Patent ID: 8295304

Claim:
A method comprising: transmitting, on a carrier at a first data transmission rate using a first modulation scheme, data packets that contain data for a plurality of services; detecting that a signal-to-noise ratio on the carrier is less than a specified threshold; in response to detecting that the signal-to-noise ratio is less than the specified threshold, transmitting, on the carrier at a second data transmission rate using a second modulation scheme, data packets that contain data for fewer services than are in the plurality of services; wherein the second data transmission rate is lower than the first data transmission rate; wherein the step of transmitting data packets at the second data transmission rate comprises: determining a number of subframes by (a) multiplying a superframe frequency by a specified number of slots in the superframe to produce a first value, (b) dividing the second data transmission rate by the first value to produce a second value, and (c) setting the number of subframes equal to an integer portion of the second value; selecting, from the plurality of services, one or more services in number equal to (a) the number of services in the plurality of services minus (b) the number of subframes; and excluding, from at least one data packet that is to be sent at the second data transmission rate, subframes that would contain data for any of the one or more services.