Showing papers on "Frame aggregation published in 2009"

An empirical study on achievable throughputs of IEEE 802.11n devices

Abstract: The empirical performance studies on the emerging IEEE 802.11n technology by an independent and vendor-neutral party have not really been explored. In this paper, we conduct performance measurements for the IEEE 802.11n network using a mixture of commercially available IEEE 802.11n devices from various manufacturers. With the same standard 20-MHz channel width configuration, the results demonstrate that IEEE 802.11n significantly outperforms the IEEE 802.11g network. The performance improvements of IEEE 802.11n are measured to be roughly about 85% for the downlink UDP traffic, 68% for the downlink TCP traffic, 50% for the uplink UDP traffic, and 90% for the uplink TCP traffic. We also observe that the UDP throughputs are largely imbalanced for the uplink and downlink traffics in most test networks, while the downlink and uplink TCP throughput results are quite balanced for all test networks. In addition, the 40-MHz channel configurations only provide marginal performance improvements. Unlike other existing work, here we also capture and analyze the IEEE 802.11n packets transferred during the performance tests in order to technically explain the measured performance results. It is observed that when the frame aggregation and block acknowledgement mechanisms are utilized, the superior performance results are achieved. However, the decisions on how and when to use these mechanisms are very hardware dependent.

MAC Enhancement for High Speed Communications in the 802.15.3c mmWave WPAN

Abstract: Millimeter-wave (mmWave) is highly focused as a powerful mean enabling to perform very high data transmission. This paper proposes the enhancement of media access control (MAC) for the mmWave WPAN. The existing MACs have limits to achieve high data transmission over 1---2 Gbps by reasons of the low frame transmission efficiency and the high overhead of signal exchanges. In addition, the transmitting frames need to be protected in a poor channel condition for the high quality of service. The proposed MAC provides frame aggregation with unequal error protection (UEP) and block acknowledgment (Blk-ACK), which can solve the problems of the existing MACs and guarantee the high quality of service. Our theoretical throughput analysis shows that the proposed MAC does the high throughput enhancement compared to the existing MACs and achieves the MAC throughput over 2Gbps in the mmWave WPAN.

Supporting voice and video applications over IEEE 802.11n WLANs

Abstract: In this paper, an analytical model is developed for the performance study of an IEEE 802.11n wireless local area network (WLAN) supporting voice and video services, considering the new features of the medium access control (MAC) protocol proposed in IEEE 802.11n, i.e., frame aggregation and bidirectional transmission. We show that these enhanced MAC mechanisms can effectively improve the network capacity by not only reducing the protocol overheads, but also smoothing the AP-bottleneck effect in an infrastructure-based WLAN. Voice and video capacity under various MAC mechanisms are compared as well.

Supporting MAC Layer Multicast in IEEE 802.11n: Issues and Solutions

Abstract: In this paper, we propose a MAC layer multicast protocol for 802.11n WLAN for the first time. In IEEE 802.11n, new feature at MAC layer, such as frame aggregation and more flexible link adaptation are defined to increase the effective throughput. Recently, several multicast protocols at MAC layer have been proposed for WLAN. However, these protocols don't consider the new features defined in 802.11n, and cannot satisfy the requirement of fast speed transmission. In our proposed multicast protocol, "Double Piggyback Mode Multicast Protocol (DPMM)", we use new features (frame aggregation and link adaptation) in 802.11n to improve the multicast throughput. With DPMM, ACK packets are eliminated and collisions of control frames are avoided. A CHs (Cluster Heads) selection mechanism using Success Threshold is also developed to further improve upon DPMM. Simulation results, using the OPNET, confirm that the improvements are encouraging.

