Showing papers on "Frame aggregation published in 2004"

Throughput enhancement of IEEE 802.11 WLAN via frame aggregation

Abstract: The popular IEEE 802.11 WLAN is known to achieve relatively small throughput performance compared to the underlying physical layer (PHY) transmission rate. This is due mainly to the large overheads composed of medium access control (MAC) header, PHY preamble/header, backoff time, acknowledgement (ACK) transmission, and some inter-frame spaces (IFSs). Since these overheads are added to each frame transmission, the throughput degradation is relatively high with small-size frames. In this paper, we present a frame aggregation (FA) scheme, which can improve the throughput performance. By aggregating small-size frames into a large frame, we can reduce these overheads relatively. We propose a simple method to implement the FA into the real testbed using off-the-shelf products via device driver modifications. The performance of the FA is evaluated by both numerical analysis and actual measurements from the real testbed. According to the measurement results, the FA can improve the throughput performance by 2 to 3 Mbps, when multiple frames are aggregated.

Frame aggregation in wireless communications networks

Abstract: A method aggregates frames to be transmitted over a channel in a wireless network into a single frame. Multiple MSDU frames having identical destination addresses and identical traffic classes, received in the media access control layer from the logical link layer in a transmitting station are aggregated into a single aggregate MPDU frame, which can be transmitted on the channel to a receiving station. In addition, aggregate MSDU frames with different destination addresses and different traffic classes received from the media access control layer can be further aggregated into a single aggregate PPDU frame before transmission.

Frame aggregation format

Abstract: A frame format for frame aggregation into a physical-layer packet employs an aggregated frame descriptor appended to one or more sub-frames. Each sub-frame comprises a header comprising logical-layer and sub-frame protocol information, optional verification information to verify the sub-frame data, and aggregated user data. The aggregated frame descriptor includes information identifying the packet as conforming to an aggregated frame format, and sub-frame descriptors identifying at least one of a position, a length, and a data rate of a corresponding sub-frame. The aggregated frame is then formed into a physical layer packet for transmission through a medium.

Aggregated frame, generated above, within or below a MAC layer or in a physical layer

Abstract: A packet network employs frame aggregation to reduce the number of physical-layer frames employed to transfer a given amount of user data. A packet network might employ physical (PHY) and medium access control (MAC) layers of a wireless local area network (WLAN) operating in accordance with one or more IEEE 802.11 standards. Frame aggregation combines several separate, higher-layer frames with user data into one PHY-layer frame, thus increasing the amount of user data per PHY-layer frame transmitted. Frame aggregation improves the efficiency by reducing both PHY-layer overhead and MAC-layer overhead.

I-wlan: intelligent wireless local area networking

Abstract: Future wireless networks require intelligent components that can automate, scale and manage the network in order to handle the demand for ubiquitous access. In this dissertation, we first evaluate existing problems, and then we introduce components that improve the performance of existing systems. We introduce a new Markov model for Distributed Coordination of Function of IEEE 802.11 with which we formulate the throughput and delay for saturated and non-saturated traffic. We introduce a novel formulation for individual throughput when stations operate with mixed data rates. We introduce an admission control mechanism to maintain the highest achievable throughput by controlling the access. After that we use our throughput formulation to obtain the performance of an indoor network. We introduce a packet size adjustment scheme with respect to data rate so that a slow station sends small packets to prevent throttling of the network. We introduce a frame aggregation scheme for wireless voice over IP We introduce a fast and fair sub-optimal algorithm to allocate sub-carriers and bits adaptively in an OFDMA system for point-to-multipoint communication, and investigate MAC performance of the wireless LAN with adaptive antennas for point-to-point communication. We find that ignoring the consecutive transmission probability in the previous Markov models is incomplete. Consequently, our model which takes this into account is closer to the standard. We find that the individual throughput of a station is the same for fast and slow stations, and slow stations throttle the performance, since the CSMA/CA scheme gives equal access but not equal time of channel usage. Our packet size optimization scheme increases the throughput of the total network and the fast station but not that of the slow station. The admission control mechanism can tune the network from random access to controlled access. Network management can monitor the whole network and do real-time adjustments for optimum performance. Our frame aggregation scheme for wireless voice over IP reduces the number of access by concatenating the packets in the accesses point in order to be sent at one time. The results of our resource allocation scheme for adaptive sub-carrier and bit allocation is appealing and can be close to optimal. We find that a directional antenna increases the performance significantly and can provide enhancements for wireless LANs.

Aggregate frame with aggregate frame descriptor including a header indicating the type of frame, the number of sub-frames, and sub-frame descriptors each including the address of the receiving device for the corresponding sub-frame

Abstract: A frame format for frame aggregation into a physical-layer packet employs an aggregated frame descriptor (1310) appended to one or more sub-frames (1311 (1) - (N)). Each sub-frame comprises a header comprising logical-layer and sub-frame protocol information (1314 (N)), optional verification information to verify the sub-frame data (1316 (N)), and aggregated user data (1315 (N)). The aggregated frame descriptor includes information identifying the packet as conforming to an aggregated frame format, and sub-frame descriptors (1320 (1) - (N)) identifying at least one of a position (1337 (N)), a length (1338 (N)), and a data rate of a corresponding sub-frame. The aggregated frame is then formed into a physical layer packet for transmission through a medium.