KR20010023715A - System for selectively downloading information at user terminals from the internet using a satellite system - Google Patents

Abstract

It provides a satellite direct digital broadcasting system that broadcasts selected Internet information such as news, weather, stock quotes, etc. together with a radio program. The broadcast channel includes one service control header for identifying internet information and internet information included in the broadcast channel. The user terminal 22 comprises a radio broadcast receiver 2 for receiving program broadcasts via satellite 20. The audio program is played in one speaker connected to one radio broadcast receiver 21. The user terminal 22 also comprises a multimedia device, such as one personal computer 29 connected to the receiver. The multimedia device is programmed to present a computer output that instructs a user to select a heading of Internet information. The multimedia device stores the received packets and optionally retrieves the packets to generate a screen output such as a web page using packets corresponding to the heading of information selected by the user.

Description

SYSTEM FOR SELECTIVELY DOWNLOADING INFORMATION AT USER TERMINALS FROM THE INTERNET USING A SATELLITE SYSTEM}

With the widespread use of personal computer equipment, telecommunications equipment and the Internet, the global economy is experiencing an important information revolution comparable to the industrial revolution of the 19th century. However, many still use unsatisfactory telecommunications options and services, which limit their participation in today's information revolution. Suffering from these inconveniences, they are primarily in Africa, Latin America, and other countries, which still receive communications services for short-wave radio broadcasts with poor sound quality, or for amplitude-modulated (AM) and frequency-modulated (FM) band terrestrial radio broadcast systems, which have limitations in audible areas. I live in Asia.

Therefore, a satellite-based direct radio broadcast system has been proposed that transmits audio and data signals, including images, to low-cost receivers that are essentially distributed throughout the world. Satellite-based direct radio broadcasting system has a number of advantages, such as being portable than the existing satellite system. Many existing satellite systems require large satellite antennas for system connectivity and are not portable. Numerous other existing satellite systems can provide portable or mobile communication services, but these systems have adequate channel capacity to provide the fast data rates needed to transmit information from the Internet or the World Wide Web to multiple users. Do not have

However, satellite-based direct radio broadcast systems have the disadvantage that the user cannot transmit voice or other information because the receiver function is one-way. That is, through satellite-based direct radio information system, users of the receiver cannot communicate in both directions and therefore cannot access the Internet. In many existing Internet access systems, a user connects to an Internet access device using one computer and one communication link, such as a public switched telephone network. A series of screens appear on the user's computer monitor, which prompts the user to select the kind of information they want to get from the Internet. For example, a user would choose to use the Netscape Navigator software provided by Netsscape Communications Corporation of Mountain View, California, USA, to access documents on the World Wide Web. Netscape Navigator software allows a user to enter keywords associated with a selection topic to be sent to a web search engine to obtain information about the selection topic. Conventional radio broadcast receivers do not have a communication link between the user and the Internet access device, which allows the user to select and download material on the Internet.

However, much of the information on the Internet is large enough to provide the same information to different users over different communication channels, at different times, in line with individual user needs, inefficient use of bandwidth, and other satellite communication system resources. Suitable for the population Thus, in addition to being able to receive the information desired by the user from the Internet, low-cost users can provide users with the advantages of satellite-based direct radio broadcasting systems, such as wide geographic range, good sound quality, high data rate, and low cost You need a terminal.

The present invention relates to a system for providing Internet broadcast information to remote user terminals without requiring one backhaul link from the user terminal to the Internet service providing apparatus.

Various objects, advantages and novel features of the present invention will be more readily understood from the accompanying drawings and the following detailed description.

1 is a schematic diagram showing how Internet information is broadcast to users via one satellite direct radio broadcast system, in accordance with a preferred embodiment of the present invention;

2 is a block diagram showing operation of the broadcasting station shown in FIG. 1, according to an embodiment of the present invention;

3 is a schematic diagram showing how broadcast channels are formatted by a broadcast station into a prime rate channel for transmission to the satellite shown in FIG. 1, according to one embodiment of the present invention;

FIG. 4 shows how on-board satellite signal processing is performed in a satellite direct radio broadcast system of the type shown in FIG. 1; FIG.

