PCS Base Stations Research Articles

Realization of FPGA based numerically Controlled Oscillator

Numerically Controlled Oscillator (NCO) is an important components in many Digital Communication Systems such as Digital Radio and Modems, Software Defined Radios, Digital Down/Up converters for Cellular and PCS base stations etc. A common method for digitally Generating a complex or Real valued sinusoid employs a Look-Up table based scheme. The NCO Design is first simulated and optimized on the software tool Xilinx 10.1 and then coded in VHDL for Hardware Realization. The Designs are tested on Xilinx Spartan2 FPGA Development Platform. The test Results are matching with theoretical and simulated results. This paper presents a FPGA-based Implementation method which can greatly improve the performance, shorten development cycle and reduces cost. Keywords - Numerically Controlled Oscillator, FPGA, Look-up table, Register

Measurement of angular and distance correlation properties of log-normal shadowing at 1900 MHz and its application to design of PCS systems

This paper investigates the correlation properties of shadow fading as a function of the angle between two PCS base stations over urban, light urban, and suburban terrain. Results from this study are relevant to the analysis of interference, handoff gain, and to various frequency planning applications in modern cellular and PCS systems. Using a significantly larger data set than previous experiments, we observed that on the average, the shadow fading components of the signals are not correlated, even at small angles. Our results contradict the conventional wisdom, as expressed in several papers, which says that there is relatively high correlation at small angles. Our results indicate that a mathematically simpler uncorrelated model for the relationship between signals from multiple base stations at small angles can be used in analysis tools. Distance correlation measurements computed by forming the autocorrelation function on a large number of data sets showed that the correlation distance of the shadowing process ranges from about 25 to 100 m.

Design of a wideband microstrip array antenna for PCS and IMT‐2000 service

AbstractIn this letter, a wideband microstrip array antenna for a PCS and IMT‐2000 base station is designed. To obtain the wideband characteristic, we utilized a multilayered structure composed of foam materials and a parasitic element with an aperture‐coupled feeding network. The return‐loss characteristic is improved by placing the gaps between coupling slots. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 261–265, 2001.

A low‐cost microstrip‐line‐fed shorted‐patch antenna for a PCS base station

AbstractA low‐cost microstrip‐line‐fed shorted‐patch antenna suitable for applications in a PCS (1710–1880 MHz band) base station is presented. Both the shorted patch and the 50 Ω microstrip feed line have an air substrate, and the material cost is thus reduced to be minimum. And by using a pair of shorting plates of proper widths for shorting the radiating patch to the antenna's ground, the proposed antenna can be directly fed by the 50 Ω microstrip feed line, which greatly simplifies the antenna's impedance‐matching design. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 146–148, 2001.

Transmit filters for wireless basestations

Transmit filters for PCS basestation applications will be required to handle peak power levels up to hundreds of watts. To achieve this goal, filters based on high temperature superconductor patch resonators have been investigated. Among these, circular resonators operating in the TM/sub 010/ mode, due to its radial current flow, are particularly promising. However, the large size of these resonators places limits on the frequency and number of poles of planar filters. As an alternative, we have designed and tested 3-pole filters based on the vertical coupling of stripline circular resonators. For operation in the PCS frequency range each resonator was fabricated from two double-sided YBCO films deposited on 2-in. lanthanum aluminate substrates. The measured Q of these resonators at 50 K and 2 GHz was higher than 100,000 and is limited by the dielectric losses of the substrate. The measured circulating power of above 1 MW at 50 K extrapolates to power handling, for a 9-pole, 1% bandwidth filter, of more than 1 kW. A 1.2% bandwidth, 3-pole filter based on this design has been characterized, and does not show any power dependence up to 72 W, the limit of our test setup.

A two-element adaptive antenna array for IS-136 PCS base stations

We describe computer simulation and laboratory performance results of a real-time two-element adaptive antenna array testbed for the uplink of a 1.9-GHz IS-136 PCS base station. Our simulations and real-time experimental results with a channel emulator show less than a 1-dB implementation loss as compared to theoretical results for the noise-only case. With interference, at low fading rates the implementation loss to is only a few decibels. However, the performance degrades with increasing fading rate, such that the adaptive array performance is similar to maximal ratio combining at 60-m/h fading rates (179 Hz at 1.9 GHz).