KR100704110B1 - System of satellite mobile communication service with spread-spectrum - Google Patents

Abstract

The present invention relates to a satellite mobile communication service system for providing voice, fax, and data transmission / reception services between terrestrial and mobile terminal stations in the Korean peninsula and nearby maritime regions using geometries of geostationary orbit. In a mobile communication service system, a satellite mobile communication network is controlled and managed, a pool of pseudo noise (PN) codes are provided, and reverse link data transmitted as a binary phase shift keying (BPSK) signal is generated, Control means for converting the spread received carrier into a voice and data channel and recording and preserving all call related materials; And attaching a satellite tracker and a receiver so that an optimal signal can be transmitted to and received from the satellite, and searching and tracking the position of the satellite, and transmitting and receiving voice, fax, and data through the satellite mobile communication network under the control of the control means. It includes a plurality of terminals.

Mugunghwa Satellite, Central Station, Terminal, Satellite Mobile Communication, DS-CDMA, LPC-VQ

Description

Satellite mobile communication service system using frequency spreading method {System of satellite mobile communication service with spread-spectrum}

1 is an explanatory diagram showing a concept of satellite mobile communication service to which the present invention is applied;

2 is an exemplary configuration diagram of a satellite mobile communication service system according to the present invention;

3 is an exemplary detailed configuration of a mobile terminal station in a satellite mobile communication service system according to the present invention;

4 is a flowchart illustrating an embodiment of a satellite mobile communication service method according to the present invention;

5 is a flowchart of another embodiment of a satellite mobile communication service method according to the present invention;

* Explanation of symbols for the main parts of the drawings

11: Mugunghwa Satellite 12: Central Station (HUB)

13: mobile terminal station 14: ground terminal station

The present invention relates to a satellite mobile communication service system using a frequency spreading method. In particular, the present invention provides voice, fax, and data transmission / reception services between terrestrial and mobile terminal stations in the Korean peninsula and nearby maritime areas by using Mugunghwa satellite on a geostationary track. A Ku-band satellite mobile communication service system using a frequency spreading scheme.

The satellite mobile data service is a service that provides two-way data communication for location information and mobile management by constructing data links from satellites and terrestrial networks from moving vehicles or ships to companies that manage mobile vehicles. It is used for the management of moving objects such as companies and security service shipping companies.

The communication method using satellite has advantages such as wide area covering a large area compared to terrestrial communication means, broadcasting ability to transmit signals to various areas at the same time, and flexibility in network construction to quickly establish various communication networks.

The communication means for ships at sea in Korea is a communication method used by the maritime (VHF) and the navy (UHF), and voice service is provided through about 20 relay stations centering on the callable area within a radius of 100 miles. . However, this communication method has various problems such as restriction of communication right due to visible distance wave and degradation of call quality due to increased frequency demand.

In terms of consumer demand, we have reached the fundamental limits of existing maritime communication networks, such as restricting communication rights and managing relay stations, and in order to improve operational capability by directly conducting identity and crime inquiries through limited communication sites. There is a need to establish a comprehensive information communication network that can provide various services such as data and fax (FAX).

On the other hand, from the technical point of view, various satellite communication services are being provided using the geodesic satellite, which is a geostationary satellite, and the recent series of hardware and software technologies such as antenna tracking technology, frequency spreading technology, voice compression technology, network management technology, etc. With the development, satellite communication service is expanding its application range from fixed one way to mobile service.

The terms used in the present invention are defined as follows.

The central station (HUB) is a gateway that controls and manages the flow of the entire satellite mobile communication network and is connected to the ground network.

A mobile terminal station has a Code Division Multiple Access (CDMA) satellite mobile communication terminal and is a subscriber or terminal station having mobility.

A terrestrial terminal station is a terminal such as a telephone, a fax machine or a personal computer (PC) which is linked to a central station through a terrestrial network.

In the double-hop star network, the forming network is a type of communication network, in which all terminals communicate through a main computer installed in a central station.

