Introduction:

Some basic knowledge on networks would help the readers to understand the details of the project. Here we deal mainly with the IEEE 802.11b wireless network protocol.

The International Standards Organization (ISO) developed the OSI (Open Systems Interconnection) model. It divides network communication into seven layers. Each layer has specific functionality and passes the data onto the next layer. First, application layer (layer 7) supports software application such as e-mail, file transfers and other computer application. Most probably we can ignore the function of layers 5 and 6. Second, (layer 4) the transport layer where the port number of the source and destination application is attached to the message as a header. It ensures complete data transfer. Third, (layer 3) the network layer provides the source and destination IP address, error handling and packet sequencing. Fourth, (layer 2) data link or link layer, data packets are encoded and decoded into bits. It has two sub layers. Media Access Control (MAC) gain access to the channel and permission to transmit a packet. Logical Link Control (LLC) controls frame synchronization, flow controls and error checking. Fifth, (layer 1) the physical layer, the information is physically transmitted as an electrical impulse, light or radio signal. IEEE 802.11b protocol uses the 2.4 GHz Radio Signal. To avoid overlap between the channels, 2.4 GHz spectrum divided into 5 Megahertz apart. So mostly 1, 6, 11 channels were used for the research. The study of MAC layer properties provides information about the channel occupancy in the wireless medium.
It is crucial to monitor and study an operational congested network. To achieve this goal of understanding congested networks, UCSB Researchers performed experiments and monitored the wireless network at the IETF meeting (Internet Engineering Task Force)[1] They used laptops (wireless network sniffers) and adopted the method “Vicinity Sniffing”. Their strategy to understand (1) what is congestion in the wireless network? (2)How do we analyze the congestion in the wireless network? (3)How does it affect the link-layer behavior? There are no specific answers to these questions. It could be hardware and software limitations or hidden terminals. They performed the monitoring in an uncontrolled environment. Monitoring link layer information is limited, because it cannot capture all data packets.
The research paper mainly focused on the plenary session only. It satisfied the network conditions on both congested and large scale usage. The main observation was smaller frames are received more and use of higher rates reduces channel occupancy. Also the research estimated congestion in the large scale wireless networks. To estimate congestion, researchers analyzed throughput of the network. Most importantly, they could analyze the access point activity by recorded data set. Uncaptured frames were computed based on the number of data frames sent and received. By understanding and analyzing the properties of the MAC layer to reduce congestion or balance them across devices by “Channel Utilization”.
What UCSB researcher found finally
• Multirate adaption implementation is not useful in the range of 2Mbps & 5.5Mbps
• RTS (request to send), CTS (clear to send) prevents nodes from gaining access to a heavy congested network in detrimental to network performance.