Turbo codes apply aniterative message passing mechanism between two concatenated decoders. Theirastounding performance has led to their widespread adoption in severalcommunication standards such as Long Term Evolution (LTE), and Code Divisionfor Multiple Access (CDMA) 2000. This paper gives an overview of three bit-leveldecoding Max-Log-MAP algorithms with Sign Difference Ratio (SDR)-based earlystopping that can be used in LTE Turbo Codes. A detailed computationalcomplexity analysis is given for the three methods. It is observed that thecomplexity of the decoding methods decrease significantly as the Eb/N0increases when SDR is used. Moreover, the Bit Error Rate (BER) performance ofthe methods was also assessed and compared for different modulation schemes.Results show that the different methods perform differently in the waterfalland error-floor regions with different modulation schemes. Moreover, thecomputational complexity analysis show that Method 2 requires fewer overallnumber of computations compared to Methods 1 and 3.