Corrigendum to "Knot Floer homology detects fibred knots"

We correct a mistake on the citation of JSJ theory in \cite{Ni}. Some arguments in \cite{Ni} are also slightly modified accordingly.Comment: 3 page

An intelligent genetic algorithm for PAPR reduction in a multi-carrier CDMA wireless system

Abstract— A novel intelligent genetic algorithm (GA), called Minimum Distance guided GA (MDGA) is proposed for peak-average-power ratio (PAPR) reduction based on partial transmit sequence (PTS) scheme in a synchronous Multi-Carrier Code Division Multiple Access (MC-CDMA) system. In contrast to traditional GA, our MDGA starts with a balanced ratio of exploration and exploitation which is maintained throughout the process. It introduces a novel replacement strategy which increases significantly the convergence rate and reduce dramatically computational complexity as compared to the conventional GA. The simulation results demonstrate that, if compared to the PAPR reduction schemes using exhaustive search and traditional GA, our scheme achieves 99.52% and 50+% reduction in computational complexity respectively

A connection-level call admission control using genetic algorithm for MultiClass multimedia services in wireless networks

Call admission control in a wireless cell in a personal communication system (PCS) can be modeled as an M/M/C/C queuing system with m classes of users. Semi-Markov Decision Process (SMDP) can be used to optimize channel utilization with upper bounds on handoff blocking probabilities as Quality of Service constraints. However, this method is too time-consuming and therefore it fails when state space and action space are large. In this paper, we apply a genetic algorithm approach to address the situation when the SMDP approach fails. We code call admission control decisions as binary strings, where a value of “1” in the position i (i=1,…m) of a decision string stands for the decision of accepting a call in class-i; a value of “0” in the position i of the decision string stands for the decision of rejecting a call in class-i. The coded binary strings are feed into the genetic algorithm, and the resulting binary strings are founded to be near optimal call admission control decisions. Simulation results from the genetic algorithm are compared with the optimal solutions obtained from linear programming for the SMDP approach. The results reveal that the genetic algorithm approximates the optimal approach very well with less complexity

Performance analysis of the IEEE 802.11e block ACK scheme in a noisy channel

A block ACK (BTA) scheme has been proposed in IEEE 802.11e to improve medium access control (MAC) layer performance. It is also a promising technique for next-generation high-speed wireless LANs (WLANs) such as IEEE 802.11n. We present a theoretical model to evaluate MAC saturation throughput of this scheme. This model takes into account the effects of both collisions and transmission errors in a noisy channel. The accuracy of this model is validated by NS-2 simulations

WLC22-4: Efficient request mechanism usage in IEEE 802.16

IEEE 802.16 protocols for metropolitan broadband wireless access systems have been standardized recently. According to the standard, a subscriber station can deliver bandwidth request messages to a base station by numerous methods. This paper provides both the simulation and analytical models for the investigation of specified random access method, which is compared with centralized polling and station- grouping mechanisms. Based on the assumptions of Bernoulli request arrival process and ideal channel conditions, the mean delay of a request transmission is evaluated for varying number of transmission opportunities and different arrival rates

Study on QoS support in 802.11e-based multi-hop vehicular wireless ad hoc networks

Multimedia communications over vehicular ad hoc networks (VANET) will play an important role in the future intelligent transport system (ITS). QoS support for VANET therefore becomes an essential problem. In this paper, we first study the QoS performance in multi-hop VANET by using the standard IEEE 802.11e EDCA MAC and our proposed triple-constraint QoS routing protocol, Delay-Reliability-Hop (DeReHQ). In particular, we evaluate the DeReHQ protocol together with EDCA in highway and urban areas. Simulation results show that end-to-end delay performance can sometimes be achieved when both 802.11e EDCA and DeReHQ extended AODV are used. However, further studies on cross-layer optimization for QoS support in multi-hop environment are required

An effective ant-colony based routing algorithm for mobile ad-hoc network

An effective Ant-Colony based routing algorithm for mobile ad-hoc network is proposed in this paper. In this routing scheme, each path is marked by path grade, which is calculated from the combination of multiple constrained QoS parameters such as the time delay, packet loss rate and bandwidth, etc. packet routing is decided by the path grade and the queue buffer length of the node. The advantage of this scheme is that it can effectively improve the packet delivery ratio and reduce the end-to-end delay. The simulation results show that our proposed algorithm can improve the packet delivery ratio by 9%-22% and the end-to-end delay can be reduced by 14%-16% as compared with the conventional QAODV and ARA routing schemes