KR19990014653A - Code Division Cell Phone Jammer - Google Patents

Abstract

A communication disturbance device of a code division multiple access (CDMA) mobile phone, which spreads a pilot channel and a synchronization channel with a pseudo noise (PN) code having a random offset, and transmits it throughout the frequency band of a CDMA mobile phone. The CDMA mobile phone is locked to the present device, not the actual base station, thereby disturbing the communication of the CDMA mobile phone.

Description

Code Division Mobile Phone Jammer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication disturbance apparatus of a code division multiple access (CDMA) mobile phone. In particular, a PN (Pseudo Noise) having a random offset between a pilot channel and a sync channel is provided. The present invention relates to an apparatus for disturbing communication of a nearby CDMA mobile phone by spreading the code and transmitting it throughout the frequency band of the CDMA mobile phone.

In recent years, as the number of mobile phone subscribers has exceeded 10 million, there has been a problem of indiscriminate use of mobile phones in public places such as theaters and concerts. In other words, in such public places, the phone should be turned off or at least changed to vibrate mode. Forgotten to turn off the phone or bothering to change the phone to vibrate mode will leave the phone ringing during the performance. It is happening frequently.

To solve this problem, recently released mobile phones have etiquette function or etiquette function, which enables one-touch switching of vibration mode, as well as message reception notification, button press sound, call connection sound, call disconnect sound, etc. To make it work.

However, this is also the same as the existing mobile terminal in that the user has to switch to etiquette mode, it is difficult to expect a very large effect.

As another method, it is proposed to automatically convert a ringing tone of a mobile phone into a vibration when a radio transmitter mounted in a public place enters a public place. This can be said to be an advanced method in that the existing operators use channels that are not currently used and change them to the vibration mode uniformly regardless of the user's will.

However, this method has the disadvantage of upgrading the mobile phone terminal. In other words, the existing mobile phones are not automatically converted to vibration mode, so all mobile phones cannot be automatically converted into vibration mode. In addition, even if the mobile phone is automatically switched to the vibrate mode, when a user makes a call on the spot when a call is made, there is a disadvantage in that it causes inconvenience to those around.

So, the way to think about it is to cut out the strong radio waves over the entire frequency band of the cell phone to block the transmission and reception of nearby cell phones. However, this method loses its practicality in that the digital mobile phone currently adopted in Korea is CDMA, a kind of spread spectrum communication.

Spread-band communication was originally designed to develop a system that is less susceptible to communication disturbances. In the CDMA communication method, the original signal is spread by spreading the original signal using a long code of 32768 chips, called a PN code, and the original signal is extracted by using the same PN code having exactly the same synchronization. Since the PN code has a much larger bandwidth than the original signal, the PN code must interfere with a very wide band in order to disturb the signal spread by the PN code. In addition, eavesdropping is very difficult because the same PN code must be precisely synchronized to catch a signal spread with the PN code. On the other hand, the receiving side has the advantage that the original signal can be extracted even if the surrounding radio wave environment is not very good if the PN code of the transmitting side is exactly synchronized.

Therefore, in order to block the call of the CDMA mobile phone, it is not effective to shoot radio waves which are not as strong as wide band. Therefore, a very high power radio wave should be shot over a wide band, which is difficult to adopt because it may cause a malfunction of the surrounding electronic equipment or harm the human body.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a device that can automatically block a call of a digital cellular phone in a public place.

Another object of the present invention is to provide a device capable of blocking a call of a mobile phone while emitting a low power radio wave.

1 is an overall block diagram of a jammer of the code division mobile phone of the present invention.

2 is a block diagram of a pilot channel generator of a jammer of the code division mobile phone of the present invention.

3 is a block diagram of a synchronization channel generator of a jammer of the code division mobile phone of the present invention.

4 is a block diagram of a PN quadrature modulator of the present invention.

Explanation of symbols for main parts of the drawings

100: PN generator, 200: multicarrier generator,

300: pilot channel generator, 400: synchronization channel generator,

430: synchronization channel bit generator, 440: convolutional encoder,

450: symbol repetition, 460: block interleaver.

510: baseband filter, 520: baseband filter,

First, prior to explaining the configuration and operation of the present invention, the procedure for establishing communication in the current CDMA system will be briefly described.

Basic Configuration and Behavior of CDMA Forward Link

A forward link refers to a signal transmission link from a base station to a terminal. The channel structure is configured to transmit up to 64 channels simultaneously on the same RF carrier using various functions having orthogonality with each other.

One of these 64 channels is a pilot channel, which is continuously transmitted at high power in a reference synchronization phase for the reception of carriers modulated by information. Similarly, another channel continuously transmitted is a synchronization channel for informing transmission system information to all users in a cell. In addition, there are up to seven paging channels, which are used to assign signals and transport channels for incoming calls to terminals in the cell, and to inform other terminals of other signals. All other channels except these can be used as a traffic channel, each of which is used to exchange voice and data with individual terminal users.

1. Orthogonal Multiplexing Scheme

Each channel in the forward link is distinguished by orthogonal Walsh sequence modulation. The Walsh column uses a two-dimensional Hamadad matrix and is orthogonal when correlated. The data on the paging and call channels are mixed by assigning an offset of a long PN code, which is 2 ⁴¹ chips in length with a high level of security, but it is not used to distinguish between channels. 64, each channel is assigned a Walsh column is packed by being represented by H _i, where i = 0,1, ..., 63) .

The highest baseband data rate from each channel is 19.2 kilo-symbols / sec (ksps). The baseband data flow of each channel is combined with 64 chips of the assigned Walsh column. Therefore, the orthogonal multiplexed forward link is a baseband data flow with a data rate of 1.2288 Mcps (= 64 x 19.2 ksps).

The multiplexed data flow for a particular channel is combined into two different short PN codes. These two short PN codes are used for the I and Q carrier components, respectively, and denote them as PN _I (t, θ _i ) and PN _Q (t, θ _i ), respectively. These are all generated by a 15-step linear feedback shift register (LFSR). The offset phase θ _i of the PN code is assigned to each base station. This is chosen as one of 512.

Unlike general QPSK, IS-95 (the CDMA standard currently used in Korea) allocates the same data to quadrature channels. This is called quadrature spreading. Two quadrature data are transformed by the FIR filter. The I phase is then modulated with cos (2πf _c t) and the Q phase with sin (2πf _c t), and the two outputs are then summed and transmitted.

2. Forward Link Channel

The forward link channel consists of a pilot channel, a synchronization channel, a paging channel, and a call channel. Each of which is modulated by Walsh column (H _i) are assigned to the channel. The IS-95 standard assigns H ₀ to the pilot channel, H ₃₂ to the synchronization channel, and H ₁ to H ₇ for the paging channel. And the rest are allocated to the call channel.

Each channel sends out spread band modulation using a quadrature PN code. Now let's take a quick look at the pilot and synchronization channel types that each channel will focus on in this patent.

2.1 Pilot Channel and Quadrature PN Codes

The pilot channel is used primarily for phase synchronization for demodulation of other channels. This is necessary in IS-95 to match chip timing with the carrier phase of each forward link channel. The pilot channel can be easily obtained at the receiving terminal since no modulation other than quadrature PN modulation is performed. The pilot channel is necessary for the crucial code offset information and therefore must be transmitted with higher energy than other channels.

The pilot baseband data (logically all zeros) is modulated at 1.2288 Mcps with H ₀ , so it is also composed of 64 zeros. This is virtually like a pure PN code with no modulation.

Two different PN codes are the ones with the largest column length generated by a 15-stage shift register by inserting one chip per cycle at a specific location in the PN column. Therefore, this modified PN code has 32 768 chips with 2 ¹⁵ -1 = 32767 plus one chip. As pointed out above, the base station allocates different phase offsets (θ _i ) to PN codes of I and Q to distinguish them. Each offset is a product of 64 PN chips. That is, there can be 64 chip offsets of 32768/64 = 512 types.

Using a rate of 1.2288 Mcps, columns I and Q appear 25 times every 26.666 ms, in other words every 2 seconds. The characteristic polynomials for I and Q are given by

This can easily be done using a binary adder (XOR) and shift registers.

2.2 synchronization channel

The synchronization channel is demodulated by all terminals and carries a synchronization channel message, which is transmitted continuously. This signal identifies the particular base station being transmitted and carries information for synchronization of the long PN code.

From this channel, there is important information to be recovered except for I, Q PN code spreading. Therefore, we use convolutional encryption, which is a channel encryption method for recovering errors through channels, and weaving machines for recovering from continuous errors. This channel is performed by using the Walsh modulation H _32. The Walsh code has a square wave shape, with 0 of 32 chips followed by 1 of 32 chips at 1.2288 Mcps. Since the other two channels (paging and call channels) are spread using long PN codes, accurate reception up to this synchronization channel is the primary requirement for a real call.

The method of the present invention for communication disturbance

The present invention prevents communication at the terminal by letting the terminal know that the device of the present invention is a base station and locking it to the device of the present invention rather than the actual base station.

The terminal searches the pilot channel and the synchronization channel to determine whether it is a valid base station. Therefore, in order to let the terminal know that the apparatus of the present invention is a base station, the present invention is intended to disturb the pilot channel and the synchronization channel.

