KR0164085B1 - Apparatus of mock experimentation of baseband fading channel for mobile communication - Google Patents

Abstract

The present invention relates to a device for inspecting fading phenomenon in a baseband modulation and demodulation device for mobile communication. In particular, the present invention can test fading phenomenon in a baseband without decorating an actual RF (Radio Frequency) circuit. The present invention relates to a baseband fading CH simulation apparatus for mobile communication.

Description

Baseband fading CH simulator for mobile communication

1 is a signal transmission diagram of a baseband modulator through a conventional RF circuit.

2 is a conceptual diagram of a baseband fading CH simulator.

3 is a baseband fading CH simulator using DSP.

* Explanation of symbols for the main parts of the drawings

Tx: Radio wave transmitter and demodulator Rx: Radio wave receiver and demodulator

DP: Duplexer for transmission and reception from common antenna

Ⓧ: Multiplier S (t): Transmission signal

S '(t): Received signal S (t) baseband: Baseband equivalent transmit signal

S '(t) baseband: Baseband equivalent received signal

The present invention relates to a device for inspecting fading phenomenon in a baseband modulation / demodulation device for mobile communication. In particular, the present invention can experiment with fading in a baseband without decorating an actual RF (Radio Frequency) circuit. The present invention relates to a baseband fading CH simulation apparatus for mobile communication.

In general, the fading phenomenon refers to the temporal variation of the received electric field strength according to the propagation state of radio waves, and it is one of the most important things to consider when designing an RF circuit because it acts as a factor that causes signal-to-noise ratio degradation and code error rate. One.

The design and implementation through the performance analysis of the conventional mobile communication modulation and demodulator is shown by the Figure 2, the error caused by the fading phenomenon by transmitting the result to the RF circuit and receiving a number of multipath components The design of the demodulator to properly reconstruct the normalized signal dictated the system's performance.

Therefore, the conventional method for checking the performance of the demodulator is a method of analyzing the performance in the RF channel of the mobile communication device using a foreign-made RF channel simulator (for example, HP model 11759C).

However, it is not easy to connect the RF circuit to the baseband modulator and demodulator, and it is cumbersome to go outside and drive a vehicle in order to change the design parameters while analyzing the performance after actual fabrication. .

In addition, as the demand for mobile communication such as CT2, TRS, Cellular, and PCS increases rapidly, various digital multiple access methods such as TDMA and CDMA are adopted in various analog and demodulation methods, and the frequency band is newly introduced at 800MHz. Because of the shift to 1.8 GHz, testing the performance of a system against each of these system specifications has been a real problem.

An object of the present invention for solving the above problems is that the baseband signal can give an equivalent effect to the fading phenomenon experienced during the transmission and reception in the RF circuit unit, and the fading effect without the need to go out and experiment outdoors after the actual development It is to provide a baseband fading CH simulation device for mobile communication that can be easily obtained indoors to analyze the performance of a demodulation device suitable for various environments by obtaining it at baseband.

A feature of the present invention for achieving the above object is, a baseband equivalent transmission signal generator for generating an arbitrary reference transmission frequency: first and second Gaussian random change generator for generating a white Gaussian random variable: the first, First and second doppling filters connected one-to-one to a second Gaussian random variable generator and outputting a white Gaussian random variable generated by a corresponding Gaussian random variable generator after filtering by the Doppler effect: the baseband equivalent transmission A phase delay unit for delaying the signal generated by the signal generator by 90 ° and outputting the phase delay unit: a first multiplexer for mixing and outputting a signal output from the first doping filter and a signal generated from the baseband equivalent transmission signal generator; : Mixing a signal output from the second doping filter and a signal generated from the phase delay unit And there there is composed of the first adder for adding the output first received, the input signals outputted from the second rear multiple: a second force to the multiple rear.

