduling co-design method that integrates controller and scheduler design is proposed. The transmission periods of control packets are calculated to optimize the overall performance of control loops. The transmission phases and resource utilization of sporadic and non-periodic packets are controlled by the resource reservation server running on each node to guarantee the temporal requirements of those data and also to limit the effect on the transmission of control packets. Further more, a harmonization algorithm of transmission periods of packets is also presented to improve the bandwidth utilization. An integrated simulation platform based on Truetime is present, and the experimental results show that the scheme is more effective than the former ones.

Multi-User Scheduling Method Considering Fairness and Mitigation of Multi-Cell Interference for Multi-Hop Cellular System

In order to improve the cell boundary throughput performance and to extend the coverage area, relaying transmission with relay stations (RSs) is becoming a promising architecture for the next generation cellular systems. However, if RSs are operated in every cell, the interference between cells increases and the throughput improvement effect with RSs is prone to be restricted. In this paper, we propose a scheme reducing the interference from other cells by using packet transmission control. This packet transmitting control technique is realized by the compound scheduling technique with the Proportional fair (PF) scheduling and the Maximum Carrier-to-Interference power Ratio (Max CIR) scheduling. The proposed scheme can improve the throughput around the cell boundary by controlling the timing of transmission of each cell with appropriate power and user assignment. The simulation results show that the proposed method can also improve the fairness of user throughput and system throughput considering the users of whole cell.

A quality based routing protocol for wireless mesh networks

Wireless mesh networks can provide low-cost solutions for extending the reach of wireless access points by using multi-hop routing over a set of stationary wireless routers. The routing protocol for these networks may need to address quality considerations to meet the requirements of the user. In this paper, we present a quality based routing protocol for wireless mesh networks that tries to maximize the probability of successful transmissions while minimizing the end-to-end delay. The proposed routing protocol uses reactive route discoveries to collect key parameters from candidate routes to estimate the probability of success and delay of data packets transmitted over them. To achieve accurate route quality assessments, a new route quality metric is proposed that uses performance models of data packet transmissions as opposed to estimating route quality from the transmission of control packets, which have different transmission characteristics. These models are developed after careful evaluations of multi-hop wireless transmissions and validated by computer simulations. Relevant parameters that can be used to assess the route quality metric using these models are explained. Extensive performance evaluations of the proposed quality based routing protocol are presented and its benefits in comparison to some other known routing protocols are discussed.

Performance of Dominating and Adaptive Partial Dominating Sets in AODV Routing protocol for MANETs

A mobile ad hoc network (MANET) is a wireless network that does not rely on any fixed infrastructure (i.e., routing facilities, such as wired networks and access points), and whose nodes must coordinate among themselves to determine connectivity and routing. The broadcast can target a portion of the network (e.g. gathering neighborhood information), or the entire network (e.g., discovering routes on demand). Broadcasting of signaling and data in MANETs raise redundant transmission of control packets to overcome these problems we applied dominating set and Adaptive partial Dominating (APDP) approach to existing routing protocols such as Ad-hoc On-demand Distance Vector (AODV). The focus of this paper is to apply the concept of DS and APDP to AODV and evaluate the performance of dominating sets in AODV that improve broadcasting, End-to-End Delay, Network load, Packet Latency, and also maintains secure packet transmission. IndexTerms—Adaptive partial dominating, Dominating sets, AODV

Efficient angular routing protocol for inter-vehicular communication in vehicular ad hoc networks

Inter-vehicular communication involves the exchange of data between two mobile devices in an ad hoc network. Since the devices are not stationary and the topology is wide, the passage of messages between source and destination nodes involves various intermediate nodes that act as links between the two. The more the number of nodes involved in a network at a time, the more is the power consumed by them, thereby adding to the average power consumption of the network and the transmission time. The authors aim to develop an efficient routing protocol, which finds the minimum possible path length between a source and a destination involving minimum nodes to transmit data. Information regarding the angular position of the nodes is exploited in selecting the most suitable node for transmission, thereby achieving proper network connectivity among nodes with minimum power consumption. The proposed protocol has been compared with dynamic source routing (DSR) and DSR with stale route removed (DSR-SRR). The results achieved by implementing the proposed protocol establish the fact that our protocol is better than DSR and DSR-SRR in terms of the following: (i) average power consumption during transmission, (ii) throughput of transmission and (iii) number of control packets used. The proposed protocol proves to work relatively efficiently even under dense traffic conditions.

Location-free topology control protocol in wireless ad hoc networks

Topology control emphasizes the proper adjustment of the transmission power of each node in wireless mobile ad hoc networks. It not only saves power but also increases the system throughput by increasing the spatial reuse of communication channels. However, there is a hidden terminal problem at the medium access control (MAC) layer if we merely address the topology control issue at the network layer. This paper proposes a distributed protocol that deals with topology control at the network layer and at the same time overcomes the hidden terminal problem at the MAC layer. Each node in the networks determines its power for data transmission and control packets transmission according to the received beacon messages from its neighbors. The proposed protocol works without location information and use little control packet overhead to prevent potential collisions due to hidden terminals. Simulations show that our protocol significantly decreases the total power consumption in the networks and has a better network throughput compared to other protocols.

