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You should realize that when you say "telecommunications" you are talking about a huge field involving lots of different technologies. Based on the mention of AM/FM modulations I infer that you are r …

No, scrambling does not increase the bandwidth. Scrambling does even out the bandwidth, such that the power is spread evenly over the signal bandwidth. You are thinking of chipping, which is used in …

BPSK is, at heart, a digital signal. It is comprised of +1, -1 symbols. It is only analog in the sense that when things have to exist in the real world (in this case in radio waves) everything is an …

It is just the control channel that is spread. It appears that it is spread primarily to make the signal more robust in the face of frequency selective fading, which is probably a major problem at 60 …

You could theoretically use anything in that first section, including dead space- i.e. no signal at all. They use the cyclic prefix in case the demodulator isn't perfectly synced up in time and thus …

It comes from the Nyquist rate. The Nyquist sample rate for a signal with bandwidth $B$ is $2B$. In other words, that is the lowest sample rate that will contain all of the information in the signal …

I'm sure that you are familiar with the idea of how Doppler affects a sine wave. When the transmitter and/or receiver move towards the other the wave arrives more quickly, which makes the wave appear …

I am familiar with 802.11a, so I'll answer your questions with regard to how 802.11a does it. What are the nature of those Pilot tones? There are 64 sub-carriers in 802.11a. Four of them are used …

How is a pilot tone found? The location of pilot tones in terms of sub-carriers is defined by the signal protocol. For instance, in the case of 802.11a the pilot sub-carriers are -21, -7, 7, and 21 …

That is a nasty signal environment. I would do a little DSP judo and make the multi-path work for you by using a rake receiver, which should make the multi-path signals increase your SNR rather than …

I'm afraid that this will be an incomplete answer, but I'm giving it in the hopes that it is better than nothing. It is impossible to recover any information with a BER of 50% because, as information …

I do not think that your problem is noise quantization. Your curve shows that the BER levels out somewhere around EbN0 = 4, which means that that is around where the quantization noise equals the int …

I would use a frame alignment word to synchronize your data. The basic idea is to insert your FAW at the beginning of every $N$ bytes. After you demodulate the data you look for the FAW to synchroni …

It is not a good idea to do 1 sample/chip because if you happen to have the samples at the chip transitions then demodulation will go poorly. Also, if you have much carrier offset you will likely los …

I think the part that you are missing is that the burst of errors out of the convolutional decoder is (or at least should be) a rare event. Thus, every once in a while there will be a burst of errors …