By dynamically adjusting the transmit time of instances of the keep-alive messages, this communication technique may ensure continuity of communication using the granted portion of the spectrum. For example, by adjusting the transmit time, the communication technique may ensure that the keep-alive responses are received prior to the instances of the transmit expire time, even when there are dynamic or time-varying delays at the computer or in communication with the computer, and/or one or more retries of keep-alive messages (e.g., because of dropped packets). Consequently, the updated transmit time may ensure that there is sufficient temporal margin between an instance of the receive time and an instance of the transmit expire time. Therefore, the communication technique may ensure that the granted portion of the spectrum remains authorized for use by the radio node across multiple instances of the transmit expire time, which may eliminate the need for a subsequent grant request for the portion of the spectrum. Thus, the communication technique may reduce or eliminate time delays, and may ensure improved communication and quality of service in a network that includes the radio node.