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Showing papers on "Frame aggregation published in 2014"


Journal ArticleDOI
TL;DR: In this article, the authors developed an analytical framework for evaluating the capacity and delay performance of a wide range of routing algorithms in converged fiber-wireless (FiWi) broadband access networks based on different next-generation PONs and a Gigabit-class multiradio multichannel WLAN-mesh front end.
Abstract: Current Gigabit-class passive optical networks (PONs) evolve into next-generation PONs, whereby high-speed Gb/s time division multiplexing (TDM) and long-reach wavelength-broadcasting/routing wavelength division multiplexing (WDM) PONs are promising near-term candidates. On the other hand, next-generation wireless local area networks (WLANs) based on frame aggregation techniques will leverage physical-layer enhancements, giving rise to Gigabit-class very high throughput (VHT) WLANs. In this paper, we develop an analytical framework for evaluating the capacity and delay performance of a wide range of routing algorithms in converged fiber-wireless (FiWi) broadband access networks based on different next-generation PONs and a Gigabit-class multiradio multichannel WLAN-mesh front end. Our framework is very flexible and incorporates arbitrary frame size distributions, traffic matrices, optical/wireless propagation delays, data rates, and fiber faults. We verify the accuracy of our probabilistic analysis by means of simulation for the wireless and wireless-optical-wireless operation modes of various FiWi network architectures under peer-to-peer, upstream, uniform, and nonuniform traffic scenarios. The results indicate that our proposed optimized FiWi routing algorithm (OFRA) outperforms minimum (wireless) hop and delay routing in terms of throughput for balanced and unbalanced traffic loads, at the expense of a slightly increased mean delay at small to medium traffic loads.

102 citations


Journal ArticleDOI
TL;DR: This paper presents a bi-dimensional Markov model to estimate the uplink and downlink throughput of clients and formulate AP association into an optimization problem, aiming at providing each client a bandwidth proportional to its usable data rate, and proposes an on-line AP association algorithm under the condition that each client can acquire timely information of all clients associated with nearby APs.
Abstract: As the latest amendment of IEEE 802.11 standard, 802.11n allows a maximum raw data rate as high as 600 Mbps, making it a desirable candidate for wireless local area network (WLAN) deployment. In typical deployment, the coverage areas of nearby access points (APs) usually overlap with each other to provide satisfactory coverage and seamless mobility support. Clients tend to associate (connect) to the AP with the strongest signal strength, which may lead to poor client throughput and overloaded APs. Although a number of AP association schemes have been proposed for IEEE 802.11 WLANs in the literature, the challenges brought by the new features in 802.11n have not been thoroughly studied nor the impact of legacy 802.11a/b/g clients in 802.11n WLANS on AP association. To fill in this gap, in this paper, we explore AP association for 802.11n with heterogeneous clients (802.11a/b/g/n). We first present a bi-dimensional Markov model to estimate the uplink and downlink throughput of clients and formulate AP association into an optimization problem, aiming at providing each client a bandwidth proportional to its usable data rate. Based on this Markov model, we propose an on-line AP association algorithm under the condition that each client can acquire timely information of all clients associated with nearby APs. Furthermore, for WLANs with densely deployed APs, we provide another on-line AP association algorithm with lower complexity, which takes full advantage of 802.11n transmissions by simply associating different types of clients with different APs. We have conducted extensive simulations and experiments to validate the proposed algorithms. The results show that our algorithms can significantly improve both 802.11n throughput and aggregated network throughput under various network scenarios, compared to previous AP association schemes. Our experiments also confirm the effectiveness of the algorithms in enhancing network throughput, maintaining proportional fairness among clients, and balancing load among APs.

40 citations


Proceedings ArticleDOI
02 Dec 2014
TL;DR: MoFA is developed, a standard-compliant mobility-aware A-MPDU length adaptation scheme with ease of implementation that achieves the throughput 1.8x higher than a fixed duration setting (i.e., 10 ms, the maximum frame duration according to IEEE 802.11n standard).
Abstract: IEEE 802.11n WLAN supports frame aggregation called aggregate MAC protocol data unit (A-MPDU) as a key MAC technology to achieve high throughput. While it has been generally accepted that aggregating more subframes results in higher throughput by reducing protocol overheads, our measurements reveal various situations where the use of long A-MPDU frames frequently leads to poor performance in time-varying environments. Especially, since mobility intensifies the time-varying nature of the wireless channel, the current method of channel estimation conducted only at the beginning of a frame reception is insufficient to ensure robust delivery of long A-MPDU frames. Based on extensive experiments, we develop MoFA, a standard-compliant mobility-aware A-MPDU length adaptation scheme with ease of implementation. Our prototype implementation in commercial 802.11n devices shows that MoFA achieves the throughput 1.8x higher than a fixed duration setting (i.e., 10 ms, the maximum frame duration according to IEEE 802.11n standard). To our best knowledge, this is the first effort to optimize the A-MPDU length for commercial 802.11n.

