Showing papers on "Frame aggregation published in 2012"
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07 Dec 2012
TL;DR: In this paper, a network comprising two RBridges connected by a link where the two RBbridges are not the ingress and egress RBR for said frames, where said RBridges automatically exchange information as to their support of hop-by-hop reversible frame aggregation, reversible header compression, and reversible data compression, increasing the throughput of the link.
Abstract: Some embodiments relate to a network comprising two RBridges connected by a link where the two RBridges are not the ingress and egress RBridge for said frames, wherein said RBridges automatically exchange information as to their support of hop-by-hop reversible frame aggregation, reversible header compression, and reversible data compression, and wherein if both RBridges support any or all of these features in the same fashion, one or more of said features are automatically applied to appropriate frames at the transmitting RBridge and removed at the receiving RBridge, increasing the throughput of the link.
70 citations
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TL;DR: This article reviews the main thrusts in next-generation passive optical network 1 and 2 technologies that enable short-term evolutionary and long-term revolutionary upgrades of coexistent gigabit-class PONs, and explores powerful layer-2 optical-wireless, hierarchical frame aggregation, and network coding techniques that significantly improve the throughput-delay performance, resource utilization efficiency, and survivability of NG-PON and FiWi networks.
Abstract: This article reviews the main thrusts in next-generation passive optical network 1 and 2 technologies that enable short-term evolutionary and long-term revolutionary upgrades of coexistent gigabit-class PONs, respectively. It provides insight into the key requirements and challenges of the major candidate NG-PON 1&2 architectures such as long-reach XG-PON, wavelength-routing WDM PON, OCDMA and OFDMA PON, and reports on recent progress toward enhanced data and control plane functionalities, including real-time dynamic bandwidth allocation, improved privacy and guaranteed QoS, bandwidth flexibility, as well as cost-effective in-service monitoring techniques for NG-PONs. We then elaborate on converged optical fiber-wireless access networks, which may be viewed as the endgame of broadband access, and explain the inherent coverage and QoS issues of conventional radio-over-fiber networks for distributed wireless MAC protocols and how their limitations can be avoided in so-called radio-and-fiber networks. We explore powerful layer-2 optical-wireless, hierarchical frame aggregation, and network coding techniques that significantly improve the throughput-delay performance, resource utilization efficiency, and survivability of NG-PON and FiWi networks. Finally, we inquire into the opportunities of sensor-enhanced FiWi networks and propose our novel Uber-FiWi network, whose potential is demonstrated by studying the beneficial impact of inter-home scheduling of emerging plug-in electric vehicles on the resource management of a more sustainable future smart grid.
64 citations
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TL;DR: An aggregation scheme (mA-MSDU) is proposed that reduces the aggregation headers and implements a retransmission control over the individual subframes at the MSDU level and the significance of the proposed scheme is shown, specifically for applications that have a small frame size such as VoIP.
Abstract: The main goal of the IEEE 802.11n standard is to achieve a minimum throughput of 100 Mbps at the MAC service access point. This high throughput has been achieved via many enhancements in both the physical and MAC layers. A key enhancement at the MAC layer is frame aggregation in which the timing and headers overheads of the legacy MAC are reduced by aggregating multiple frames into a single large frame before being transmitted. Two aggregation schemes have been defined by the 802.11n standard, aggregate MAC service data unit (A-MSDU) and aggregate MAC protocol data unit (A-MPDU). As a consequence of the aggregation, new aggregation headers are introduced and become parts of the transmitted frame. Even though these headers are small compared to the legacy headers they still have a negative impact on the network performance, especially when aggregating frames of small payload. Moreover, the A-MSDU is highly influenced by the channel condition due mainly to lack of subframes sequence control and retransmission. In this paper, we have proposed an aggregation scheme (mA-MSDU) that reduces the aggregation headers and implements a retransmission control over the individual subframes at the MSDU level. The analysis and simulations results show the significance of the proposed scheme, specifically for applications that have a small frame size such as VoIP.
56 citations
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TL;DR: A novel MAC-level multicast protocol for IEEE 802.11n, named Reliable and Efficient Multicast Protocol (REMP) is proposed, and results show that REMP outperforms existing multicast protocols for normal multicast traffic and S-REMP offers improved performance for scalable video streaming.
