Radio communication device and method thereof

1. A channel estimation device that performs channel estimation more than once using a plurality of pilot symbols inserted at predetermined intervals by a pilot symbol insertion unit into a received data sequence, comprising:

a channel estimation unit configured to perform the channel estimation using the pilot symbols;

a storage unit configured to store a plurality of estimated values obtained by the channel estimation unit;

a determination unit configured to compare the estimated values stored in the storage unit and determine an amount of change of the estimated values, said change of the estimated values being used for adjusting the intervals of the inserted pilot symbols.

2. The channel estimation device as claimed in claim 1 , wherein

the determination unit further determines whether the amount of change of the estimated values is within a preset threshold range, and notifies the pilot symbol insertion unit of a determination result.

3. The channel estimation device as claimed in claim 1 wherein

the determination unit

requests the pilot symbol insertion unit to adjust the intervals when inserting the pilot symbols according to the amount of change of the estimated values.

4. The channel estimation device as claimed in claim 1 , wherein the determination unit notifies the pilot symbol insertion unit of the amount of change of the estimated values.

5. A channel estimate method comprising the steps of:

transmitting radio signals from a transmitter including a data sequence together with a plurality of pilot symbols inserted into the data sequence at predetermined intervals;

receiving the radio signals by a receiver;

performing channel estimation more than once using the received pilot symbols at the receiver;

storing a plurality of estimated values obtained in the channel estimation into the receiver;

comparing the stored estimated values and determining an amount of change of the estimated values at the receiver, and

adjusting the intervals based on the change of the estimated values at the transmitter when inserting the pilot symbols into the data sequence.

6. The channel estimate method as claimed in claim 5 , wherein

the receiver transmits change of the estimated values to the transmitter; and

the transmitter adjusts the intervals according to the received amount of change of the estimated values when inserting the pilot symbols into the data sequence.

7. The channel estimate method as claimed in claim 5 , wherein the receiver requests the transmitter to adjust the intervals when inserting the pilot symbols according to the amount of change of the estimated values.

8. The channel estimate method as claimed in claim 5 , wherein the receiver determines whether the amount of change of the estimated values is within a preset threshold range.

9. A channel estimation system, comprising:

a pilot symbol insertion unit that inserts a plurality of pilot symbols at intervals into a data sequence;

a channel estimation unit configured to perform channel estimation more than once using the pilot symbols;

a storage unit configured to store a plurality of estimated values obtained by the channel estimation unit;

a determination unit configured to compare the estimated values stored in the storage unit and determine a change of the estimated values; and

a pilot symbol insertion interval adjustment unit configured to adjust the intervals of inserting the pilot symbol based on the change of the estimated values, the pilot symbol insertion unit inserting the pilot symbols at the adjusted intervals into the data sequence.