Subject: Mobile Communication Sysytem

Topic: 3GPP LTE

Difficulty High

FCA – Fixed Channel Association

1. In FCA schemes, a set of channels is permanently allocated to each cell in the network
2. If the total number of available channels in the system S is divided into sets, the minimum number of channel sets N required to serve the entire coverage area is related to the frequency reuse distance D
3. Due to short term fluctuations in the traffic, FCA schemes are often not able to maintain high quality of service and capacity attainable with static traffic demands.
4. One approach to address this problem is to borrow free channels from neighbouring cells.

DCA- Dynamic Channel Association

1. In DCA schemes, all channels are kept in a central pool and are assigned dynamically to new calls as they arrive in the system.
2. After each call is completed, the channel is returned to the central pool.
3. It is straightforward to select the most appropriate channel for any call based simply on current allocation and current traffic, with the aim of minimizing the interference.
4. DCA scheme can overcome the problem of FCA scheme.
5. However, variations in DCA schemes center around the different cost functions used for selecting one of the candidate channels for assignment.