Abstract: The legacy multicasting over IEEE 802.11-based WLANs has two well-known problems-poor reliability and low-rate transmission. In the literature, various WLAN multicast protocols have been proposed in order to overcome these problems. Existing multicast protocols, however, are not so efficient when they are used combining with the frame aggregation scheme of IEEE 802.11n. In this paper, we propose a novel MAC-level multicast protocol for IEEE 802.11n, named Reliable and Efficient Multicast Protocol (REMP). To enhance the reliability and efficiency of multicast services in IEEE 802.11n WLANs, REMP enables selective retransmissions for erroneous multicast frames and efficient adjustments of the modulation and coding scheme (MCS). In addition, we propose an extension of REMP, named scalable REMP (S-REMP), for efficient delivery of scalable video over IEEE 802.11n WLANs. In S-REMP, different MCSs are assigned to different layers of scalable video to guarantee the minimal video quality to all users while providing a higher video quality to users exhibiting better channel conditions. Our simulation results show that REMP outperforms existing multicast protocols for normal multicast traffic and S-REMP offers improved performance for scalable video streaming.
53 citations
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25 Mar 2012TL;DR: Simulation results show that under hotspot client distribution, the proposed algorithms can boost the throughput of 802.11n clients and overall throughput by 106% and 89% compared to other AP association schemes, and experiments confirm the effectiveness of the algorithms in enhancing aggregated throughput, maintaining proportional fairness among clients and balancing load among APs.
Abstract: As the latest amendment of IEEE 802.11 standard, 802.11n allows a maximum raw data rate as high as 300Mbps, 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 one another to provide satisfactory coverage and seamless mobility support. Clients tend to associate (connect) to the AP with the strongest signal strength, which might lead to poor client throughput and overloaded APs. Although a number of AP association schemes have been proposed for IEEE 802.11 WLANs in previous studies, none of them have considered the frame aggregation feature in 802.11n. Moreover, the impact of legacy 802.11a/b/g clients in 802.11n WLANS has not been considered in 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 formulate it into an optimization problem based on a bi-dimensional Markov model, aiming at providing clients with the bandwidth proportional to their highest physical data rates, and then propose two heuristic AP association algorithms that can efficiently make online decisions on AP association. We have also conducted extensive simulations and experiments to validate the proposed algorithms. Our simulation results show that under hotspot client distribution, the proposed algorithms can boost the throughput of 802.11n clients and overall throughput by 106% and 89%, respectively, compared to other AP association schemes. Experiments also confirm the effectiveness of the algorithms in enhancing aggregated throughput, maintaining proportional fairness among clients and balancing load among APs.
49 citations
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01 Apr 2012TL;DR: It is observed that the multi-user frame aggregation scheme with STBC always outperforms a single-user transmission scheme withSTBC in terms of average throughput due to enhanced MAC layer efficiency through frame aggregation.
Abstract: IEEE 802.11ac standard has newly adopted a downlink multi-user multiple-input and multiple-output (DL-MU-MIMO) scheme. For user multiplexing in downlink WLAN, we can also use a frame aggregation scheme for multiplexing multiple users' data with space-time block coding (STBC) for achieving spatial diversity. We compare the performance of the two downlink user multiplexing schemes: multi-user MIMO and frame aggregation in IEEE 802.11ac. If each user's encoded data stream has a similar length, the multi-user MIMO scheme yields better average throughput than the frame aggregation scheme. On the other hand, if each user's encoded data stream has a different length, the frame aggregation scheme outperforms the multi-user MIMO scheme in terms of average throughput. In a fast-varying channel, the multi-user MIMO scheme yields worse throughput due to the channel feedback overhead, compared to that with the frame aggregation scheme. We also observe that the multi-user frame aggregation scheme with STBC always outperforms a single-user transmission scheme with STBC in terms of average throughput due to enhanced MAC layer efficiency through frame aggregation.
41 citations
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06 May 2012TL;DR: The results indicate that the traditional RTS/CTS handshake mechanism faces shortcomings and needs to be modified in order to support the newly defined 802.11ac amendment.