In satellite communication, when all terminals communicate through a central station, traffic moves in the order of a transmitting terminal → satellite → a central station → satellite → a receiving terminal. In this case, the traffic passes through the satellite twice, which is a double jump.

Spread Spectrum communication is a communication method that spreads and transmits an information data signal by using a code having a bandwidth much wider than that of the information data signal frequency band. In this case, the code used is independent of the information data signal, and the receiver recovers the original information data after spreading using the same code that is synchronized with the code used by the transmitter.

Code division multiple access (CDMA), as described above, spread spectrum communication can be multiplexed by assigning different codes to a plurality of users, and this multiplexing scheme is called CDMA. The CDMA method includes a DS-CDMA (Direct-Sequence CDMA) method that directly spreads the spectrum using a user's unique code corresponding to the information data, and a frequency synthesizer using a PN code at the center frequency of the information data. There is a frequency hopping CDMA (FH-CDMA) scheme in which a band is spread by using other hops.

Linear Predictive Coding (LPC) refers to speech analysis based on a model that linearly predicts a sample of a speech waveform from a contiguous series of adjacent sample values and from the parameter vector extracted by the analysis. To restore the signal. Usually, LPC divides speech into 15 ~ 30ms units of time to construct a frequency band spectrum model, extracts coefficients from this model, and quantizes them.

Now, a more detailed description of a conventional satellite mobile communication service is given.

Currently, naval and maritime maritime communication uses the VHF and UHF communication methods for terrestrial relay stations, which provide voice and data through more than 20 relay stations scattered around the country, centering on callable areas within a radius of 100 miles. Providing a service. Table 1 below summarizes and compares the advantages of the satellite mobile communication service of the present invention with respect to the VHF / UHF communication method.

Item UHF and VHF Communication Satellite mobile communication service Frequency of use UHF / VHF Ku-band   Service area -It is limited to a sea area within a radius of 180km around 20 relay stations installed in coastal areas.- In areas without islands such as the east coast, it is difficult to install a relay station, making it difficult to expand service area. In rural areas, communication blind spots occur due to shading of radio waves. Regardless of the location of the relay station and the characteristics of the island, the same quality of service is always available without the communication blind spot in the area where Mugunghwa satellite service is available (offshore area within 250 km radius of the Korean peninsula when using fixed beams).  Communication quality  Call quality deteriorates sharply due to interference caused by recent demand for wireless phones Spread Spectrum technology using DS-CDMA reduces the effects of interference and provides excellent call quality

With the development of satellite communication technology, the satellite mobile communication service currently being serviced or planned over the Korean Peninsula is service using international satellite "INMARSAT", service using low-orbit satellite mobile communication satellite (GMPCS), and geostationary satellite. There are services using Mugunghwa satellite.

Among them, the service using the international satellite "INMARSAT" is currently serving the marine vessel using the L-band small antenna. In addition, the low-orbiting satellite "GMPCS" plans to provide services for marine and land mobile subscribers with its relatively low cost terminal.

However, since these services are operated in the form of a consortium with foreign institutions or foreign companies, they are inadequate for navy / marine communication networks requiring communication security and multilateral communication, and operational problems are expected due to the characteristics of navy / marine communication networks. Moreover, since "INMARSAT" is an expensive L-band satellite and "GMPCS" is accompanied by an expensive communication cost due to the use of a large number of satellites, an excessive communication cost is required for maritime communication requiring a long time call. Table 2 below compares these "INMARSAT" and "GMPCS" and satellite mobile communication services.

Item IMMARSAT, GMPCS Satellite mobile communication service service Multiparty communication is impossible Multi-party communication is possible Security Service is operated in consortium form with international organizations and foreign companies, so it is difficult to apply to military communication networks requiring communication security Excellent external security by using Mugunghwa satellite, a spot beam satellite dedicated to Korea, and independent service operation by Korea Telecom

Mugunghwa satellite, the only possessed and operated in Korea, is located on geostationary orbit and uses low-cost Ku band.

