I need analogy for CDMA,FDMA,TDMA,SDMA?

Answer 1

Code Division Multiple Access (CDMA) uses different digital codes on the same frequency. Like a comb with teeth missing, only the matching teeth missing comb will receive signals. This way many users can use the same frequency simultaneously. Doesn't extent forever because too many signals make it look like noise, even to a correct receiver.

Frequency Division Multiple Access (FDMA) is used on analog phones where every phone needs a channel for no interference. It is also used on CDMA & TDMA services to get more users service. This is why digital is so popular; More users per channel.

Time Division Multiple Access (TDMA) uses time slots in a given channel for different users. All start counting at the start pulse, and use either the first, second, third etc. time slot for their service. When all the time slots are in use, the phone is directed to a different frequency (FDMA) to get a time slot there.

Space Division Multiple Access (SDMA) is how cell phones actually work. Small cells are set up, according to predicted use, and certain frequencies are assigned to that cell. Surrounding cells are assigned different frequencies. When you get a couple of cells away from the same frequency cell, that set of channels can be used again. This way, a frequency can be used over and over. The problems occur when two many customers are using cell phones and enter a cell from different directions. When the cell tries to find a new frequency to switch to, sometimes there anen't any available, and the call is dropped.

I hope that this helps

Answer 2

The first three are easier, since they are all just different spread spectrum techniques Code Division Multiple Access, Frequency Division Multiple Access, and Time Division Multiple Access. CDMA shares one frequency, but uses different modulation strings (codes), FDMA spreads the info in the frequency domain, TDMA spreads the info in the time domain. Space Division Multiple Access is a whole different beast - it refers not to the modulation technique, but to trying to "point" the receiving antenna at the phone(transmitter) to increase reception and reject other similar signals from other directions.

Answer 3

He's right that the puddle is drying up. No one disagrees that this universe is temporary, regardless of which side of the debate they're on. But Adams is forgetting one important thing: Purpose. Can a man live life to the fullest in a puddle? Can he even live out a day to its fullest in a puddle? Does a puddle offer what a man needs to fulfill his potential? That same puddle may offer an amoeba, a mosquito larva or even a salamander the opportunity to reach their full potential. But they were made for the puddle and the puddle for them. We were not made for puddles, and that's why puddles were not made for us. @ Scrubbag: Actually, cells DO have internal parts, called organelles. All cells have nuclei, and most cells at least have mitochondria. Those are but two organelles present in almost every cell in the known universe.

Answer 4

Google "acronym dictionary" and look them up under any number of databases.