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Staff details

 

Personal photograph uploaded by Cen Tjhai

Dr Cen Tjhai - (CJ)

  • Job title: Lecturer in Computer Networks, School of Computing and Mathematics
  • Address: B328, Portland Square, Drake Circus,
    Plymouth, Devon, PL4 8AA
  • Telephone: +44 (0)1752 586276
  • Email: cen.tjhai@plymouth.ac.uk


Qualifications & background
Qualifications:

  • PhD (A Study of Linear Error Correcting Codes), 20042007 
  • MSc (Distinction) Communications Engineering and Signal Processing, 20022003
  • B.Eng (First Class Honours) Computer Engineering, 19992002


Employment background:
Acterna Plymouth Ltd (industrial placement), electronic/software engineer, 20002001


Consultancy activities:
  • Comtech AHA Ltd, ``Design of high-rate DVB-S2 LDPC codes'', 2004-2005
  • TRL Technology Ltd, ``Implementation and demonstration of digital video compression with low latency'', 20062007


 

Professional membership
Professional membership:
IEEE

 



Research interests

  1. Error correcting codes: construction of linear codes with high minimum distance (best known linear codes) and the design of efficient soft-decision decoder. I am also interested in the design of low-density parity-check (LDPC) codes with low-error floor and techniques of improving iterative decoding performance.
  2. Digital signal processing: real-time DSP, adaptive filtering and equalisation
  3. Coding for packet networks: erasure-correcting codes
  4. Cryptography: cryptanalysis and development of cryptosystem based on coding theory
 


Publications

Journal publications


Ntokas, I. T., Nutter, P. W., Tjhai, C. and Ahmed, M., `Improved Data Recovery from Patterned Media With Inherent Jitter Noise Using Low-Density Parity-Check Codes', IEEE Transactions on Magnetics 43(10): 3925-3929, October 2007.

Shah, P., Ahmed, M., Ambroze, M., Tjhai, C. and Davey, P, `Novel Soft-Feedback Equalization Method for Multilevel Magnetic Recording', IEEE Transactions on Magnetics 43(6): 2280-2282, June 2007.

Tomlinson, M., Tjhai, C., Cai, J. and Ambroze, M., `Analysis of the Distribution of the Number of Erasures Correctable by a Binary Linear Code and the Link to Low Weight Codewords', IET Proceedings Communications 1(3): 539-548, June 2007.

Tomlinson, M., Tjhai, C., and Ambroze, M., `Extending the Dorsch Decoder Towards Achieving Maximum Likelihood Decoding for Linear Codes', IET Proceedings Communications 1(3): 479-488, June 2007.

Tjhai, C. and Tomlinson, M., `Results on Binary Cyclic Codes', Electronics Letters 43(4): 234-235, 15 February 2007.

Tjhai, C. , Tomlinson, M., Grassl, M., Horan, R., Ahmed, M. and Ambroze, M., ‘New Linear Codes Derived from Cyclic Codes of Length 151’, IEE Proceedings Communications 153 (5), 581-585, October 2006.  

Horan, R., Tjhai, C. , Tomlinson, M., Ambroze, M. and Ahmed, M., ‘Idempotents, Mattson-Solomon Polynomials and Binary LDPC Codes’, IEE Proceedings Communications 153 (2), 256–262, April 2006. 

Tjhai, C. , Tomlinson, M., Ambroze, M. and Ahmed, M., ‘Cyclotomic Idempotent based Binary Cyclic Codes’, Electronics Letters 41 (3), 341–343, 17 March 2005.



Conference publications


Tjhai, C., Tomlinson and Grassl, M., Chains of Cyclic Codes, Construction X and Incremental Redundancy, accepted for publication at IEEE Information Theory Workshop, Porto, Portugal, 5–9 May 2008. (PDF postprint)

Tjhai, C., Tomlinson, M., Ambroze, M. and Ahmed, M., On the Weight Distribution of the Extended Quadratic Residue Code of Prime 137, 7th International ITG Conference on Source and Channel Coding, Ulm, 14–16 January 2008. (PDF postprint)

Ambroze, M., Tomlinson, M., Tjhai, C. and Ahmed, M., Analysis of the Distribution of the Number of Correctable Erasures for Turbo Codes with DRP Interleavers, IEEE Information Theory Workshop, Lake Tahoe, California, USA, 2–6 September 2007, pp. 214–217

Tjhai, C., Tomlinson, Perry, P. and Fossorier, M., Comparison of Bose-Chaudhuri-Hocquenghem and Goppa Codes for Error Detection, in ‘Proc. 9th International Symposium Communication Theory and Applications’, Ambleside, UK, 16–20 July 2007.