Another aspect of the present invention for achieving the above object is a baseband equivalent transmission signal generator for generating an arbitrary reference transmission frequency: first to third code error rate generator for generating a fading element that is a data table: First to third delay means configured to sequentially delay the signals generated at the baseband equivalent transmission signal in the first, second, and third order: according to fading elements output from the first code error rate generator. A first multiplexer for mixing and outputting a signal and a baseband equivalent transmission signal output by being delayed by the first delay means; a signal according to a fading element output from the second code error rate generator and the second delay means And a second multiplexer for mixing and outputting a baseband equivalent transmission signal to be output: a fading yaw output from the third code error rate generator. A third multiplexer for mixing and outputting a signal according to a signal and a baseband equivalent transmission signal delayed and output from the third delay means; and an adder for receiving, adding, and outputting a signal output from the first to third multiplexers. It is composed.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2 is a conceptual diagram of a baseband fading CH simulation apparatus using a Gaussian random generator according to the present invention, Figure 3 is a conceptual diagram of a baseband fading CH simulation apparatus using a DSP.

In the present invention, a method using a Gaussian random variable generator and a method using a DSP are implemented.

Looking at the embodiment of the present invention with reference to Figure 2, the fading CH simulation apparatus generates the components of the Inphase term and Quadrature term using a separate white Gaussian random generator to produce a fading effect per multipath.

That is, if the signal to be transmitted is S (t) = A (t) cos {ω _c t + θ (t) + φ (t)},

The received signal is R (t) = A '(t) cos {ω _c t + θ (t) + φ (t)}

The above equation can be expressed in terms of inphase and quadrature as follows.

R (t) = A '(t) cosφ (t) cos {ω _c (t) + θ (t) +}-A' (t) sinφ (t) sin {ω _c (t) + θ (t) }

That is, the fading effect can be provided by having a white gaussian random noise independent of each other in the inphase term and the quadrature term of the originally transmitted signal S (t) and a phase change value having statistical characteristics uniformly distributed from 0 to 2π. .

If we consider the above equation to have only a baseband component, it is expressed as follows.

That is, R (t) _baseband = A '(t) cosφ (t) cosφ (t) cosθ (t) -A' (t) sinφ (t) sinθ (t) is performed in the same manner as in the formula including the RF term.

By implementing the above-mentioned fading effect and doppler frequency shift coefficient as a DSP (see FIG. 3) and multiplying the value by an input baseband signal, a signal having a fading effect in the RF band may be implemented.

Since multiple paths occur on the real fading channel with time differences, consider three or four of them, and implement each component with a DSP to add these components from the outside to add a baseband fading effect. Can generate a signal.

Claims (2)

A baseband equivalent transmission signal generator for generating a random reference transmission frequency; and a first and second Gaussian random variable generator for generating a white Gaussian random variable: connected one-to-one to the first and second Gaussian random variable generators First and second doppling filters for receiving a white Gaussian random variable generated by a Gaussian random variable generator and outputting the same after filtering by the Doppler effect: delaying the signal generated by the baseband equivalent transmission signal generator by 90 ° out of phase. A phase delay unit for outputting a first multiplexer for mixing and outputting a signal output from the first doping filter and a signal generated from the baseband equivalent transmission signal generator; and a signal output from the second doping filter A second multiplexer for mixing and outputting signals generated by the phase delay unit; and the first and second multipliers Mobile communication baseband fading, characterized in that consisting of the adder and outputting the addition receives the signal output from the rear CH simulator. A baseband equivalent transmission signal generator for generating an arbitrary reference transmission frequency; first to third code error rate generators for generating fading elements that are data-tabled: a signal generated at the time of generation of the baseband equivalent transmission signal First to third delay means connected to each other so as to sequentially perform second and third delays: a signal according to a fading element output from the first code error rate generator and a delay output from the first delay means; A first multiplexer for mixing and outputting a band equivalent transmission signal; and mixing and outputting a signal according to a fading element output from the second code error rate generator and a baseband equivalent transmission signal delayed and output from the second delay means. A second multiplexer: a signal according to a fading element output from the third code error generator and a delay in the third delay means A third multiplexer for mixing and outputting output baseband equivalent transmission signals; and an adder configured to receive and add a signal output from the first to third multiplexers to output the baseband fading CH. Simulator.