FIG. 5 is a block diagram illustrating onboard components of the satellite shown in FIG. 1; FIG.

6 is a block diagram showing the configuration of a user terminal combining a digital broadcasting receiver and a multimedia apparatus such as a PC, according to a preferred embodiment of the present invention;

7 is a flow diagram summarizing a series of operations performed by a user terminal of FIG. 5 when downloading a selection packet of received broadcast internet information, in accordance with a preferred embodiment of the present invention; And

8 is an example of a computer screen generated on a user terminal, in accordance with one embodiment of the present invention.

In the drawings, like reference numerals refer to like parts or components.

Detailed description of the preferred embodiment

The satellite communication system 10 of the present invention is described below according to the following heading.

I. System operation overview

II. Broadcast stations

III. satellite

Ⅳ. User terminal

I. System operation overview

In Figure 1, in accordance with the present invention, remotely located receivers can receive sound, data and images of good quality using a low cost receiver and select one or more broadcast channels comprising Internet information. One system 10 is provided that can be downloaded to a computer connected to the system. The system 10 of the present invention is preferably implemented using one satellite direct digital broadcast system. The direct digital broadcast system preferably consists of three geostationary satellites (one of which is indicated at 20 in FIG. 1), low cost radio receivers or user terminals and associated terrestrial networks. For purposes of illustration, a single user terminal 22 is shown comprising one portable radio receiver 21 connected to a multimedia device such as one computer 29.

The broadcast programs are transmitted to the satellite 20 via one or more broadcast stations 26. As will be described in more detail below, the broadcast station 26 encodes a program comprising each or all of the audio and data to make broadcast channels (BCs) transmitted to the satellite 20 by uplink 28 ( coding, multiplexing, and other signal processing. The uplink 28 is preferably a frequency division multiple carrier (FDMC) that transmits BCs in terms of prime rate channels (PRCs). Each PRC provides one PRI (rate rate increment) of 16 kbps in the baseband. One broadcast channel (BC) is preferably configured to include 1 to 8 PRC. Each PRC is assigned a broadcast channel of 224 bits every 432 milliseconds in one Service Control Header (SCH). Broadcast channels transmit packets, some of which make up programs transmitted over the Internet. In accordance with the present invention, the type of Internet information is identified within the SCH. The satellite 20 performs baseband processing on the uplink 28 to transmit prime rate channels of the broadcast channel to the user terminal 22 in at least one of the three time division multiple downlinks 30.

With continued reference to FIG. 1, broadcast station 26 provides multimedia information, such as acoustic bytes, video and web pages, directly from the Internet 25 via one system gateway 23 and one hub 27. I can receive it. The system gateway 23 also serves as one Internet service providing apparatus in addition to the role normally performed by the two or more Internet service providing apparatuses 31 coupled to the hub 27.

According to one aspect of the invention, news, weather forecasts, stock quotes, educational programs, product catalogs and other information accessible via the Internet are provided to the broadcast station 26 of the system 10 of the invention. The system 10 of the present invention determines what type of internet information should be broadcasted when. The system 10 of the present invention comprises one Local Broadcast Control Facility (RBCF) 39 that can be used to assign channels of the uplink 28 to different broadcast stations 26. For example, the channels of uplink 28 may be assigned to one or more stations 26 to send news continuously 24 hours a day. One of the stations 26 may be adjusted to provide stock market data at the time of stock market opening. In the rest of the time, it may be adjusted to broadcast the stock market-related commentary or local news alternately for 30 minutes. It is also possible for one station to broadcast only weather forecasts on one broadcast channel and at the same time broadcast information about education programs or products on a specific time of day. A program schedule, a broadcast time, and a schedule of a corresponding channel may be distributed to users to determine when and to which receiver the TDM downlink 30 should be tuned to receive a specific program including a program consisting of Internet information. To make it possible.

