Patent ID: 7209443

Claim:
A dynamic bandwidth updating method for a communications system in which a plurality of subscriber apparatuses and a station apparatus are connected to the same transmission channel for bidirectional communication, for dynamically updating a bandwidth allocated in a direction of upstream transmission from the subscriber apparatuses to the station apparatus, comprising the steps of: calculating a bandwidth usage rate from a bandwidth allocated in a bandwidth updating period and a bandwidth actually used in the bandwidth updating period; and determining a bandwidth to be allocated in a subsequent bandwidth updating period based on the bandwidth usage rate, wherein the allocation of bandwidth involves ensuring that a minimum guaranteed bandwidth guaranteeing a minimum level of communication is allocated to the subscriber apparatus, and determining a surplus bandwidth which is a result of subtraction of the minimum guaranteed bandwidth from an allocated bandwidth, and the surplus bandwidth is calculated using a first upper threshold value for determination that there is a bandwidth shortage when an allocated bandwidth is equal to the minimum guaranteed bandwidth, a second upper threshold value for determination that there is a bandwidth shortage when the allocated bandwidth is larger than the minimum guaranteed bandwidth and a lower threshold value for determination that there is an excessive bandwidth when the allocated bandwidth is larger than the minimum guaranteed bandwidth.