Channel

Q1. Explain the process of channel Allocation in detail?

Channel Allocation usually covered how a Base Station should assign traffic channel to the MS. As the channel is only managed by the base station of a cell, MS try to make a new call needs to submit a request for a channel. The Base station grant such as access to the MS.

Q2. Define static channel allocation?

In static a fix number of channel is allocated to each cell.

Q3. Define dynamic channel allocation?

In dynamic channel allocation of channel two different cells is done dynamically as needed.

Q4. Classify the channel allocation scheme?

The channel allocation scheme is classified into

a) Fixed channel allocation (FCA).

b) Dynamic channel allocation (DCA).

c) Hybrid channel allocation (HCA).

Q5. Define fixed channel allocation?

In this scheme, set of channels is permanently allocated to each cell of system. One approach to address increase traffic of originating & end of call in a cell is to borrow free channel from neighboring cell.

Q6. Define simple borrowing scheme?

This scheme implies that if channels allocated to a cell have already been used then additional channel can be borrowed from any cell that has some free unused channel. Such a cell is known as donor cell.
The adjacent cell having the largest number of free channel are selected as a donor this is known as borrowing from the richest and then further return from the borrowed channel to the donor. When channel become available in the cell, such a algo is known as basic algo.

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Q7. Define complex borrowing scheme?

The basic strategy for complex scheme is to divide the channel into two groups. First group kept reserved as donors to be borrowed by neighboring cell.
The ratio between the two groups of channels can be based on traffic in the system, an alternative called as borrowing with channel ordering is to assigned priorities to all channel of each cell with highest priorities channel being used in a order in the cell and the channel borrowing is done starting the lowest priorities.

Q8. Define Dynamic channel allocation?

Dynamic channel allocation implies that channels are allocated dynamically & is achieved by keeping all free channels in a central pool. It means, when a call is completed the channel currently being used is return to the central pool.

Q9. Define centralized dynamic channel allocation?

In this scheme, a channel is selected for a new call from a central pool or free channels and a specific fun is used to select one among different free channels.
The simplest scheme is to select the first available free channel that can satisfy the re-use distance.
An alternative is to select free channel that can minimize the future blocking probability in the neighborhood of the cell that needs on additional channel this is known as locally optimized dynamic assignment.

Q10. Define distributed dynamic channel allocation?

This scheme is based on parameter link co-channel distance, signals strength measurement, signal noise ratio (SNR). In a cell based distributed scheme it able indicates if other co-channels cell in the neighborhood are not using one or, more channel & a selecting one of the free channels for the requesting cells.

Q11. Define Hybrid channel allocation?

Hybrid channel allocation is a combination of fixed & dynamic channel allocation scheme, with the channels divided into fixed and dynamic (Emergency or flexible) set.
This means, each cell is given a fixed number of channels i.e. exclusively used by a cell. A request for a channel from the dynamic set is started only when a cell has exhausted using all channels in the fixed set. The number of fixed and dynamic ratio is depending on traffic intensity and it can be vary as the load increase.