The implementation of an RP front end for a BPSK transceiver also forms part of the work in this section. Furthermore, I would like to express my sincere appreciation to AA T for the donation of the software radio.
Poss ible extensions and topics of further study 10-7
LIST OF FIGURES / TABLES
CHAPTER!
INTRODUCTION
Motivation and focus of thesis
In the wireless communication industry, it is widely known that the RF front-end transceiver is one of the key elements of the communication system. Part of the analysis and results includes some theory on mixer noise figures and the effect of mixer noise on system performance.
HAPTER2
ANTENNA ARRAY THEORY
Introduction
To provide many directional patterns, it is necessary for the fields of the elements of the array to constructively interfere (add) in the desired directions and to destructively interfere (cancel each other) in the remammg space. In a series of identical elements, there are five controls that can be used to shape the overall pattern of the antenna [11]. a).
Basic concepts of antenna arrays
This results in the gain of the array (or equivalently the gain of the combined antenna) being equal to the sum of the gains of all the individual antennas. The array pattern drops to a low value on either side of the beam direction.
Applic ation of arrays in mobile communication system s [12)
In receive mode, this helps to reduce the contribution of these mobile phones in the database. An increase in the number of users of a mobile communication system without loss of capacity results in an increase in spectrum efficiency.
Demonstration of beamscanning using linear arrays
The array factor is a function of array geometry and excitation phase. Suppose that the maximum radiation of the array is required to be oriented at an angle So (00 ~ So ~ 18(0).
Mutual coupling
In addition, the current from the power distribution network into the array element is partially reflected due to the mismatch, as shown in the figure. A sample measured under these conditions is called an "element sample in an array environment" and is generally distinguished from an isolated element sample.
ANALOGUE AND DIGITAL BEAMFORMING
In trodu ction
ANALOG AND DIGITAL BEAM SHAPING CHAPTER 3. The property of a semiconductor diode of interest in phase shifter design is that its impedance can be varied with a change in the bias control voltage. ANALOG AND DIGITAL BEAMFORMJNG CHAPTER 3. The use of an adaptive array in a communications system requires some degree of compatibility between the signaling waveforms and the adaptive array. There are several reasons for this [47]:. a) The adaptive weights are random processes and they modulate the desired signal.
There are several reasons why the amplitude of the reference signal should be controlled [47]:. a) The amplitude of the reference signal determines the amplitude of the signals present at the output of the array, which must be within a certain range for the proper operation of the multipliers, etc., in the feedback loops.
Synopsis of some implemented adaptive array systems
The weighting and summing of the received signals is performed on the received RF signal which allows the use of an ordinary base station as a receiver. In a real system. the pilot signal can be used as part of the reference signal, but in the work reported in this paper, the antenna array is operated in a decision mode, which means that the reference signal is obtained by the detected symbols with phase and amplitude -adjustment to redistribute. . This method simulates a real adaptive array and therefore gives a realistic picture of the operation of practical adaptive array radio systems.
Due to the difference in application (center frequency, bandwidth, technology, etc.), a performance comparison of the above systems cannot be made.
CDMA CONCEPTS
Background
To understand why there is a demand for CDMA, it is necessary to know the background of the previous spread spectrum systems. Its strength in the military arena lies in its ability to resist enemy jamming and ensure secure communications. Its civilian mobile radio application was theoretically proposed in the late 1940s, but its practical use in the market did not occur until 40 years later due to many technical obstacles that had yet to be overcome.
The first commercial CDMA service was launched in Hong Kong in 1995, followed by launches in Korea and Pennsylvania.
Comparison between FDMA, TDMA and CDMA
CDMA is the first digital technology to meet the exact standards of the CTIA (Cellular Telecommunications Industry Association) [1]. In the IS-95 CDMA system using QPSK (on mobile) and OQPSK (on base) modulation, the speed of the final spread signal is 1.2288 MHz, resulting in an RF bandwidth of approximately 1.2 SrvrHz. Both the sidelobe power level and the mainlobe width are reduced by this Gaussian filter.
One of the parameters of interest in the design of the Gaussian baseband filter is the bandwidth time product (normalized 3dB bandwidth), Bb T where T is the data pulse width. The power spectrum density plot as a function of normalized frequency difference from the carrier center frequency Cf - fc)T, with the normalized 3dB bandwidth of the baseband Gaussian filter (Bb T) as a parameter is shown in Figure (4.6).
Simulation of a simple COMA system
It should also be noted that a decrease in sampling time results in an increase in simulation running time. In the receiver diagram (figure (4.10») the mixers MI and M2 are used as a downconverter and demodulator respectively. In the receiver it is used to synchronize the PN code with the demodulated (spread) data.
In the receiver (figure (4.10), they are used (in connection with the spreading process) to retrieve the transmitted data.