Shah, P., Ahmed, M., Ambroze, M., Tjhai, C. and Davey, P., A Novel  Turbo Coded Soft-Feedback Equalisation Method for Multilevel Magnetic Recording: New Results and Comparisons, in ‘Digests of 10th Joint Magnetism & Magnetic Materials/Intermag Conference', Baltimore, Maryland, USA, 7–11 January 2007.

Tjhai, C., Tomlinson, M., Horan, R., Ahmed, M. and Ambroze, M., Some Results on the Weight Distributions of the Binary Double Circulant Codes Based on Primes, in `Proc. 10th IEEE International Conference on Communication Systems, Singapore, 30 October–1 November. 2006.

Tjhai, C., Tomlinson, M., Horan, R., Ahmed, M. and Ambroze, M., On the Efficient Codewords Counting Algorithm and the Weight Distributions of the Binary Quadratic Double Circulant Codes, in `Proc. IEEE Information Theory Workshop, Chengdu, China, 22–26 October 2006.

Cai, J., Tomlinons, M., Tjhai, C., Ambroze, M. and Ahmed, M., Comparison of Concatenated Reed-Solomon Coding with  Hard-decision to Soft-decision LDPC Coding for the Rayleigh Fading Channel, in `Proc. IEEE Information Theory Workshop, Chengdu, China, 22–26 October 2006.

Shah, P., Ahmed, M., Ambroze, M., Tjhai, C. and Davey, P., Novel Multi-level Magnetic Recording using Modern Error Correction, in ‘Proc. 1st joint E-PCOS/IMST conference’, Grenoble, France, 29–31 May 2006.


Ntokas, I., Nutter, P., Middleton, B., Tjhai, C. and Ahmed, M., Read Channel Designs for Efficient Data Recovery in Storage Systems Employing Imperfect Patterned Media, in 'Digests of the IEEE International Magnetic Conference’, San Diego, USA, 8–12 May 2006.
 

Tjhai, C. , Tomlinson, M., Horan, R., Ahmed, M. and Ambroze, M., GF(2m) Low-Density Parity-Check Codes Derived from Cyclotomic Cosets, in ‘Proc. 4th International Symposium on Turbo Codes in connection with 6 th International ITG Conference on Source and Channel Coding’, Munich, Germany, 3–7 April 2006.


Cai, J., Tomlinson, M.,
Tjhai, C. , Ambroze, M. and Ahmed, M., Advances in Iterative Decoding and Maximum Likelihood Decoding for the Packet Network with Comparisons to Fountain Codes over the Erasure Channel, in ‘Proc. 4th International Symposium on Turbo Codes in connection with 6 th International ITG-Conference on Source and Channel Coding’, Munich, Germany, 3–7 April 2006.


Cai, J., Tjhai, C. , Tomlinson, M., Ambroze, M. and Ahmed, M., An Efficient Solution to Packet Loss: Erasure Correcting Codes, in C. E. Palau Salvador, ed., ‘Proc. 4th IASTED International Conference Communication Systems and Networks’, ACTA Press, Benidorm, Spain, 12–14 September 2005, pp. 224–229.

Horan, R., Tjhai, C. , Tomlinson, M., Ambroze, M. and Ahmed, M., A Finite-Field Transform Domain Construction of Binary Low-Density Parity-Check Codes, in M. J. Dinneen, ed., ‘Proc. IEEE ITSOC Information Theory Workshop on Coding and Complexity', Rotorua, New Zealand, 28 August–1 September 2005, pp. 72–76.


Ntokas, I., Nutter, P., Middleton, B., Tjhai, C. and Ahmed, M., Performance Evaluation of LDPC Codes for Patterned Media, in ‘Digests of the IEEE International Magnetic Conference, Nagoya, Japan, 4–8 April 2005, p. 494.


Tjhai, C., Tomlinson, M., Horan, R., Ambroze, M. and Ahmed, M., Near Maximum-Likelihood Performance of Some New Cyclic Codes Constructed in the Finite-Field Transform Domain, in ‘Proc. 8th International Symposium Communication Theory and Applications’, Ambleside, UK, 17–22 July 2005, pp. 194–199.

Papagiannis, E.,
Tjhai, C. , Ahmed, M., Ambroze, M. and Tomlinson, M., Improved Iterative Decoding for Perpendicular Magnetic Recording, in ‘Proc. 8th International Symposium Communication Theory and Applications’, Ambleside, UK, 17–22 July 2005, pp. 332–336.

Tjhai, C. and Ahmed, M., Iterative Decoding and Adaptive Equalisation in Two-Track High-Density Magnetic Recording, in ‘Proc. PREP’, Lancaster, UK, 30 March–1 April 2005, pp. 199–200.

 



Additional information

  1. Weight distributions of quadratic residue and quadratic double circulant codes over GF(2).
  2. I contribute towards the development of GUAVA, a Groups, Algorithms, Programming (GAP) package that implements coding theory algorithms.