The channel bonding technique proposed in the IEEE 802.11ac draft makes it possible to multiply the physical layer data rate of the network. Unfortunately, the medium access control (MAC) protocol in 802.11ac that allocates the entire extended bandwidth to a single user at a time is very inefficient if the transmitted data frames are not sufficiently long. A partial bonding MAC (pbMAC) protocol is proposed that allocates only a part of the available bandwidth to a single user at a time. The simulation results show that the pbMAC gives a better utilisation of extended bandwidth than the MAC protocol in 802.11ac. Introduction:The channel bonding technique is one of the enhancements proposed in the IEEE 802.11ac draft [1] for increasing the physical layer (PHY) data rate of the wireless local area network (WLAN). The 40, 80 and, optionally, 160 MHz width channels are obtained by bonding 20 MHz channels. However, it is necessary to increase the length of the data frames transmitted in the extended bandwidth in order to obtain an increase in throughput proportional to the increase in the PHY data rate. The maximum length of an aggregate medium access control (MAC) protocol data unit (A-MPDU) is then increased from 65 kB in 802.11n to 1 MB in 802.11ac. At the same time, a significant part of WLAN traffic is generated by real-time applications (e.g. VoIP or video conference) that do not accept long delay caused by the frame aggregation technique, or by client-server applications, such as web browsing (HTTP), in which short messages (requests/responses) are often exchanged between the client and the server. For short data frames, the 802.11ac uses the extended bandwidth very inefficiently. In this Letter, we present a partial bonding MAC (pbMAC) protocol that allows the WLAN to transfer short data frames with a greater efficiency than the 802.11ac network.

Efficient utilization of the IEEE 802.11ac 80 and 160 MHz channels has been considered recently. In this paper it is shown, how the successive interference cancellation (SIC) method can be used in a 80 MHz receiver to reject the interfering legacy 802.11a/n OFDM signal occupying any secondary 20 MHz channel inside the 80 MHz 802.11ac channel. The method can be also utilized in 160 MHz receiver in a similar manner. The simulation shows, that if the conditions specified in the paper are fulfilled then no frequency guard band is necessary between the interfering OFDM signal and the desired OFDM signal occupying the remaining part of the 802.11ac 80 MHz channel. Both OFDM signals, the interfering and the desired one, are transmitted with no symbol timing synchronization. The simulation results show that two or three iterations are enough to completely reject the interfering OFDM signal by the 80 MHz (or 160 MHz) receiver.

This paper is to contribute a new dynamic channel access method for wireless local area networks. It allows a station accessing the 80 or 160 MHz channel to capture every idle non-primary 20 MHz channel along with the primary 20 MHz channel, whereas the number of channel configurations in which the station can transmit according to the 802.11ac standard is strictly limited. Simulation results shown in the paper prove the proposed access method to be superior to the method provided by the 802.11ac standard in terms of average network throughput. What is important for legacy reasons, the proposed method employs the conventional clear channel assessment function to determine which of the 20 MHz channels are idle and which are busy. The paper proposes a new receiver design that is able to reject the adjacent channel interference, arising as a result of the presence of the legacy 802.11a/n station signals inside the 80 or 160 MHz accessed channel.

The channel access method, defined in the IEEE 802.11ac draft, forces stations (STAs) to transmit data over the widest currently available channel supported by the basic service set (BSS). Unfortunately, the transmission in a wide channel is very inefficient if data frames are short. A channel width selection scheme (CWSS) is proposed which reduces the bandwidth used by the STA, if the transmitted data frame is not sufficiently long. Simulation results show that the CWSS allows a better bandwidth utilisation in an environment of overlapping 802.11ac BSSs. The CWSS is compatible with the channel access procedure defined in the IEEE 802.11ac.Introduction: Increasing the channel bandwidth is the simplest way to increase the physical layer (PHY) data rate. This technique is used in the IEEE 802.11ac [1], in which 40, 80 and, optionally, 160 MHz width channels are obtained by bonding 20 MHz channels. Fig. 1a shows 20 MHz channel pairings in the 80 MHz basic service set (BSS). The 40 MHz channel is formed by two adjacent 20 MHz channels, one of which is the primary 20 MHz channel and the other is the secondary 20 MHz channel. Similarly, the primary 40 MHz channel and the secondary 40 MHz channel together form the 80 MHz channel.

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