Abstract: Recently, the IEEE 802.11 standard based Wireless Local Area Networks (WLAN) have become more popular and are widely deployed. It is anticipated that WLAN will play an important rule in the future wireless communication systems in order to provide several gigabits data rate. IEEE 802.11ac is one of the ongoing WLAN standard aiming to support very high throughput (VHT) with data rate of up to 6 Gbps below the 6 GHz band. In the development of IEEE 802.11ac standard, several new physical layer (PHY) and medium access control layer (MAC) features are taken into consideration, such as employing wider bandwidth in PHY and incrementing the limits of frame aggregation in MAC. However, due to the newly introduced features, some traditional techniques used in previous standards could face some problems. This paper presents a performance analysis of 802.11ac Distributed Coordination Function (DCF) in presence of hidden nodes in overlapping BSS (OBSS) environment. The effectiveness of DCF in IEEE 802.11ac WLAN when using different primary channels and different frequency bandwidth has also been discussed. Our results indicate that the traditional RTS/CTS handshake mechanism faces shortcomings and needs to be modified in order to support the newly defined 802.11ac amendment.
41 citations
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TL;DR: This paper designs CA-DFA, an algorithm that, using only information available at layer two, adapts the amount of 802.11n aggregation used by a Wi-Fi station according to the level of congestion in the network, and demonstrates the benefits of this algorithm in terms of QoS, energy efficiency and network capacity with respect to state of the art alternatives.
33 citations
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TL;DR: This paper introduces and evaluates a comprehensive video MAC protocol (VMP) to efficiently deliver prerecorded video downstream to wireless consumers over a FiWi network in the presence of voice and data upstream and downstream traffic.
Abstract: Optical and wireless network technologies are expected to converge in the near to midterm, giving rise to bimodal fiber-wireless (FiWi) broadband access networks. In triple-play (voice, video, and data) service scenarios for such FiWi access networks, video traffic will likely dominate due to the widely predicted increase in video network services and the high traffic volume of compressed video compared to voice and data services. In this paper, we introduce and evaluate a comprehensive video MAC protocol (VMP) to efficiently deliver prerecorded video downstream to wireless consumers over a FiWi network in the presence of voice and data upstream and downstream traffic. VMP consists of three main novel components: (i) frame fragmentation in conjunction with hierarchical frame aggregation for efficient MAC frame transport over the integrated optical and wireless network segments, (ii) multi-polling medium access control for upstream voice and data packets and acknowledgements for downstream video packets, and (iii) prefetching of video frames over the optical and wireless network segments in conjunction with hybrid reservation/contention-based medium access. Our simulation results indicate that VMP achieves significant improvements in throughput-delay performance for all three traffic types as well as reductions in the playback starvation probability for video traffic compared to existing state-of-the-art MAC mechanisms.
28 citations
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TL;DR: Simulation results confirm that AMPDU, and Two level frame aggregation methods improve extensively data throughput, and conclude that overall, the two-level aggregation can improve throughput performance of 802.11n.
Abstract: IEEE 802.11n Draft is next-generation wireless LAN standard. This article gives detailed description and comparative study of A-MPDU and Two level frame aggregation mechanisms proposed in the latest 802.11n draft standard, which improve extensively the channel efficiency and data throughput. Ns 2 simulator is used for simulation of 802.11n WLAN frame aggregation. Simulation results confirm that AMPDU, and Two level frame aggregation methods improve extensively data throughput. It analyse the performance of each frame aggregation scheme in distinct scenarios, and it conclude that overall, the two-level aggregation can improve throughput performance of 802.11n. Two level aggregation can more effectively deliver data from multiple sources, PDR rate is much higher with much lower delay and Two level aggregation consumed less energy as compared with A-MPDU approach..
28 citations
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24 Dec 2012TL;DR: The main contribution of this paper is that it provides an adaptive aggregation scheme in which the sender conveys A-MSDUs within A-MPDUs in an adaptive manner, in order to resolve this potential problem in A- MPDU.
