# An Analytical Model for CBAP Allocations in IEEE 802.11ad

## TL;DR

This paper presents a Markov Chain model for CBAPs in IEEE 802.11ad, analyzing their performance and interference to optimize transmission scheduling in millimeter wave WiFi networks.

## Contribution

It introduces a novel Markov Chain model that accounts for directional communication challenges and interference, aiding in efficient resource allocation.

## Key findings

- Analytical expressions for throughput, delay, and packet drops.
- Impact assessment of transmission parameters on performance.
- Guidelines for designing transmission schedulers based on analysis.

## Abstract

The IEEE 802.11ad standard extends WiFi operation to the millimeter wave frequencies, and introduces novel features concerning both the physical (PHY) and Medium Access Control (MAC) layers. However, while there are extensive research efforts to develop mechanisms for establishing and maintaining directional links for mmWave communications, fewer works deal with transmission scheduling and the hybrid MAC introduced by the standard. The hybrid MAC layer provides for two different kinds of resource allocations: Contention Based Access Periods (CBAPs) and contention free Service Periods (SPs). In this paper, we propose a Markov Chain model to represent CBAPs, which takes into account operation interruptions due to scheduled SPs and the deafness and hidden node problems that directional communication exacerbates. We also propose a mathematical analysis to assess interference among stations. We derive analytical expressions to assess the impact of various transmission parameters and of the Data Transmission Interval configuration on some key performance metrics such as throughput, delay and packet dropping rate. This information may be used to efficiently design a transmission scheduler that allocates contention-based and contention-free periods based on the application requirements.