Problem 1.
1. When the poor channel quality is not due to interference or collision occur, but is affected by low signal strength, we will decrease the rate to improve the channel quality.
2. When channel quality changes quickly, and we cannot sure the poor quality is due to noise or interference or collision.
3. Send test packets at different bit rate, and calculate the transmission time of those packets, so we can choose the smallest predict time.
The bit rate which has more than 4 fail packets to transmission will not be sample, so if all bit rate have fail packets more than 4 or all predict time are too long, we can assume that the interference or collision is occurring.
Problem 3.
Problem 4.
4-2