Distributed network control for optical networks

This paper describes an architecture for controlling a wavelength-routed optical network. The optical network provides reconfigurable connections that can be used to carry different types of data, at possibly different bit rates. A connection consists of a path in the network and a wavelength on each link in that path. This work focuses on the mechanisms for controlling the optical connections. Distributed control protocols are provided for setting up and taking down connections reliably. These protocols allow connection originators to obtain resources with high probability by minimizing reservation conflicts, allow connections to stay up even if controllers along the path in the network fail, ensure that controllers in the network have a consistent view of the state of each connection, and ensure that all resources taken up by a connection are released once the connection is taken down. Fast protocols are also proposed for handling link failures and wavelength failures on a link. These protocols are general in that they can be used in networks with: (1) different kinds of node architectures (electrical/optical switching, with or without wavelength conversion, etc.), (2) different route-computation algorithms that reflect the underlying constraints imposed by the nodes and the physical layer, and (3) any kind of underlying mechanism using which the network controllers can communicate with each other     

Distributed rate adaptive packet access (DRAPA) for multicell wireless networks

Fueled by the explosive growth of the Internet, applications are demanding higher data rates and better services. Given the scarcity of radio resources, higher network capacities need to be achieved through more efficient use of the available bandwidth. Current cellular networks utilize frequency planning schemes that are optimized for circuit-switched applications, and thus is inherently problematic for future wireless packet networks with bursty, high peak-rate traffics. Random access schemes such as the ALOHA are seen as better solutions for packet networks. However, co-channel interference may significantly reduce the network throughput when the multicell load is heavy. In this paper, we propose a distributed rate adaptive packet access (DRAPA) scheme to combine the advantages of rate adaptation (in circuit-switched networks) and random access (in packet-switched networks). In particular, DRAPA allows terminal stations to transmit packets in random access fashion in the presence of brusty interference from neighboring cells. The packet code rate is adjusted according to interference level so that the retransmisson is controlled at an acceptable level. The DRAPA scheme subsumes two traditional schemes as the extreme cases, and has superior performance over the traditional schemes in terms of throughput and stability.     

A network management architecture for robust packet routing in meshoptical access networks

We describe an architecture for an optical local area network (LAN) or metropolitan area network (MAN) access. The architecture allows for bandwidth sharing within a wavelength and is robust to both link and node failures. The architecture can be utilized with an arbitrary, link-redundant mesh network (node-redundancy is necessary only to handle all node failures), and assumes neither the use of a star topology nor the ability to embed such a topology within the physical mesh. Reservation of, bandwidth is performed in a centralized fashion at a (replicated) head end node, simplifying the implementation of complex sharing policies relative to implementation on a distributed set of routers. Unlike a router, however, the head end does not take any action on individual packets and, in particular, does not buffer packets. The architecture thus avoids the difficulties of processing packets in the optical domain while allowing for packetized shared access of wavelengths. We describe the route construction scheme and prove its ability to recover from single link and single node failures, outline a flexible medium access protocol and discuss the implications for implementing specific policies, and propose a simple implementation of the recovery protocol in terms of state machines for per-link devices     

Deterministic access protocols for packet radio networks

In this paper, multiple-phase deterministic protocols for packet radio networks are introduced and analysed. Two modes of information transfer are considered, namely (a) broadcasting and (b) point-to-point transmission. We explore systematic ways of designing multiple-phase protocols and apply them on Manhattan networks. The proposed protocols are studied primarily from the point of view of throughput efficiency. Delay analysis is also presented.     

Fundamentals of packet multiple access for satellite networks

The fundamental objectives which guide the design of a packet multiple-access technique for satellite networks with large numbers of earth stations are explained. Among these objectives are low peak power in the transmitters, low average power from the satellite transponder, high channel capacity, and low complexity of the multiple-access receiver. The author reviews the fundamentals of satellite packet multiple access and relates these fundamentals to the objectives listed. Code division multiple-access (CDMA) and ALOHA multiple access are described in terms of these fundamentals. A simple linear transformation of conventional ALOHA access, called spread ALOHA, is described. For the case of a low signal-to-noise ratio in the receiver and a low duty cycle of individual and identical transmitters, it is not possible to find a multiple-access method at the same average power and are the same bandwidth which is more efficient than spread ALOHA     

Distributed adaptive rate system for wireless packet networks

A distributed adaptive rate system for wireless packet networks is proposed. Compared to the centralized adaptive rate system that needs to know the packet retransmission probability to maximize the throughput, this system need not know the packet retransmission probability in advance and can achieve the optimal adaptive rate system that maximizes the throughput for wireless packet networks.     