34 citations


Proceedings ArticleDOI
02 Dec 2014
TL;DR: This work demonstrates how different mobility modes can be distinguished by using physical layer information -- Channel State Information (CSI) and Time-of-Flight (ToF) -- available at commodity APs, with no modifications on the client side.
Abstract: With the proliferation of smartphones and tablets, mobile devices are soon becoming a preferred medium of Internet access in Wireless LANs (WLANs). Due to their smaller form factor, these truly mobile devices allow the users to access the wireless networks while undergoing different types of mobility, posing new challenges to wireless protocols. Current history-based protocols that maximize performance in static settings do not work well in mobile settings where wireless conditions change rapidly. Thus, today's WLANs need to be able to determine the type of the client's mobility and employ appropriate strategies in order to sustain high performance. While previous work tried to detect mobility using hints from sensors available in today's mobile devices, in this work, we demonstrate how different mobility modes can be distinguished by using physical layer information -- Channel State Information (CSI) and Time-of-Flight (ToF) -- available at commodity APs, with no modifications on the client side. In addition, we demonstrate how fine-grained mobility determination can be exploited to improve performance of client roaming, rate control, frame aggregation, and MIMO beamforming. Our testbed experiments show that our mobility classification algorithm achieves more than 92% accuracy in a variety of scenarios, and the combined throughput gain of all four mobility-aware protocols over their mobility-oblivious counterparts can be more than 100%.

29 citations


Proceedings ArticleDOI
01 Dec 2014
TL;DR: This paper conducts extensive experiments to understand how 802.11n impact on 802.15.4 and vice versa in a systematic way and considers primary features of 802.
Abstract: Wireless coexistence is crucial with the explosive development of wireless technologies in recent years. The coexistence issues of IEEE 802.11 b/g and IEEE 802.15.4 have been well studied, however few work focused on 802.11n new features including MIMO, channel bonding and frame aggregation. In this paper, we conducted extensive experiments to understand how 802.11n impact on 802.15.4 and vice versa in a systematic way. We consider primary features of 802.11n both in symmetric and asymmetric scenarios. The goal of our work is to gain more insights into the coexistence issues of 802.11n and 802.15.4 and thus to help protocol design and co-located network deployments.

26 citations


Proceedings ArticleDOI
08 Jul 2014
TL;DR: BLMon is presented, a framework for loss differentiation, that uses loss patterns within aggregate frames and aggregate frame retries to achieve accurate and low overhead loss differentiation in 802.11 wireless networks.
Abstract: A fundamental problem in 802.11 wireless networks is to accurately determine the cause of packet losses. This becomes increasingly important as wireless data rates scale to Gbps, where lack of loss differentiation leads to higher loss in throughput. Recent and upcoming high-speed WLAN standards, such as 802.11n and 802.11ac, use frame aggregation and block acknowledgements for achieving efficient communication. This paper presents BLMon, a framework for loss differentiation, that uses loss patterns within aggregate frames and aggregate frame retries to achieve accurate and low overhead loss differentiation. Towards this end, we carry out a detailed measurement study on a real testbed to ascertain the differences in loss patterns due to noise, collisions, and hidden nodes. We then devise metrics to quantitatively capture these differences. Finally, we design BLMon, which collectively uses these metrics to infer the cause of loss without requiring any out-of-band communication, protocol changes, or customized hardware support. BLMon can be readily deployed on commodity devices using only driver-level changes at the sender-side. We implement BLMon in the ath9k driver and using real testbed experiments, show that it can provide up to 5!improvement in throughput.

