list comparison vs integer comparison, which is more efficient?

austin aigbe eshikafe at gmail.com
Sun Jan 4 00:19:24 CET 2015


Hi,

I am currently implementing the LTE physical layer in Python (ver 2.7.7).
For the qpsk, 16qam and 64qam modulation I would like to know which is more efficient to use, between an integer comparison and a list comparison:

Integer comparison: bit_pair as an integer value before comparison

    # QPSK - TS 36.211 V12.2.0, section 7.1.2, Table 7.1.2-1
    def mp_qpsk(self):
        r = []
        for i in range(self.nbits/2):
            bit_pair = (self.sbits[i*2] << 1) | self.sbits[i*2+1] 
            if bit_pair == 0:
                r.append(complex(1/math.sqrt(2),1/math.sqrt(2)))
            elif bit_pair == 1:
                r.append(complex(1/math.sqrt(2),-1/math.sqrt(2)))
            elif bit_pair == 2:
                r.append(complex(-1/math.sqrt(2),1/math.sqrt(2)))
            elif bit_pair == 3:
                r.append(complex(-1/math.sqrt(2),-1/math.sqrt(2)))
        return r

List comparison: bit_pair as a list before comparison

    # QPSK - TS 36.211 V12.2.0, section 7.1.2, Table 7.1.2-1
    def mp_qpsk(self):
        r = []
        for i in range(self.nbits/2):
            bit_pair = self.sbits[i*2:i*2+2] 
            if bit_pair == [0,0]:
                r.append(complex(1/math.sqrt(2),1/math.sqrt(2)))
            elif bit_pair == [0,1]:
                r.append(complex(1/math.sqrt(2),-1/math.sqrt(2)))
            elif bit_pair == [1,0]:
                r.append(complex(-1/math.sqrt(2),1/math.sqrt(2)))
            elif bit_pair == [1,1]:
                r.append(complex(-1/math.sqrt(2),-1/math.sqrt(2)))
        return r

Thanks



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