| Author | Thet Htun Khine |
| Call Number | AIT Thesis no.TC-99-8 |
| Subject(s) | Spread spectrum communications
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering. School of Advanced Technologies |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. TC-99-8 |
| Abstract | Parallel Concatenated Convolutional Code (Turbo Code) is proposed to improve
downlink performance of multicarrier direct sequence code division multiple access (MC-DSCDMA) combined with frequency spread coding. Turbo codes are well known for their
immense error correction capability near Shannon's limit. The proposed system exploits
frequency diversity without additional redundancy by using frequency spread coding in a
frequency selective fading channel. Two recursive systematic convolutional codes and
iterative decoding are used for rate 1/2 turbo coding techniques. Two paths Rayleigh fading
channel is modeled and binary phase shift keying (BPSK) modulation is used. Doppler effect
is also considered. Walsh-Hadamard code of spreading gain 8 is employed for frequency
spread coding.
The system is considered for 32 users. Bit error rate (BER) performance of the turbo
coded MC-DS _CDMA is evaluated as a function of signal to noise ratio (Eb/N0). BER of the
uncoded case is also evaluated. The performance of the proposed system is compared with a
convolutional code of equal decoding complexity. Furthermore, the proposed system is also
compared with multicarrier (MC)-CDMA system and single carrier SC-DS-CDMA system.
Based on the simulation results, without error correction coding (turbo code), the
system has very poor BER perfotmance compared with turbo coded system. Performance
improvement on using turbo code over convolutional code is around 1 dB at BER of 10-4 and
hence turbo codes perform better than convolutional codes. The performance of the proposed
system is better than multicarrier CDMA system and single carrier DS-CDMA system. Hence,
turbo coded multicarrier DS-CDMA system using frequency spread coding is found attractive
to be used in indoor wireless applications. |
| Year | 1999 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. TC-99-8 |
| Type | Thesis |
| School | School of Advanced Technologies (SAT) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Telecommunications (TC) |
| Chairperson(s) | Rajatheva, R.M.A.P. |
| Examination Committee(s) | Ahmed, Kazi M. ;Teerapat Sa-nguankotchakom |
| Scholarship Donor(s) | Telecom Finland |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology |