This paper aims at precision position control of the X-Y table a computerized numeric (CNC) machining center velocity reversal. The characteristics presliding friction are analyzed, and simple effective method is proposed to compensate on basis these characteristics. A large tracking error occurs reversal due sudden transition between regime sliding regime. investigates time reduce error, derives relationship acceleration zero velocity. also proposes estimating using this relationship,...

In this paper, we investigate the issue of per-station fairness in TCP over IEEE 802.11-compliant wireless local area networks (WLANs), especially Wi-Fi hot spot. It is asserted that spot suffers from unfairness among stations exploiting medium. The source analyzed two aspects, TCP-induced asymmetry and MAC-induced asymmetry; former causes congestion control with a cumulative acknowledgment mechanism to prefer sending receiving stations, while later exacerbates problem spots. We interaction...

As public deployment of wireless local area networks (WLANs) has increased and various applications with different service requirements have emerged, fairness quality (QoS) are two imperative issues in allocating channels. This study proposes a fair QoS agent (FQA) to simultaneously provide per-class enhancement per-station channel sharing WLAN access networks. FQA implements additional components above the 802.11 MAC: dual differentiator level manager. The former is intended improve for...

IEEE 802.11ax uplink orthogonal frequency division multiple access (OFDMA)-based random (UORA) is a new feature for channel in wireless local area networks (WLANs). Similar to the legacy scheme WLANs, UORA performs OFDMA backoff (OBO) procedure and decides on OBO counter within contention window (OCW) value. An point (AP) can determine OCW range inform each station (STA) of it. However, how reasonable beyond scope standard. The crucial performance, it primarily depends number contending...

The emerging broadband wireless access technology based on IEEE 802.16 is one of the most promising solutions to provide ubiquitous service at low cost. This paper proposes an efficient uplink bandwidth request-allocation algorithm for real-time services in Mobile WiMAX networks 802.16e. In order minimize wastage without degrading quality (QoS), we introduce a notion target delay and propose dual feedback architecture. proposed calculates amount request such that regulated around desired...

We propose an adaptive token bucket algorithm for achieving proportional sharing of bandwidth among aggregate flows in differentiated service (DiffServ) networks. By observing the simulation results obtained a study throughput TCP DiffServ network, we note that flow with lower target rate occupies more than its fair share, while higher gets less share. The proposed solves this unfairness problem by adjusting according to edge-to-edge feedback information. This does not require any additional...

By analyzing the steady state throughput of TCP flows in differentiated service (DiffServ) networks, we show that current DiffServ networks are biased favor those have a smaller target rate, which results unfair bandwidth allocation. In order to solve this unfairness problem, propose an adaptive marking scheme, allocates manner is proportional rates aggregate network. This scheme adjusts rate according congestion level network, so flow can obtain its fair share bandwidth. Since it utilizes...

This paper focuses on the unfairness problem between TCP uplink and downlink flows in 802.11 Wi-Fi hot spots shows that service is prone to be unfair. The cause of analyzed from two aspects: TCP-induced asymmetry MAC-induced asymmetry. Due asymmetric behavior congestion control with a cumulative acknowledgment mechanism flows, biased toward flow tends starve. contention-based channel access MAC exacerbates this because it intends provide fair opportunity only sending stations. Next, analysis...

This paper deals with the problem of performance degradation in wireless local area networks (WLANs) based on IEEE 802.11n. When a channel is shared by heterogeneous stations that have different data rates and packet sizes, each station occupies amount airtime because basic access mechanism WLAN was originally designed to provide fair chance access, regardless size rate. leads overall network throughput fairness among stations, which known as anomaly. To resolve this problem, we firstly...

In this paper, we investigate issues of fairness and spatial reuse in heterogeneous wireless local area networks (WLANs) based on IEEE 802.11ax. According to discussions the evolving 802.11ax standardization, value carrier sensing threshold (CSTH) needs be increased, order improve spectral efficiency WLANs by means reuse. We reveal a serious problem unfairness, referred as asymmetric hidden node problem, arising when legacy devices that have smaller CSTH coexist compete for channel access...

