Hasil Pencarian  ::  Simpan CSV :: Kembali

Abstrak :
ABSTRAK
Pada penelitian ini dianalisa unjuk kerja bit error rate (BER) dari trellis coded (TC) 8PSK dengan adanya interferensi pada kanal berfading. Diasumsikan bahwa jumlah sinyal interferensi antar kanal (co-channel interference, CCI) sebanyak L buah yang mengalami redaman akibat Rayleigh fading, dan sinyal asli (desired sinyal) yang mendapatkan pengaruh redaman Nakagami fading. Disini diasumsikan pula bahwa interferensi antar simbol (inter-symbol interference, ISI) diabaikan, sehingga sinyal interferensi dapat dianggap sebagai variabel acak Gaussian, maka unjuk kerja BER TC 8PSK dengan kehadiran CCI pada kanal berfading dapat dianalisa dan dihitung dengan menggunakan metode standar Gaussian approximation (SGA), alternative Gaussian approximation (AGA) dan metoda first error event (FEE). Metode FEE digunakan sebagai pembanding untuk melihat keakuratan metode SGA dan AGA. Dari hasil analisa terlihat bahwa unjuk kerja BER TC 8PSK dengan metode SGA lebih akurat dibandingkan dengan metode AGA.

Abstrak :
The BER performance of trellis coded (TC) 8PSK with 2-branch selection (SC) and maximal ratio combining (MRC) diversities on mobile satellite communication system, which channel characterized by Nakagami fading channel is investigated. The special case of 2 branch SC and MRC diversities on independent and spatially correlated Nakagami fading are analyzed in detail, It is shown that the BER performance of TC 8PSK with diversity is better than that system without diversity, and the BER performance of system with diversity increases with increasing the Nakagami fading parameter m. Although the correlation between branches causes signal-to-noise ratio (SNR) loss relative to uncorrelated fading case for 2 branches SC and MRC diversities, the SC and MRC diversities can lead the diversity gain, that is, the improvement of BER performance of TC 8PSK with diversity is obtained over the TC 8PSK without diversity. In addition, the effect of antenna separation which causes cross correlation between the fading signals envelops on the performance of TC 8PSK with 2 branch SC and MRC diversities is also considered.

Abstrak :
Trellis coded modulation (TCM) formats with their excellent bandwidth and power efficiency have been widely employed in various communication systems. For mobile satellite communications, trellis coded (TC) M-ary phase shift keying (MPSK) is the primary candidate modulation technique. In the first generation mobile satellite systems, co-channel interference (CCI) does not pose a serious problem. However, second generation systems are expected to reuse frequency to increase the orbit slot spectral efficiency. Then the CCI from adjacent beams and adjacent satellite will be dominant factor determining the system performance and overall capacity. Mobile satellite communication is also suffered from strong variations of the received signal power due to the multipath fading. Typically, mobile satellite channels are modeled as Rician or Nakagami fading; that is the received signal consists of a constant line of sight signal component and a Rayleigh distributed diffuse signal component. Therefore, the performance of system on mobile satellite channels is subject to both fading and CCI. TCM and antenna diversity are two attractive methods to combat fading and CC1 effects in the mobile satellite communication systems. The research focuses on the using of TCM and antenna diversity to combat the fading and CCI effects on mobile satellite system, and analyze their performance characterized by bit error rate (BER). Because of multipath propagation , the mobile satellite communication channel is modeled as a Rician or Nakagami fading channel. This report, the BER performance of TC asymmetric MPSK with CCI and TC asymmetric MPSK with diversity on mobile satellite communication systems will be investigated and analyzed. First, the BER performance of TC- asymmetric MPSK in the presence of undesired CCI with multiple interferers and fading channel is investigated. The fading statistic for desired signal is Nakagami fading and the undesired interference signals are Rayleigh fading. We assume that all the interferers are unmodulated because most of errors are produced by Rayleigh fading itself rather than the modulating sequence. This model assumes that all interfering signals have aligned symbol timing and no cross channel interference symbol interfering (ISi) effects. The desired signal is assumed to have Nakagami distribution implying that a dominant multipath exists in transmission. The desired and the interfering carrier have no phase coherence. We derive the BER performance of TC asymmetric MPSK in the presence CCI and fading channels by using the first error event method. It is shown that the BER performance of TC asymmetric MPSK in the presence of CCI is better than that of system with asymmetric MPSK. The BER performance of TC asymmetric MPSK is improved as increasing either the Nakagami fading parameter or the value of signal-to-interference ratio (SIR). As the Nakagami fading parameter is increased the phase signal of MPSK is also increased. Second, the BER performance of TC MPSK with 2 branch selection combining (SC) and maximal ratio combining (MRC) diversities on independent and spatially correlated Nakagami fading channel are investigated. The upper bound bounds using the transfer function bounding technique are derived and several numerical results are shown. Is shown that the BER performance of TC 8PSK with MRC diversity is better than that of system with SC diversity. Although the correlation between branches causes the signal-to-noise ratio (SNR) loss (relative to independent fading case) for SC and MRC diversities, the diversity can lead to achieve the diversity gain compared to the system without diversity. Third, the BER performance of TC 8PSK in the presence of undesired CCI with multiple interferers and fading channel is investigated by using computer simulation. The fading statistic for desired signal is Nakagami fading and the undesired interference signals are characterized by Rayleigh fading. The I3ER performance of TC 8PSK in the presence CC1 and fading channels is simulated by using the first error event method. It is shown from the result that the simulation result of the performance of TC 8PSK in the presence CCI and fading channels is closed to the analytical result.

Abstrak :
ABSTRAK
Pada skripsi ini dianalisa kinerja dari modulasi trellis coded (TC) 2FSKJ4PSK dengan kode fasa dihilangkan sebagian pada kanal additive white Gaussian noise (AWGN) dan kanal fading Rayleigh. Kinerja TC 2FSKI4PSK dengan fasa dihilangkan sebagian yang dianalisa dinyatakan oleh jarak bebas Euclidean kuadrat (d~ ) dan bit error rate (BER) untuk kanal AWGN dan kanal fading Rayleigh Konstelasi 2FSKJ4PSK yang digunakan memiliki jarak antara sinyal 0 dan sinyal 3 yang lebih besar daripada konstelasi sinyal yang digunakan oleh Dr. Gunawan [1). Hasil diperoleh dfnY maksimum sebesar 8 untuk 4-keadaan dan 12 untuk 8-keadaan trellis_ Kinerja BER TC 2FSKJ4PSK dengan kode fasa dihilangkan sebagian yang barn tidak lebih balk daripada konstelasi yang digunakan dalam referensi [I) untuk 4-keadaan dan 8-keadaan trellis baik pads kanal AWGN maupun kanal fading Rayleigh.

---