Hello, everyone!
Today, I would like to continue to share a post on the novel features an open challenges of the IEEE 802.11ax amendment.
Medium Access Control:
In order to keep backward compatibility with previous IEEE 802.11 amendments, besides a common PHY frame preamble, compatible MAC protocols are required. This means that it is likely that EDCA will be kept as the main channel access technique in the IEEE 802.11ax amendment.
Therefore, the most relevant open challenges are related to EDCA extensions to support a large number of STAs, improve traffic differentiation capabilities, improve the energy consumption and provide mechanisms to fairly co-exist with neighboring wireless networks.
Setting a bigger backoff contention window than the amount used in the IEEE 802.11ac amendment for all ACs is a straightforward approach for supporting a large number of contenders with a low collision probability. If the time necessary to execute the CCA, switch between transmission and receiving modes, and the packet processing delay are reduced, the slot duration can be reduced to alleviate the excess backoff length when employing bigger backoff contention windows.
To improve the underlying CSMA/CA process in EDCA, another way is to propose decentralized collision-free MAC protocols. These MAC protocols can provide collision-free schedules, increasing network efficiency by reducing collisions while maintaining backward compatibility with the standard EDCA application.
A comparative review of various major protocols, including CSMA/ECA, is included in the benefits of decentralized collision-free MAC protocols.
CSMA/ECA is particularly essential because it is perfectly interoperable with EDCA and can adjust to a large number of competitors in real time. In any event, IEEE 802.11ax WLANs can depend on the IEEE 802.11aa amendment, which includes intra-AC traffic diversification and groupcast communication techniques, among other characteristics, to strengthen EDCA traffic differentiation capabilities.
IEEE 802.11ax is expected to preserve the same channel widths as the IEEE 802.11ac amendment, which are 20, 40, 80, and 160 MHz. IEEE 802.11ax, on the other hand, is intended to expand the usage of channel bonding to increase spectrum use and coexistence across neighboring WLANs.
Dynamic channel bonding, for example, has been demonstrated to deliver significant throughput increases in dense environments when compared to the static technique while limiting unfavorable inter-WLAN interactions. Additional mechanisms, such as the use of advanced algorithms to select the primary channel's position, or even considering numerous channels to expand the proportion of bonded channel combinations that can be used for transmission, are also necessary to continuously exploit the potentials of using wider channels.
In IEEE 802.11ax, the MAC layer may collaborate with the PHY layer to establish an effective Hybrid ARQ approach that may retransmit small packets with only progressive redundancy bits. By lowering the amount of transmissions in a bi - directional data exchange, spontaneous piggybacking of data packets in ACKs and vice versa may further increase the effectiveness of IEEE 802.11ax WLANs.
Furthermore, if shorter STAs identifiers are used instead of MAC addresses, and extraneous fields for the particular transmission are not included, the packet headers can be shortened.