In addition, browser pages for different consumer broadcast packages may be assembled at one central location (eg, service providing device 31a) and provided at one or more broadcast stations 26. . A browser page for one customer broadcast package may provide major news and stock quotes for the day, while another customer broadcast page provides a browser page for important sports news. Program material may be obtained from the Internet by providing a basis for entering an Internet address in a packet for selective downloading and output to a multimedia device connected to the receiver.

According to the invention, each user terminal 22 is configured to receive a satellite direct radio broadcast program via one radio receiver 21. As described above, the receiver 21 may be tuned to receive a broadcast program from a selected one of the three downlinks 30. Receiver 21 is configured to demultiplex and decode downlink 30 to obtain broadcast channels transmitted from broadcast station 26 and sent to downlink 30 by satellite 20. The computer 29 connected to the receiver 22 processes the demultiplexed, decoded and stored data to extract packets corresponding to the type or category of Internet information requested and selected by the user. The computer 29 stores the information and then announces it. This refers to outputting information on a computer monitor or vocalizing an audio portion of selected internet information with a loudspeaker connected to the computer.

A user may request to view, hear, and store demultiplexed, decoded, and stored specific types of information in the broadcast channel 100 of FIG. 3 using a multimedia device. Input devices such as a mouse and keyboard may be used to respond to screen prompts generated by the computer 29. Screen prompts preferably have one or more screens with menus listing different types of information, such as news, weather, educational programs, product information, stock quotes, and corresponding icons. The user can click on an icon with a mouse, for example. As will be described in detail below with reference to FIGS. 7 and 8, the computer 29 processes input using a mouse to determine which menu item to select and to cause the computer to present the stored Internet information selected by the user.

The system 10 of the present invention has the advantage that it is possible to download a relatively large amount of information from one or more Internet service providers efficiently and at low cost, for example, using a satellite direct radio broadcast. have. Since different types of information, such as news and weather forecasts, are very demanding, broadcasting the information to all the user terminals 22 for selective reception transmits the data to an extra segment whenever the user desires. It costs less than that. In order to broadcast popular Internet information and provide a means for screening Internet broadcasting information to user terminals, in addition to securing an extra segment, user requests and responses to the Internet service providing apparatus for receiving Internet information are exchanged. It is not necessary to modify the broadcasting system including the backhaul link.

II. Broadcast stations

Direct radio broadcast systems use digital audio coding techniques. Each satellite 20 emits a direct radio audio signal equivalent to AM mono, FM mono, FM stereo and CD stereo sound quality levels in its coverage area, paging, video. Additional data such as text is also provided directly to the user terminal 22. The system can also provide multimedia services, such as downloading large-scale business databases to PCs, travel-related text and maps, and color images to enhance the effectiveness of advertising and recreational audio programs.

Signal processing for converting digital data from one or more broadcast stations 26 into parallel streams for transmission to the satellite 20 will now be described with reference to FIG. For illustrative purposes, four sources 60, 64, 68, and 72 of program information are shown. The two sources 60 and 64 or 68 and 72 are coded and transmitted together as part of a single broadcast program or service. The coding of the program comprising the combined sources 60 and 64 will be described. The signal processing of the program including the information from the sources 68 and 72 is the same.

Broadcast station 26 assembles information from one or more sources 60 and 64 for a particular program into a broadcast channel that is preferably characterized by an increment of 16 kbps. These increments are called prime rate increments or PRIs. Thus, as shown in FIG. 3, the bit rate carried on one broadcast channel 100 is n x 16 kbps, where n is the number of PRIs used by the particular broadcast service provider. In addition, each 16 kbps PRI may be further divided into two 8 kbps segments of FIG. 3 that are routed or switched together in the system 10. Segments 101 and 103 carry a mechanism that carries two different service items within the same PRI, such as a low bit rate speech signals, or one data stream with low bit rate speech channels per two languages. To provide. It is preferable that the number of PRIs is set according to the program code, that is, predetermined. However, the number n is not a physical constraint of the system 10. The n value is generally set based on commercial interest, such as the cost of a single broadcast channel, the willingness of the service provider to pay.

