Radio terminal and transmission rate prediction method

摘要

In a radio communication system employing HARQ scheme wherein the maximum number of slots is changed, a radio terminal (1) which calculates a predictive transmission rate being the predictive value of a downlink transmission rate at a future time after the receiving time of a downlink radio signal is provided with a storage unit (15A) which stores in association with a DRC a corrected transmission rate obtained by causing a defined transmission rate being a downlink transmission rate in the case of using all the maximum number of slots to reflect the probability of succeeding in decoding data using only some of the slots, and a calculation unit (142) which predicts the reception quality at the future time on the basis of the reception quality before the receiving time, obtains from the storage unit (15A) the corrected transmission rate associated with the DRC corresponding to the predicted reception quality, and calculates the predictive transmission rate from the obtained corrected transmission rate.

主权项

1. A radio terminal that calculates a predictive transmission rate, which is a predictive value of a downlink transmission rate at a future time after a reception time of a downlink radio signal in a radio communication system employing HARQ scheme in which a maximum slot number that is a maximum number of downlink time slots used to transmit the downlink radio signal is changed according to reception quality of the downlink radio signal received from a radio base station, the radio terminal comprising:
a decoding unit configured to decode data included in the received downlink radio signal; a storage unit configured to associate a corrected transmission rate with any one index value of the downlink transmission rate or the reception quality and store the resultant corrected transmission rate, wherein the corrected transmission rate is calculated from a probability that the decoding unit succeeds in decoding data in some of the slots and a defined transmission rate as a downlink transmission rate when all the slots are used; and a calculation unit configured to predict reception quality at the future time based on reception quality before the reception time, acquire the corrected transmission rate which is associated with the index value of the predicted reception quality from the storage unit, and calculate the predictive transmission rate from the acquired corrected transmission rate, wherein the calculation unit calculates a decoding success rate, which indicates probability that the decoding unit succeeds in data decoding at an nth downlink time slot of all the slots, for each index value, and calculates the corrected transmission rate from the calculated decoding success rate and the defined transmission rate for each index value, and the storage unit associates the corrected transmission rate calculated by the calculation unit with the index value, and stores the resultant corrected transmission rate.