24 citations


Proceedings ArticleDOI
18 Dec 2014
TL;DR: An in-depth investigation into the harmful effect of FA on ABE using WBest is conducted and an enhanced version of WBest termed WBest+ is developed that incorporates two key design principles to counter FA effects.
Abstract: We consider for the first time available bandwidth estimation (ABE) in the context of 802.11n, which is fast replacing the legacy 802.11a/b/g networks. We experimentally show that the frame aggregation (FA) feature of 802.11n is the dominant one among 802.11n features affecting the ABE. Using an indoor 802.11n wireless testbed, we compare three ABE tools (WBest, DietTopp and pathChirp) in various cross-traffic scenarios. We find that FA significantly hurts the accuracy of all ABE tools; DietTopp and pathChirp are relatively more robust than WBest. Because faster available bandwidth estimation and less intrusiveness are desirable properties of any ABE tool and WBest satisfies them relatively better than the other two tools, we conduct an in-depth investigation into the harmful effect of FA on ABE using WBest. This in turn led us to come up with two key design principles to counter FA effects: (1) treating aggregated probes as one jumbo probe; and (2) generating a larger number of probes. We then develop an enhanced version of WBest termed WBest+ that incorporates these principles. Our evaluation shows that the new version is effective in achieving accurate ABE in the presence of FA. I. INTRODUCTION End-to-end available bandwidth estimation (ABE) has a wide range of uses including adaptive application content delivery; transport-level transmission rate adaptation and admission con-

19 citations


Proceedings ArticleDOI
11 Jun 2014
TL;DR: This work presents experimentally obtained results that evaluate the energy efficiency of the base standard in comparison with the latest 802.11n version, and is the first to provide such a detailed comparative analysis on the performance of both standards.
Abstract: Over the last decade, the IEEE 802.11 has emerged as the most popular protocol in the wireless domain. Since the release of the first standard version, several amendments have been introduced in an effort to improve its throughput performance, with the most recent one being the IEEE 802.11n extension. In this paper, we present experimentally obtained results that evaluate the energy efficiency of the base standard in comparison with the latest 802.11n version, under a wide range of settings. To the best of our knowledge, our work is the first to provide such a detailed comparative analysis on the performance of both standards. The followed power measurement methodology is based on custom-built hardware that enables online energy consumption evaluation at both the wireless transceiver and the total node levels. Based on in-depth interpretation of the collected results, we remark that the latest standard enables significant improvement of energy efficiency, when combined with standard compliant frame aggregation mechanisms. Our detailed findings can act as guidelines for researchers working on the design of energy efficient wireless protocols.

15 citations


Journal ArticleDOI
TL;DR: One of the first experimental studies of the performance of link quality-based routing metrics in a 21-node indoor 802.11n WMN reveals that the gains of linkquality-based metrics over the hopcount metric in legacy 802.
Abstract: In the recent past, link quality-based routing metrics, such as ETX and ETT, have been shown to significantly outperform the traditional hopcount metric in legacy 802.11a/b/g wireless mesh networks (WMNs). The new 802.11n standard introduces a number of enhancements at the MAC/PHY layers (MIMO technology, channel bonding, frame aggregation, and more aggressive modulation and coding schemes) marking the beginning of a new generation of 802.11 radios. In this paper, we conduct one of the first experimental studies of the performance of link quality-based routing metrics in a 21-node indoor 802.11n WMN. Our study reveals that the gains of link quality-based metrics over the hopcount metric in legacy 802.11 WMNs do not carry over in 802.11n MIMO WMNs. We analyze the causes of this behavior and make recommendations for the design of new routing metrics in 802.11n WMNs.

13 citations


Proceedings ArticleDOI
01 Jan 2014
TL;DR: The simulation results show an outstanding performance improvement can be achieved by applying the proposed fair scheduler as compared to the standard network protocol in terms of packet loss ratio and average delay.
Abstract: The IEEE 80211n network standard does not specify the scheduling mechanism for the packet aggregation and treats the packet the same without distinguishing them between real time and none real time In this study, we have proposed a fair scheduling algorithm for the A-MSDU aggregation that transmits the MSDUs according to their priority based on their lifetime The simulation results show an outstanding performance improvement can be achieved by applying the proposed fair scheduler as compared to the standard network protocol in terms of packet loss ratio and average delay

