A Master device (Access point /P2P GO device) also needs to contend for the medium as any regular 802.11 station connected to the BSS. There are instances when the Beacon transmission might be delayed due to a delay in obtaining channel access. The connected stations need to wait till a beacon is received by them […]
Beacons Explained
Before we discuss how a WLAN station associates to a network, it is important to understand how a beacon is transmitted and the important parameters that are a part of a beacon frame. This article provides an overview of the beacon mechanism in the 802.11 WLAN standard. 802.11 Beacons are broadcast transmissions. In WLAN Beacons […]
Associating to an Access point – Part 1
Association is the process by which a WLAN station device connects to an Access Point. The Association frame exchange for AP-Station connection which does not have any security enabled is the simplest association process and follows the below steps The WLAN station device sends out a probe-request to the Access Point On receipt of the […]
Some WLAN Network Topologies – BSS, IBSS, Mesh BSS and P2P
WLAN standard supports different Network Topologies. Infrastructure Network Topology Ad-hoc Network Topology Wireless Mesh Topology P2P Network Topology In addition to the above, WLAN is also employed in automotive communication and the Automotive Dedicated Short Range Communication topology will be discussed separately later Infrastructure Topology An Infrastructure topology is shown below. The area marked by […]
WLAN Standards
Some of the important WLAN standards are provided below The IEEE standards are defined by the 802.11 set of standards. Some of the mainline standards are provided below 802.11-1997 –> first 802.11 standard for 2.4 GHz operation 802.11b –> Defines extensions to 802.11-1997 standard in 2.4 GHz mode 802.11a –> Defines 5 GHz operation in […]
Introduction to WLAN – Part 3
WLAN networks employ CSMA/CA mechanism to gain access of the medium to transmit data packets. CSMA stands for Carrier Sense Multiple Access. All WLAN devices sense if the medium is idle. only if the medium is sensed to be idle, the 802.11 Station device can transmit the frame. The CA in CSMA/CA stands for Collision […]
Introduction to WLAN – part 2
WLAN or Wi-Fi primarily employs the following frequency bands for its operation – The 2.4 GHz band and The 5 GHz band. The 6 GHz band. The 2.4 GHz band channel centre frequencies are placed 5 MHz apart. The Channel width of each channel is 22 MHz. Since the channel centre frequencies are 5 MHz […]
Introduction to WLAN
A Wireless Local Area Network (WLAN) is a Local area network where-in the endpoint devices do not connect via wires (i.e. an Ethernet Connection) to a network. The user devices such as smart phones connect wirelessly. In most cases WLAN provides the end-point connectivity or provides a complete network in itself. WLAN uses the Industrial, Scientific […]