Implication of MAC Frame Aggregation on Empirical Wireless Experimentation

Abstract: Wireless network emulator testbeds have become increasingly important for realistic, at-scale experimental evaluation of new network architectures and protocols. Typically, wireless network performance measurements are made at multiple layers of the wireless protocol stack, i.e. link layer, MAC layer and network layer. This study highlights the impact of layer 2 frame aggregation that is enabled by default in the software drivers for commodity wireless 802.11 devices while it is still not a part of the core 802.11 standard. Using experimental measurements, it is shown that this feature has an impact across a diverse set of wireless experiments and should be considered while comparing results. Measurements on the ORBIT testbed show that throughput measurements can vary up to a startling 25% for certain packet sizes and the variance in receiver side inter-frame delays can almost double if MAC aggregation and preset transmission opportunities are not taken into consideration. Further results for VoIP traffic show a deterioration in jitter of up to 8 times when coupled with MAC layer aggregation in 802.11.

Multi-user OFDMA Frame Aggregation for Future Wireless Local Area Networking

Abstract: State-of-the-art wireless local area networking enables frame aggregation as approach to increase MAC efficiency. However, frame aggregation is limited to the aggregation of packets destined for the same station. In order to serve different stations, the access point still has to contend for the channel multiple times. In this paper we propose and evaluate a novel approach that enables multi-user frame aggregation. We combine this concept with channel-dependent OFDMA resource assignments, yielding a higher PHY efficiency (by exploiting multi-user diversity and instantaneous channel state information) as well as a higher MAC efficiency. The downside to this approach is the increase in protocol overhead to enable such multi-user OFDMA frame aggregation. However, we show that the proposed approach outperforms state-of-the-art 802.11n for different packet sizes and stations to be served.

Multi-receiver frame aggregation

Abstract: When using a multi-receiver aggregation protocol in a wireless communications network, a sub-header may be used to identify groups of data units that share common parameters, such as destination addresses, acknowledgement modes, modulation/coding rates, lengths, etc. The layout of this sub-header may permit each receiving device to identify the portion of the aggregated payload that is addressed to that receiving device, where that portion is located, how long that portion is, and how to demodulate it. In addition, by controlling the selection and timing of various acknowledgement modes used by the mobile stations, a base station may improve overall network efficiency and throughput.

Efficient dynamic frame aggregation in IEEE 802.11s mesh networks

Abstract: IEEE 802.11n could improve the network efficiency of WLAN by aggregating multiple frames into a single transmission. The frame aggregation technique especially benefits multi-hop transmissions that introduce enormous 802.11 medium access control (MAC) layer control overhead. This paper proposes a novel algorithm, namely dynamic aggregation selection and scheduling (DASS) algorithm, that can dynamically adopt the appropriate aggregation mechanism for IEEE 802.11s mesh network. The characteristics, benefits and the restrictions of three aggregation mechanisms, aggregate MAC service data units, aggregate MAC protocol data unit and aggregate physical protocol data unit, are investigated. Based on the channel condition, the quantity and the distribution of the frame arrivals, DASS could determine what aggregation mechanism to adopt and whether to wait for the next frame for aggregating transmissions. Simulation results demonstrate that the algorithm significantly increases the channel efficiency of the 802.11 MAC and further improves the overall throughput of the wireless mesh network by approximately 95p. Copyright © 2009 John Wiley & Sons, Ltd. This paper proposes the dynamic aggregation selection and scheduling (DASS) algorithm that can dynamically adopt the appropriate aggregation mechanism for IEEE 802.11s mesh network. DASS can determine what aggregation mechanism to adopt and whether to wait for the next frame for aggregating transmissions. Simulation results demonstrate that DASS significantly improves the overall throughput of the wireless mesh network by approximately 95p. Copyright © 2009 John Wiley & Sons, Ltd.

Method for transmitting and receiving frame in wireless lan

Abstract: The transmission delay of a voice frame can be reduced by performing internal collision resolution and frame aggregation according to the presence or absence of a voice frame awaiting transmission in a MAC layer, thereby reducing an end-to-end voice transmission delay time for a VoIP service.