13 citations


Proceedings ArticleDOI
06 Apr 2014
TL;DR: The results show that a single FTP transfer between two Linux wireless hosts can saturate the buffers in the network stack, leading to RTT delays exceeding 4.5 s in multi-hop configurations, and it is shown that well-designed Aggregate MAC Protocol Data Unit (A-MPDU) MAC-layer frame aggregation can reduceRTT delays while simultaneously increasing network throughput.
Abstract: In this paper, we analyze the impact of large, persistently-full buffers (`bufferbloat') on various network dynamics in IEEE 802.11n wireless networks. Bufferbloat has mostly been studied in the context of wired networks. We study the impact of bufferbloat on a variety of wireless network topologies, including wireless LAN (WLAN) and multi-hop wireless networks. Our results show that a single FTP transfer between two Linux wireless hosts can saturate the buffers in the network stack, leading to RTT delays exceeding 4.5 s in multi-hop configurations. We show that well-designed Aggregate MAC Protocol Data Unit (A-MPDU) MAC-layer frame aggregation can reduce RTT delays while simultaneously increasing network throughput. However, additional measures may still be required to meet the constraints of real-time flows (such as VoIP). Our experiments show that large buffers can deteriorate the fairness in rate allocation in parking lot based multi-hop networks.

Journal ArticleDOI
TL;DR: The proposed EEFA (Energy Efficiency Frame Aggregation), a frame aggregation based energy-effcient scheduling algorithm for IEEE 802.11n wireless network, changes the size of aggregated frame dynamically according to the frame error rate, so as to ensure the data transmission and retransmissions completed during the TXOP and reduce energy consumption of channel contention.
Abstract: Packet size is restricted due to the error-prone wireless channel which drops the network energy utilization. Furthermore, the frequent packet retransmissions also lead to energy waste. In order to improve the energy efficiency of wireless networks and save the energy of wireless devices, EEFA (Energy Efficiency Frame Aggregation), a frame aggregation based energy-effcient scheduling algorithm for IEEE 802.11n wireless network, is proposed. EEFA changes the size of aggregated frame dynamically according to the frame error rate, so as to ensure the data transmission and retransmissions completed during the TXOP and reduce energy consumption of channel contention. NS2 simulation results show that EEFA algorithm achieves better performance than the original frame-aggregation algorithm.

Proceedings ArticleDOI
18 Aug 2014
TL;DR: This work proposes WQM, a queue management scheme customized for wireless networks that reduces the end-to-end delay by up to 8x compared to Linux default buffer size, and 2xCompared to CoDel, the state-of-the-art bufferbloat solution, while achieving comparable network goodput.
Abstract: Choosing the right buffer size in Wi-Fi networks is challenging due to the dynamic nature of the wireless environment. Over buffering or 'bufferbloat' may produce unacceptable end-to-end delays, while static small buffers may limit the performance gains that can be achieved with various 802.11n enhancements, such as frame aggregation. We propose WQM, a queue management scheme customized for wireless networks. WQM adapts the buffer size based on measured link characteristics and network load. Furthermore, it accounts for aggregate length when deciding about the optimal buffer size. We implement WQM on Linux and evaluate it on a wireless testbed. WQM reduces the end-to-end delay by up to 8x compared to Linux default buffer size, and 2x compared to CoDel, the state-of-the-art bufferbloat solution, while achieving comparable network goodput. Further, WQM improves fairness as it limits the ability of a single flow to saturate the buffer.

Journal ArticleDOI
TL;DR: A greedy fast-shift (GFS) block ACK mechanism is proposed to provide the receiver-defined SSN, which can both implicitly acknowledge the correctly received packets before theSSN and explicitly identify the correctness information for the packets after the SSN.
Abstract: The techniques of frame aggregation and block acknowledgement (ACK) are utilized in the IEEE 802.11n standard for achieving high throughput performance from the medium access control perspective. Conventional greedy scheme for block ACK adopts the transmitter-defined starting sequence number (SSN) to construct the ACK window for recognizing the correctness of data packets. However, there exists correctly received packets that lie outside of the ACK window which will unavoidably be retransmitted by adopting the conventional scheme. In this paper, a greedy fast-shift (GFS) block ACK mechanism is proposed to provide the receiver-defined SSN, which can both implicitly acknowledge the correctly received packets before the SSN and explicitly identify the correctness information for the packets after the SSN. In order to evaluate the effectiveness of the GFS scheme, the analytical models for these two mechanisms are proposed based on the window utilization. Compared to the conventional greedy scheme, it is observed from the simulation results that the proposed GFS method can provide better performance owing to its fast-shift behavior on ACK window.

