• Journal of Institute of Control, Robotics and Systems
• /
• v.22 no.11
• /
• pp.977-983
• /
• 2016

This paper proposes a novel code-tracking scheme to track the fine code synchronization for BOC (pn,n)-modulated global navigation satellite system signals in a repeat-back jamming environment. The correlation function of BOC (pn,n)-modulated signals has several peaks. The correlation function in the advanced offset region remains almost unchanged due to the repeat-back signals being received later than a line-of-sight signal in the same multipath signal receiving case. Additionally, the combined pseudo-random noise signal can be treated as repeat-back jamming signals, like multipath signals. In this paper, we propose a novel code-tracking scheme utilizing the advantages of using a combined pseudo-random noise signal in the advanced offset region and verify its performance through simulation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.8
• /
• pp.3053-3059
• /
• 2010

In DS-CDMA method, Mobile Stations own jointly one radio channel and are made to use a PN code (Pseudo-Noise Code) for the purpose of minimize interference. However, corelation value of PN code is one when time delay is zero but the corelation value is 1 / N when time delay is not 0. Therefore corelation characteristic does not fully attained. As a result, when the user increase, the performance degradation and system capacity problem will be able to occur by interference among users. In this paper, the PN code has ideally self corelation. It was proved that PN code could depress interference from other users in multiple access system.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.8
• /
• pp.37-44
• /
• 1997

We implemented a code searcher which is used for the PN(pseudo noise) code acquisition in CDMA cellular mobile station. To reduce the reuired hardware and the code acquisition time, we used the double dwell structure which is an effective serial code acquisition metho. We designed a code acquisition has acquired within 1/2 PN chip range. The code searcher is implemented using 0.8 micron code searcher is successfully working in CDMA cellular mobile station and it satisfies the code acquisition time specified in IS-95 standard.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.11
• /
• pp.14-18
• /
• 2010

We propose a performance analysis of code division multiple access systems based on the combination of M-ary and pseudo-noise spreading. In spite of the total bandwidth expansion being equal, there is a difference in the system performance by the combination of M-ary and pseudo-noise spreading. The proposed analysis uses each bandwidth expansion, caused by M-ary and pseudo-noise spreading, rather than the total bandwidth expansion. If the signal to interference plus noise ratio becomes high, it is more effective to reduce biterror rate by bandwidth expansion of M-ary modulation rather than that of pseudo-noise spreading. Since the proposed analysis reflects the effect of the M-ary modulation, the bit error rate from the proposed analysis is closer to the results of the simulation than from the conventional analysis.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.9A
• /
• pp.678-683
• /
• 2003

The pseudo-noise (PN) code acquisition based on the sequential estimation (SE) proposed by Ward performs well only at relatively high chip signal-to-noise ratios (SNRs). In this paper, a seed accumulating sequential estimation (SASE) method and a PN code acquisition system based on it are proposed, which perform well at low chip SNR (of practical interest) also. Then, the mean acquisition time performance of the proposed system is investigated. Numerical results show that the system based on the SASE performs dramatically better than that based on the SE at low chip SNR, and the improvement becomes larger as the period of PN code increases.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2003.11a
• /
• pp.581-584
• /
• 2003

It is important to know phase offsets of PN (Pseudo Noise) sequences in spread spectrum communications since the acquisition is equivalent to make a phase offset between a receiving PN sequence and a PN sequence of local PN generator be identical. In this paper, a phase offset enumeration method for PN sequences with error detection, and its application to the synchronization are proposed. The phase offset enumeration far an n-tuple PN sequence and its error detection are performed when one period of the sequence is received. Once the phase offset of the receiving sequence is calculated, we can easily accomplish the synchronization by initializing shift registers of a local PN generator according to the phase offset value. The mean acquisition time of the proposed synchronization method is derived analytically, and we see that the method acquires very fast acquisition in the high SNR (Signal-to- Noise Ratio) environment.

• The KIPS Transactions:PartC
• /
• v.13C no.3 s.106
• /
• pp.311-316
• /
• 2006

We propose the optical sensor network using optical CDMA with bipolar receiver and modified Pseudorandom Noise codes which are widely used in the wireless communication network. We numerically analyze the performances in the optical sensor network. In the proposed network, multiple access interferences between two sensors are suppressed by performing synchronization between the optical encoder and the optical decoder and adjusting the delay times of optical delay lines. Numerical simulations confirm that the performance can be acquired by suppressing the beat noise among optical signals as the number of sensors increases.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.10A
• /
• pp.816-829
• /
• 2003

In this paper, we evaluate the performance of PN (Pseudo Noise) code based time hopping sequences for M-ary UWB (Ultra Wide Band) multiple access systems using the equicorrelated signal sets. In particular, we consider two different types of M-ary UWB systems in UWB indoor wireless multipath channels: The first type of the systems (System #1) has identical symbol transmission rate regardless of the number of symbols M since the length of signal pulse train is fixed while M increases, and the second type of the systems (System #2) has the same bit transmission rate regardless of M since the length of signal pulse train is extended according to the increase of M. We compare the proposed systems with those using the ideal random time hopping sequence in terms of the symbol error rate performance. Simulation results show that the PN code based time hopping sequence achieves quite good performance which is favorably comparable to that of the ideal random sequence. Moreover, as M increases, we observe that System #2 shows better robustness against multiple access interference than System # 1.

• Proceedings of the IEEK Conference
• /
• 2000.06a
• /
• pp.252-255
• /
• 2000

In this paper, a fast pseudo-noise (PN) code acquisition with novel adaptive architecture is presented in direct-sequence spread- spectrum (DS-SS) systems. Since an existing acquisition system has a fixed correlation tap size and threshold value, this system cannot adapt to various mobile communication environments and results in a low detection probability or a high false alarm rate and long acquisition time. Therefore, if a correlation tap size and a threshold value can be controlled adaptively according to received signals, problems of ail existing system will be solved. The system parameter varies adaptively by using constant false alarm rate (CFAR) algorithm well known in a field of detection and proposed signal-to-noise ratio (SNR) measurement system. By deriving formulas of the proposed system, the performance is analyzed.

• Proceedings of the IEEK Conference
• /
• 2005.11a
• /
• pp.69-72
• /
• 2005

In this paper, pseudo noise (PN) code acquisition performance with multiple antennas in a UWB time hopping/code division multiple access system is analyzed. The closed form for the conditional probability is derived, using the Gauss-Hermite quadrature formula, when the signal with Gaussian distribution goes through the lognormal fading channel. The performance comparison of the above mentioned schemes shows that the code acquisition performance with a diversity combining technique, especially when increasing the number of antennas, is more robust than that using no diversity.