Abstract: In order to reduce the overhead of legacy WLANs, the IEEE 802.11n standard defines two aggregation schemes, i.e., A-MSDU and A-MPDU. In general, A-MPDU outperforms A-MSDU due to its selective retransmission capability. However, A-MPDU has a fundamental restriction on the minimum separation in time between the start of two consecutive subframes carried on the same A-MPDU. If such a gap is smaller than the minimum MPDU start spacing of the receiver, the sender should insert additional padding, thus resulting in throughput degradation. The main contribution of this paper is that we provide an adaptive aggregation scheme in which the sender conveys A-MSDUs within A-MPDUs in an adaptive manner, in order to resolve this potential problem in A-MPDU. Our analytical and simulation results demonstrate that the proposed scheme improves throughput performance over A-MPDU and A-MSDU by up to 280% and 19%, respectively.
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26 Jun 2012
TL;DR: This paper investigates the effect of frame aggregation on the support of voice and video applications in wireless networks and proposes a new frame aggregation scheduler that considers specific QoS requirements for multimedia applications.
Abstract: The IEEE 802.11n standard promises to extend todays most popular WLAN standard by significantly increasing reach, reliability, and throughput. Ratified on september 2009, this standard defines many new physical and medium access control (MAC) layer enhancements. These enhancements aim to provide a data transmission rate of up to 600 Mbps. The frame aggregation mechanism of 802.11n MAC layer can improve the efficiency of channel utilization by reducing the protocol overheads. In this paper we investigate the effect of frame aggregation on the support of voice and video applications in wireless networks. We also propose a new frame aggregation scheduler that considers specific QoS requirements for multimedia applications. We dynamically adjust the aggregated frame size based on frame's access category defined in 802.11e standard.
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01 Sep 2012
TL;DR: This paper investigates the effect of most of the proposed 802.11n MAC and physical layer features on the adhoc networks performance, and proposes a new frame aggregation scheduler that considers specific QoS requirements for multimedia applications.
Abstract: The 802.11n standard promises to extend todays most popular WLAN standard by significantly increasing reach, reliability, and throughput. Ratified on September 2009, this standard defines many new physical layer and medium access control (MAC) layer enhancements. These enhancements aim to provide a data transmission rate of up to 600 Mbps. Since June 2007, 802.11n products are available on the enterprise market based on the draft 2.0. In this paper we investigate the effect of most of the proposed 802.11n MAC and physical layer features on the adhoc networks performance. We have performed several experiments in real conditions. The experimental results demonstrated the effectiveness of 802.11n enhancement. We have also examined the interoperability and fairness of 802.11n. We finally propose a new frame aggregation scheduler that considers specific QoS requirements for multimedia applications. We dynamically adjust the aggregated frame size based on frame's access category defined in 802.11e standard.
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06 Dec 2012TL;DR: A- MSDU real-time scheduler is proposed by exploiting the A-MSDU attributes and adopting the idea of enabling retransmission in the aggregation scheduler algorithm to obtain aggregation with small size to support time sensitive applications and satisfying the QoS requirements.
Abstract: The IEEE 802.11n network main feature is to support high throughput of more than 100Mbps at the MAC layer. To achieve this, the 802.11n Task Group has introduced frame aggregation technique which reduces the overhead and increases the channel utilization efficiency. The MAC layer defines two frame aggregation mechanisms namely the MAC protocol data unit aggregation A-MPDU and MAC service data unit aggregation A-MSDU. A-MPDU is robust against error due to subframes retransmission and large aggregation size, whereas A-MSDU is effective in error free channel due to small headers. A-MPDU has poor performance in erroneous channel because of the absence of sub frames retransmission. It is worth mentioning that some recent researches have enabled the selective retransmission which makes it robust against error. The AMSDU has becomes compatible and able to fulfill the QoS requirements for applications with small frame size such as VoIP, videos as well as interactive gaming. In this paper, we propose A-MSDU real-time scheduler by exploiting the A-MSDU attributes and adopting the idea of enabling retransmission in our aggregation scheduler algorithm to obtain aggregation with small size to support time sensitive applications and satisfying the QoS requirements.
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01 Jan 2012
TL;DR: An optimized header A-MSDU frame aggregation (OHA-MSU) with subframes retransmission capability at the MSDU level is proposed and the simulation results show the significance of the proposed scheme, especially for applications that have a small frame size such as VoIP.