For purposes of illustration, the n value of the first broadcast channel 59 of sources 60 and 64 is four. The n value of the broadcast channel 67 of the sources 68 and 72 is set to 6 in the embodiment. As described above, the n value can be changed. For example, if one of the sources 60, 64, 68, 72 is for internet information to be broadcast, or if the information consists in particular including video elements, a very large number of PRIs will be needed.

With reference to FIG. 2, one or more broadcast service providing apparatuses may access one single broadcast station 26. For example, the first service provider may generate the broadcast channel 59, and at the same time the second service provider may create the broadcast channel 67. The signal processing described herein in connection with the present invention allows digital data streams from several service providers to be broadcast in parallel streams, which reduces the broadcast cost of the service providers and maximizes the use of space segments. By maximizing the efficiency of the use of space segments, the station 20 can be implemented at a lower cost by using components that consume less power. For example, the antenna of the broadcast station 26 may be a very small aperture terminal (VSAT) antenna. Since satellite payloads require less memory and processing capacity, they do not require much power, which in turn reduces payload weight.

The broadcast channels 59 and 67 are characterized by one frame 100 with a duration of 432 ms, as shown in FIG. This duration is set to facilitate the use of an MPEG source coder, described below; However, the frame periods of system 10 may be set to different predetermined values. If the frame period is 432 ms, each 16 kbps PRI would require 6972 bits per frame (16,000 x 0.432 seconds). Therefore, one broadcast channel consists of one value n of these 16 kbps PRI carried in one group of frames 100, as shown in FIG. As described below, these bits are scrambled for demodulation at the radio receiver 29. The scramble operation also provides a mechanism to encrypt the service according to the service provider selection. Each frame 100 is assigned n 224 bits corresponding to one Service Header (SCH) 102, resulting in nx 7136 bits per frame and nx (16,518 + 14/27) bits per second. It has a bit rate. The purpose of the SCH 102 is to send data to each of the radio receivers 29 that are adapted to receive the broadcast channel 29 or 67 to control the reception mode of various multimedia services, among other features, data and images. To screen, send sensitive decryption information, and address a specific receiver. The service control header 102 is provided with the information necessary to select the Internet information, the information necessary to decrypt the Internet information of the "pay-per-use" type.

Sources 60 and 64 are coded using, for example, MPEG layer 3 coders 62 and 66, as shown in FIG. These two sources are then added via a combiner and then processed using the processor of the broadcast station 26 to code the signals encoded in period frames of 432 ms, i.e., FIG. As shown by the processing module 78 of the SCH, it provides nx 7136 bits per frame. Information-type identification data may also be provided in the SCH of BC.

The blocks represented in broadcast station 26 of FIG. 2 correspond to programmed modules, operated by one processor and associated hardware such as digital memory, coder circuitry, and the like. Frame 100 using a large scale integration (LSI) chip, digital signal processing (DSP) software, and application specific integration circuits (ASICs) for two associative coding methods. Bits are then coded for FEC protection. First, one Reed Solomon Coder 80a is installed so that 255 bits are generated for every 223 bits entering the coder. Then, as indicated by reference numeral 80b, the bits of frame 100 are reordered according to a known interleaving scheme. This interleaving coding spreads the damaged bits across multiple channels, so it can better prepare for error outbreaks in one transmission. Continuing with reference to the processing module 80, one known convolution coding scheme with a constraint length of 7 uses one Viterbi coder 80c. Apply. The Vitelbi coder 80c generates two output bits for each input bit, resulting in 16320 FEC-coded bits per frame for each increment of 6912 bits per frame applied to the broadcast channel 59. Generates. Thus, each FEC-coded broadcast channel (e.g., channel 59 or 67) is comprised of nx 16320 bits of coded, rearranged and recoded information, and the original broadcast 16 kbps PRI is no longer identified. You will not be able to. However, the FEC-coded bits are organized into the original 432 ms frame structure. The overall coding rate for error protection is (255/223) x 2 = 2 + 64/223.