Currently, communication services provided by Mugunghwa Satellite are mainly voice (Demand Assigned Multiple Access), video (TVRO: TV Receive Only, SNG: Satellite News Gathering), and data (VSAT: Very Small Aperture Terminal, TSAT: T1 Carrier). Due to the recent rapid development of fixed services such as Small Aperture Terminal (SAP) service, satellite multimedia service, multiple access such as CDMA, antenna tracking, etc., it is a mobile service such as Satellite Mobile Data Service (SMDS). Can be divided.

Here, "DAMA-SCPC is capable of voice, fax and data transmission and reception services, but there is a problem that the size of the antenna and the tracking equipment increases when the fixed service is applied to the mobile service. In addition, SMDS, a mobile service, has a low speed (55). To 165bps) data only, not only voice services, but also fax, high-speed data, etc. are not available in Table 3. Table 3 compares these SMDS, DAMA-SCPC, and satellite mobile communication services.

Item SMDS DAMA-SCPC Satellite mobile communication service service -Low speed data (55 ~ 165bps) service available-Multi-party communication impossible Multiparty communication not possible -Voice, fax, high-speed data transmission and reception possible-Multi-party communication antenna Difficult to apply to mobile communication by using large antenna 4.8kbps Voice Compression Using LPC-VQ Miniaturizes Antennas Tracking device  It is difficult to apply to high speed data transmission and reception such as voice and fax at sea due to the limitation of tracking device.  Since there is no tracking device in the antenna, when it is applied to the marine environment where there is a lot of fluctuation, the communication quality may be deteriorated and it may interfere with other satellite networks. -Attaching tracking equipment and stabilization platform to the antenna ensures the same quality of service even in marine environment including the ground-Eliminating the possibility of interference with other satellite networks that can occur when using a small antenna in the terminal by applying DS-CDMA

Therefore, geostationary orbit satellite based on technologies such as DAMA-SCPC service (voice processing technology, call processing and network management technology), VSAT service (forming network type) and SMDS service (frequency spreading technology, antenna tracking technology) Ku-band satellite mobile communication using a new type of spreading method that uses wide area (i.e., covers a large area compared to terrestrial communication means) and broadcast (i.e., transmits signals to several areas at the same time) using an Mugunghwa satellite. Service development is essential.

In order to solve the above problems, the present invention, a satellite for providing voice, fax and data transmission and reception services between the ground and mobile terminal stations in the Korean Peninsula and the nearby maritime area using the Mugunghwa satellite on a geostationary track The purpose is to provide a mobile communication service system.

In order to achieve the above object, the present invention provides a mobile communication service system using a satellite, and controls and manages a satellite mobile communication network, provides a pool of pseudo noise (PN) codes, and binary phase shift keying (BPSK). Control means for generating reverse link data transmitted in a signal, converting a spread spectrum received carrier into a voice and data channel, and recording and preserving all call related materials; And attaching a satellite tracker and a receiver so that an optimal signal can be transmitted to and received from the satellite, and searching and tracking the position of the satellite, and transmitting and receiving voice, fax, and data through the satellite mobile communication network under the control of the control means. It includes a plurality of terminals.

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The present invention relates to a Ku-band satellite mobile communication service using a frequency spreading method. The present invention relates to a miniaturization and security of a satellite mobile communication terminal, a 1: N or multi-party voice conference function, and an existing telephone in a satellite mobile communication terminal. It implements interface configuration to accommodate terminals such as, fax, PC, antenna tracking to ensure mobile communication service quality in offshore area around Korean Peninsula, communication network management and interworking with existing network.

The present invention applies a voice signal compression and DS-CDMA scheme using LPC-VQ to reduce the size and security of the satellite mobile communication terminal. In addition, to implement 1: N or multi-party voice conferencing, a voice conference card is applied to the central station. In addition, a user interface module is inserted into the mobile communication terminal in order to configure an interface for accommodating a terminal such as an existing telephone, a fax, or a PC in the satellite mobile communication terminal. In addition, in order to apply antenna tracking to guarantee the quality of mobile communication service in the maritime area around the Korean peninsula, an automatic satellite tracking device considering the environmental factors of the marine vessel around the Korean peninsula and a stabilization platform for stably fixing it to the vessel are applied. In addition, for communication network management and interworking with the existing network, software and hardware implementation in the central station, terrestrial private network and PSTN network are interworked with the E1 trunk interface.