Abstract: The IEEE 802.11n standard is defined to achieve a high throughput at the MAC layer. This high throughput is accomplished via many enhancements in both the physical and MAC layers. A key enhancement introduced in the 802.11n standard is frame aggregation. Two types of aggregation defined by the 802.11n standard, aggregate MAC service data unit (A-MSDU) and aggregate MAC protocol data unit (A-MPDU). Frame aggregation reduces both the headers and timing overheads at the MAC layer by aggregating multiple frames into a single large frame before being transmitted. The aggregation headers themselves still have a negative impact on the network performance especially when aggregating frames of small payload. Moreover, the lack of partial retransmission in the A-MSDU aggregation is behind its poor performance in error-prone channels. In this paper we proposed an optimized header A-MSDU frame aggregation (OHA-MSDU) with subframes retransmission capability at the MSDU level. The simulation results show the significance of the proposed scheme, especially for applications that have a small frame size such as VoIP.
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05 Jun 2012
TL;DR: This chapter summarizes all the reference papers and analyzes the IEEE 802.11b/g/a/n MAC performance for wireless LAN with fixed and mobile stations, and presents the analytical evaluation of saturation.
Abstract: Over the past few years, mobile networks have emerged as a promising approach for future mobile IP applications. With limited frequency resources, designing an effective MAC (Medium Access Control) protocol is a hot challenge. IEEE 802.11b/g/a/n networks are currently the most popular wireless LAN products on the market [1]. The conventional IEEE 802.11b and 802.11g/a specification provide up to 11 and 54 Mbps data rates, respectively. However, the MAC protocol that they are based upon is the same and employs a CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) protocol with binary exponential back-off. IEEE 802.11 DCF (Distributed Coordination Function) is the de facto MAC protocol for wireless LAN because of its simplicity and robustness [2,3]. Therefore, considerable research efforts have been put on the investigation of the DCF performance over wireless LAN [2]. With the successful deployment of IEEE 802.11a/b/g wireless LAN and the increasing demand for real-time applications over wireless, the IEEE 802.11n Working Group standardized a new MAC and PHY (Physical) layer specification to increase the bit rate to be up to 600 Mbps [3]. The throughput performance at the MAC layer can be improved by aggregating several frames before transmission [3]. Frame aggregation not only reduces the transmission time for preamble and frame headers, but also reduces the waiting time during CSMA/CA random backoff period for successive frame transmissions. The frame aggregation can be performed within different sub-layers. In 802.11n, frame aggregation can be performed either by A-MPDU (MAC Protocol Data Unit Aggregation) or A-MSDU (MAC Service Data Unit Aggregation). Although frame aggregation can increase the throughput at the MAC layer under ideal channel conditions, a larger aggregated frame will cause each station to wait longer before its next chance for channel access. Under errorprone channels, corrupting a large aggregated frame may waste a long period of channel time and lead to a lower MAC efficiency [4]. On the other hand, wireless LAN mobile stations that are defined as the stations that access the LAN while in motion are considered in this chapter. The previous paper analyzed the IEEE 802.11b/g/n MAC performance for wireless LAN with fixed stations, not for wireless LAN with mobile stations [5, 6, 7, 8, 9, 10]. On the contrary, Xi Yong [11] and Ha Cheol Lee [12] analyzed the MAC performance for IEEE 802.11 wireless LAN with mobile stations, but considered only IEEE 802.11 and 802.11g/a wireless LAN specification. So, this chapter summarizes all the reference papers and analyzes the IEEE 802.11b/g/a/n MAC performance for wireless LAN with fixed and mobile stations. In other words, we will present the analytical evaluation of saturation
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25 Jun 2012
TL;DR: It is discovered that limiting frame aggregation severely impacts both the delay and video quality, and this should help for developing an effective cross-layer design for video streaming over IEEE 802.11n multi-hop networks.