Proceedings ArticleDOI
23 Jul 2014
TL;DR: The performance of the proposed QoS mechanism, Adaptation of Frame Aggregation AFA-CAC, on supporting real time applications particularly on audio and video services is investigated.
Abstract: IEEE 802.11n WLAN was mainly developed to support a high data transmission rate toward 600Mbps based on the aggregation scheme that accumulates several sub-frames to transmit them into a larger frame. This concept reduces overheads and increases efficiency and throughput. Nevertheless, it cannot provide QoS satisfaction for delay sensitive application since it badly affects the delay. To outperform this inefficiency, we have proposed an admission control mechanism named Adaptation of Frame Aggregation AFA-CAC. In this paper, we further investigate the performance of our proposed QoS mechanism on supporting real time applications particularly on audio and video services.

Proceedings ArticleDOI
01 Dec 2014
TL;DR: An adaptive aggregation scheme for MAC 802.11 is proposed to improve the transmission efficiency in unstable wireless delay-tolerant environments and reduces the number of transmission times by aggregating data; thus saving sensor energy consumption.
Abstract: In delay-tolerant sensor networks where connectivity is not guaranteed, sensors are seeking efficient ways to send the collected data during relatively rare transmission opportunities. Aggregation is one of the major ways to improve the data throughput while consuming less energy consumption. This paper proposes an adaptive aggregation scheme for MAC 802.11 to improve the transmission efficiency in unstable wireless delay-tolerant environments. The aggregation scheme not only considers the upper layer separation of quality of service (QoS) requirements into different queues, but also adapts the wireless channel status to the aggregation procedure. The simulation results show that the scheme improves the transmission efficiency and reduces the number of transmission times by aggregating data; thus saving sensor energy consumption.

Proceedings ArticleDOI
17 Jun 2014
TL;DR: An experimentation of the 802.11n MAC improvements: frame aggregation is introduced to demonstrate the contribution of such technology on wireless performance and the network response.
Abstract: There has been major changes in the emergent standards of wireless networks. These changes aims to improve more and more the wireless performance and the network efficiency. It would be interesting to achieve high level of throughput without requiring sophisticated software improvement. In this context this paper stands to introduce an experimentation of the 802.11n standard. It displays a number of simulation based on a C++ program. This application implements one side of the 802.11n MAC improvements: frame aggregation. The main objective is to demonstrate the contribution of such technology on wireless performance and the network response.

Posted Content
TL;DR: In this paper, the authors proposed a Bi-Scheduler algorithm to improve the throughput of the wireless LAN through effective frame aggregation using scheduler mechanism, which aims to segregate frames based on their access categories and decide whether to apply Aggregated-MAC Service Data Unit (A-MSDU) aggregation technique or send the data without any aggregation.
Abstract: IEEE 802.11n mainly aims to provide high throughput, reliability and good security over its other previous standards. The performance of 802.11n is very effective on the saturated traffic through the use of frame aggregation. But this frame aggregation will not effectively function in all scenarios. The main objective of this paper is to improve the throughput of the wireless LAN through effective frame aggregation using scheduler mechanism. The Bi-Scheduler algorithm proposed in this article aims to segregate frames based on their access categories. The outer scheduler separates delay sensitive applications from the incoming burst of multi-part data and also decides whether to apply Aggregated - MAC Service Data Unit (A-MSDU) aggregation technique or to send the data without any aggregation. The inner scheduler schedules the remaining (delay-insensitive, background and best-effort) packets using Aggregated-MAC Protocol Data unit (A-MPDU) aggregation technique

Proceedings ArticleDOI
06 Apr 2014
TL;DR: Computer simulation results confirm that the proposed superframe division multi-hop data collection scheme with frame aggregation achieves over a 95% frame success probability under the high-traffic situation in which 1,000 meter nodes generate frames at a 10-minute interval.
Abstract: This paper proposes an effective multi-hop data collection scheme using a superframe division technique with frame aggregation on a Wi-SUN profile for ECHONET Lite. In the proposed scheme, a Wi-SUN MAC layer profile deploying IEEE 802.15.4/4e-compliant LE superframe-based multi-hop transmission mitigates the bottleneck problem by controlling the radio link numbers in a superframe, thereby preventing the data collection throughput degradation expected in high-traffic situations such as emergencies. Computer simulation results confirm that the proposed superframe division multi-hop data collection scheme with frame aggregation achieves over a 95% frame success probability under the high-traffic situation in which 1,000 meter nodes generate frames at a 10-minute interval.

