I know I said I wasn’t going to blog my notes just yet until after I finished the exam. But it’s a funny thing.. studying is. I used to complain that I need to get rid of my distractions so I can study better. I have had a lot of things in my mind the past few days. But last night, after watching the Lakers beat the Celtics I got to study a little bit and took some notes. The weird thing about it is that, ironically, studying became a huge distraction from my own thoughts.  The game was a huge distraction too. I just needed a little distraction. And studying was the ticket.

I read halfway through the wireless section of the BCMSN Exam Guide. I went back to re-read and took some notes on key points and definitions until I got too tired and lazy to continue.  Nothing new or revealing on the following notes. They can be helpful for review later. It’s also not complete or comprehensive.

• 802.11 uses CSMA/CA vs. 802.3 which uses CSMA/CD – Avoidance vs. Detection.
• Distributed Coordination Function (DCF) – wireless stations wait a certain duration value before transmitting frames.
• Service Set – group of wireless devices
• Service Set Identifier (SSID) – A string included in every frame set; the devices must share a common SSID.
• Independent Basic Service Set (IBSS) – ad hoc network; where 2 or more wireless clients directly communicate with each other with no other means of network connectivity.
• Basic Service Set (BSS) – one access point
  • Match SSID
  • Compatible wireless data rate
  • Authentication

• Extended Service Set (ESS) – More than one APs placed at different geographic locations.
• Access Points can act:
  • As connection point for wireless clients, or
  • Act as a bridge to form a single wireless bridge from one LAN to another over a long distance – AP-to-AP or line of sight links.
• An AP is in charge of mapping a VLAN to an SSID.
  • When an AP uses multiple SSIDs, it is in effect trunking VLANs over the air to end users.
  • Example: VLAN 10 mapped to SSID “Marketing” and VLAN 20 mapped to SSID “Engineering”
• Cell – an AP’s coverage area.
• Reducing the transmit power on an AP reduces the cell size -  causing only clients close by to associate with it. That means less clients hogging the bandwidth. The others can associate with another AP closer to them.
• Microcells – when cell sizes are reduced
• Picocells – cell sizes are minimized even more
• Frequency – oscillating signal based around a constant.
  • Radio Frequency (RF)
• Band – broad range of frequencies used for similar funcations
  • AM Radio band consists of the frequency range 550 MHz through 1720 MHz.
  • Wireless can be in 2.4 GHz band or 5GHz band.
• Carrier Signal – the signal transmitted by a wireless station.
  • No audio, video, or data is present in the carrier itself.
• Modulate/Demodulate – in order to transmit information, the transmitter must modulate the carrier signal by inserting or encoding the information in a unique fashion. Receiving devices demodulates the signal.
• Channel – a fixed frequency, that varies within a certain range, which a transmitter and receiver expects the carrier to appear on