Through this, the present invention provides a voice, fax, and data transmission and reception service between the ground and mobile terminal stations in the Korean Peninsula and the nearby maritime area by using the Mugunghwa satellite on the geostationary track. This includes not only 1: 1 communication but also voice call services between specific groups (1: N or multiparty). Therefore, the mobile station subscriber can use the existing equipment suitable for the type of service desired, that is, a telephone, a fax or a PC, by connecting to the mobile communication terminal of the system.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a concept of a satellite mobile communication service to which the present invention is applied.

As shown in FIG. 1, in order to perform a satellite mobile communication service, a basic station (HUB) 12, a mobile terminal station 13, and a ground terminal station 14 are basically required. Here, the form of the communication network is a double hopping network (Star Network) through which all traffic including signal processing is transmitted and received through the central station 12.

When the ground terminal station 14 or the mobile terminal station 13 sends a call setup request to the central station 12 via the Mugunghwa satellite 11, the central station 12 allocates a transmission / reception channel to each terminal station 13 or 14. do. As such, all traffic is transmitted and received via the central station 12.

The satellite communication method has advantages such as wide area covering a large area, broadcasting ability to provide signals to various areas at the same time, and flexibility in network construction to quickly establish various communication networks, compared to the land communication method. Based on these advantages, various satellite communication services are being developed and provided. With the recent rapid development of antenna tracking technology, frequency spreading technology, voice compression technology, and network management technology, the service area has been fixed to mobile in the past. The trend is to expand.

Currently, mobile communication services provided or planned on the Korean Peninsula and in the adjacent seas, as described above, UHF and VHF communication method using the terrestrial relay, service using the international satellite "INMARSAT", low-orbit mobile communication such as Iridium GMPCS and fixed and mobile services using Mugunghwa satellite, a geostationary satellite.

2 is an exemplary configuration diagram of a satellite mobile communication service system according to the present invention, in which, "21" is a network interface unit, "22" is a digital switch, "23" is a codec / modem, " 24, 26 denotes a radio frequency (RF) processor, 25 denotes a network manager, 27 denotes a baseband processor, and 28 denotes a user interface.

As shown in FIG. 2, the satellite mobile communication service system according to the present invention includes a central station (HUB) 12 for controlling and managing a satellite mobile communication network, generating and managing call setup and release, and billing statistical information. A satellite tracker and a receiver are attached and attached so that an optimal signal can be transmitted to and received from the Rose of Sharon (11), and the location and location of the Rose of Sharon (11) can be searched and tracked through the satellite mobile communication network under the control of the central station (12). Voice between a plurality of mobile terminal stations 13 or between a terrestrial terminal station 14 and a mobile terminal station 13 under the control of a plurality of mobile terminal stations 13 and a central station 12 for transmitting and receiving data. And a green light satellite 11 for mediating fax data.

The central station 12 controls and manages the entire network, and acts as a gateway to the ground network (PSTN or private network), as well as a central point for generating and managing call information, and generating and managing statistical information for billing. Acts as

Its main functions include real-time call processing functions such as call setup and release, broadcast communication function, RF scrambling function, priority and emergency emergency call function, CDMA signal transmission and reception, modulation and demodulation. / Demodulation) function, private network / PSTN access through E1 trunk, interface with mobile terminal, RF and BB signal processing function, and central station network management and operation function (i.e. resource management function in network, network Configuration change management function, statistics information collection function, terminal station status monitoring and control function, each unit control function, central station management information transmission and reception function, self-diagnosis function, fault message collection function, management object test function, etc.) Do this.

Central station 12 must be redundant to meet system availability.

The central station 12 includes a network interface unit 21, a digital switch 22, a codec / modem 23, a radio frequency processor 24, and a network manager 25 to control and manage the entire satellite mobile communication network. Create and manage statistics for setting, clearing, and billing.

