Noise suppression using optimum filtering of OCs generated by a multiport encoder/decoder

We propose a novel receiver configuration using an extreme narrow band-optical band pass filter (ENB-OBPF) to reduce the multiple access interference (MAI) and beat noises in an optical code division multiplexing (OCDM) transmission. We numerically and experimentally demonstrate an enhancement of the code detectability, that allows us to increase the number of users in a passive optical network (PON) from 4 to 8 without any forward error correction (FEC)

Cdma blind channel equalization: a weighted subsface a proach

This paper considers the problem of blind demodulation of multiuser information symbols in a direct-sequence code-division multiple access (DS-CDMA) environment. Channel estimation and symbol detection in the presence of both multiple access interference (MAI) and intersymbol interference (ISI) is carried out with second order statistics methods from the received data. This problem is similar to direction of arrival (DOA) estimation, where many solutions like the MUSIC algorithm orPeer ReviewedPostprint (published version

Uplink performance investigations of the service area based beyond 3G system JOINT

The joint transmission and detection integrated network (JOINT) is a novel OFDM-based vNP00 air interface solution for beyond 3G (B3G) mobile radio communications systems WMSL02. JOINT aims at eliminating the multiple access interference (MAI) and improving the system capacity by the application of MIMO techniques applied in the service area (SA) based system architecture. In a SA based structure the intra-SA multiple access interference (MAI) can be easily combated by algorithms like, e.g., joint detection (JD) Kle96,Ver98 in the uplink. The parameters like, e.g., the SA size, the system load and reuse factor show great impacts on the system performances, in terms of the average bit error rate (BER) and the BER statistics. Spectrum efficiency of JOINT is also investigated based on the simulation results

Statistical Modeling of Multiple Access Interference Power: a Nakagami-m Random Variable

This paper proposes a statistical model for the total multiple access interference (MAI) power for both Direct-Sequence Code Division Multiple Access (DS-CDMA) and Multicarrier Code Division Multiple Access (MC-CDMA) systems. We consider the use of both Walsh-Hadamard (WH) and Gold spreading codes transmitting over the asynchronous uplink channel. Detailed signal models of both CDMA systems are derived illustrating the production of MAI under asynchronous conditions. The paper demonstrates the Gaussian nature of the total MAI and shows that the probability density function (pdf) of the total MAI power can be very accurately characterized by the Nakagami-m distribution

Performance analysis of a 2-D time-wavelength OCDMA wavelength-aware receiver with beat noise

The effect of beat noise on two-dimensional time-wavelength optical code-division multiple-access systems utilising wavelength-aware receivers is examined. A derivation of a general formula for the bit error probability taking into consideration multiple access interference (MAI) and other noise sources is given. In addition, a comparison between the system performance of such a receiver and the traditional configuration is presented. Studies to date that have focused only on the MAI limited case showed that the wavelength-aware configuration yields a better performance when compared to the traditional receiver. When beat noise is considered, the numerical results reveal that the performance of wavelength-aware receiver is very sensitive to beat noise and is not superior over the traditional receiver

