Computing a polar transformation

A radio apparatus comprising:

• radio transmitter circuitry;
• and
• a processing system,
• wherein the processing system is configured to compute a polar transformation of an input sequence of 2n bits and wherein the radio transmitter circuitry is configured to transmit the polar transformation of the input sequence by radio, and wherein the processing system comprises an electronic memory and is configured, when computing the polar transformation, to:
• store the input sequence of 2n bits, optionally interleaved with an integer multiple of 2n additional bits, as a working bit sequence in the electronic memory;
• and
• perform the following sequence of steps n times:
• i) compute a bitwise XOR of a contiguous first half of the working bit sequence with a contiguous second half of the working bit sequence, wherein the second half is disjoint from the first half;
• ii) store a result of the bitwise XOR in the electronic memory;
• iii) generate a bit-interleave sequence by interleaving the result of the bitwise XOR and the second half of the working bit sequence as alternate bits of the bit-interleave sequence;
• and
• iv) update the working bit sequence by storing the bit-interleave sequence in the electronic memory as an updated working bit sequence;
• wherein, after performing the steps n times, the working bit sequence, or a contiguous subsequence thereof, is the polar transformation of the input sequence, for transmission by the radio transmitter circuitry.