Enhancing 802.11 carrier sense for high throughput and QoS in dense user settings
29 Nov 2012-pp 253-259
TL;DR: These methods enable the application of signal to interference and noise (SINR) based scheduling algorithms to WiFi networks resulting in tremendous increase in throughput and QoS/fairness.
Abstract: The distributed coordination function (DCF) for 802.11 medium access control (MAC) leads to poor spatial spectral reuse and results in low user throughput in dense user settings. In this paper, we consider simple modifications to the carrier sense mechanism that substantially improve the bits/sec/Hz/area, without increasing transceiver complexity. For 802.11g and 802.11ac, we augment the CTS with channel gain information and modify the virtual and physical carrier sense for the duration of NAV in the CTS. In addition, we consider a roughly synchronized network with alternate control and data transmission phases. During the control phase, a carrier sense multiple access with collision avoidance (CSMA-CA) MAC is used to exchange a few RTS-CTS messages in a local network neighborhood to determine the transmission scheme in the ensuing data phase. Our methods enable the application of signal to interference and noise (SINR) based scheduling algorithms to WiFi networks resulting in tremendous increase in throughput and QoS/fairness.
Citations
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01 Jan 2008
TL;DR: A novel power controlled MAC protocol based on SNR in mobile Ad hoc networks is presented and simulation results demonstrate that compared to the IEEE 802.11 MAC protocol, the proposed protocol can decrease the power consumption greatly, and improve the energy utilization of mobile terminals while maintaining the throughput performance.
Abstract: The mobile Nodes in wireless Ad hoc networks are fed by batteries,so the energy limitation has become a performance bottleneck for mobile ad hoc networks.IEEE 802.11 has been used as the current standard MAC protocol for ad hoc networks.However,it has not the ability of adjusting power level dynamically,which reduces the performance of network.Power control can enhance the power efficiency of nodes,reduce the interferer of neighbor nodes and improve the performance of network.A novel power controlled MAC protocol based on SNR in mobile Ad hoc networks is presented in this paper.Simulation results demonstrate that compared to the IEEE 802.11 MAC protocol,the proposed protocol can decrease the power consumption greatly,and improve the energy utilization of mobile terminals while maintaining the throughput performance.
188 citations
09 Mar 2015
TL;DR: The Dynamic Sensitivity Control (DSC) Algorithm proposed for IEEE 802.11ax is evaluated and it is shown that the aggregate throughput of a dense network utilizing DSC is considerably improved when compared with the IEEE802.11 legacy network.
Abstract: The explosive growth in the usage of IEEE 802.11 network has resulted in dense deployments in diverse environments. Most recently, the IEEE working group has triggered the IEEE 802.11ax project, which aims to amend the current IEEE 802.11 standard to improve efficiency of dense WLANs. In this paper, we evaluate the Dynamic Sensitivity Control (DSC) Algorithm proposed for IEEE 802.11ax. This algorithm dynamically adjusts the Carrier Sense Threshold (CST) based on the average received signal strength. We show that the aggregate throughput of a dense network utilizing DSC is considerably improved (i.e. up to 20%) when compared with the IEEE 802.11 legacy network.
82 citations
Cites background from "Enhancing 802.11 carrier sense for ..."
...Authors in [4] demonstrate simple modifications that can be made in carrier sensing mechanism to increase the overall throughput in dense networks....
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TL;DR: Three options, loose, tight, and hybrid integration, are presented to providing enhanced capacity and coverage at hotspots in conjunction with broadband cellular networks.
Abstract: Wi-Fi provides cost-effective data capacity at hotspots in conjunction with broadband cellular networks. The hotspots are required to capture a large number of users and provide high data rates. Data rates, over the Wi-Fi interface, are influenced by the media access protocol, which loses throughput due to contention based protocol delays and unintended collisions when a large number of users are active. The hotspot range that determines the number of users that can associate is limited by the lower power of the client rather than the access point. By diverting the traffic destined to the access point via another access network, both range and efficiency can be improved. This uplink redirection or diversion is achieved by simultaneous use of the Wi-Fi and LTE radio interfaces. Three options, loose, tight, and hybrid integration, are presented to providing enhanced capacity and coverage.
45 citations
22 May 2016
TL;DR: This paper proposes a Dynamic Sensitivity Control for Access Point (DSC-AP) algorithm, which dynamically adjusts the Carrier Sensing Threshold (CST) of an AP based on received signal strength from its associated stations and interfering APs and shows that the aggregate throughput of a dense network utilizing DSC is considerably improved.
Abstract: The popularity and wider acceptance of IEEE 802.11 based WLANs has resulted in their dense deployments in diverse environments. While this massive deployment can potentially increase capacity and coverage, the current physical carrier sensing of IEEE 802.11 cannot limit the overall interference induced and also cannot insure high concurrency among transmissions. Recently, the IEEE 802.11 working group has continued efforts on developing WLAN technology through the creation of the TGax, which aims to improve efficiency of densely deployed IEEE 802.11 networks. In this paper, we propose a Dynamic Sensitivity Control for Access Point (DSC-AP) algorithm for IEEE 802.11ax. This algorithm dynamically adjusts the Carrier Sensing Threshold (CST) of an AP based on received signal strength from its associated stations and interfering APs. We show that the aggregate throughput of a dense network (under asymmetric traffic conditions) utilizing DSC (both at the stations and AP) is considerably improved (i.e. up to 32%) when compared with legacy IEEE 802.11.