Wi-Fi Direct is one of the most prevailing technologies in field wireless networking. With advent various useful applications, it facing many challenges namely: efficient group formation/communication, power saving, compatibility issues etc. In this paper, we focus on fundamental problem reliability multicast communication context Direct. To end, our paper makes following contributions: 1) It explores problems 2) checks performance Standard Multicast (SM) and Leader Based (LBM) protocols for...

In this paper, we deal with the problem of assuring medical-grade quality service (QoS) for real-time medical applications in wireless healthcare systems based on IEEE 802.11e. Firstly, show that differentiated channel access 802.11e cannot effectively assure QoS because priority inversion. To resolve problem, propose an efficient algorithm. The proposed algorithm adjusts arbitrary inter-frame space (AIFS) protocol depending measurement traffic, to provide near-absolute traffic. addition,...

The IEEE 802.11 standard has been evolved to support multiple transmission rates in wireless local area networks (WLANs) cope with diverse channel conditions and increase throughput. However, when stations different coexist, the basic access mechanism of WLAN, distributed coordination function (DCF), not only fails assure airtime fairness among competing but also decreases overall network throughput, because DCF was designed provide fair opportunity access, regardless rate. As an effective...

Location-based services (LBSs), such as location-specific contents-providing services, presence and E-911 locating have recently been drawing much attention in wireless network community. Since LBSs rely on the location information providing enhancing their service quality, we need to devise a framework of directly using provide different level differentiation and/or fairness for them. In this paper, investigate how use QoS provisioning IEEE 802.11-based Hot Spot networks. is from existing...

This paper aims to improve energy efficiency of IEEE 802.11 wireless local area networks (WLANs) by effectively dealing with idle listening (IL), which is required for channel sensing and unavoidable in a contention-based access mechanism. Firstly, we show that IL dominant source drain WLANs it cannot be alleviated the power saving mechanism proposed standard. To solve this problem, propose an energy-efficient combines three schemes systematic way: downclocking, frame aggregation, contention...

In dense wireless local area networks (WLANs), the primary causes of interference and hindrance to spatial reuse are well-known hidden node problem (HNP) exposed (ENP). this paper, we propose a joint solution these problems. The proposed mechanism, referred as Probe/PreAck (PR/PA), utilizes concept two-way handshake for efficient channel reservation by means two control frames called PR PA. frame is designed semi-reservation initiated transmitting node, while PA used receiver-oriented...

A virtual rate control (VRC) algorithm for active queue management (AQM) to regulate the length with small variation and achieve high utilisation packet loss is proposed. Through ns simulations, effectiveness of proposed VRC as compared several well-known AQM schemes such RED, REM, AVQ algorithms shown.

Wi-Fi-enabled portable devices have recently been introduced into the consumer electronics market.These download or upload content, from to a host machine, such as personal computer, laptop, home gateway, media server.This paper investigates fairness among multiple in network when they are simultaneously communicated with machine.First, we present that, simple IEEE 802.11-based suffers unfairness, and is exaggerated by wireless link errors.This unfairness due asymmetric response of TCP...

We propose an efficient request-based uplink bandwidth allocation algorithm for variable-rate real-time service in broadband wireless access networks. By introducing a notion of target delay under the framework dual feedback, proposed can regulate while minimizing jitter and waste.

In this paper, we design an admission control mechanism on top of our previous study medical-grade wireless LAN. The proposed scheme controls the total number real-time electrocardiogram (ECG) monitoring connections in order to guarantee quality service. We verify performance with ns-2 simulation.

The virtual rate control (VRC) algorithm has been proposed for active queue management (AQM) in TCP networks. This uses an adaptive instead of length order to respond quickly traffic change with high utilization and small loss. By introducing the notion target rate, VRC can maintain input around while attempting regulate length. In this paper, we analyze stability a linearized model. From results our analysis, provide design guideline system remain stable. We show validity analysis...

We propose a novel media access control (MAC) protocol, referred to as signaling-free max-min airtime fair (SMAF) MAC, improve fairness and channel utilization in ad hoc networks based on IEEE 802.11 wireless local area (WLANs). introduce busy time ratio (BTR) measure for fairness. Each node estimates its BTR adjusts the transmission duration by means of frame aggregation fragmentation, so that it can implicitly announce neighbor nodes. Based announced BTR, each nodes controls contention...