Frame-aggregated link adaptation algorithm for IEEE 802.11n networks

Abstract: Channel condition is considered an important issue that affects the performance in wireless networks. Link Adaptation techniques have been proposed to improve the degraded network performance by adjusting the design parameters, e.g. the modulation and coding schemes, in order to adopt the dynamically changing channel conditions. Furthermore, due to the advancement of the IEEE 802.11n standard, the network goodput can be enhanced with the exploitation of its frame aggregation schemes. However, none of the existing link adaption algorithm is designed to consider the feasible aggregated frame length that should be adapted according to the changing environments. In this paper, A frame-aggregated link adaptation (FALA) algorithm is proposed to dynamically adjust system parameters in order to improve the network goodput under varying channel conditions. For the purpose of maximizing the network goodput, both the optimal frame payload size and the modulation and coding schemes are jointly acquired according to the signal-to-noise ratio under specific channel condition. Numerical results illustrate that the proposed FALA protocol can effectively increase the goodput performance comparing with other existing link adaptation schemes, especially under dynamically changing environments.

Enhanced frame aggregation in a wireless network system

Abstract: Variable-length information-containing frames (e.g., MPDUs) are aggregated into a bitstream using frame delimiters to distinguish the frames. Aggregation and frame extraction techniques are provided that support recovery from bit errors that may be present in a frame delimiter. One class of techniques involves providing redundant length information in the frame delimiters, e.g., by using multiple copies of a length field or error correction codes usable to correct errors in the length field. The receiver can use the redundant information to detect and correct errors in the length field. Another receiver-side technique iteratively attempts to locate the end of the corresponding frame when a corrupt frame delimiter is detected. Conventional synchronization fields may be eliminated.

Design and evaluation of a high throughput MAC with QoS guarantee for wireless LANs

Abstract: The IEEE 80211e and the IEEE 80211n focus on quality of service (QoS) and enhancements for high throughput respectively Modern wireless LAN (WLAN) products should integrate both features This paper presents a design of a high throughput MAC with QoS guarantee which combines the Hybrid Coordination Function (HCF) of the 80211e with the frame aggregation technique in the 80211n The basic idea of the design is to improve the throughput of best-effort traffic under the constraint that QoS is just met for real-time traffic Simulation results show that the proposed MAC has high channel utilization and the delay of best-effort traffic is also reduced

Robust coding in multi-hop networks

Abstract: The present invention relates to a method and apparatus which make use of a multiple receiver (MR) frame aggregation for creating data units so that they require acknowledgment of a single packet data unit by a group of several intended receivers. A multi-hop topology information regarding the neighborhood of a destination node can be used to derive the intended receivers which acknowledge a packet transmission besides the primary destination node of the packet.

On the Design of a Point-to-Multipoint Gigabit WLAN System on 60 GHz Millimeter Wave

Abstract: Increasing demand on the broadband wireless communication over Gigabits has focused renewed attention on 60 GHz millimeter wave. We developed a novel Point-to-Multipoint (P2MP) Gigabit WLAN System on 60 GHz millimeter wave. The proposed system employed wide angle beams antenna overcomes the usability of the conventional system, covers larger areas. Maximum transmission rate was designed to be 1.2 Gigabit/sec. Orthogonal frequency division multiplex (OFDM) using 1024 points FFT, and convolutional code were implemented with PHY layer of the WLAN equipments. Superframe for multiple beams and frame aggregation for high throughput were designed for MAC layer. All control channels for downlink such as broadcast, frame control and access feedback were aggregated to reduce overhead in addition to aggregation of data frame. Maximum improvement of throughput due to control channel aggregation was evaluated to be 200 % compared with individual transmission. Evaluated throughput using proposed frame aggregation was confirmed to be more than 852 Mbit/sec in the case of aggregation size of 16 × 1500byte.

Performance analysis for aggregated selective repeat ARQ scheme in IEEE 802.11n networks

Abstract: The next generation wireless local area networks (WLANs) with enhanced throughput performance have attracted significant amounts of attention in recent years. Based on the IEEE 802.11n standard, frame aggregation is considered one of the major factors to improve the system performance of WLANs from the medium access control perspective. In order to fulfill the requirements of the high throughput performance, feasible design of automatic repeat request (ARQ) mechanisms is considered important for providing reliable data transmission. In this paper, an aggregated selective repeat ARQ (ASR-ARQ) algorithm is proposed, which incorporate the conventional selective repeat ARQ scheme with the consideration of frame aggregation. A novel analytical model based on the signal flow graph is established in order to realize the behaviors of ASR-ARQ algorithm. Simulations are also conducted to validate the effectiveness of proposed ASR-ARQ mechanism.