Proceedings ArticleDOI
01 Dec 2014
TL;DR: This work determines VoIP capacity over User Datagram Protocol (UDP) and TCP Friendly Rate Control (TFRC) protocol in the presence of Transmission Control Protocol (TCP) traffic and reveals that simultaneous use of optimal values of both FA and TXOP further increase VoIPcapacity.
Abstract: Wireless Fidelity (WiFi) networks have gained unprecedented growth in recent years and have played an important role in the popularity of wireless VoIP. IEEE 802.11n is the most widely used WiFi standard today. Transmission Opportunity (TXOP) and Frame Aggregation (FA) are two important Medium Access Control (MAC) Layer enhancements provided by IEEE 802.11n standard. In this work our focus is on the determination of optimal values of TXOP and FA that maximize VoIP capacity. We first determine the optimal value of FA that maximizes VoIP capacity. Our simulation results show that optimal value of FA that maximizes VoIP capacity is 14. At 10 ms packetization interval this value of FA provides a gain of 26% in VoIP capacity as compared to the VoIP capacity with no FA. Secondly, we find that the optimal value of TXOP that maximizes VoIP capacity is 13. At 10ms packetization interval this value of TXOP gives a gain of 32% in VoIP capacity as compared to VoIP capacity with default value of TXOP. We then determine the VoIP capacity when optimal values of TXOP and FA are simultaneously used. Our study reveals that simultaneous use of optimal values of both FA and TXOP further increase VoIP capacity. A gain of 44% in VoIP capacity is achieved when optimal values of TXOP and FA are used simultaneously as compared to the VoIP capacity with default values of both FA and TXOP. We further determine VoIP capacity over User Datagram Protocol (UDP) and TCP Friendly Rate Control (TFRC) protocol in the presence of Transmission Control Protocol (TCP) traffic. We note that in the presence of TCP traffic, TFRC with optimal values of TXOP and FA provides an average gain of 37% as compared to TFRC with default values of FA and TXOP.

Patent
28 Jan 2014
TL;DR: In this article, a method of a wireless local area network (WLAN) transmitter includes, in response to interference with a long-term evolution (LTE) receiver, determining a de-sense value of the LTE receiver; determining a transmission rate for the WLAN transmitter, the transmission rate requiring an equal or lower receiver sensitivity than a received signal strength threshold, and determining a frame aggregation size based on the transmission rates and an LTE frame configuration for the LTE receiver.
Abstract: In some implementations, a method of a wireless local area network (WLAN) transmitter includes, in response to interference with a long term evolution (LTE) receiver, determining a de-sense value of the LTE receiver; determining a transmission rate for the WLAN transmitter, the transmission rate requiring an equal or lower receiver sensitivity than a received signal strength threshold; determining a frame aggregation size based on the transmission rate and an LTE frame configuration for the LTE receiver; determining a transmission power based on the de-sense value; and transmitting data during a downlink receiving period of the LTE receiver using the transmission rate, the frame aggregation size, and the transmission power.


Journal ArticleDOI
TL;DR: Simulation results show that the proposed channels assignment algorithms can significantly improve the network throughput of 802.11n WLANs, compared with other channel assignment algorithms.

Patent
31 Jan 2014
TL;DR: In this paper, a method and a network device for efficient frame aggregation is described, where the network device transmits the first set of packets before at least one of the first sets of aggregation limits is detected.
Abstract: The present disclosure discloses a method and network device for efficient frame aggregation. Specifically, a network device queues a first set of packets until one of the first set of aggregation limits is detected. The network device then transmits the first set of packets, and receives feedback information. Then, the network device modifies the first set of aggregation limits to obtain a second set of aggregation limits based on the feedback information. The network device queues a second set of packets until one of the second set of aggregation limits is detected, and then transmits the second set of packets. Also, the network device determines whether a received packet has a particular characteristic. If so, the network device transmits the first set of packets before at least one of the first set of aggregation limits is detected.