ANALISA PARALLEL INTERFERENCE CANCELLATION (PIC) SEBAGAI TEKNIK PENANGANAN MULTIPLE ACCESS INTERFERENCE (MAI) PADA WiMAX

ABSTRAKSI: Fokus dari sistem komunikasi wireless (nirkabel) dewasa ini adalah menyediakan layanan dengan data rate (laju data) yang tinggi bahkan untuk layanan multimedia dan akses internet. Salah satu cara yang dapat dilakukan untuk mendukung hal tersebut adalah menggunakan teknik modulasi multicarrier. Sistem OFDM (Orthogonal Frequency Division Multiplexing) merupakan skema komunikasi multicarrier dimana antar frekuensi subcarriers saling orthogonal dan dapat saling overlapping.Karena kelebihan tersebut, sistem OFDM dipakai sebagai teknik modulasi dan akses jamak, lebih dikenal dengan OFDMA (Orthogonal Frequency Division Multiple Access), pada teknologi WiMAX (Worldwide Interoperability for Microwave Access), Broadband Wireless Access yang dianggap sebagai generasi selular keempat (4G). Performansi sistem multiuser Wimax sangat dipengaruhi salah satunya oleh efek Multiple Access Interference (MAI). Pada arah uplink system Orthogonal Frequency Division Multiple Access (OFDMA), Multiple Access Interference (MAI) terjadi karena perbedaan Carrier Frequency Offsets (CFO) dari user yang berbeda di receiver (penerima). Salah satu cara memperbaiki performansi system multiuser Wimax terkait efek MAI adalah menggunakan teknik multiuser detection (MUD). Ada beberapa jenis multiuser detection (MUD), seperti Successive Interference Cancellation (SIC), Parallel Interference Cancellation (PIC), Decorrelator, MMSE, dan lainnya.Pada tugas akhir ini performansi sistem dianalisa dengan menggunakan metode Parallel Interference Cancellation (PIC). PIC merupakan jenis multiuser detection sub optimum yang paling sederhana dalam pengaplikasiannya pada jaringan WiMAX yang menggunakan teknik OFDMA sebagai akses jamaknya. simulasi menunjukkan peningkatan performansi sistem. Hal ini ditunjukkan dengan adanya perbaikan SNR sebesar 6 dB untuk mencapai BER 10-3 pada kondisi jumlah user 4, kecepatan user 3 km/jam dan jumlah stage PIC yang digunakan adalah 2 stage dibandingkan dengan tanpa menggunakan PIC. Performansi sistem pun menurun seiring dengan pertambahan kecepatan user. Peningkatan pada nilai SNR ditunjukkan dengan metode dari Parallel Interference Cancellation (PIC) dibandingkan dengan kinerja tanpa menggunakan PIC.Kata Kunci : OFDM, OFDMA, WiMAX, PIC, MUDABSTRACT: The focus of the wireless communication system today is providing services with data rate is high even for multimedia services and Internet access. One way that can be done to encourage it is to use multicarrier modulation technique. OFDM (Orthogonal Frequency Division Multiplexing) system is a scheme where the multicarrier communication between mutually orthogonal frequency subcarriers and overlapping each other.Because of these advantages, OFDM systems are used as the modulation technique and multiple access, better known as OFDMA (Orthogonal Frequency Division Multiple Access), the WiMAX technology (Worldwide Interoperability for Microwave Access) Broadband Wireless Access is considered a fourth-generation wireless (4G). Wimax multiuser system performance is strongly influenced by the effects of one Multiple Access Interference (MAI). In the uplink direction systems Orthogonal Frequency Division Multiple Access (OFDMA), Multiple Access Interference (MAI) occurs because of differences Carrier Frequency Offsets (CFO) of different users at the receiver. One way to improve performance multiuser Wimax systems related MAI effect is to use the technique of multiuser detection (MUD). There are several types of multiuser detection (MUD), such as successive Interference Cancellation (SIC), Parallel Interference Cancellation (PIC), Decorrelator, MMSE, and more.In this final assignment system performance will be analyzed by using the method of Parallel Interference Cancellation (PIC). Parallel Interference Cancellation (PIC) is a type of sub-optimum multiuser detection is the simplest to apply in WiMAX networks using OFDMA as access techniques plurality. Simulations show the performance improvement system. This is demonstrated by the improvement of SNR by 6 dB to achieve BER of 10- 3 on the condition of the user 4, user speed of 3 km / h and the number of PIC stages are used compared with 2 stage without using the PIC. Any system performance declines with the increase speed of the user. The increase in SNR values shown by the method of Parallel Interference Cancellation (PIC) compared with the performance without using the PIC.Keyword: OFDM, OFDMA, WiMAX, PIC, MU

Large Families of Ternary Sequences with Aperiodic Zero Correlation Zone Sequences for a Multi-Carrier DS-CDMA System

A new method for generating families of ternary spreading sequences is presented. The sequences have aperiodic zero correlation zones and large families are created for a specific sequence length. The sequences are proposed as spreading sequences to provide high capacity and cancel multipath and multiple access interference (MAI) in a single carrier (SC) or multi-carrier (MC) direct-spread code division multiple access (DS-CDMA) system. A Multi-carrier DS-CDMA system is simulated that employs the new sequences as spreading sequences in a multipath channel. Bit error rates (BER) and frame error rates (FER) for a range of Eb/No values are presented and it is demonstrated that the proposed sequences improve the BER and FER performance when used in place of masked Walsh Codes for the frequency selective fading channel evaluated, when a single correlator receiver is used on each sub-carrier

Statistical Modeling of Bit-Error-Rates in Asynchronous Multicarrier CDMA and Direct-Sequence CDMA Systems

This paper presents a method for modeling the bit-error-rate (BER) probability density functions (pdf) of asynchronous Multicarrier Code Division Multiple Access (MC-CDMA) and Direct-Sequence Code Division Multiple Access (DS-CDMA) systems. An uplink channel is considered and it is assumed that the only channel distortion introduced by the channel is caused by the timing misalignments. Deterministic spreading sequences are used and the pdfs of each interferer'’s multiple access interference (MAI) are determined as a function of timing offset. A Nakagami-m distribution is fitted to the pdf of the total MAI power and the BER pdf is obtained directly from this Nakagami-m pdf. Both Walsh-Hadamard (WH) and Gold sequences are analyzed and the mean BERs are compared amongst the two multiple access systems for both sets of spreading sequences of varying lengths. The results suggest a higher resistance to MAI in the MC-CDMA technique for the considered environment