Conference Paper

Performance analysis of A-MPDU and A-MSDU aggregation in IEEE 802.11n

Intel Corp., Haifa
DOI: 10.1109/SARNOF.2007.4567389 Conference: Sarnoff Symposium, 2007 IEEE
Source: IEEE Xplore

ABSTRACT With recent improvements in physical layer (PHY) techniques, the achievable capacity for wireless LANs (WLANs) has grown significantly. However, the overhead of IEEE 802.11 MAC layer has limited the actual throughput of a WLAN. A-MPDU aggregation suggested in IEEE 802.11n draft is a key enhancement reducing the protocol timing overheads that enables aggregation of several MAC-level protocol data units (MPDUs) into a single PHY protocol data unit (PPDU). Another aggregation scheme proposed in IEEE 802.11n is A-MSDU aggregation, which allows several MAC-level service data units (MSDUs) to be aggregated into a single MPDU. In this work we present a novel analytic model for estimating the performance of a 802.11n high throughput wireless link between a station and an Access Point (AP). We consider a 2 times 2 MIMO system and investigate how the MAC goodput under TCP and UDP traffic is affected by the aggregation size, packet error rate and PHY settings. Our results demonstrate that for UDP traffic, A-MPDU aggregation allows to achieve a high channel utilization of 95% in the ideal case while without aggregation the channel utilization is limited by just 33%. We also show that A-MPDU aggregation outperforms A-MSDU aggregation, whose performance considerably degrades for high packet error rates and high PHY rates.

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    • "Several studies have investigated the effect of A-MPDU and/or A-MSDU frame sizes on the achievable throughput and their optimal sizes to improve throughput [6] [7] [8] [9]. In addition, a hybrid frame aggregation scheme known as http://dx.doi.org/10.1016/j.comnet.2014.08.006 1389-1286/Ó 2014 Elsevier B.V. All rights reserved. "
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    ABSTRACT: The increase in physical (PHY) layer transmission rates in IEEE WLAN does not necessarily give the corresponding increase of MAC layer throughput because of MAC overhead such as PHY headers and contention time. To improve MAC layer efficiency, we propose the Transmission Order Deducing MAC (TOD-MAC) protocol, which controls packet length in such a way that the transmission duration is adjusted to implicitly provide necessary information for a node to determine its transmission order among all the nodes in a network. Each node transmits frames of different duration, and thus the other nodes can determine the time when they can transmit, which has the same effect as announcing the transmission order, without using a control message. Each node transmits a frame in a round robin manner, which minimizes the idle time between two consecutive transmissions without collisions, and significantly improves the MAC efficiency in very high speed CSMA/CA wireless networks. Extensive simulation results indicate that TOD-MAC achieves high throughput performance, short/long-term air-time fairness in multi-rate networks and excellent transient behavior in dynamic environments.
    Computer Networks 11/2014; 73:302–318. DOI:10.1016/j.comnet.2014.08.006 · 1.28 Impact Factor
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    • "[10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] the Throughput and Delay performance Figure 4: The generation and transmission of A-MSDU and A-MPDU frames in Two-level aggregation of the A-MSDU, A-MPDU and Two-level aggregation schemes is investigated. Several papers assume an error-free channel with-no collisions, several papers assume an error-prone channel and some papers also assume collisions. "
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    ABSTRACT: We compare between the Throughput performance of IEEE 802.11n and IEEE 802.11ac under the same PHY conditions and in the three aggregation schemes that are possible in the MAC layer of the two protocols. We find that for an error-free channel 802.11ac outperforms 802.11n due to its larger frame sizes, except for the case where there is a limit on the number of aggregated packets. In an error-prone channel the bit error rate sometimes determines the optimal frame sizes. Together with the limit on the number of aggregated packets, these two factors limit the advantage of 802.11ac.
    Physical Communication 09/2014; DOI:10.1016/j.phycom.2014.01.007
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    • "The authors conclude that the enhanced MAC and physical layer features of IEEE 802.11n can significantly enhance capacity of VoIP. In [16], the authors study frame aggregation mechanism and show that upto 95% channel utilization can be increased for UDP traffic by using frame aggregation. Their study shows that combining multiple physical layer data units is more effective than combining multiple MAC layer data units because of physical bit error rate. "
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    ABSTRACT: Internet Protocol Television (IPTV) and Voice over Internet Protocol (VoIP) have gained unprecedented growth rates in the past few years. Data rate and high coverage area of IEEE 802.11n motivate the concept of combined IPTV and VoIP over IEEE 802.11n. Transmission of combined IPTV and VoIP over a wireless network is a challenging task. In this paper, we deal with the capacity evaluation of combined IPTV and VoIP over IEEE 802.11n. We evaluate the use of Datagram Congestion Control Protocol (DCCP) at transport layer of IPTV and VoIP. Our study shows that DCCP can enhance capacity of IPTV by 25%. Our study confirms that performance of DCCP deteriorates severely in presence of any other UDP flow because of congestion-less mechanism of UDP. Our fairness analysis with TCP traffic shows that IPTV and VoIP using DCCP provides fair share in bandwidth to TCP with 19% increase in combined capacity. We study the effect of IEEE 802.11n parameters and obtain optimal values. We show the optimal values and trends of Access Point (AP) parameters including Queue size, Transmission Opportunity, Aggregation and Block ACK etc. Our study shows that nearly 9 more VoIP users are supported with a queue size of 70 packets and transmission opportunity of 9. Our study concludes that selection of DCCP and optimized parameters over IEEE 802.11n can enhance the capacity of IPTV and VoIP by atleast 25% and 19% respectively as compared to the use of UDP.
    38th IEEE Conference on Local Computer Networks (LCN), Sydney, Australia; 08/2013
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