Performance analysis of the frame aggregation mechanisms in IEEE 802.15.3c

Abstract: To achieve ultra high data rate communications in 60 GHz Wireless Personal Area Networks (WPANs), frame aggregation is devised in IEEE 802.15.3c to increase the MAC transmission efficiency. In this work, we propose a novel statistical model to analyze the behavior of two types of frame aggregation mechanisms: standard frame aggregation and low latency frame aggregation. Through our model, we could fully understand the performance of the frame aggregation mechanisms in terms of transmission delay and system capacity. The accuracy of our model is validated by extensive simulations. Our work provides valuable insights for ultra high performance transmission using 60 GHz radio.

Throughput enhancement of IEEE 802.11 WLAN for multimedia communications

Abstract: This paper mainly focuses on the throughput enhancement of legacy IEEE 802.11 MAC protocol. The two parameters, throughput and QoS are now main challenge for multimedia applications in wireless networks. Throughput parameter are very poor as compare with PHY data rate, even data rate goes infinite high. After certain PHY data rate, throughput are almost independent of data rate when data packets are fixed size. This is only due to large amount overhead adding with every data packets. So overhead reduction is the best solution to enhance the throughput for future communications. In this paper, I discussed two important overhead reduction mechanisms, w hich sufficiently improve the throughput performance. One is frame aggregation and another is block acknowledgement scheme. In performance analysis graph of both schemes, shows that the throughput performance are below 100 Mbps. But industries are seeking higher data rate for multimedia applications. i.e more than 100 Mbps. So it is easy make a comment that the above two important components are not sufficient enough for IEEE 802.11n individually. To fulfil the throughput performance of IEEE 802.11n, I proposed a new MAC mechanism. The new Frame Aggregation and Block Acknowledgement (FABA) MAC mechanism is the collecting of some features of above two important components, which improve the throughput performance as our desire. In this research work I also simulate the FABA scheme, which shows the throughput performance more than 160 Mbps when the number of burst within TXOP duration is 5 and PHY data rate 600 Mbps.

Frame Aggregation and Concatenation Schemes for IEEE EDCF 802.11e: A First Order MAC and PHY Cross-Layer Model to Estimate the Throughput

Abstract: We develop a first order analytical medium access control (MAC) and physical (PHY) cross-layer model to estimate the saturation net throughput of IEEE 802.11e wireless local area networks (WLANs) with MAC enhancements schemes. The MAC improvements analyzed consist of minor modifications of the IEEE 802.11e enhanced distributed coordination function (EDCF) MAC protocol in order to support frame aggregation and concatenation.

Improving QoS of Video Transmitted Over 802.11 WLANs Using Frame Aggregation

Abstract: Wireless local area networks (WLANs) are widely used at home and enterprise as a connection to the Internet. In order to meet the quality service (QoS) demands for the increasing number of multimedia applications on these home and enterprise networks new features are included in the 802.11n draft. One of these features is frame aggregation at the medium access control (MAC) layer which adds the ability to the base station to serve two or more users in one frame simultaneously. In this paper we investigate how the quality of H.264 video sequences are affected when we aggregate a group of packets for one or multiple users. We show that the frame aggregation improves the video quality and the packet delay.

Method and apparatus for forwarding packets

Abstract: A method for forwarding packets first checks a forwarding table of a bridge to find whether the destination information for a packet is included in the forwarding table. If the information is found, this packet is forwarded to the destination through a physical layer directly without passing through the bridge. This method improves the efficiency of the frame aggregation of an AP (Access Point) and enhances the throughput in a WLAN (Wireless Local Area Network).

