Fast Collision Resolution Research Articles

Throughput of distributed queueing-based LoRa for long-distance communication

LoRa, due to its advantage of long-range communication capability, is promising for Internet of Things (IoT) and space-air-ground communications. However, the conventional MAC protocol used with LoRa is classified as an Aloha-based algorithm, which leads to drastic decrease in throughput when a huge amount of end-devices try to access the network. To achieve stable and high throughput of LoRa, we propose a design to combine the distributed queueing (DQ) and in-band-full-duplex (IBFD) technologies. The usage of DQ mechanism is benefit for fast collision resolution, while the IBFD-enabled gateway helps to reduce the heavy control overhead of DQ. The designs of access procedure and frame structure are discussed in detail. The outage probability and average throughput are evaluated under imperfect self-interference cancelation. Also, a mathematical programming method is developed to optimize the spreading factor and code rate. Numerical results show that our proposal gains an extra enhancement of 1.83-fold in throughput.

Receiver initiated fast sequential collision resolution in 802.11 WLAN

Future wireless local area networks (WLANs) have potential bit rates of the order of hundreds of Mbps. However, the current IEEE 802.11 medium access control (MAC) protocol does not scale well to high bit rate WLANs. By using collision detection in wireless networks, the time spent on collision can be reduced, thus improving system throughput. In this paper, we propose an enhancement that uses a tone transmitted on a small time slot (called contention slot) which enables receiver initiated collision detection to the transmitters. In this proposed protocol, the receiver detects the collision when multiple data packets are received and it transmits a jamming signal to all the transmitting stations so that they can immediately stop their ongoing transmissions. In addition to collision detection, we propose a sequential collision resolution mechanism where preferential access is given to all the colliding packets to reduce unfairness and to increase system throughput.

An Accurate Collision Detection Method for Cable Simulation

In this paper, we present a fast and robust collision detection (CD) and resolution scheme for deformable cable using a new method based on the shortest distance of cable segment axis. We employ a bounding sphere hierarchy (BVH) by exploiting the topology of cable for reducing the collision detection query space. After searching the collision through the bounding sphere hierarchy, the collision detection algorithm will find the two segments which are close enough to require an exact collision check. Furthermore, the exact collision state is decided by our proposed method. Penalty force method is applied to the collision resolution. The comparative experiments show that the proposed method performs more accurate than existing algorithms for deformable cable simulation without substantial computational cost.

Efficient contention-based MAC protocol using adaptive fuzzy controlled sliding backoff interval for wireless networks

Efficient medium access control (MAC) protocol should be able to provide high throughput performance and efficient share of the medium. In this paper, a new contention-based MAC protocol based on adaptive fuzzy controlled sliding backoff interval is proposed to maximize the channel throughput and improve the fairness of random access channels. In the proposed protocol, every node that experiences packet collisions increases its sliding backoff interval (SB) range by a forward sliding factor (FSF). In case of successful transmission the node decreases its SB range by a backward sliding factor (BSF). Forward and backward sliding factors are controlled by the channel offered traffic using a fuzzy controller. Furthermore, the operation of the proposed backoff algorithm does not depend on the knowledge of the number of active nodes. A computer simulation is developed using MATLAB to evaluate the performance of the proposed algorithm and compare it with other backoff schemes. Simulation results show that the proposed algorithm significantly outperforms other backoff schemes, such as binary exponential backoff (BEB) and the fast collision resolution (FCR) scheme. It provides a significant efficient fair sharing performance improvement which converges to the ideal fairness performance while providing high throughput performance.

In-home power line communication media access control protocol based on collision resolution

Most existing media access control (MAC) protocols in power line communication (PLC) networks just discard the colliding data packets when collision occurs. The collision deteriorates throughput and delay performance of system under high traffic conditions. This article presents a novel media access scheme with fast collision resolution for in-home power line networks. It works by first recognizing the colliding stations through detecting the inserted unique ID sequence ahead of data packets, then the source nodes retransmitting their packets immediately after the collision slot. The proposed protocol maintains the benefits of ALOHA systems. It needs no scheduling overhead and is suitable for bursty sources, such as multimedia data packets. Computer simulations have demonstrated that this approach can achieve high throughput due to its ability of resolving collisions.