Abstract: In this paper, we study the effects of frame aggregation on video streaming performance in a real-world IEEE 802.11n testbed. We quantitatively characterize delay, video quality, and mean aggregate size in two multi-hop scenarios. We observe that streaming applications naturally take advantage of frame aggregation, both in single- and multi-stream environments, and that a Full-HD video can be transmitted with excellent quality and delay, even on a 6-hop chain. Furthermore, we discover that limiting frame aggregation severely impacts both the delay and video quality. We believe these insights on frame aggregation help for developing an effective cross-layer design for video streaming over IEEE 802.11n multi-hop networks.
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01 Jul 2012TL;DR: QoS-HAN is a new scheme for the 802.11n aggregation process mainly designed to meet the requirements of multimedia services over Home Automated Networks (HAN), which takes into consideration the size of the packet during aggregation.
Abstract: Demands for QoS challenging wireless multimedia services are continuously increasing for both professional and entertainment needs. Efficient wireless technologies, able to offer the corresponding throughput and QoS are required. The IEEE 802.11n is the latest wireless standard. It introduces many improvements at both Physical and MAC layers. However, and despite the increase of the physical data rate, the large overhead associated with channel access and packet transmission schemes reduces its overall efficiency, mainly at the MAC layer. In this paper, we propose QoS-HAN: a new scheme for the 802.11n aggregation process. QoS-HAN is mainly designed to meet the requirements of multimedia services over Home Automated Networks (HAN). It takes into consideration the size of the packet during aggregation. The proposed scheme is evaluated and examined for different types of traffic. Simulation results demonstrate the efficiency of the proposed scheme in terms of throughput, delay and PDR.
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12 Nov 2012TL;DR: This study will show that careful parameterization at the MAC and application layers can provide an improve quality of service for many video streaming applications when deployed over an 802.11n network.
Abstract: The massive acceptance of the high data rate IEEE 802.11n standard enables the adoption of demanding audiovisual services, such as high definition TV over wireless local area networks. In this context, one of the key features of the IEEE 802.11n is the frame aggregation mechanism, which can improve the channel efficiency and data throughput. In this work, the efficiency of video transmissions schemes over 802.11n wireless networks is studied. The focus is centered on the new features introduced at the MAC layer of IEEE 802.11n such as frame aggregation, still considering the advances made in physical layer such as multiple input multiple output (MIMO). In addition, the H.264/AVC video coding standard is exploited to maximize the overall coding efficiency in such wireless network scenario. This study will show that careful parameterization at the MAC and application layers can provide an improve quality of service for many video streaming applications when deployed over an 802.11n network.
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24 Apr 2012TL;DR: This paper analyzes several aggregation mechanisms proposed to improve the MAC layer performance of 802.11n and adapts Bianchi’s analytical model and applied it for various aggregation techniques to provide a unified analytical framework for continued research in this direction.
Abstract: Increased expectations and demand for higher rates led to the development of new physical layer technologies in Wireless LANs. However, the current medium access control (MAC) needs to be improved to fully utilize higher physical-layer transmission rates. Several aggregation mechanisms have been recently proposed to improve the MAC layer performance of 802.11n. In this paper, we analyze some of the key aggregation mechanisms proposed. For analysis we adapted widely used Bianchi’s analytical model and applied it for various aggregation techniques. We also compare the analytical details of various strategies and provide a unified analytical framework for continued research in this direction.
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31 Dec 2012TL;DR: The Dynamic Frame Aggregation (DFA) scheme can avoid transmission errors and reduce transmission overhead simultaneously and the results show that the DFA provides better throughput than the frame aggregation scheme.
Abstract: The IEEE 802.11a can provide up to 54Mbps data rate and the IEEE 802.11n provide much higher data rates by the supporting PHY layer technique such as MIMO (Multiple Input Multiple Output). However, the medium access control of IEEE 802.11 WLANs were designed for low data rate such as 2Mbps. So, in high data rate WLANs, IEEE 802.11 WLANs are not efficient. Due to fixed overhead (control frames, preamble, and PLCP header are transmitted low data rate and IFS time is fixed irrespective of transmission rate), increasing of data transmission rate is not easy. To reduce fixed transmission overhead, frame aggregation has been proposed. However, in a noisy channel environment, frame aggregation leads to longer frame and it may be provoked transmission errors. In this paper, we propose the Dynamic Frame Aggregation (DFA) scheme. The DFA can aggregate frames according to channel condition properly. And the DFA works based on optimal pair of transmission rate and transmission frame length. So the DFA can avoid transmission errors and reduce transmission overhead simultaneously. The performance of the proposed scheme is evaluated by analytic modeling. The results show that the DFA provides better throughput than the frame aggregation scheme.