With continued reference to FIG. 3, the nx 16320 bits of the FEC-coded broadcast channel frame transmits 16320 bits each in a set of 8160 2-bit symbols using a channel distributor 82. It is subsequently subdivided or demultiplexed into n parallel prime rate channels (PRCs). This process is shown in more detail in FIG. Shown is a broadcast channel 59 featuring one 432 ms frame 100 with one SCH 102. The remainder of this frame 104 consists of n 16 kbps PRIs corresponding to 6912 bits per frame for each n PRIs. The FEC coded broadcast channel 106 is obtained after the associated Reed Solomon 255/223, interleaving and FEC 1/2 convolutional coding described above with respect to module 80.

As described above, the FEC-coded broadcast channel frame 106 consists of n × 16320 bits corresponding to 8160 sets of 2-bit symbols, each symbol denoted by 108 for illustrative purposes. In accordance with the present invention, the symbols are assigned across the PRC 110 in the manner shown in FIG. Thus, the symbols are spread based on time and frequency, thereby further reducing the error of the radio receiver 21 due to interference in transmission. For illustrative purposes, it is assumed that the service provider of the broadcast channel 59 has purchased 4 PRCs, while the service provider of the broadcast channel 67 has purchased 6 PRCs. 3 shows the assignment status of symbols 114 spanning the first broadcast channel 59 and each of the PRCs 110a, 110b, 110c and 110d of n = 4. In order to perform recovery of each set of two-bit symbols 114 set in the receiver, one PRC sync header or preambles 112a, 112b, 112c and 112d are located in front of each PRC, respectively. The PRC sync header (hereinafter generally referred to as 112) has 48 symbols. This PRC sync header 112 is located in front of each group of 8160 symbols, thereby increasing the number of symbols per 432 ms frame to 8208. Thus, the symbol rate is 8208 / 0.432, corresponding to 19,000 kilosymbols per second for each PRC 110. In order to recover the symbols from the downlink satellite transmission 27, a 48 symbol PRC preamble 112 is necessary for the synchronization of the PRC clock of the radio receiver. In the on-board processor 116, this PRC preamble is used to absorb the timing difference between the symbol rate of the arriving uplink signal and the symbol rate used to switch the signal and assemble the downlink TDM stream. This is done by adding or subtracting zero to each 48 symbol PRC in the rate alignment used on-board in the satellite 20. Thus, the PRC preamble carried in the TDM downlink has 47, 48 or 49 symbols determined by the rate alignment process. As shown in FIG. 3, symbol 114 is a round-robin, in which symbol 1 is assigned to PRC 110a, symbol 2 to PRC 110b, symbol 3 to PRC 110c, symbol 4 to PRC 110d, and symbol 5 to 110e. Assigned to consecutive PRCs in a round-robin fashion. This PRC demultiplexing process is executed by one processor in broadcast station 26, and is shown by channel distribution (DEMUX) module 82 in FIG.

PRC channel preambles are allocated to mark the start of PRC frames 110a, 110b, 110c and 110d for broadcast channel 59 using preamble module 84 and adder module 85. The n PRCs are then differentially encoded and then QPSK modulated at the IF carrier frequency using the bank of QPSK modulator 86 as shown in FIG. Four QPSK modulators 86a, 86b, 86c and 86d are used for each PRC 110a, 110b, 110c and 110d for the broadcast channel 59. Thus, there are four PRC IF carrier frequencies that make up the broadcast channel 59. The four carrier frequencies are each upconverted to an assigned frequency location in the X-band using an up-converter 88 for transmission to the satellite 25. The upconverted PRCs are then transmitted via an amplifier 90 to antennas (eg, VSAT) 91a and 91b.