The RF processor 24 performs a Radio Frequency (RF) Carrier Coupling / Splitting function, an RF and antenna unit test function, and a transmission / reception signal separation function.

The codec / modem 23 has a frame function, RS coding / convolutional coding function, interleaving / deinterleaving function, symbol repetition function, code generation function, spread / despread function, PN code synchronization function, It performs symbol detection, low pass filter and gain control.

Network Management Subsystem 25 collects resource status data, stores and manages base station-related operations and maintenance (OAM) data, detects each unit failure and alarm, real-time call handling, and outbound TDM carrier transmission And inbound CDMA carrier reception function, frequency and carrier management function, bulletin board correction function, network resource management function including channel equipment management and dedicated line trunk capacity management, remote terminal status monitoring and data collection function, traffic and other network related factors statistics It performs data collection function, charging information collection function, and ground network access function through private network or digital E1 trunk.

The central station 12 provides a pool of PN codes for the mobile station 13, generates data transmitted in a Binary Phase Shift Keying (BPSK) signal, and spreads the spectrum. It converts carrier to voice channel and records and preserves all call details in detail.

When using the entire 36 MHz repeater of the Mugunghwa satellite 11, the capacity of the network is 6 channels per 1 MHz, so 6 to 216 channels can be accommodated including the signaling channel. It can accommodate -21,600 lines.

The 1MHz repeater bandwidth supports six full-duplex 4.8Kbps voice signals and can increase the repeater bandwidth in 1MHz increments as the user increases.

On the other hand, the mobile terminal station 13 is a terminal with an antenna tracking device and provides voice, fax and data services.

It has an antenna of 60 cm or less in diameter, a multi-layer data port up to 9.6 Kbps, sleep / sleep mode, and can be installed with two antennas. Its main functions include 4.8 Kbps voice compression, CDMA signal transmission and reception, and demodulation ( Modulation / Demodulation (FEC), Forward Error Correction (FEC), Terminal Security, Baseband Signal Processing, Power Control, Call / Mobility / Voice Signal Processing, Voice and Data Signal Interface do.

Communication security is maintained between the central station 12 and the mobile terminal station 13 using the CDMA scheme.

The mobile terminal station 13 has an antenna, a radio frequency processor 26, a baseband processor 27, and a user interface 28 from a functional point of view. A more detailed description thereof will be described with reference to FIG. 3.

The present invention uses DS-CDMA, small antenna tracking technology, 4.8kbps LPC-VQ (Linear Predictive Coding-Vector Quantization) voice compression technology, network management and interworking with existing networks in order to realize a compact high quality mobile communication terminal. I use it.

This will be described in more detail.

First, DS-CDMA will be described. The CDMA scheme is a multiple access scheme utilizing a spread spectrum scheme originally developed for military purposes, and is divided into a time division multiple access (TDMA) or a frequency division multiple access (FDMA). Due to its unique characteristics, it is widely used in mobile communication systems. In this satellite mobile communication system, DS-CDMA system is applied to construct an efficient communication system that provides a large number of channel capacities.

Spread-Spectrum using DS-CDMA has the advantage of eliminating jamming and interfering waves instead of consuming a wide bandwidth.

The L-band "INMARSAT" satellite system, which is already commercially available and widely used, does not consider the interference between carriers and near-satellite satellites in the same frequency band that occurs when a small antenna with a wide beam width exceeds about 30 degrees of satellite separation. You don't have to.

However, in the case of satellites in the Ku band where the orbits of the satellites are usually arranged at 2 to 3 degrees, the off-axis radiation caused by the small antenna exceeds the limit set out in the Recommendation of ITU-R 728. Interfere with carriers or other satellite networks.

Therefore, the CDMA method of spreading the spectrum by lowering the power of the transmission antenna to alleviate the off-axis emission value solves this problem and contributes to the miniaturization of the terminal since the transmission power is reduced.

