Nautilus IT Consulting (NITC) is a computer technology business that helps organ

Question

Nautilus IT Consulting (NITC) is a computer technology business that helps organizations with IT solutions. NITC has asked for your help. Castleview Medical Associates operates several physician offices, clinics, and free-standing surgical centers in a large region. Castleview wants to upgrade to IEEE 802.11n technology but is unsure if DCF, PCF, or HCF would be best for its operations.

Create a PowerPoint presentation of eight or more slides that covers a comparison of these three types of functions. Include the strengths and weaknesses of each. Because you will be addressing Castleview's IT staff this presentation should contain technical information.

After your presentation, Castleview's IT staff is still struggling with the best approach. Create a one-page memo that contains your choice and why they should explore this option

Explanation / Answer

Answer: See the details below:

Introduction: IEEE 802.11n refers to Wireless Networking standard. It is an extension of IEEE 802.11 standard that is a well established standard for Wireless Local Area Network (WLAN) aka WiFi. The basic objective of this standard is to increase data rates through the use of multiple anttenas. It uses technologies like MIMO (Multiple Input Multiple Output), OFDM (Orthoginal Frequency Division Multiplex). Its main features are as follows:

Media Access Types: Any wireless network consists of access points and stations. And, data needs to be transferred between access points and stations. For this purpose, IEEE 802.11 standards provides access method and access types. Originally 802.11 following access types:

However, new extensions of 802.11 also provide a new access type called Hybrid Coordination Funtion (HCF) that is nothing but a combination of DCF and PCF.

Details of these are given below:

Distributed Coordination Function (DCF): It is default access method method under 802.11. It should be mandatorily implemented. Actually it is the basis of CSMA/CA mechanism in wireless networking. DCF employs contention-based mechanism to determine who will transmit next on the wireless medium. It enables multiple stations to communicate with other without using a central control. DCF utilizes multiple checks and balances to try to minimize collisions in the medium.

Point Coordination Function (PCF): This method comes under optional category of the standard and has not been implemented by any vendor so far. So this method exists only in theory as of now. As per theory, it is possible for an access point to take control of the medium and poll the clients. PCF may allow a station to transmit frames after a shorter interval to gain priority over standard DCF.

In case of PCF, time on the medium is broken into two types: contention-free period (CFP), contention period. During contention free period, medium uses PCF, while during contention period, medium uses DCF.

Hybrid Coordination Function (HCF): This method combines the charavteristis of DCF and PCF both. It provides two new access variants:

Feature Value Maximum data rate 600 Mbps RF band 2/4/5 GHz Modulation CCK, DSSS, OFDM Spatial streams 1/2/3/4 nos. Width of channel 20/40 MHz

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