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22 Aug 2012
TL;DR: This paper investigates the effect of most of the proposed 802.11n MAC and physical layer enhancements on the adhoc networks performance, and proposes a new frame aggregation scheduler that considers specific QoS requirements for multimedia applications.
Abstract: The IEEE 802.11n protocol, ratified on September 2009, promises both higher data rates up to 600 Mbit/s and further range. In this paper we investigate the effect of most of the proposed 802.11n MAC and physical layer enhancements on the adhoc networks performance. Experimental results in a real indoor wireless testbed demonstrated the effectiveness of 802.11n enhancement. The channel bonding feature has the most significant impact on the throughput. The aggregation mechanism is not always effective. Then, we propose a new frame aggregation scheduler that considers specific QoS requirements for multimedia applications.
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31 Dec 2012TL;DR: Overall, the two-level aggregation can improve throughput performance of 802.11n and can more effectively deliver data from multiple sources, PDR rate is much higher with much lower delay and less energy consumption as compared with A-MPDU approach.
Abstract: IEEE 802.11n Draft is an ongoing next-generation wireless LAN standard. This paper describes detailed description and comparative study of various frame aggregation mechanisms proposed in the latest 802.11n draft standard, which improve extensively the channel efficiency and data throughput. Ns 2 simulator is used for simulation of 802.11n WLAN frame aggregation. Simulation results confirm that A-MPDU, and Two level frame aggregation methods improve extensively data throughput. It analyze the performance of each frame aggregation scheme in distinct scenarios, and it conclude that overall, the two-level aggregation can improve throughput performance of 802.11n. Two level aggregation can more effectively deliver data from multiple sources, PDR rate is much higher with much lower delay and less energy consumption as compared with A-MPDU approach.
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25 Jun 2012TL;DR: This paper proposes two algorithms to improve the performance of this standard: time-based frame aggregation and selective frames and evaluates these proposals under different conditions using performance indices including delay, throughput, and collision rate.
Abstract: IEEE 802.15.4 is the first recognized standard that can replace the large number of proprietary PHY and MAC protocols for Low Rate Wireless Personal Area Networks (LR- WPANs). To balance the conflicting demands of low-delay data delivery and consumed energy, this standard employs CSMA-CA as the multiple-access scheme. However, a critical study of this protocol's operation under different conditions shows room for improvement. In this paper we propose two algorithms to improve the performance of this standard: time-based frame aggregation and selective frames. We evaluate these proposals under different conditions using performance indices including delay, throughput, and collision rate. Our simulation results together with analytical expressions from related work demonstrate the benefits of our proposed ideas.
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27 Mar 2012
TL;DR: This project proposed an efficient MAC scheme ‘Frame Aggregation Method’ that would mitigate the overhead inefficiency of MAC layer and new MAC frame formats and the corresponding dynamic logic such as queuing mechanisms are designed.
Abstract: In recent years, IEEE 802.11 Wireless LAN (WLAN) has emerged as a prevailing technology for the broadband wireless networking. Along with many emerging applications and services over WLANs, the demands for faster and higher-capacity WLANs have been growing fast. However, MAC layer restrains the performance improvement due to its different overhead. We proposed an efficient MAC scheme ‘Frame Aggregation Method’ that would mitigate the overhead inefficiency. The principle of ‘Frame Aggregation Method’ is to aggregate as many as possible packets from the upper layer into large frames. Thus, the frames will be very large as long as there are enough packets to be aggregated. To support various functionalities provided by ‘Frame Aggregation Method’, new MAC frame formats and the corresponding dynamic logic such as queuing mechanisms are designed. The main contribution of this project is the exact calculation of the theoretical maximum throughput for a variety of IEEE 802.11 technologies. This formula is important to researchers as well as system designers. It is a strict barrier that cannot be overcome by any means while remaining standard-compliant.
