Project 2 Physical layer of communication

CS380 — Project 2

Description
In this project, we will be simulating the physical layer of communication. To do this, I will have a server
running that will send “signals” to you by sending numbers in the range [0, 255] (i.e., unsigned bytes) and
you need to implement the client that properly interprets them.
The numbers will fluctuate but all be either slightly higher or slightly lower than some average. The average
value will be randomly chosen each time you connect. This means to send 10101 directly, It might look like
this one time: 65, 43, 66, 40, 71 and the next time it might be 181, 167, 188, 160, 179. However, to add
another layer of complication I will also be implementing NRZI on top of the actual bits being sent.
When you first connect, the server will send a preamble of 64 alternating high and low signals so that you
can establish the baseline. After this point, it will send you 32 bytes of randomly generated data encoded
using 4B/5B with NRZI. You need to properly decode this data and record the 32 bytes sent to you.
Once you have figured out the 32 bytes I sent, you must reply it back to me directly, don’t use any encoding.
Just send me the array of 32 bytes. Once I receive the response, I will send a final byte (not encoded) that
is either 0 or 1. If it is 0, I didn’t receive the correct 32 bytes. If it’s 1, then I did and your program worked
correctly.
The 4B/5B table is below:
4-Bit Data 5-Bit Code 4-Bit Data 5-Bit Code
0000 11110 1000 10010
0001 01001 1001 10011
0010 10100 1010 10110
0011 10101 1011 10111
0100 01010 1100 11010
0101 01011 1101 11011
0110 01110 1110 11100
0111 01111 1111 11101
The server will be running at codebank.xyz on port 38002
A few test runs of your client program might look like this:
$ java PhysLayerClient
Connected to server.
Baseline established from preamble: 102.84
Received 32 bytes: E695AB1F3D6D4BFB06A06200F378C1EF3772E67DF3EF7FCFD26FFD496881CDC7
Response good.
Disconnected from server.
1
$ java PhysLayerClient
Connected to server.
Baseline established from preamble: 216.06
Received 32 bytes: 221BB41C341531437CF4C500A3FC6194435D839D79AB6261629C22EE9E79D3B4
Response good.
Disconnected from server.
$ java PhysLayerClient
Connected to server.
Baseline established from preamble: 199.78
Received 32 bytes: 0704000434B278D75F124DF7CDD2B9931CDA90F2573C3ED0F45D401628DB1849
Response good.
Disconnected from server.
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