The SCH 102 inserted into each coded PRC carries instructions that allow the receiver to recombine the coded prime rate channel to reconstruct the coded program channel and identify the program channel to which the PRC belongs. In order to achieve this, it is preferable to include a control word. An example of an 80 bit control word is as follows.

# Show bits

2 Quantity of related groups

(00 = irrelevant, maximum of four related groups)

2 group identification number

(00 = group # 1,11 = group 4)

4 Group Type

(0000 = audio, 0001 = video, 0010 = data,

Other types or pending)

16 kbps prime rate channel quantity in 3 groups

(000 = 1 channel, 001 = 2 channels, ..., 111 = 8 channels)

3 Prime Rate Channel Identification Number

(000 = channel 1, ..., 111 = channel 8)

3 Subgroup Quantity

(000 = 1, ..., 111 = 8)

Number of 16 kbps prime rate channels in 3 subgroups

(000 = 1, ..., 111 = 8)

2 subgroup identification number

(000 = cohort # 1, ..., 111-cohort 8)

3 Group / Subgroup Block

(000 = no blocking, 001 = type 1 blocking, ...,

111 = type 7 blocked)

11 reservations

40 CRC

Control word entries for related group quantities create relationships between groups of different groups. For example, some broadcasters may wish to provide additional information or related services, such as audio, video and data services, such as electronic newspapers containing audio text. Ensemble Identification Number identifies the group number to which the channel belongs. The number of 16 kbps prime rate channels in the population defines the number of prime rate channels in the population. The number of sub-ensemble and the number of 16 kbps prime rate channels in the subgroup is one, such as the use of four prime rate channels for the left stereo signal and four prime rate channels for the right stereo signal in the CD sound quality stereo population. It defines the relationships within the group. You could even combine music with multiple voice signals consisting of voice signals in different languages. The number of subgroups of 16 kbps prime rate channels defines the number of prime groups of subgroups. The subgroup identification number identifies the subgroup to which the channel belongs.

The group / sub group blocking bit enables cooperative blocking of broadcast information. For example, some countries may ban alcohol advertising. In the user terminal 22 to be used in such a country, a code for blocking specific information can be set or made to be loaded in response to a blocking signal. The blocking function may block the dissemination of sensitive information such as military information or government information, or may block broadcast service that may bring revenue to a specific user.

As described above, each coded program source is divided into separate prime rate channels. For example, one audio source may consist of four prime rate channels to represent a stereo signal in FM quality. Other audio sources consist of six prime rate channels that can be used as stereo signals close to CD or FM stereo signals connected to 32-bit data channels (for example, with signal transmission for output on a radio receiver LCD). will be. Alternatively, six prime rate channels may be used for the 96 kbps broadcast data channel. The image source can be configured to include one or several 16 kbps channels. As will be described in more detail below, the user terminal 22 automatically determines the prime rate channels needed to generate a user-selected digital audio program or other digital service program according to the group information contained in the TDM frame and each prime rate channel. It is preferable to select.

According to the present invention, the transmission method adopted by one broadcasting station 26 integrates a plurality of n single channel fur carriers and frequency division multiple access (SCPC / FDMA) carriers into the uplink 21. These SCPC / FDMA carriers are spaced on a grid of center frequencies which are preferably spaced at 38,000 hertz (Hz) apart from each other and organized into 48 adjacent center frequencies or groups of carrier channels. The grouping of these 48 carrier channels is useful for preparing demultiplexing and demodulation processing performed at satellites. Several groups of 48 carrier channels do not necessarily need to be adjacent to each other. Carriers associated with a particular broadcast channel (ie, channel 59 or 67) do not necessarily need to be contiguous within one group of 48 carrier channels, nor do they need to be assigned within the same group of 48 carrier channels. Therefore, the transmission method described in connection with FIGS. 2 and 3 maximizes the flexibility of frequency positioning and the ability to fill the available frequency spectrum and avoids interference with other users sharing the same radio frequency spectrum.