29 citations
Cites background from "Enhancing 802.11 carrier sense for ..."
...Similarly, [6][7] investigate the increase in performance of IEEE 802....
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01 Sep 2016
TL;DR: Simulation results show that in typical enterprise scenarios, Boost significantly decreases packet delay up to 85 % and increases user throughput up to 3.5x, which is beneficial for delay-sensitive and best effort applications, respectively, positioning Boost as a strong candidate for realising the all-wireless enterprise.
Abstract: Wireless fidelity (Wi-Fi) benefits from large downlink bandwidth but suffers from inefficient uplink contention, while long term evolution (LTE) benefits from efficient scheduling in the uplink but suffers from bandwidth scarcity in the downlink. In this paper, we quantify the performance gain of Boost, a new technology that blends the advantages of Wi-Fi and LTE in an efficient manner to overcome their individual disadvantages. By redirecting uplink traffic from Wi-Fi to LTE, Boost avoids resource waste due to Wi-Fi contention in the uplink. Since the radio channel is now fully under the control of an scheduler, downlink controlled by Wi-Fi AP scheduler and uplink controlled by LTE scheduler, delays and rates can be guaranteed. Simulation results show that in typical enterprise scenarios, Boost significantly decreases packet delay up to 85 % and increases user throughput up to 3.5x, which is beneficial for delay-sensitive and best effort applications, respectively. This positions Boost as a strong candidate for realising the all-wireless enterprise.
11 citations
Cites background from "Enhancing 802.11 carrier sense for ..."
...For interested readers, the performance degradation of a Wi-Fi AP with the number of connected UEs is presented in [1] [2] [3]....
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..., carrier sense multiple access/collision avoidance (CSMA/CA) [1] [2] [3], while LTE capacity is limited due to the scarcity of licensed spectrum [4]....
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References
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TL;DR: The technical and business arguments for femtocells are overview and the state of the art on each front is described and the technical challenges facing femtocell networks are described and some preliminary ideas for how to overcome them are given.
Abstract: The surest way to increase the system capacity of a wireless link is by getting the transmitter and receiver closer to each other, which creates the dual benefits of higher-quality links and more spatial reuse. In a network with nomadic users, this inevitably involves deploying more infrastructure, typically in the form of microcells, hot spots, distributed antennas, or relays. A less expensive alternative is the recent concept of femtocells - also called home base stations - which are data access points installed by home users to get better indoor voice and data coverage. In this article we overview the technical and business arguments for femtocells and describe the state of the art on each front. We also describe the technical challenges facing femtocell networks and give some preliminary ideas for how to overcome them.
3,298 citations
"Enhancing 802.11 carrier sense for ..." refers methods in this paper
...While systems such as LTE macrocells, FlashLinQ [5], and femtocells [6] have been designed to allow for good spatial reuse of spectrum, in this paper we ask the question: Is it...
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22 Apr 2001
TL;DR: The initial simulation results show that the PCMA can improve the throughput performance of the non-power controlled IEEE 802.11 by a factor of 2 with potential for additional scalability as source-destination pairs become more localized, thus providing a compelling reason for migrating to a new power controlled multiple access wireless MAC protocol standard.
Abstract: Multiple access-based collision avoidance MAC protocols have typically used fixed transmission power, and have not considered power control mechanisms based on the distance of the transmitter and receiver in order to improve spatial channel reuse. This work proposes PCMA, a power controlled multiple access wireless MAC protocol within the collision avoidance framework. PCMA generalizes the transmit-or-defer "on/off" collision avoidance model of current protocols to a more flexible "variable bounded power" collision suppression model. The algorithm is provisioned for ad hoc networks and does not require the presence of base stations to manage transmission power (i.e. it is decentralized). The advantage of implementing a power controlled protocol in an ad-hoc network is that source-destination pairs can be more tightly packed into the network allowing a greater number of simultaneous transmissions (spectral reuse). Our initial simulation results show that the PCMA can improve the throughput performance of the non-power controlled IEEE 802.11 by a factor of 2 with potential for additional scalability as source-destination pairs become more localized, thus providing a compelling reason for migrating to a new power controlled multiple access wireless MAC protocol standard.
685 citations
"Enhancing 802.11 carrier sense for ..." refers background in this paper
...The designs in [12], [7], and [13] are closer to our work....
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...The authors in [12] consider an out of band signal and significant changes to the MAC, where the data destination on a link periodically transmits an out-of-band busy tone signal with power that can be varied on the basis of the link gain between the data source and destination....
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...While [12] considered out-ofband PHY signaling and [7] considered significant changes to the MAC to enable careful reuse, we show how we can improve spatial reuse with only small changes to the carrier sense mechanism....
