An encoder receives an input bit stream and generates, based on the input bit stream, a first output bit stream based on at least a first polynomial and a second output bit stream based on at least a second polynomial. The first and second polynomials are each different from each other. The encoder forms a first packet of code symbols, having a first code rate, based on bits from the first output bit stream. A transmitter transmits the first packet. A receiver receives a first negative acknowledgment indicating unsuccessful decoding of the first packet after transmitting of the first packet. The encoder punctures bits from the second output bit stream and forms a second packet of code symbols having a second code rate. The second code rate is different from the first code rate. The transmitter transmits the second packet in response to the receiver receiving the first negative acknowledgment.