Distributed code assignments for CDMA packet radio networks

Code-division multi-access (CDMA) techniques allow many users to transmit simultaneously in the same band without substantial interference by using approximately orthogonal (low cross-correlation) spread-spectrum waveforms. Two-phase algorithms have been devised to assign and reassign spread-spectrum codes to transmitters, to receivers and to pairs of stations in a large dynamic packet radio network in polynomial times. The purpose of the code assignments is to spatially reuse spreading codes to reduce the possibility of packet collisions and to react dynamically to topological changes. These two-phase algorithms minimize the time complexity in the first phase and minimize the number of control packets needed to be exchanged in the second phase. Therefore, they can start the network operation in a short time, then switch to the second phase with the goal of adapting to topological changes. A pairwise code-assignment scheme is proposed to assign codes to edges. Simulations based on well-controlled topologies (sparse topologies) show that the scheme requires much fewer codes than transmitter-based code assignment, while maintaining similar throughput performance     

LHAP: A lightweight network access control protocol for ad hoc networks

Most ad hoc networks do not implement any network access control, leaving these networks vulnerable to resource consumption attacks where a malicious node injects packets into the network with the goal of depleting the resources of the nodes relaying the packets. To thwart or prevent such attacks, it is necessary to employ authentication mechanisms to ensure that only authorized nodes can inject traffic into the network. We propose LHAP, a hop-by-hop authentication protocol for ad hoc networks. LHAP resides in between the network layer and the data link layer, thus providing a layer of protection that can prevent or thwart many attacks from happening, including outsider attacks and insider impersonation attacks. Our detailed performance evaluation shows that LHAP incurs small performance overhead and it also allows a tradeoff between security and performance.     

Distributed collision control with the integration of packet size for congestion control in wireless sensor networks

Several great features offered by wireless sensor networks (WSN) result in its wide deployment in various remote and continuous monitoring applications. As such, managing huge collected readings in this domain posted many challenges due to its design limitations. In order to provide seamless data transmission, which is of utmost importance in those delay‐sensitive applications, minimum delay and packet loss occurrence should be considered. Specifically, this paper addresses the common issue of congested networks in WSN with the combination technique of variance‐based distributed contention control (DCC‐V) and packet size optimization. The proposed integration technique, which operates on medium access control layer, takes into consideration the packet size advantages as it plays a key role in determining successful data delivery, given the error‐prone nature of WSN. While ensuring fewer corrupted packets, the proposed contention window (CW) in DCC‐V minimizes the chances of packet collisions and so alleviates congestion. In this technique, CW is determined based on slot utilization and average collision values, which also involve standard deviation measurements. Simulation analysis using network simulator‐2 shows outstanding performance of the proposed solution compared with the existing IEEE 802.15.4 protocol. Copyright © 2014 John Wiley & Sons, Ltd.     

A packet media access protocol for mobile networks*

In this paper, we propose and analyze a packet time division multiple access protocol for the media access control (mac) sublayer of a radio interface suitable to be implemented in the third generation of mobile networks. This protocol is considered to be adequate for future personal communications networks that should interwork with the broadband-isdn. The protocol is designed to work in a microcell environment employing low power terminals, and to support a wide spectrum of services with both asynchronous and isochronous traffic profiles and different bandwidth requirements.     

Distributed source coding for sensor networks

In recent years, sensor research has been undergoing a quiet revolution, promising to have a significant impact throughout society that could quite possibly dwarf previous milestones in the information revolution. Realizing the great promise of sensor networks requires more than a mere advance in individual technologies. It relies on many components working together in an efficient, unattended, comprehensible, and trustworthy manner. One of the enabling technologies in sensor networks is the distributed source coding (DSC), which refers to the compression of the multiple correlated sensor outputs that does not communicate with each other. DSC allows a many-to-one video coding paradigm that effectively swaps encoder-decoder complexity with respect to conventional video coding, thereby representing a fundamental concept shift in video processing. This article has presented an intensive discussion on two DSC techniques, namely Slepian-Wolf coding and Wyner-Ziv coding. The Slepian and Wolf coding have theoretically shown that separate encoding is as efficient as joint coding for lossless compression in channel coding.     