The reverse signal from the mobile station 13 to the central station 12 uses a CDMA / FDMA access scheme that spreads the frequency band in units of 1 MHz, and the forward signal from the central station 12 to the mobile station 13 Since the large antenna of the central station is used, the interference does not have to be greatly considered, and accordingly, the TDMA / FDMA scheme is used.

This structure can reduce the cost and size of the terminal since it is not necessary to install the PN code despreader in the receiver in the mobile terminal station 13. In addition, apart from the purpose of communication, a spread spectrum modulated signal can accurately calculate the relative value of its arrival time. In particular, the GPS system uses these characteristics to estimate the current position of the moving object by transmitting radio waves at a number of points where a place is known in advance, and measuring a difference in radio wave arrival times from each point. Therefore, by using the spread spectrum method can be used to reduce the GPS estimation error for the current position of the mobile communication terminal.

On the other hand, when looking at a small antenna tracking technology, the transmission and reception of satellite signals in a ship requires a complicated antenna control device to successfully orient the satellite by performing the correction according to the position fluctuations and shaking of the moving object.

The antenna tracking equipment attached to the mobile terminal station 13 determines the performance requirements in consideration of the environmental conditions to which the moving object is to be placed, that is, the fluctuation tendency and the degree of the object on which the antenna is to be installed.

Antenna automatic tracking technology combined with the CDMA applied to the present invention, assuming that the mobile terminal station 13 is installed in a marine vessel, a three-axis automatic tracking device and gyro compass attached to the antenna continuously through the Rose of Sharon (11) By searching and tracking the location of the satellite, the optimal signal can be transmitted to and received from the satellite. In addition, stabilization platforms are used to more reliably install antennas and trackers.

On the other hand, when looking at the 4.8kbps LPC-VQ voice compression technology, to reduce the size of the mobile station 13 including the antenna while ensuring a constant communication quality, it is necessary to increase the compression rate of the transmitted and received signal.

To this end, in the present invention, the LPC-VQ method of 4.8kbps is applied to compress the voice signal. This ensures that a good call can be made even at a bit error rate (BER) of 1 × 10 ⁻² (less than 1%).

LPC-VQ is a method of mathematically modeling vocal organs of the human body to reproduce voice in a terminal. Very efficient compression down to 4.8kbps.

On the other hand, looking at the network management technology and the interworking technology with the existing network, the basic network form of the satellite mobile communication service system is a forming network composed of one central station 12 and a plurality of mobile terminal stations (13). That is, all traffic including signal processing is transmitted and received in a double hop form through the central station 12, and call establishment, release, and related information recording are all performed by the network manager 25 of the central station 12.

The network manager 25 includes channel equipment, radio frequency (IF) combination and distribution equipment, network management device hardware and software, and a telephone switch suitable for the CDMA frequency plan applied to the satellite mobile communication system terminal.

As such, all information generation, storage, and management functions related to network management are implemented in software in the network management unit 25 and implement a server that stores and manages related data.

The central station 12 is interworked with the existing terrestrial private network and public switched telephone network (PSTN) via a digital E1 trunk interface.

3 is an exemplary configuration of a mobile terminal station in a satellite mobile communication service system according to the present invention, in which "31" is a duplexer, "32" is a low noise amplifier (LNA), "33". "Down Converter", "34" Analog / Digital Converter, "35" Modem, "36" Micro-Processor, "37" Vocoder ( VOCODER: VOice COder decoDER), "38" is memory (ie, RAM, ROM, Electronic Erasable PROM), "39" is Digital / Analog Converter (D / A) Converter, "40" is Up Converter, "41" is High Power Amplifier (HPA), "42" is Other Peripherals, "43" is Keypad and Screen A liquid crystal display (LCD) and "44" represent a speaker and a microphone, respectively.

The mobile terminal station 13 includes a radio frequency processor 26, a baseband processor 27, and a user interface 28 to provide voice, fax, and data services. In addition, the mobile terminal station 13 further includes a memory 38 such as RAM, ROM, EEPROM, or the like.

