32 Questions
What is the purpose of frequency division duplex (FDD) in cellular networks?
To allow for simultaneous transmission in both directions using different frequencies
What is the main function of frequency division multiple access (FDMA)?
To allocate frequencies to transmission channels according to frequency division multiplexing
What distinguishes uplink and downlink frequencies in the context of cellular networks?
Uplink frequencies are from mobile station to base station, and downlink frequencies are from base station to mobile station
What is the significance of knowing the frequencies in advance in cellular networks?
To prevent interference and ensure efficient communication
In a cellular network based on GSM standard for 900 MHz, what is the basic frequency allocation scheme for uplinks?
Between 890.2 and 915 MHz
What role does frequency division multiplexing (FDM) play in cellular networks?
It is used for simultaneous access to the medium by base station and mobile station
What is the main characteristic of time division multiple access (TDMA)?
It allocates certain time slots for communication
What is the typical solution for wireless phone systems using Fixed TDM?
Allocating fixed bandwidth and using a fixed pattern for time slots
What is the term used to describe assigning different slots for uplink and downlink using the same frequency in TDM?
Time division duplex (TDD)
What is the main characteristic of Classical Aloha?
No coordination among the users, with no collision detection and no central arbiter
What is the main improvement provided by Slotted Aloha compared to Classical Aloha?
Introduction of time slots for synchronized transmissions
What is the main feature of non-persistent CSMA?
Stations sense the carrier and start sending immediately if the medium is idle
What does p-persistent CSMA involve?
Sensing the medium and transmitting with a probability p
What does SDMA (space division multiple access) involve?
Assigning an optimal base station to a mobile phone user based on different quality
What is the main drawback of Classical Aloha compared to Slotted Aloha?
Data retransmission is not supported after collision
What type of multiple access involves allocating separated space to users in wireless networks?
Space division multiple access (SDMA)
What is the purpose of frequency division duplex (FDD) in cellular networks?
To allow for simultaneous transmission in both directions by using different frequencies for uplink and downlink.
What is the main function of frequency division multiple access (FDMA)?
Allocating frequencies to transmission channels according to frequency division multiplexing (FDM).
What distinguishes uplink and downlink frequencies in the context of cellular networks?
Uplink frequencies are from mobile station to base station, and downlink frequencies are from base station to mobile station.
What type of multiple access involves allocating separated space to users in wireless networks?
Space Division Multiple Access (SDMA).
What does frequency division multiplexing (FDM) allow for in cellular networks?
Simultaneous access to the medium by base station and mobile station.
What is the significance of knowing the frequencies in advance in cellular networks?
It allows for establishing a duplex channel, i.e., a channel that allows for simultaneous transmission in both directions.
What is the main difference between Fixed TDM and TDMA in terms of flexibility?
Fixed TDM results in a fixed bandwidth, while TDMA offers a much more flexible scheme by allocating certain time slots for communication.
What is the term used to describe the allocation of different time slots for uplink and downlink using the same frequency in TDM?
Time division duplex (TDD)
What is the main drawback of Classical Aloha compared to Slotted Aloha?
No coordination among the users and lack of collision detection in Classical Aloha, leading to a lot of collisions.
What is the main function of frequency division multiple access (FDMA)?
FDMA involves allocating different frequency bands to multiple users for simultaneous communication.
What type of multiple access involves allocating separated space to users in wireless networks?
SDMA (space division multiple access)
What is the main characteristic of Classical Aloha?
Lack of coordination among users and no collision detection
What is the main feature of non-persistent CSMA?
Stations sense the carrier and start sending immediately if the medium is idle, or pause a random amount of time before sensing the medium again if it is busy.
What is the main purpose of frequency division duplex (FDD) in cellular networks?
FDD allows simultaneous transmission and reception on different frequencies, enabling full-duplex communication.
What distinguishes slotted Aloha from classical Aloha?
Slotted Aloha introduces time slots and synchronized transmissions, reducing collisions compared to the lack of coordination and collision detection in Classical Aloha.
What is the main characteristic of time division multiple access (TDMA)?
TDMA allocates certain time slots for communication, achieving synchronization between sender and receiver in the time domain.
Test your knowledge on Frequency Division Multiple Access (FDMA) algorithms and their use in cellular networks for simultaneous access by base stations and mobile stations.
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