Proceedings ArticleDOI
01 Nov 2014
TL;DR: QoS-aware Adaptive MPDU aggregation scheduler is proposed which applies aggregation to voice traffic and adaptively adjusts the aggregation size based on time-varying end-to-end delay and WLAN contention, and QoS requirements.
Abstract: MPDU aggregation is not applied to real-time voice traffic (e.g., VoIP) in currently available IEEE 802.11n WLAN implementations considering the strict upper bounds of end-to-end delay and jitter. As a result, when real-time voice and non-real-time heavy load traffics are intermixed the resource utilization and overall throughput become poor due to the overhead produced by individual voice MPDU transmissions. In this paper, we propose QoS-aware Adaptive MPDU aggregation scheduler which applies aggregation to voice traffic and adaptively adjusts the aggregation size based on time-varying end-to-end delay and WLAN contention, and QoS requirements (e.g. less than 150 ms end-to-end delay). Experimental results of the proposed scheme show that the overall throughput increased by 57% when 10 stations generate 64 Kbps PCM voice traffic on 270 Mbps PHY rate for 2 ms transit delay representing campus network communication. For 120 ms transit delay configuration that represents intercity communication, the throughput enhancement was 45 % compared to the existing scheme1.

Proceedings ArticleDOI
01 Aug 2014
TL;DR: This paper investigates the traditional analytical model of DCF and proposes an adaptive Block ACK scheme to achieve higher throughput by reducing package loss and a MATLAB simulation is established to show that the proposed block ACK enhancement can improve system performance.
Abstract: The Wireless Local Area Network (WLAN) has experienced tremendous changes through these days, both in usage and technological aspects. Recently, 802.11ac and 802.11ad protocols for WLAN have been standardized by IEEE. They are both amendments to the 802.11-2012 protocol and their primary Medium Access Control (MAC) technique is Distributed Coordination Function (DCF). What's more, in order to improve high speed throughput especially in MAC layer, 802.11ac and 802.11ad both extend frame aggregation mechanisms utilizing the MAC Protocol Service Unit Aggregation (A-MSDU) and MAC Protocol Data Unit Aggregation (A-MPDU) schemes and block acknowledgement (Block ACK) schemes. In this paper, we investigate the traditional analytical model of DCF. Then based on that model, we propose an adaptive Block ACK scheme to achieve higher throughput by reducing package loss. A MATLAB simulation is established to show that the proposed Block ACK enhancement can improve system performance.

Journal ArticleDOI
TL;DR: The results show the proposed scheme has notably better goodput than existing schemes such as SW and ASR-ARQ.
Abstract: This letter proposes an efficient frame aggregation transmission scheme based on random linear network coding in 802.11n/ac networks. The proposed scheme dynamically utilizes either systematic coding or mixed generation coding for network changing characteristics to maximize wireless bandwidth use. A simple and accurate analytical model for performance analysis of the proposed scheme is developed and verified via simulations. The results show the proposed scheme has notably better goodput than existing schemes such as SW and ASR-ARQ.

Proceedings ArticleDOI
07 Sep 2014
TL;DR: It is shown that a simple adaptive MIM scheme can potentially achieve throughput that is close to the optimal, and can be easily implemented in existing commodity 802.11 adapters.
Abstract: We study the performance impact of the Message in Message (MIM) mechanism in modern 802.11 networks. The MIM mechanism refers to the capability of receiver to abandon an ongoing reception of an 802.11 MAC frame and shift to decode another frame with a higher signal strength. MIM is a common feature in modern 802.11 adapters and it has been shown to improve spatial concurrency. However, our measurement study in a campus WLAN shows that under certain conditions, MIM could cause a throughput degradation of more than 30% when enabled, instead of improving it as expected. With comprehensive experiments using commercial 802.11n adapters, we characterize the impact of MIM for a range of parameters and for different scenarios. We show that a simple adaptive MIM scheme can potentially achieve throughput that is close to the optimal. Our method is practical because it can be easily implemented in existing commodity 802.11 adapters.

Patent
31 Dec 2014
TL;DR: In this paper, the authors proposed a MAC frame aggregation method to realize intra-frame dimming, which is independent of a modulation method and channel encoding scheme utilized in data transmission and accordingly realizes flexible and precise dimming of a visible light communication.
Abstract: Disclosed are a dimming method and a dimming device. The dimming method includes dividing an MSDU (Mac service data units) on an MAC (media access control) layer into two or more than two sub MSDU of the same length; packaging the divided sub MSDU into individual MPDU (Mac protocol data units) and generating compensation frames for the MPDU respectively; aggregating the MPDU and the compensation frames which are of the same address as a PSDU (presentation service data) part of a PPDU (physical protocol data unit) and transmitting physical frames. The dimming method is independent of a modulation method and channel encoding scheme utilized in data transmission and accordingly realizes flexible and precise dimming of a visible light communication. Besides, since the MAC frame aggregation technology is utilized to realize intra-frame dimming, cost is saved.