1. What is the typical application of the communication technology that you choose to study? Give some examples and pictures. What products use this technology?

Answer: Wireless LAN.

2. What is the frequency band allocated by FCC for this technology?

Answer: 5Ghz for 802.11a and 2.4GHz for 802.11g

3. Who is the standard body? Where can one find the documents of the standard?

Which part of the document is about physical layer?

Answer: IEEE, __http://www.ieee802.org/11/__

Page 3 of the IEEE document entitled

"Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)

specifications" talks about Physical layer.

4. Show/draw and explain system block diagrams that process information bits,

perform error control encoding, and modulation.

Answer:
__802.11a System Description__

Figure 1: 802.11a Transmitter block diagram

Figure 2: 802.11a Receiver Block Diagram

5. What error control codes are used? (Convolutional codes, turbo codes, LDPC codes,

Reed-Solomon codes, etc.)

Answer: Convolution Encoding

Figure 3. Rate 1/3 non-recursive, non-systematic convolution encoder with constraint length 3

To convolutionally encode data, start with *k* memory registers,
each holding 1 input bit. Unless otherwise specified, all memory
registers start with a value of 0. The encoder has *n* modulo-2
adders, and *n* __generator
polynomials__ -- one for
each adder (see figure above). An input bit *m _{1}* is
fed into the leftmost register. Using the generator polynomials and
the existing values in the remaining registers, the encoder outputs

The
figure above is a rate 1/3 (*m/n*) encoder with constraint
length (*k*) of 3. Generator polynomials are G_{1} =
(1,1,1), G_{2} = (0,1,1), and G_{3} = (1,0,1).
Therefore, output bits are calculated as follows:

*n _{1}*
= mod2 (

6. What constellations (BPSK, QPSK, 8PSK, 16-QAM, etc.) are used?

Answer: The modulation parameters dependent on the data rate used is set according to

Table 1. below.

7. IQ modulation used? What is in the I part of the base band complex signal and

what is the Q part of the base band complex signal?

Answer:

Figure4: BPSK, QPSK, 16-QAM, and 64-QAM constellation bit encoding

8. What kind of pulse shape is used? Can you show a picture of the pulse shape?

Where can one find the pulse shape in a document of the standard?

Answer:

9. What multi-access and broadcast technologies are used? (TDM(A), CDM(A),

FDM(A), OFDM(A), etc.)

How do they work? (Multi-access, or uplink, means that multiple users send signals

to the base station. Broadcast, or downlink, means that a base station sends different

signals to different users.)

Answer: OFDM for 802.11a, OFDM + DSSS for 802.11g

10. Does it use multi-antenna technology? How?

Answer: Single Omnidirectional Antenna

11. Is the standardization on-going? Which companies are the major players?

Answer: No,

Some a few companies are Cisco, Seimens, Alcatel, Nortel Network, etc.

References:

__http://www.vocal.com/white_paper/80211a_wp1pdf.pdf__ ^{4}

__http://www.Stanford.edu/class/ee360/lecture7.ppt__ ^{4}

__http://ieeexplore.ieee.org/iel5/7152/19253/00891003.pdf__ ^{5}

__http://grouper.ieee.org/groups/802/15/pub/2003/Mar03/03151r1P802-15_TG3a-Wisair-CFP-Presentation.ppt__ ^{8}

__http://en.wikipedia.org/wiki/Convolution_code__