Academic literature on the topic 'FO-CDMA'

Dalam perjalanannya teknologi telekomunikasi berbasis Code Division Multiple Acces (CDMA) adalah teknologi telepon seluler yang sudah ada di dunia hampir 20 tahun lebih. Setiap kali ada penantangnya dari teknologi Global System fo Mobile Communication (GSM), teknologi CDMA selalu berhasil menandinginya. Teknologi CDMA yang berawal di Amerika Serikat ini telah dicermati selalu mengimbangi perkembangan teknologi GSM . Pada saat itu GSM pertama muncul dan mengancam, teknologi CDMA dikembangkan menjadi CDMA 1X sebagai jawaban terhadap ancaman GSM. Kemudian ketika operator GSM meluncurkan GSM/EDGE, sekali lagi CDMA dikembangkan menjadi teknologi CDMA Evolution-Data Optimized (CDMA/EV-DO). Tetapi dengan munculnya 3G-UMTS dan HSDPA, kemudian dengan adanya rencana LTE (Long Term Evolution dari kamp GSM) dan WiMax dari dunia wireless broadband, kebanyakan operator dan carrier di Amerika Serikat enggan mendukung perkembangan teknologi CDMA lebih lanjut. Melihat perkembangan teknologi CDMA di dunia yang demikian tentu saja sedikit banyak mempengaruhi perkembangan CDMA di Indonesia tidak terkecuali PT. Indosat Tbk. dengan brand Starone yang sudah berlangsung hampir 10 tahun sejak kemunculannya pada tahun2004. Melihat bisnis CDMA ke depan khususnya Starone perlu dilakukan penelitian yang dapat menggambarkan kelanjutan bisnis ini bisa dikembangkan atau tidak.Dengan pendekatan teori Balanced Scorecard dan Gap Analysis serta melihat profil keuangan yang mempunyai kecenderungan revenue yang menurun secara drastis, darisisi pelanggan jumlah pelanggan aktif semakin hari semakin menurun, bisnis proses internal yang tidak memasukkan Key Performance Indicator (KPI) sebagai tolok ukurutama dalam kinerja operasional serta pertumbuhan dan pembelajaran dari Starone ini dapat disimpulkan bahwa bisnis ini secara kontinuitas tidak dapat dilanjutkan lagi. Selanjutnya dicarikan jalan keluar bagi pelanggan yang masih berada pada layananStarone untuk menggunakan teknologi lain sehingga layanan komunikasi masih bisa dirasakan oleh pelanggan.Kata Kunci: Code Division Multiple Access, Strategy, Balanced Scorecard, Key Performance Indicato,Gap Analysis

Dalam perjalanannya teknologi telekomunikasi berbasis Code Division Multiple Acces (CDMA) adalah teknologi telepon seluler yang sudah ada di dunia hampir 20 tahun lebih. Setiap kali ada penantangnya dari teknologi Global System fo Mobile Communication (GSM), teknologi CDMA selalu berhasil menandinginya. Teknologi CDMA yang berawal di Amerika Serikat ini telah dicermati selalu mengimbangi perkembangan teknologi GSM . Pada saat itu GSM pertama muncul dan mengancam, teknologi CDMA dikembangkan menjadi CDMA 1X sebagai jawaban terhadap ancaman GSM. Kemudian ketika operator GSM meluncurkan GSM/EDGE, sekali lagi CDMA dikembangkan menjadi teknologi CDMA Evolution-Data Optimized (CDMA/EV-DO). Tetapi dengan munculnya 3G-UMTS dan HSDPA, kemudian dengan adanya rencana LTE (Long Term Evolution dari kamp GSM) dan WiMax dari dunia wireless broadband, kebanyakan operator dan carrier di Amerika Serikat enggan mendukung perkembangan teknologi CDMA lebih lanjut. Melihat perkembangan teknologi CDMA di dunia yang demikian tentu saja sedikit banyak mempengaruhi perkembangan CDMA di Indonesia tidak terkecuali PT. Indosat Tbk. dengan brand Starone yang sudah berlangsung hampir 10 tahun sejak kemunculannya pada tahun2004. Melihat bisnis CDMA ke depan khususnya Starone perlu dilakukan penelitian yang dapat menggambarkan kelanjutan bisnis ini bisa dikembangkan atau tidak.Dengan pendekatan teori Balanced Scorecard dan Gap Analysis serta melihat profil keuangan yang mempunyai kecenderungan revenue yang menurun secara drastis, darisisi pelanggan jumlah pelanggan aktif semakin hari semakin menurun, bisnis proses internal yang tidak memasukkan Key Performance Indicator (KPI) sebagai tolok ukurutama dalam kinerja operasional serta pertumbuhan dan pembelajaran dari Starone ini dapat disimpulkan bahwa bisnis ini secara kontinuitas tidak dapat dilanjutkan lagi. Selanjutnya dicarikan jalan keluar bagi pelanggan yang masih berada pada layananStarone untuk menggunakan teknologi lain sehingga layanan komunikasi masih bisa dirasakan oleh pelanggan.Kata Kunci: Code Division Multiple Access, Strategy, Balanced Scorecard, Key Performance Indicato,Gap Analysis

To take advantage of the high speed in an optic fiber, one of the basic concept in fiber optic communication is to allow several users to simultaneously transmit data over the channel. One technique that provides multiple access is it fiber optic-code division multiple access (FO-CDMA). In FO-CDMA each user is assigned one or more signature sequences called codewords, which are subsets of a type of optical orthogonal code (OOC). The channel input/output consists of the superposition of several users codewords and at the receiver end an optical correlator extracts the information.