Fair Bandwidth Allocation Using Effective Multicast Traffic Share in TDM-PONs

In this paper, the effects of optical traffic-sharing on the performance of multicast video delivery in terms of the efficiency of bandwidth allocation and the fairness of link-sharing are discussed for the downstream direction of a time-division-multiplexed passive optical network (TDM-PON). We analyze the practical issues associated with multicast packet switching and transmission control in a TDM-PON and also propose a fair bandwidth allocation mechanism, called share-based proportional bandwidth allocation (S-PBA), to effectively support multicast services. In order to provide an optical network unit with a fair amount of link bandwidth and high throughput independent of traffic type, S-PBA arbitrates the amount of unicast timeslot by using effective multicast traffic share, which is determined based on multicast traffic load distribution and traffic-sharing density. Analytic and simulation results clearly validate the effectiveness of the proposed mechanism. This work is applicable to multicast video delivery or multicast traffic transmission in general, such as voice traffic, or a combination of both in the case of video conferencing, for example.

Using Dynamic Control Frames to Reduce Packet Delays in Transceiver Array-Based Single-Hop WDM Networks

This paper considers transceiver array-based single-hop wavelength division multiplexing (WDM) networks with reservation-based packet scheduling algorithms. In reservation-based packet scheduling algorithms for single-hop WDM networks, one or more of the wavelengths are used as control channels for transmitting reservation information. Time on a control channel is divided into control frames and each control frame is further divided into control slots. Each node is usually assigned a dedicated control slot in each control frame. Before transmitting a data packet, a node sends a control packet in a control slot to all other nodes to reserve a data slot. This paper proposes to adjust the lengths of the control frames dynamically according to the loads of the nodes by removing unused control slots. A dynamic control frame structure with variable number of control slots is proposed. A method is devised to enable the nodes in the network to dynamically acquire and release control slots depending on their loads such that the control frames include only necessary control slots for those nodes that have or potentially have data packets to send. Therefore, the delays for transmitting control packets and data packets can be reduced. Dynamically adjusting the lengths of the control frames is able to reduce the delays for transmitting control packets and data packets when the network load is light to medium or the traffic pattern is moderately or highly nonuniform; however, it introduces extra overhead in each control frame such that the length of the control frame may become larger than the size of the control frame in the fixed control frame structure resulting in higher mean packet delay when the load of the network is heavy and the traffic pattern is uniform or nearly uniform. Therefore, this paper further proposes a hybrid fixed and dynamic scheme that dynamically employs the fixed control frame scheme or the dynamic control frame scheme depending on the loads of the nodes. The performance of the proposed hybrid scheme is studied via simulations. Our simulation results show that the hybrid scheme is able to dynamically choose the better of the fixed and dynamic control frame schemes such that it yields the lowest mean packet delay for the entire range of network loads and traffic patterns.

A High-Throughput MAC Protocol for Wireless Ad Hoc Networks

One way to improve the throughput of a wireless ad hoc network at the media access (MAC) layer is to allow as much as possible concurrent transmissions among neighboring nodes. In this paper, we present a novel high-throughput MAC protocol, called Concurrent Transmission MAC(CTMAC), which supports concurrent transmission while allowing the network to have a simple design with a single channel, single transceiver, and single transmission power architecture. CTMAC inserts additional control gap between the transmission of control packets (RTS/CTS) and data packets (DATA/ACK), which allows a series of RTS/CTS exchanges to take place between the nodes in the vicinity of the transmitting or receiving node to schedule possible multiple, concurrent data transmissions. To safeguard the concurrent data transmission, collision avoidance information is included in the control packets and used by the neighboring nodes to determine whether they should begin their transmissions. Also, to isolate the possible interference between DATA packets and ACK packets, a new ACK sequence mechanism is proposed. Simulation results show that a significant gain in throughput can be obtained by the CTMAC protocol compared with the existing work including the IEEE 802.11 MAC protocol.

A novel channel assignment scheme for improving channel reuse efficiency in multi-channel ad hoc wireless networks

How to increase channel reuse efficiency is one of the most important issues in wireless cellular networks. Recently, many multi-channel MAC protocols have been proposed for ad hoc wireless networks. However the channel assignment schemes used in these protocols do not consider the issue of channel reuse. The channel assignment schemes only let a mobile host select a channel from the channels which are not currently being used by its one-hop neighbors. To form a channel reuse pattern, the mobile host should consider its two-hop channel usage and select a channel which is been used by its two-hop neighbors. In this paper, we propose a novel channel assignment scheme for improving the channel reuse efficiency. By overhearing control packets of one-hop neighbors, a host can easily know the channel condition within the range of two-hop hosts and then select a suitable transmitting/receiving data channel to form the better reuse pattern. To enhance the probability of forming channel reuse pattern, we propose a backoff counter adjustment scheme such that a host with more channel information can transmit control packets early than with less channel information. We verify the performance of our protocol via simulations and give some comments on the simulation results.

IP‐HDTV multicast distribution system architecture with nonstop service availability

AbstractThis paper proposes a new system architecture which achieves stable HDTV distribution service using ISP multicast networks. With the recent spread of broadband access networks including FFTH, the distribution of broadcasting contents using IP multicast is becoming indispensable in the ISP service menu. The important issues in the development of such a content distribution service are to provide high service availability and to construct a highly flexible distribution system that can handle various distribution formats. The authors have proposed a nonstop IP multicast technique without modification of router implementation intended for the ISP network, and also a packet transmission control procedure which works independently of the distribution format. A prototype was implemented and a video distribution experiment is performed on an IP multicast network corresponding to digital HDTV broadcasting by satellite. It is shown that nonstop service can be provided using the prototype system, compensating the loss of approximately 27,500 packets, accompanied by detection and recovering of network failure at the router. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(12): 73–85, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20346