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My implementation of LDPC codes. For details visit:https://yairmz.github.io/LDPC/
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My implementation of LDPC codes.My notes regarding theory and implementation appears on GitHub Pages:https://yairmz.github.io/LDPC/
To install:
pip install sim-ldpc
To run tests simply clone, cd into the cloned repo, and run:
python -m pytest
or
python -m pytest --cov-report=html
to run also coverage tests, or
python -m pytest -n auto --cov-report=html
to run tests in parallel (with number of CPU's dictated by machine) to speed up tests.
Verify static typing with
mypy --strict --config-file .mypy.ini.- Utilities: implementing various utility operations to assist with encoding, decoding andsimulations.
- Encoder: implementing a generator based encoder, and encoders for IEEE802.11 (WiFi) LDPC codes.
- Decoder: implementing several decoders
- Log-SPA based BP decoder
- MS decodcer
- Gallager bit filpping decoder
- Weighted bit flipping decoders, several variants
- Parallel probabilistic bit flipping decoder (PPBF)
importnumpyasnpfrombitstringimportBitArray,Bitsfromldpc.decoderimportDecoderWiFi,bsc_llrfromldpc.encoderimportEncoderWiFifromldpc.wifi_spec_codesimportWiFiSpecCodefromldpc.utilsimportQCFile# create information bearing bitsrng=np.random.default_rng()info_bits=np.array(Bits(bytes=rng.bytes(41))[:648//2],dtype=np.int_)# create encoder with frame of 648 bits, and rate 1/2. Possible rates and frame sizes are per the ieee802.11n spec.enc=EncoderWiFi(WiFiSpecCode.N648_R12)# encode bitsencoded=enc.encode(info_bits)# verify validity of codewordh=enc.hnp.dot(h,np.array(encoded))%2# creates an all zero vector as required.# create a decoder which assumes a probability of p=0.05 for bit flips by the channel# allow up to 20 iterations for the bp decoder.p=0.05decoder=DecoderWiFi(spec=WiFiSpecCode.N648_R12,max_iter=20,channel_model=bsc_llr(p=p))# create a corrupted version of encoded codeword with error rate pcorrupted=BitArray(encoded)no_errors=int(len(corrupted)*p)error_idx=rng.choice(len(corrupted),size=no_errors,replace=False)foridxinerror_idx:corrupted[idx]=notcorrupted[idx]decoded,llr,decode_success,num_of_iterations,syndrome,vnode_validity=decoder.decode(corrupted)# Verify correct decodingprint(Bits(decoded)==Bits(encoded))# trueinfo=decoder.info_bits(decoded)# a decoder can also be instantiated without a channel model, in which case llr is expected to be sent for decoding instead of# hard channel outputs.channel=bsc_llr(p=p)channel_llr=channel(np.array(corrupted,dtype=np.int_))decoder=DecoderWiFi(spec=WiFiSpecCode.N648_R12,max_iter=20)decoded,llr2,decode_success,num_of_iterations,syndrome,vnode_validity=decoder.decode(channel_llr)print(Bits(decoded)==Bits(encoded))# trueinfo=decoder.info_bits(decoded)
The example is also included as a jupyter notebook. Note however, that you need to launch the notebook from the correctpath for it to be able to access installed packages. To run the notebook:
- create a new virtualenv
python3 -m venv~/.virtualenv/LDPC_env- activate it and install
sim-ldpc, andnotebook:
source~/.virtualenv/LDPC_env/bin/activatepip install sim-ldpcpip install notebook
- run jupyter from within the virtual env for it to have access to all requirements:
~/.virtualenv/LDPC_env/bin/jupyter-notebook- run the notebook
- Cai Z., Hao J., Tan P.H., Sun S., Chin P.S., Efficient encoding of IEEE 802.11n LDPC codes. Electronics Letters 25,1471--1472 (2006).
- IEEE802.11 encoder tested against the implementation inhttps://github.com/tavildar/LDPC
- Channel codes : classical and modernby William E. Ryan, 2009.
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My implementation of LDPC codes. For details visit:https://yairmz.github.io/LDPC/
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