In the parallel code constructions, presented in this report, each user j is assigned a subset Cj from a code C. The subsets are disjoint and their union is the whole set C. A new way to map the information bits is to insert up to L zeros before each codeword from Cj and let this represent information aswell. This gives high rates for active users but an investigation is needed to ensure that this does not compromise the systems wanted property of sending information with a small probability of errors for all users. Therefore a simulation environment has been implemented in Matlab.

The result from these simulations shows that BER for the L parallel codes is acceptable and not much higher than for the traditional constructions. Because of the higher rate these construction should be preferred but an analysis if a hardware implementation is possible.

Asynchronous multiplexing schemes are efficient than synchronous schemes, in a bursty traffic environment of multiple access local area network (LAN), as fixed bandwidth is not allocated among the users and there is no access delay. Fiber- Optic Code-Division Multiple Access (FO-CDMA) is one such asynchronous multiplexing scheme suitable for high speed LAN networks. While FO-CDMA offers potential benefits it also faces challenges in three diverse areas which are 1) coding algorithms and schemes 2) advanced encoding and decoding hardware and 3) network architecture. In this thesis, as a solution to the first challenge, we propose the design and construction of a new family of codes, wavelength/time multiple-pulses-per-row (W/T MPR) codes. These codes have good cardinality, spectral efficiency and minimal cross-correlation values. Performance analysis of the W/T MPR codes is carried out and found to be superior to other codes. In unipolar 1-D Optical Orthogonal Codes (OOCs) proposed by Salehi et al., the ratio of code length/code weight grows rapidly as the number of users is increased for a reasonable weight. Hence, for a given pulse width, the data rate decreases or in other words for a given data rate very narrow pulses have to be used, because of which dispersion effects will be dominant. To overcome the drawbacks of non-linear effects in large spread sequences of 1-D unipolar codes in FO-CDMA networks, several two-dimensional codes have been proposed. Wavelength-time (W/T) encoding of the two-dimensional codes is practical in FO-CDMA networks. W/T codes reported so far can be classified mainly into two types: 1) hybrid sequences, where one type of sequence is crossed with another to improve the cardinality and correlation properties and 2) matrix codes, 1-D sequences converted to 2-D codes or 2-D codes by construc- tion, to reduce the ’time’ spread of the sequences/codes. Prime-hop and eqc/prime W/T hybrid codes have been proposed where one type of sequence is crossed with another to improve the cardinality and correlation properties. Other constructions deal with conversion of 1-D sequences to 2-D codes either by using Chinese remainder theorem or folding GoLomb rulers. W/T single-pulse-per-row (W/T SPR) codes are 2-D codes constructed using algebraic method Addition Modulo Group operation. Motivation for this work: To design a family of 2-D codes which have the design choice of length of one dimension over the other, and also have better cardinality, spectral efficiency and also low cross-correlation values (thereby have low BER) than that of the reported unipolar 2-D codes. In this thesis, we describe the design principles of W/T MPR codes, for in- coherent FO-CDMA networks, which have good cardinality, spectral efficiency and minimal cross-correlation values. Another feature of the W/T MPR codes is that the aspect ratio can be varied by trade off between wavelength and temporal lengths. We lay down the necessary conditions to be satisfied by W/T MPR codes to have minimal correlation values of unity. We analytically prove the correlation results and also verify by simulation (of the codes) using Matlab software tool. We also discuss the physical implementation of the W/T MPR FO-CDMA network with optical encoding and decoding. We show analytically that when distinct 1-D OOCs of a family are used as the row vectors of a W/T MPR code, it will have off-peak autocorrelation equal to ‘1’. An expression for the upper bound on the cardinality of W/T MPR codes is derived. We also show that 1-D OOCs and W/T SPR codes are the limiting cases of W/T MPR codes. Starting with distinct 1-D OOCs, of a family, as row vectors, we propose a greedy algorithm, for the construction of W/T MPR codes and present the repre- sentations of the results. An entire W/T MPR code family, generated using greedy algorithm, is simulated for various number of interfering users. Performance analysis of the W/T MPR codes and their limiting cases is carried out for various parameter variations such as the dimensions of wavelength, time and weight of the code. We evaluate the performance in terms of BER, capacities of the networks, temporal lengths needed (to achieve a given BER). Multiple access interference (MAI) signal can be reduced, by using a bistable optical hard-limiter device in the W/T MPR code receiver, by eliminating those signal levels which exceed a certain preset level. Performance analysis of the W/T MPR codes and their limiting cases is studied for various parameter variations. For given wavelength × time dimensions, we compare various W/T codes, whose cardinalities are known, and show that W/T MPR family of codes have better cardinality and spectral efficiency than the other (reported) W/T codes. As W/T MPR codes are superior to other W/T codes in terms of cardinality, spectral efficiency, low peak cross-correlation values and at the same time have good performance, makes it a suitable coding scheme for incoherent FO-CDMA access networks.