The radio frequency processor 26 includes a duplexer 31, a low noise amplifier 32, a down converter 33, an analog / digital converter 34, a digital / analog converter 39, an up converter 40, and a high output amplifier ( 41).

The baseband processor 27 includes a modem 35, a controller 36, and a vocoder 37.

The user interface unit 28 includes other peripherals 42, a keypad / display 43, and a speaker / microphone 44.

The radio frequency processor 26 amplifies the received RF signal by the low noise amplifier 32 by receiving the RF signal from the light of the satellite 11, and then amplifies the RF signal by the down converter 33 for baseband signal processing. After converting to the downlink frequency, the analog-to-digital converter 34 converts the analog signal into a digital signal and transfers it to the baseband processor 27. On the contrary, in order to transmit an intermediate frequency (IF) signal transmitted from the baseband processor 27 to the other mobile terminal station 13 or the terrestrial terminal station 14 through the green light satellite 11, the baseband signal is transmitted. The digital signal is converted into an analog signal by the digital-to-analog converter 39, and then converted by the up-modulator 40 into an up-frequency, and then amplified by the high output amplifier 41 and then transmitted through an antenna.

The baseband processor 27 transmits and receives a CDMA signal with the central station 12, manages and controls the state of the terminal station 13, and receives the voice received from the user interface unit 28 under the control of the controller 36. The data signal is received by the modem 35 and the vocoder 37, modulated, and then transmitted to the RF processor 26. The reverse process is also performed.

The user interface unit 28 provides a transmission / reception service through connection with an external communication terminal 42 such as a general telephone and a telex, and transmits a voice and data signal to the baseband processor 27, and transmits a baseband processor ( 27) receives a signal from the subscriber and delivers it to the subscriber. In addition, it is in charge of the interface between the user and the terminal station 13 performs a function of delivering voice and data to the user commands, signals from the network, and the like.

Referring to the tracking antenna provided in the mobile terminal 13 in more detail as follows.

The mobile terminal station 13 attaches a satellite tracker and a receiver to provide a transmission and reception service through the green light satellite 11 during the movement. At this time, the antenna provided in the mobile terminal station 13 uses a small Ku band dish or a flat antenna.

The method for acquiring the initial position of the small parabola antenna that tracks the optimal signal is to search and track the position of the Mugunghwa satellite 11 by using the information from the gyro compass and the GPS position information indicating the moving direction of a moving object such as a ship. It is. After that, after the position of the Mugunghwa satellite is confirmed, the tracking device is continuously operated within the directional error.

4 is a flowchart illustrating an exemplary embodiment of a satellite mobile communication service method according to the present invention. The procedure for servicing voice, fax, and data between the mobile terminal station 13 and the terrestrial terminal station 14 through the Mugunghwa satellite 11 is shown in FIG. Indicates.

As shown in FIG. 4, in the satellite mobile communication service method according to an embodiment of the present invention, first, when the mobile station 13 is hooked off (401), the central station 12 is a mobile terminal. The transmission / reception channel is allocated to the station 13 (402).

Then, when the mobile terminal station 13 dials (403), the central station 12 transmits a ring signal to the ground terminal station 14 of the dialed number (404). At this time, if the ground terminal station 14 responds (405), the call is in a state where charging begins. Here, voice, fax, and data are transmitted and received between the mobile terminal station 13 and the terrestrial terminal station 14 through the green light satellite 11.

Next, when the mobile terminal station 13 hooks on (406), the central station 12 notifies the ground terminal station 14 of this (407), terminates the call and ends charging again. At this time, the central station 12 calculates and records all call details and charges for them in detail.

5 is a flowchart of another embodiment of a satellite mobile communication service method according to the present invention, and illustrates a procedure for servicing voice, fax, and data between mobile terminal stations 13 through the Mugunghwa satellite.

As shown in FIG. 5, in the satellite mobile communication service method according to another embodiment of the present invention, when the originating mobile terminal 13 first hooks off (501), the central station 12 makes an origination. The transmission and reception channel is allocated to the mobile terminal station 13 (502).