Conclusion
CHAPTERS
THE EFFECT OF INTERN ALL Y GENERATED RF COMPONENT
PERFORMANCE
For a sound source at room temperature (290K or 17°C), the sound power is -1 74 dBm per Hertz of system bandwidth. Equation (5.2) shows that the noise figure of the system or network is the degradation of the signal-to-noise ratio as a signal passes through the system. The noise figure is also often expressed in terms of the internally generated noise Ne (equivalent noise power).
It is also noted that the noise figure of the first stage of the FI system.
BPSK
BER Measurem e nt methodology
However, the bit error rate reduction in ADS using this LIS technique does not consider external noise in the bit error rate calculation. Instead, the user must have a priori knowledge of this information and express it in tens of noise bandwidths, variance, and the ratio of energy per bit to noise power spectral density (EIINo). Both SNR and EtlNo are calculated at the output of the IF amplifier in figure (5.3) i.e.
PESREF = source power in reference RF signal (IF amplifier output) Tb = bit time. 5.9) Where Ne = one-sided power spectral density of band-limited white noise in WlHz.
Simulation results and analy sis
The mixer noise figure goes from SdB to lSdB, within the range of typical noise figures of diode mixers. As a result of this increase in the mixing noise figure, there is a deterioration in the SNR from 4.4 dB to -2.6 dB (figure (5.16)). With a passive mixer the noise figure is usually equal to or only a few tenths of a decibel above.
In figures (5.19) and (5.20) it can be observed that in both cases (system with and without LNA), an increase in the noise figure of the mixer causes an increase in BER and a decrease in EtlNo and SNR.
Concluding remarks
THE IMPACT OF LOCAL
OSCILLATOR GENERATED PHASE NOISE ON DS-CDMA
Introduction
Internally generated spurious signals
For example, consider a mixer that has an RF input of - IOOdB and an LO that has an RF frequency spurious signal that is 60 dB below the LO signal. Assuming a conversion loss of 7 dB, [F is the output level of the desired signal. With a conversion loss of 7 dB and rejection of 20 dB due to mixer balance, the spurious IF signal is - 77 dBm or 30 dB above the desired output. Eliminating spurious signals requires careful selection of frequencies not only on the front end of the receiver, but also in the LO synthesizer.
The bandwidth of the fF amplifier should be kept as narrow as possible so that traces outside the IF passband are not amplified to the level where they can saturate the fF amplifier or generate intermodulation components.
Amplitude (AM) uois e
- Modulation bv noise
If no measures are taken to eliminate La noise, the increase in noise temperature of the mixer can be very large. The fF frequency should typically be at least 5% to 10% of the La frequency if AM noise is expected to be removed by filtering. The general form of the expression for the noise oscillator output wave can be written as
In general, AM noise and FM or phase noise &(1) and r/(I) are present, respectively, which is the reason for the lack of symmetry in the envelope of the spectrum.
Phase noise
- Simulation work
Phase noise is also expressed as the one-sided spectral density of phase fluctuations (denoted Sif"J). To resolve the phase noise component at the highest shift frequency (f"lmax), the sampling time must be set such that Tstep< However, noise power calculation (using Friis' equation [18]) in the absence of phase noise yielded an IF noise power of -91.35 dBm. If the same signal is applied to a nonlinear circuit, harmonics of the input frequency then appear at the output. Furthermore, the operating point and excursion along the characteristic CUlVe (i.e. the amplitude of the local oscillator) should be such that cross products of order greater than 2 are negligible. Here the lower limit of the input frequency range is lower than the LO frequency. The value of the IdB compression point is related to the amplitude of the LO signal. There are several types of amplifiers that serve specific functions in the RF front end of a communications system. Regarding the s-parameter simulation results (Figure (8.2)), the following points are of interest: At 2 GHz, the gain of the amplifier converter (1 52]1) is 12.89 dB. Thus, this corresponds to a minimum specified gain of 10 dB. It is the ratio between the reflected and transmitted input power at port 1 of the device. In this case, the length of the quarter-wave transformer (between the 50n input line and the input circuit opening) has been tuned/optimized for improved input matching. The author's intention was to specify, design and manufacture an LNA with parameters that would provide acceptable HPSK RF front-end performance of Chapter 9. Nevertheless, a low-cost, homemade 2GHz broadband low-noise amplifier (with a gain of 13.ldB and a bandwidth of 520MHz 3dB), for possible use in an adaptive CDMA system, was developed. Tuning, shielding, proper grounding techniques, and planning a good layout play an important role in designing a fully functional amplifier. In conclusion, this chapter has laid a solid theoretical and practical basis for the design of microwave silent amplifiers. Objectives System description ZEL-I724LN 1700 -2400MHz 9.3: 2GHz, -20dBm BPSK modulated spectrum (400MHz span) measured at output of Rohde and Schwarz SMIQ 03 signal generator.MIXER THEORY
LOW NOISE AMPLIFIER DESIGN
Ea Al.JCj 001
C onclu sio n
MEASUREMENTS
SIF-70