B-EDCA: A QoS mechanism for multimedia communications over heterogeneous 802.11/802.11e WLANs

Multimedia communications over WLAN is widely acknowledged as one of the key, emerging applications for wireless LANs. As with any multi-service network, there is the need to provision the WLANs with the QoS mechanisms capable of guaranteeing the requirements of various services. The IEEE 802.11e (EDCA) standard defines the required QoS mechanisms into the protocol architecture of IEEE 802.11 WLANs. However, recent studies have shown that EDCA performs poorly when the medium is highly loaded due to the high collision rate. This situation has led many researchers to design techniques aiming to improve the performance of EDCA, such as real-time fast collision resolution (RT-FCR) and adaptive fair EDCF (AFEDCF). However, the main deficiency of many of the proposed mechanisms to date comes from their inability to properly interoperate with legacy IEEE 802.11 (DCF) systems. Moreover, the implementation of many of the proposed QoS mechanisms requires important and incompatible changes to the IEEE 802.11e specifications. In this paper, we introduce a novel IEEE 802.11e-based QoS protocol capable of providing QoS support to multimedia communications, and able to properly interoperate with legacy DCF-based stations. Our design has been based on an in-depth analysis of the several operation modes of both standards. This should ensure full compatibility of operation: an important feature since the transition from the IEEE 802.11 to the IEEE 802.11e will take some time making more likely the existence of hybrid scenarios where both standards will have to coexist. In this work, we carry out a comparative performance evaluation when supporting different services, such as, voice, video, best-effort, background and in the presence of traffic generated by legacy 802.11 (DCF)-based stations. Our simulation results show that the proposed mechanism outperforms the EDCA and other QoS-aware schemes recently reported in the literature.

Performance of a Tree-Based Collision Resolution Algorithm in Cellular Systems with Smart Antennas

A smart antenna's ability to simultaneously resolve more than one user on the same channel is exploited to help expedite the process of random access, especially for the reverse channel. However, use of a smart antenna requires frequent array adaptation, a difficult task in a random access environment. In papers H. Jin and Acampora (2005), we proposed and studied the SINR performance of a media access protocol intended for use with smart antennas. In this paper, we study the random access performance of the proposed protocol when a fast collision resolution algorithm is used. Found are the maximum achievable throughput and an upper bound on the expected delay. The impact of the number of antennas on the performance with both flat fading and frequency selective fading is studied. Topical results show significant improvement in throughput for systems with smart antennas. For example, when the fading is flat, the gain in maximum achievable throughput can be as large as 232% and 550% with four and eight antenna elements respectively. Even when severe frequency selective fading is present, there is a gain of 40% and 145% with four and eight antenna elements, respectively. We also show that dynamically adjusting the retransmission probability in the collision resolution process is not worthwhile since this extra complexity produces a gain of only about 6.2% in the best case

Performance Analysis for a New Medium Access Control Protocol in Wireless LANs

One fundamental issue in high-speed wireless local area networks (LANs) is to develop efficient medium access control (MAC) protocols. In this paper, we focus on the performance improvement in both MAC layer and transport layer by using a novel medium access control protocol for high-speed wireless LANs deploying carrier sense multiple access/collision avoidance (CSMA/CA). We first present a recently proposed distributed contention-based MAC protocol utilizing a Fast Collision Resolution (FCR) algorithm and show that the proposed FCR algorithm provides high throughput and low latency while improving the fairness performance. The performance of the FCR algorithm is compared with that of the IEEE 802.11 MAC algorithm via extensive simulation studies on both MAC layer and transport layer. The results show that the FCR algorithm achieves a significantly higher efficiency than the IEEE 802.11 MAC and can significantly improve transport layer performance.

Design of MAC protocols with fast collision resolution for wireless local area networks

Development of efficient medium access control (MAC) protocols providing both high throughput performance for data traffic and good quality of service (QoS) support for real-time traffic is the current major focus in distributed contention-based MAC protocol research. In this paper, we propose an efficient contention resolution algorithm for wireless local area networks, namely, the fast collision resolution (FCR) algorithm. The MAC protocol with this new algorithm attempts to provide significantly higher throughput performance for data services than the IEEE 802.11 MAC algorithm and more advanced dynamic tuning backoff (DTB) algorithm. We demonstrate that this algorithm indeed resolves collisions faster and reduces the idle slots more effectively. To provide good fairness performance and to support good QoS for real-time traffic, we incorporate the self-clocked fair queueing algorithm and a priority scheme into the FCR algorithm and come up with the real-time FCR (RT-FCR) algorithm, and show that RT-FCR can simultaneously achieve high throughput and good fairness performance for nonreal-time traffic while maintaining satisfactory QoS support for real-time traffic.

Wireless ATM: Performance Evaluation of a DSA++ MAC Protocol with Fast Collision Resolution by a Probing Algorithm

In general, the users of wireless ATM terminalsrequest the same functionality and quality of service asusers of wired terminals. These user requirements can betransformed into the demand for building an ATM multiplexer around the air interfacewhich is characterized by a radio channel inside. Themain difference between this virtual ATM multiplexeraround the air interface and a fixed ATM multiplexer is the distribution of the multiplexingfunction between wireless terminals and the basestation. For the uplink this requires a frequentnotification of the ATM cell scheduler in the basestation about the status of the incoming buffers inside thewireless terminals. This paper focuses on differentmethods for transmitting capacity request messages (alsodesignated as reservation request) over theuplink.