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TL;DR: By computer simulations, it is shown that the derived optimal frame aggregation level significantly enhances the PCF MAC performance in IEEE 802.11 wireless LANs.
Abstract: In this paper, we analyze the effect of the frame aggregation level on the PCF (Point Coordination Function) MAC performance in IEEE 802.11 wireless LANs and analytically derive the optimal frame aggregation level for maximizing the PCF MAC performance. For various values of unit data frame size and transmission error probability, we propose the optimal frame aggregation levels. By computer simulations, we show that the derived optimal frame aggregation level significantly enhances the PCF MAC performance in IEEE 802.11 wireless LANs.
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29 Nov 2012TL;DR: A tight FER bound is derived to obtain instantaneous link condition, and extended Kalman filter is used to estimate frame size optimally for next transmission with current channel information, and results show that the proposed FSE scheme improves the throughput two times higher than a nonadaptation approach in high-stressed network condition.
Abstract: Demands for high throughput and stable service quality are increasing. Frame aggregation mechanisms in IEEE 802.11n wireless local area networks (WLANs) can provide improved throughput, but the effect of A-MSDU decreases significantly in error-prone channels. Therefore, adaptive frame size estimation (FSE) depending on the channel condition is required to maintain the improved throughput. In this paper, we proposed frame error rate (FER) based FSE scheme in error-prone and time-varying channel such as a high-stressed network. A tight FER bound is derived to obtain instantaneous link condition, and extended Kalman filter (EKF) is used to estimate frame size optimally for next transmission with current channel information. Our simulation results show that the proposed FSE scheme improves the throughput two times higher than a nonadaptation approach in high-stressed network condition.
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18 Apr 2012TL;DR: An experimental investigation of adapting 802.11n MAC and PHY layer parameters in an indoor 3 × 3 MIMO testbed demonstrates how overall application performance may be influenced by the Link layer; some of which may also be applicable to the upcoming802.11ac IEEE standard.
Abstract: Due to its low cost wireless communication methodology and improvements in both its physical (PHY) and MAC (Link) layers, the IEEE 802.11n wireless LAN (WLAN) technology has been adopted widely. However, fairness of current 802.11n rate adaptation (RA) mechanisms and analysis of practical user end-to-end throughput are among important issues still in their infancy. Thus in this paper, we conduct an experimental investigation of adapting 802.11n MAC and PHY layer parameters in an indoor 3 × 3 MIMO testbed. We detail the deployment of our infrastructure mode testbed and compare the performance of 802.11n RA mechanisms under various conditions, including simultaneous transmissions and Co-Channel Interference (CCI). We then examine a range of elements affecting application performance including the number of spatial streams, packet length, frame aggregation subframe number and length. Favorable results are observed across a set of configurations and parameters, such as the increase in A-MPDU subframe length and its impact on end-to-end throughput. We believe our results demonstrate how overall application performance may be influenced by the Link layer; some of which may also be applicable to the upcoming 802.11ac IEEE standard.
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01 Mar 2012TL;DR: The cross layer results show that the MIMO and beamforming schemes with frame aggregation and block acknowledgement enhance the throughput and operation range compared to the case of single antenna with reasonable hardware complexity.
Abstract: This paper studies the throughput and range of the OFDM based IEEE 802.11ad millimeter-wave WPANs. The cross layer results show that the MIMO and beamforming schemes with frame aggregation and block acknowledgement enhance the throughput and operation range compared to the case of single antenna with reasonable hardware complexity.
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01 Sep 2012
TL;DR: Flexible frame aggregation strategies are designed for different carrier aggregation situation in order to reduce the duplex delay existed in time division duplex (TDD) mode.
Abstract: In IMT-Advanced system, carrier aggregation makes use of continuous or non-continuous spectrum which may be scattered in many channels, and then the individual component carrier frame is combined to form a new frame structure named frame aggregation. In this paper, flexible frame aggregation strategies are designed for different carrier aggregation situation in order to reduce the duplex delay existed in time division duplex (TDD) mode. The flexible frame aggregation not only supports backward compatibility and asymmetric business but also improves the efficiency of hybrid automatic repeat request (HARQ) and channel quality information (CQI) feedback process.