1. The disturbance of pilot channels

As described above, the pilot channel uses Walsh string H _{0. Since} Walsh string H ₀ is composed of 64 zeros, the code of the pilot channel is substantially the same as a pure PN code without any modulation. Therefore, if the same PN signal is continuously transmitted in the form of a pilot channel with only an offset in order to disturb the pilot channel, the terminal recognizes a wrong offset instead of the offset of the PN signal sent from the actual base station. To be locked into the device of the invention.

2. Disturbance of the synchronization channel

However, when only the pilot channel is used, communication disturbance is not completely achieved. Currently, IS-95 detects the reference value of the PN signal through the pilot channel and checks whether it is a useful value. This process is performed through the search of the synchronization channel. From the synchronization channel, the actual data remains even after despreading of the short PN code. This data content must satisfy the data format of IS-95. That is, if the PN despreading does not match this type, the offset recognized by the pilot channel is ignored. If it is determined to be an error, the terminal generates a false alarm signal and returns to the pilot channel to start searching at a new position instead of the current position. This way back to the beginning must be blocked, and for this purpose, the synchronization channel must also create a virtual data value that is exactly the same as the actual data format. In this way, the pilot channel should detect the wrong PN reference point, and through the synchronization channel to recognize that the false offset detection received from this pilot channel is real.

Therefore, in the present invention, by sending a virtual data value equal to the actual data format to the synchronization channel, the terminal is locked to the apparatus of the present invention rather than the actual base station.

Example

Hereinafter, with reference to the accompanying drawings will be described in detail with reference to the configuration and operation according to the present invention.

1 is an overall block diagram of a jammer of the code division mobile phone of the present invention.

As shown in FIG. 1, the jammer of the code division mobile phone according to the present invention includes a PN generator 100 for generating an I-channel and Q-channel PN sequence used for quadrature spreading, and an entire CDMA mobile phone. A multicarrier generator 200, a pilot channel generator 300, a synchronization channel generator 400, an I-channel and Q-channel PN sequence from the PN generator, and the pilot channel for generating a carrier frequency over a frequency band. A PN quadrature modulator 500 for performing PN quadrature modulation using a pilot channel sequence from a generator, a synchronization channel sequence from the synchronization channel generator, and a carrier frequency from the multicarrier generator, and the PN An adder for adding modulated signals from a quadrature modulator, an amplifier for amplifying the combined signal in the adder, The pokdoen signal and an antenna for radio waves over the air.

The PN generator 100 of the present invention has the same configuration as a PN generator in a conventional CDMA digital cellular phone, and thus a detailed description thereof will be omitted.

2 is a block diagram of a pilot channel generator of a jammer of the code division mobile phone of the present invention. Since the pilot channel is generated by adding the Walsh function 0 that is similar to '0' to '0', the pilot channel is generated without actually providing a separate generator. However, in order to indicate that a pilot channel is generated in the present invention, the pilot channel generator is schematically illustrated in FIGS. 1 and 2.

3 is a block diagram of a synchronization channel generator of a jammer of the code division mobile phone of the present invention. The synchronization channel generator of the present invention is the same as that of a conventional CDMA cellular phone, and thus its detailed description is omitted.

4 is a block diagram of the PN quadrature modulator 500 of the jammer of the code division mobile phone of the present invention. The PN quadrature modulator 500 is a conventional CDMA mobile phone and its configuration except that the baseband signal passed through the baseband filters 510 and 520 is multiplied by all carrier frequencies used in the CDMA digital mobile phone. Is like this. That is, in the conventional CDMA mobile phone, the baseband signal that has passed through the baseband filter is multiplied by one carrier frequency, but in the present invention, the carrier frequency is multiplied over the entire band in order to disturb the call over the entire band.

A signal _{(I 1 ..I n, Q 1} ..Q n) modulation from the quadrature PN modulator 500 is generated in this way is that the mobile phone around after being added by the adder, is amplified and propagated over the air through antenna Will disturb your currency.

As described above, according to the present invention, by automatically blocking the call of the digital cell phone in public places, it is possible to prevent the harm caused by the indiscriminate use of the cell phone in public places.

In addition, according to the present invention, it is possible to cut off the call of the mobile phone while emitting a low-power radio waves, there is an effect that the power consumption is low, does not disturb the surrounding electronic devices and does not harm the human body.

Claims (1)

A PN generator for generating I-channel and Q-channel PN sequences, a multicarrier generator for generating carrier frequencies over the entire frequency band of a CDMA mobile phone, a pilot channel generator, a synchronization channel generator, and an I-channel from the PN generator And performing PN quadrature modulation using a Q channel PN sequence, a pilot channel sequence from the pilot channel generator, a synchronization channel sequence from the synchronization channel generator, and a carrier frequency from the multicarrier generator. And a PN quadrature modulator, an adder for adding modulated signals from the PN quadrature modulator, an amplifier for amplifying the combined signal from the adder, and an antenna for wirelessly propagating the signal amplified by the amplifier. Code Division Type Cell phone jammer.