Overflow control for UMTS high-speed downlink packet access

This paper proposes overflow control schemes to support high-speed downlink packet access (HSDPA) mechanism in the universal mobile telecommunication system (UMTS). To access the UMTS services, a user equipment (UE) communicates with all cells (base stations) in an active set. However, multiple links between the UE and the cells in the active set may reduce the transmission speed due to interference. Third-Generation Partnership Project specification TR 25.950 proposes HSDPA. In this mechanism, the UE only selects one cell (referred to as the serving cell) in the active set for high-speed downlink transmission. In HSDPA, the radio network controller sends the packet frames to the cells in the active set. For the serving cell, the packet frames are forwarded to the UE. On the other hand, every nonserving cell in the active set queues the packet frames in a buffer. If the link quality between the serving cell and the UE degrades below some threshold, the UE selects the best cell in the active set as the new serving cell. Since the nonserving cells do not send packet frames to the UE, their buffers may overflow. In this paper, we propose schemes to address the buffer overflow issue. Our schemes guarantee that when the buffer of a nonserving cell is full, the previously received packet frames in the buffer can be safely dropped, and after the UE has switched wireless link to the new serving cell, no packet frames are lost.     

Topology control for multihop packet radio networks

A distributed topology-control algorithm has been developed for each node in a packet radio network (PRN) to control its transmitting power and logical neighbors for a reliable high-throughput topology. The algorithm first constructs a planar triangulation from locations of all nodes as a starting topology. Then, the minimum angles of all triangles in the planar triangulation are maximized by means of edge switching to improve connectivity and throughput. The resulting triangulation at this stage, the Delaunay triangulation, can be determined locally at each node. The topology is modified by negotiating among neighbors to satisfy a design requirement on the nodal degree parameter. Simulations show that the final topology is degree-bounded, has a rather regular and uniform structure, and has throughput and reliability that are greater than that of a number of alternative topologies     

Distributed antenna network for gigabit wireless access

For gigabit wireless data services, there are three important technical issues to be addressed: limited bandwidth, severe frequency-selective fading, and limited transmit power. A distributed antenna network (DAN) is a promising solution to the above three technical issues. In DAN, each mobile user is served by using multiple distributed antennas close to it. In this paper, recent advances in various distributed multi-input/multi-output (MIMO) techniques combined with single-carrier (SC) frequency-domain signal processing are presented for DAN. Particular attention is paid to SC frequency-domain MIMO diversity, relay, beamforming, and multiplexing jointly used with frequency-domain equalization (FDE) to significantly improve the signal transmission performance.     

Techno‐economic analysis of FiWi access networks based on optimized source packet traffic

Fiber wireless access networks (FiWi) are capable of providing broadband 100 Mbit/s services with acceptable costs and can be considered as a competitive alternative to fiber to the home (FTTH). Techno‐economic analysis of viable FiWi architectures is needed in order to obtain the most suitable solution taking into account both technical and economical viewpoints. In this paper, a new approach to techno‐economic analysis of the FiWi networks is proposed. The proposed approach is based on the net present value calculation with the source packet traffic generation rate and traffic intensity as input parameters. As a precondition to net present value calculation, a traffic optimization procedure that assures the quality of experience is performed. Case study results indicate the usability of the proposed method.     

Distributed access algorithms for portable meshed vsat networks

In recent years technological evolution has made it possible to develop portable meshed VSAT networks (PMVN). Among the distinguishing features of this satellite network family we can cite the following: portable terminals, direct connectivity is allowed between any pair of network nodes (meshed topology), the network may comprise a high number of terminals, the network is intended to offer low rate voice and data communication services. For this satellite network family, the most widely used technique of resource allocation is centralized allocation. But in any network with a high number of nodes, the dependence on a single resource is a potential bottleneck of the network, in terms of flexibility, reliability and scalability of costs. In order to avoid this drawback, two distributed access algorithms are proposed in this paper. Both algorithms are based on carrier sensing (CS). In order to evaluate their performance, a model for PMVNs is proposed. This model is used to study the behaviour of the conventional access technique (central allocation) and the proposed distributed algorithms. We conclude that the use of the proposed distributed algorithms is feasible with present technology, with a performance comparable to that of the central allocation algorithm, but with the advantages associated with distributed algorithms concerning flexibility, reliability and cost.     

Rule-based network design: application to packet radio networks

A heuristic, rule-based approach to network design is presented. The problem of designing high-performance packet radio networks by altering individual radio powers (i.e. by altering network connectivity) is considered. It is assumed that node locations, traffic requirements, and a multiaccess protocol are specified. The focus is on the dependence of capacity on connectivity for two reasons: connectivity is always a design parameter, whereas radio locations, protocol, and traffic may not always be; and the relationship between capacity and connectivity is well documented in the literature, even though the exact nature of this reliance remains unclear. Packet radio performance analysis models found in the literature are used for performance evaluation     

Rate control feedback mechanism for packet video networks

The authors incorporate a newly proposed rate control feedback mechanism (RCFM) in an H.263 video coder. RCFM adapts to network conditions to locally drop video packets and then discard corresponding macroblocks (MBs) from any further prediction process. The proposed RCFM regulates the output bitrate of an H.263 codec while keeping all encoder parameters fixed and maintaining a good QoS