Hello, everyone!
Today, I would like to share a post on some of the novel features of IEEE 802.11ac amendment in WLAN.
IEEE 802.11ac promises to provide consumers with a throughput of around 1 Gbps, which is roughly four times faster than IEEE 802.11n. IEEE 802.11ac enables greater channel widths (up to 160 MHz) than IEEE 802.11n, as well as a new modulation technique, 256-QAM modulation, and downlink multiuser MIMO (DL-MU-MIMO).
The following are the most important new features incorporated in IEEE 802.11ac:
Channel Bonding.
IEEE 802.11ac supports channel bandwidths of 20, 40, 80 (required), and 160 MHz (optional). Bonding (i.e., grouping) a series of sequential 20 MHz channels produces channel bandwidths greater than 20 MHz, with the goal of or higher transmission rates.
In IEEE 802.11ac, two enhancements to the basic DCF (Distributed Coordination Function) access technique have been suggested to provide channel bonding:
(i) The Static Bandwidth Channel Access Protocol (SBCA), which transmits over the same group of 20 MHz channels every time and requires that all sub-channels be idle before transmitting a packet.
(ii) The Dynamic Bandwidth Channel Access (DBCA) technique, which is capable of dynamically adapting the channel width to the current spectrum availability. As expected, DBCA performs substantially better than SBCA in congested circumstances due to its versatility.
The IEEE 802.11ac amendment includes additional RTS/CTS frames to communicate the maximum channel width that can be used at both the transmitter and the receiver in order to preclude hidden terminals functioning in any of the 20MHz bonded channels.
The transmitter will use the CTS if it has a narrower channel width than the RTS. When the RTS and CTS frames are transmitted, they are duplicated over all of the 20 MHz sub-channels used, just like the ACK frames.
It's worth noting that this improved RTS/CTS technique is also required to allow IEEE 802.11ac APs and other neighboring legacy APs to coexist, as the latter may transmit at various times on separate sub-channels.
The operation and performance of channel bonding in WLANs is thoroughly examined, demonstrating the potential for new interactions between surrounding WLANs and their impact on each one's throughput.
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