Then, when the calling mobile terminal station 13 dials (503), the central station 12 transmits a ring signal to the called mobile terminal station 13 of the dialed number (504). At this time, if the incoming mobile terminal station 14 responds (505), it is in a call state and charging starts from this time. Here, voice, fax, and data are transmitted and received between the originating mobile terminal station 13 and the terminating mobile terminal station 13 through the Mugunghwa satellite 11.

Next, when the originating mobile terminal 13 is hooked-on (506), the central station 12 notifies it to the terminating mobile terminal 13 (507), terminates the call and ends the charging again. . At this time, the central station 12 calculates and records all call details and charges for them in detail.

As described above, the present invention applies a DS-CDMA technology, an LPC-VQ voice signal compression technology, and a small antenna tracking technology to a satellite communication system. Can be implemented.

Therefore, the present invention can solve the problem of communication quality degradation caused by interference blind spots and interference waves, which has been raised as a problem in the existing terrestrial and marine mobile communication services by applying a satellite network with wide area guarantee to the mobile communication system. This problem can be solved by applying the voice compression technology and DS-CDMA technology. In addition, in the existing mobile communication service, the multi-party call service, which was limitedly provided in the offshore region near the Korean peninsula, can be spread to all regions.

In addition, the present invention implements a mobile communication service system using a Mugunghwa satellite, which is a domestic spot beam satellite, and can be actively used for a demand for a special purpose mobile communication service such as a military communication network requiring external security and disaster resistance.

In conclusion, the present invention implements a more advanced satellite mobile communication service system that successfully supplements the problems of the existing mobile communication service and adds external security and disaster resistance, thereby contributing to the activation and advancement of domestic satellite mobile communication service. The bar is big.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains, and the above-described embodiments and accompanying It is not limited to drawings.

As described above, the present invention implements a micro-satellite mobile communication service system capable of simultaneously serving voice and data on the ground and at sea by using Mugunghwa satellite, which is a geostationary satellite, thereby reducing existing mobile communication costs, There is an effect that can be activated.                     

Claims (14)

delete In the mobile communication service system using a satellite, Control and manage satellite mobile communications networks, provide a pool of pseudonoise (PN) codes, generate reverse link data transmitted in binary phase shift keying (BPSK) signals, and Control means for switching to a data channel and recording and preserving all call related materials; And A satellite tracker and a receiver are attached and attached so that an optimal signal can be transmitted to and received from the satellite, and a plurality of devices for transmitting and receiving voice, fax and data through the satellite mobile communication network under the control of the control means. Terminal Satellite mobile communication service system applying a frequency spreading method including a. The method of claim 2, The plurality of terminals, A satellite mobile communication service system using a frequency spreading method characterized by compressing a voice signal by applying a linear predictive encoding-vector quantization (LPC-VQ) method of 4.8 Kbps to increase the compression rate of the transmitted and received signals. The method of claim 3, wherein The mobile terminal provided in the mobile unit of the plurality of terminals, So that the optimum signal can be transmitted and received with the satellite. A satellite mobile communication service system using a frequency spreading method, characterized by continuously searching and tracking the position of the satellite through a three-axis automatic tracking device and a gyro compass attached to the antenna. The method according to any one of claims 2 to 4, The satellite mobile communication network, In order to mitigate off-axis radiation, the direct sequence code division multiple access (DS-CDMA) scheme, which spreads the spectrum by lowering the power of the transmit antenna, provides a large number of channel capacities, so that all traffic including signal processing Compose a communication network with a star network that is transmitted and received in a double hop form, and the code division multiple access (CDMA) / frequency division multiplexing in which a reverse signal from the mobile terminal to the control means spreads the frequency band in units of 1 MHz. It is transmitted in a connected (FDMA) manner, and since the forward signal from the control means to the mobile terminal uses a large antenna of the control means, it is not necessary to consider much interference, and time division multiple access (TDMA) / frequency division multiple access (FDMA) Satellite mobile communication service using a spread spectrum method system. delete delete delete delete delete delete delete delete delete

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