Question

16. Briefly compare FDMA, TDMA, and CDMA in terms of bandwidth for each user, cost, and guard band/time.

Answer 1

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(FDMA): Frequency division multiple access	TDMA: Time Division Multiple Access	CDMA: Code Division Multiple Access
FDMA is the division of the frequency band allocated for wireless cellular telephone communication into channels	TDMA is digital transmission technology that allows a number of users to access a single radio-frequency (RF) channel without interference by allocating unique time slots to each user within each channel.	There is no restriction on time and frequency in this scheme. Parallel communication without collision and whole bandwidth can be used
Users are separated by frequency slots. FDMA divides the shared medium bandwidth into individual channels. Subcarriers modulated by the information to be transmitted occupy each sub channel	Users are separated by Time Slot.. Each time slot is allocated to one user. The high data rate makes the user unaware of the lack of simultaneity	Users are separated by code not by time slot and frequency slot. Spread spectrum is the technique of CDMA.The result is that the digital voice is spread over a much wider bandwidth that can be shared with other users using different codes.
Continuous signals are used	Signals are burst	Signals are Discrete or Digital signals used.
COST: Overall Higher cost	COST: Medium cost overall	COST: Installation cost is high but operation cost is low.
Guard Bands are required	Guard Times are Required	Both Guard times and bands are required.
Low flexibility in this technique	Moderate Flexibility	High Flexibility
Capacity of system is low	Capacity of system is Moderate	Capacity of system is Larger.