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The Viterbi algorithms of the tail biting convolutional code in TD-LTE system is introduced. Aiming at the decoding commons for the convolutional codes of TD-LTE system, this paper presents an implementation program of Viterbi decoding algorithm based on the soft-decision, and validates the algorithm by means of FPGA in the Xinlinx's XC5VSX95T chip, the program simplifies some decoding operations. The simulation result shows that the program has a good feasibility and can meet the decoding requirements.

PoC is a group communication service using VoIP technology based on 3G cellular network packet domain carrier. ROHC can complete the header compression in PS domain of 3G network, which can improve the efficiency of wireless transmission. This paper analyzes the working principle and the operation modes of ROHC, designs the processing of the compressor and decompressor. Simultaneity an improved algorithm applied to the U mode is presented against PoC service features, with great benefits on cost and quality of service (QoS).

A UV-visible spectrometer based on a micro-silicon-slit was developed by using the Micro-electro-mechanical System(MEMS) technology.The generated reasons of the stray-light from the UV-visible spectrometer were analyzed and the relationships between the straightness and thickness of micro-silicon-slit with the stray-light were discussed.Then,an experimental verification was carried out for the stray-light caused by the slit straightness.Furthermore,a new combining filter method was proposed to solve the problem that the radiation power of UV region is much lower than that of visible light region and it is seriously affected by the stray-light when the spectra are measured by a spectrometer with the halogen tungsten light source.The method combines a neutral density filter and a balanced filter in the front of the micro-silicon-slit and the detector to balance the radiation powers of different spectral regions and to inhibit the stray-light of UV spectrometer.It is shown that the stray-light of the UV-visible spectrometer has been reduced by 23% as compared with that by using the traditional method.

Swept-source optical coherence tomography (SS-OCT) has high sensitivity and signalnoise ratio compare with time-domain optical coherence tomography and spectral-domain optical coherence tomography. Therefore, SS-OCT is the form of Fourier domain optical coherence tomography predominantly used in experimental research and biomedical image. However, polygon tunable laser-based SS-OCT suffers sweep range fluctuation and spectral misplacement. Under certain circumstances, in the current resampling methods cross-correlation is widely used to align spectrum misplacement, and truncate A-lines in order to ensure the consistency of frequency-scanning range, which, however, degrades the image SNR and resolution. We use the Mach-Zehnder interference (MZI) signal to quantify and analyze this problem in two typical polygon tunable lasers. The periodical change of sweep range and spectrum misplacement show the instability derived from polygon mirror. The parallelism among unwrapped phase curves indicates that polygon tunable laser output spectra have consistent wavelength distributions, and thus it is suited to implement cross-correlation between MZI signals in time domain, and an unwrapped phase curve can represent the wavelength distribution of all A-lines.According to the above conclusions, we demonstrate a resampling method in which the zero-padding interpolation and cross-correlation are used to align A-lines in time domain and eliminate the residual phase noise caused by integer shift. Then the unwrapped phase curve that has a largest sweep range is used to resample all the aligned A-lines, and the interference signals can be fully utilized. The experiments for signal truncation and Pomelo fruit flesh indicate that the proposed method can improve image SNR but does not make the intensity image dislocated. The phase noise (3.9 mrad for a 49 dB SNR) from static mirror is close to theory limit after resampling, thus showing good phase stability and resampling precision. The proposed resampling method also needs less computational work than one-to-one resampling method because it only fits unwrapped phase curve and calculates interpolation coefficient once.

Group call communication can meet the demand of the different location users sharing the same information at the same time. In TD-SCDMA network, the group call communication is realized by the high-speed packet-switched domain (PS). TD-SCDMA network can provide a wide communication range and other multimedia services for the group call user. The group call communication includes the group call service and the presence service. The presence service is to achieve the efficient, reliable and fast connection of the group call service. In view of the communication features of group call service, the limited PS resources and the non realtime packet switching, TD-SCDMA network structure which supports the group call service is designed. At the same time, the functions of packet-switched domain equipments are described. Then it is a focused discussion that TD-SCDMA system adopts packet data link allocation mechanism for group call service. The PS protocols of the group call communication are given in detail. Finally, the group call communication is simulated by using OPNET software. The performance of group call and the impact on TD-SCDMA network PS are analyzed. The result shows that the PS resources can be efficiently shared by group call members after adopting the rational network structure and PS access mechanism. It provides technical support for the development of group call service based on TD-SCDMA network.

In order to enhance the performance of AlGaN/GaN high electron mobility transistor (HEMT) biosensor, millimeter grade AlGaN/GaN HEMT structure have been designed and successfully fabricated. Factors influencing the capability of the AlGaN/GaN HEMT biosensor are analyzed. UV/ozone is used to oxidize GaN surface and then 3-aminopropyl trimethoxysilane (APTES) self-assembled monolayer can be bound to the sensing region. This serves as a binding layer in the attachment of prostate specific antibody (anti-PSA) for prostate specific antigen detection. The millimeter grade biomolecule-gated GaN/AlGaN HEMT sensor shows a quick response when the target prostate specific antigen in a buffer solution is added to the antibody-immobilized sensing area. The detection capability of this biomolecule-gate sensor estimated to be below 0.1 pg/ml level using a 21.5 mm2 sensing area, which is the best result of GaN/AlGaN HEMT biosensor for PSA detection till now. The electrical result of the biomolecule-gated GaN/AlGaN HEMT biosensor suggests that this biosensor might be a useful tool for the prostate cancer screening.