Yoriko Utsunomiya

Compressed Block Ack, an efficient selective repeat mechanism for IEEE802.11n

The standardization of IEEE802.11n which aims to achieve 100 Mbps at MAC-SAP (medium access control - service access point) is under work in IEEE802.11, wireless LAN standardization committee. The frame aggregation scheme in which MAC (medium access control) frames are aggregated into one PHY (physical) frame is proposed for IEEE802.11n, because it decreases MAC overhead. In this paper, we propose the compressed block ack mechanism as a selective repeat mechanism to be adapted to the frame aggregation scheme. We present simulation results to compare performance of the compressed block ack mechanism and the legacy block ack of IEEE802.11e and show that the proposed method improves the total throughput by 10% than the conventional method

A MAC Protocol for Coexistence between 20/40 MHz STAs for High Throughput WLAN

IEEE 802.11 is widely known as a standard of WLAN and has a number of amendments and supplements. The one now attracting a great deal of attention is IEEE 802.11n, which is aimed at achieving high throughput. To achieve high throughput, one of the main discussion points is the channel bundling method which extends the channel bandwidth from 20 MHz to 40 MHz. By doubling the channel bandwidth, the data rate can be increased. But a question how to cope with the legacy 20 MHz stations will arise. For this problem, we are proposing to control the 20 MHz and 40 MHz STAs by setting NAV to them in MAC layer. This paper explains our coexistence proposal for the system where transmission in both 20 MHz and 40 MHz channel bandwidths is enabled, and the performance is examined to confirm the effect of our coexistence proposal

A Simple and Efficient Selective Repeat Scheme for High Throughput WLAN, IEEE802.11n

The standardization of IEEE802.11n aims to achieve 100 Mbps at MAC-SAP (medium access control - service access point). The frame aggregation scheme in which MAC (medium access control) frames are aggregated into one PHY (physical) frame is proposed as the main MAC technique of IEEE802.11n, because it decreases MAC overhead. The block ack mechanism of IEEE802.11e is applied as a selective repeat method of the frame aggregation. In this paper, we propose the extended block ack mechanism as a selective repeat mechanism to be adapted to the frame aggregation scheme. We present the performance evaluation to compare the throughput of the extended block ack mechanism and the legacy block ack of IEEE802.11e and show that the average improvement is expected to be around 10% and the maximum improvement is about 39% compared with the conventional method.