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...1, the DCF mechanism is one where the relative channel gains between (i) A to B, and (ii) B to I are not taken into account to determine whether I can transmit concurrently without degrading the SINR at B to a very low value – hence, the reuse is not based on SINR( [7], [12])....
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TL;DR: New paradigms for design and operation of heterogeneous cellular networks, focusing on cell splitting, range expansion, semi-static resource negotiation on third-party backhaul connections, and fast dynamic interference management for QoS via over-the-air signaling are described.
Abstract: Embedding pico/femto base-stations and relay nodes in a macro-cellular network is a promising method for achieving substantial gains in coverage and capacity compared to macro-only networks. These new types of base-stations can operate on the same wireless channel as the macro-cellular network, providing higher spatial reuse via cell splitting. However, these base-stations are deployed in an unplanned manner, can have very different transmit powers, and may not have traffic aggregation among many users. This could potentially result in much higher interference magnitude and variability. Hence, such deployments require the use of innovative cell association and inter-cell interference coordination techniques in order to realize the promised capacity and coverage gains. In this paper, we describe new paradigms for design and operation of such heterogeneous cellular networks. Specifically, we focus on cell splitting, range expansion, semi-static resource negotiation on third-party backhaul connections, and fast dynamic interference management for QoS via over-the-air signaling. Notably, our methodologies and algorithms are simple, lightweight, and incur extremely low overhead. Numerical studies show that they provide large gains over currently used methods for cellular networks.
524 citations
"Enhancing 802.11 carrier sense for ..." refers background or methods in this paper
...We consider a simple heuristic motivated by the maximum weight algorithm and similar to that in [14], to illustrate the gains that can be enabled by our MAC mechanism....
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...pAB , of packets buffered at A ; the priority can depend on number of bytes enqueued at the source, packet delays, and/or average rate at which A transmitted data to B in the past (see, for example, marginal utility framework in [14])....
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...11ac, a scheme similar to the nominal interference computation in [14] can be implemented....
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...In such topologies, power control is not always adequate to mitigate interference [14]....
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...We consider a deployment model similar to that in [14],...
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TL;DR: An overview of the HIPERLAN/2 and 802.11a standards is presented together with software simulated physical layer performance results for each of the defined transmission modes.
Abstract: At present, WLANs supporting broadband multimedia communication are being developed and standardized around the world. Standards include HIPERLAN/2, defined by ETSI BRAN, 802.11a, defined by the IEEE, and HiSWANa defined by MMAC. These systems provide channel adaptive data rates up to 54 Mb/s (in a 20 MHz channel spacing) in the 5 GHz radio band. An overview of the HIPERLAN/2 and 802.11a standards is presented together with software simulated physical layer performance results for each of the defined transmission modes. Furthermore, the differences between these two standards are highlighted (packet size, upper protocol layers etc.), and the effects of these differences on throughput are analyzed and discussed.
468 citations
"Enhancing 802.11 carrier sense for ..." refers background in this paper
...Also, HIPERLAN/2 considers a synchronized MAC at an AP, but the focus of the design is on resource allocation to all clients associated with a given AP ( [17]), as opposed to the distributed setting considered here....
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TL;DR: This paper proposes FlashLinQ - a synchronous peer-to-peer wireless PHY/MAC network architecture for distributed channel allocation that develops an analog energy-level based signaling scheme that enables SIR (Signal to Interference Ratio) based distributed scheduling.
Abstract: This paper proposes FlashLinQ--a synchronous peer-to-peer wireless PHY/MAC network architecture. FlashLinQ leverages the fine-grained parallel channel access offered by OFDM and incorporates an analog energy-level-based signaling scheme that enables signal-to-interference ratio (SIR)-based distributed scheduling. This new signaling mechanism, and the concomitant scheduling algorithm, enables efficient channel-aware spatial resource allocation, leading to significant gains over a CSMA/CA system using RTS/CTS. FlashLinQ is a complete system architecture including: 1) timing and frequency synchronization derived from cellular spectrum; 2) peer discovery; 3) link management; and 4) channel-aware distributed power, data rate, and link scheduling. FlashLinQ has been implemented for operation over licensed spectrum on a digital signal processor/ field-programmable gate array (DSP/FPGA) platform. In this paper, we present FlashLinQ performance results derived from both measurements and simulations.
451 citations
"Enhancing 802.11 carrier sense for ..." refers background or methods in this paper
...If the contention windows during each control phase are chosen uniformly at random, then all links will on an average have equal priority (see [5])....
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...While one round of coordination was studied in [5], it requires much tighter (symbol-level) synchronization....
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...The simplest scheme would be one similar to that in [5] where the data destination sets MinRxPowNav to be 10 dB lower than the received power of the RTS....
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...After the RTS-CTS transmissions, if the data sources transmits pilots to indicate whether they intend to transmit during the data phase, a more accurate estimate of interference can be obtained [14], [5]....
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...While systems such as LTE macrocells, FlashLinQ [5], and femtocells [6] have been designed to allow for good spatial reuse of spectrum, in this paper we ask the question: Is it...
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