Frame aggregation

About: Frame aggregation is a research topic. Over the lifetime, 487 publications have been published within this topic receiving 14295 citations.

Evaluation of Frame Aggregation in Giga-bit WLANs

Abstract: Recently, the very high throughput (VHT) IEEE 802.11ac amendment has emerged as the fifth generation of wireless local area networks (WLANs). Enhancements to the physical and MAC layers have been defined which elevate the data rate to 6.933 Gbps. The 802.11ac amendment extends the frame size from 8000 bytes to approximately 11454 bytes, which increases the ability to aggregate frames from upper layers. Moreover, frame aggregation is employed in 802.11ac which states that all MAC protocol data units (MPDU) must use the aggregate MPDU (A-MPDU) format. In this paper we evaluate the techniques of frame aggregation adopted by IEEE 802.11ac. In particular, we study the impact of frame aggregation on the system throughput. Simulation results show that frame aggregation is a powerful mechanism in terms of increasing system throughput through reducing overhead in MAC layer.

Overcoming MAC Overhead Using Packet-Size Dependent Channel Widths

Abstract: : In this paper, we propose to reduce the MAC overheads in random access protocols by partitioning the channel spectrum used into a narrow channel and a wide channel. The narrow channel is used for transmitting the short packets (approximately 100 bytes long) and the wide channel is used for transmitting the longer packets. We intend to use multiple radios, one each for the different channel partitions. Narrow width channels have a reduced capacity, which lowers the maximum transmission rate achievable on these channels. As a result the channel wastage due to the rate-independent MAC overhead can be reduced. We propose a protocol called WiSP (channel Width Selection based on Packet size) to estimate the appropriate channel widths depending on the relative traffic load involving short and long packets in the network. We evaluate our protocol using extensive simulations and demonstrate its effectiveness in achieving higher throughputs. We propose our algorithm to complement frame aggregation (which is an existing approach for minimizing MAC overheads). We show that there are scenarios during which the frame aggregation can perform poorly, and show that our proposed algorithm can provide a good performance even in those situations.

Two-Level Frame Aggregation Scheme Under Unreliable Channel Conditions for IEEE 802.11n WLANs: A Survey

Abstract: Frame Aggregation schemes defined by IEEE 802.11n is the combination of the Aggregate MAC Service Data Unit (A-MSDU) and MAC Protocol Data Unit (A- MPDU). The units are aimed at maximizing Wireless Local Area Networks (WLANs) efficiency at Media Access Control (MAC) level, via the sharing of headers and timing overheads. Moreover, the combination of A-MSDU and A-MPDU is known as Two-level frame aggregation. In spite of their abilities in improving the throughput of MAC Layer, the scheme is still limited by other overheads as a result of aggregation which affects the system performance. Block Acknowledgement (Block ACK) and Frame aggregation were introduced in order to minimize MAC Layer overheads. Still, there are some parameters that affect the aggregation performance, such as aggregate length, sub frame size and channel condition overheads. A-MPDU in other hand minimizes the effect of error condition through sub frame transmission. Therefore, A- MPDU aggregation performances, its limitations, and its promising performances motivated this survey to focus on enhancing Aggregation Mac Protocol Data Unit (eA-MPDU) performance by minimizing the headers overheads of the Two-Level Frame Aggregation Scheme, for the reduction of the channel noise, which by its role will increase the Signal Noise Ratio (SNR) and improve the throughput.

Cross-layer queuing control in mobile router for power saving

Abstract: To extend the lifetime for mobile routers, it is necessary to introduce a power saving function A mobile router has a wide area network (WAN) interface and a local area network (LAN) interface Of the two interfaces, the LAN interface, which is operating as a wireless LAN (WLAN) access point (AP), does not have a power saving function in the IEEE 80211 standard In the conventional method, the AP enters the sleep state to save consumed power only when the Media Access Control (MAC) queue is empty To reduce consumed power further, the AP has to actively enter the sleep state by creating an empty queue in the MAC layer Therefore, this paper proposes a queuing control, PSAP/QC, between the Layer 3 and the MAC queue in a mobile router The purpose is to create the opportunity of an empty MAC queue, assuming best-effort communication By controlling dequeuing from the Layer 3 queue adequately, the MAC queue is emptied, and frames stored in the Layer 3 are aggregated That is, the likelihood of the sleep state is increased by aggregating frames into the Layer 3 queue The contribution of this paper is the cross-layer queuing control based on the frame arrival rate into the Layer 3 queue, in addition to the small amount of unnecessary delay caused by this control Numerical analysis and simulation results revealed that the PSAP/QC reduces power consumption compared to the conventional method in a part of the offered traffic, and is low failure rate of dequeuing for frame aggregation