Performance Analysis of IEEE 802.11n System adapting Frame Aggregation Methods

Abstract: IEEE 802.11n is an ongoing next-generation WLAN(Wireless Local Area Network) standard that supports a very high-speed connection with more than 100Mb/s data throughput measured at the MAC(Medium Access Control) layer. Study trends of IEEE 802.11n show two aspects, enhanced data throughput using aggregation among packets in MAC layer, and better data rates adapting MIMO(Multiple-Input Multiple-Output) in PHY(Physical) layer. But, the former doesn`t consider wireless channel and the latter doesn`t consider aggregation among packets for reality. Therefore, this paper analyzes data throughput for IEEE 802.11n considering MAC and PHY connection. A-MPDU(Aggregation-MAC Protocol Data Unit) and A-MSDU(Aggregation-MAC Service Unit) is adapted considering multi-service in MAC layer, WLAN MIMO TGn channel using SVD(Singular Value Decomposition) is adapted considering MIMO and wireless channel in PHY layer. Consequently, Simulation results shows throughput between A-MPDU and A-MSDU. Also, We use Ns-2(Network simulator-2) for reality.

Frame aggregation-based power-saving scheduling algorithm for broadband wireless networks

Abstract: The limitation on the battery lifetime has been a critical issue for the advancement of mobile computing. Different types of power-saving techniques have been proposed in various fields. In order to provide feasible energy-conserving mechanisms for the mobile subscriber stations (MSSs), three power-saving types have been proposed for the IEEE 802.16e broadband wireless networks. However, these power-saving types are primarily targeting for the cases with a single connection between the base station (BS) and the MSS. With the existence of multiple connections, the power efficiency obtained by adopting the conventional scheduling algorithm can be severely degraded. In this paper, with the consideration of the multiple connections and their quality-of-service (QoS) constraints, a frame aggregation-based power-saving scheduling (FAPS) algorithm is proposed to enhance the power efficiency by aggregating multiple underutilized frames into fully-utilized ones. The performance evaluation is conducted and compared via the simulations. Simulation results show that the sleep frame ratio (i.e., a power efficiency metric) of the proposed FAPS algorithm outperforms the baseline protocols with tolerable delay.

Scheduling for next generation WLANs: filling the gap between offered and observed data rates

Abstract: Summary In wireless networks, opportunistic scheduling is used to increase system throughput by exploiting multi-user diversity. Although recent advances have increased physical layer data rates supported in wireless local area networks (WLANs), actual throughput realized are significantly lower due to overhead. Accordingly, the frame aggregation concept is used in next generation WLANs to improve efficiency. However, with frame aggregation, traditional opportunistic schemes are no longer optimal. In this paper, we propose schedulers that take queue and channel conditions into account jointly, to maximize throughput observed at the users for next generation WLANs. We also extend this work to design two schedulers that perform block scheduling for maximizing network throughput over multiple transmission sequences. For these schedulers, which make decisions over long time durations, we model the system using queueing theory and determine users’ temporal access proportions according to this model. Through detailed simulations, we show that all our proposed algorithms offer significant throughput improvement, better fairness, and much lower delay compared with traditional opportunistic schedulers, facilitating the practical use of the evolving standard for next generation wireless networks. Copyright © 2009 John Wiley & Sons, Ltd.

Performance Analysis of Two-Level Frame Aggregation in IEEE 802.11n

Abstract: Frame Aggregation is a promissing technology for improving MAC throughput in IEEE 802.11n. In IEEE 802.11n, two frame aggregation schemes, Aggregate MSDU (A-MSDU) and Aggregation MPDU (A-MPDU), are defined. In this paper, we analyze the performance the two-level frame aggregation scheme where A-MSDU and A-MPDU are combined. We develop the analytical model for the two-level frame aggregation scheme and present numerical results on the effect of bit error rate, aggregation size, and the number of nodes.

Robust coding in multi-hop networks

Abstract: The invention generates the data unit to a method and apparatus utilizing a multi-receiver (MR) to the frame aggregation to require an acknowledgment of a single packet data unit by the group of which they are intended receiver. In addition to the main destination of the packet, the neighbors of a destination node of a multi-hop topology information may be used to obtain the intended receiver of the acknowledgment packet transmission.