Enhancements in MAC Layer

There are three notable MAC layer enhancements introduced by the amendment:

Frame Aggregation

This method consists of combining multiple data frames into an aggregate frame. New 802.11n devices have the option of bundling frames together for transmission. Frame aggregation reduces MAC layer overhead caused by inter-frame spacing and preamble. It avoids the time wasted due to backoff and collisions of 802.11 MAC protocol.

There are two different forms of aggregation supported by 802.11n:

MAC Service Data Unit Aggregation (A-MSDU)

MSDU comprises of an LLC header (Logical Link Control), IP header and the IP packet payload. This technique combines multiple MSDUs with the same 802.11 QoS into a single MAC frame (MPDU).

MAC Protocol Data Unit Aggregation (A-MPDU)

This aggregation occurs later, after MAC headers are added to each MSDU. It groups multiple MPDUs frames as a single frame. Unlike A-MSDU, all MSDUs need not be destined to the same MAC address.

Block Acknowledgement

In the traditional 802.11 MAC protocol, every piece of data sent to a specific address gets an immediate acknowledgement from the receiver.

To reduce the overhead involved, the 802.11n amendment introduced the Block Acknowledgment (BACK) technique. Instead of acknowledging each piece of data individually, it groups several ACKs together into one response. This way, one BACK frame can confirm the receipt of multiple MPDUs.

Reverse Direction

Reverse direction is a tool that makes exchanging data in wireless networks faster and more efficient, especially when data needs to move back and forth, like in Voice over IP or TCP traffic because of backward TCPAck flow.

Here’s how it works:

• Normally, devices take turns sending and receiving data, which can slow things down.
• With reverse direction, whenever there is an opportunity to send data (called a TXOP), the device that’s usually just receiving can also send its data back at the same time.
• Imagine a two-way street instead of a one-way lane: it lets traffic flow both ways, making the process more efficient and quicker.

IEEE 802.11 Architecture, more popularly known as WiFi is widely used to provide anywhere-anytime networking access. New enhancements keep getting introduced as global connectivity demands evolution and improvement. The IEEE 802.11 amendment was introduced to enhance the traditional 802.11 for higher throughput and improve wireless technologies.

The primary objective of this amendment is to bolster the MAC (Medium Access Control) layer’s Quality of Service (QoS). By refining QoS, the IEEE aspires to cater more efficiently to the escalating demands for bandwidth. This is increasingly crucial in an era where high-definition streaming, online gaming, remote work, and the proliferation of Internet of Things (IoT) devices are driving unprecedented levels of data traffic.

In this article, we will delve deeper into the enhancements introduced in this amendment. This will encompass improvements in both the physical layer communications design and the MAC layer. We will discuss how these enhancements not only facilitate higher throughput but also offer a more resilient and efficient wireless communication system.