1 shows the overall operation of a system 10 that broadcasts Internet information as well as other broadcast programs in connection with a preferred embodiment of the present invention. In the case of the satellite processing payload, the uplink signal 28 is broadcasted via individual frequency division multiple access (FDMA) channels from the broadcast station 26 located at an elevation of 10 degrees or more within the terrestrial viewing range of the satellite 20. Is generated from. Each station has the ability to uplink directly from its facility to one of the satellites 20 by installing one or more 16 kbps prime rate channels on the FDMA carriers. Otherwise, broadcasters who do not have the capacity to directly access the satellite 20 are connected to the satellite 20 through one hub station. For example, the system gateway 23 may broadcast the broadcast web page either directly with one of the direct radio broadcast satellites 20 or indirectly through the hub 27. The use of FDMA for uplink 28 provides the highest flexibility among multiple independent broadcasters.

III. satellite

The preferred satellite 20 of the direct radio broadcast system 10 covers the Africa-Arabia region, the Asia region, the Caribbean region, and the Latin America region along the following geostationary orbit.

● Location of Tokyo's 21˚ orbit: service to Africa and the Middle East

● 95-degree orbit in West Gyeong-do Location: Providing service to Central and South America

● 105 ° orbit west longitude: service to Southeast Asia and the Pacific Rim

Other regions, such as North America and Europe, may add satellites to provide services.

Direct radio broadcast systems preferably use a frequency band of 1467 to 1492 MHz, which is the Broadcast Satellite Service (BSS) Direct Audio Broadcast (DAB) service in WARC 92, in accordance with resolutions 33 and 528 of the ITU. Assigned for The broadcast station 26 uses a feeder uplink in the X band of 7050 to 7075 MHz. Each satellite 20 preferably has three downlink spot beams, having a beam width of about 6 degrees. Each beam covers 14 million kilometers in the power distribution contour 4 dB lower from the beam center and 28 million kilometers in the power distribution range 8 dB lower from the beam center. The beam center margin will be 14 dB based on a receiver gain-to-temperature ratio of -13 dB / K.

Each satellite 20 has two types of payload. One is a “processing payload” that regenerates uplink signal 28 and assembles three TDM downlink carriers, and the other repeats the uplink signal on three TDM downlink carriers 30. Is the "transparent payload". TDM signals 30 from two payloads are transmitted in the form of a processing signal and a transparent signal in three beams with opposite circular polarization (LHCP and RHCP), respectively. Each TDM downlink signal 30 transmits 96 prime rate channels in the assigned time slot. In the user terminal 22, all of the TDM downlink signals 30 except for the carrier frequency appear the same. The total capacity of one satellite is 2 x 3 x 96 = 576 prime rate channels.

The conversion between the uplink FDMA signal 28 and the downlink multiple-channel-per-carrier / time division multiplexing (MCPC / TDM) signal 30 of the direct radio broadcast system of FIG. 1 is performed by the satellite 20 on-board processor. Is made by At satellite 20, each prime rate channel transmitted by broadcast station 26 is demultiplexed and demodulated into a separate 16 kbps baseband signal. Each channel is routed through the switch to one or more downlink beams 30, each of which is a single TDM stream. This baseband processing provides a high level of channel control in terms of uplink frequency allocation and channel routing between uplink and downlink. Uplink signals are received in the X band at the satellite and converted to the L band for the on-board processor. The downlink 30 to the user terminal uses an MCPC / TDM carrier. One such carrier is used in each of the three beams of each satellite 20. The way in which direct radio broadcast systems format FDMA uplinks and perform payload processing for generating TDM downlinks, among other things, allows for the reception of significant amounts of data, including good quality audio programs using low cost receivers.

In the case of a transparent payload, the TDM signals are assembled at the broadcast station and appear exactly in the same structure as assembled at the satellite 20 by the processing payload. The TDM signal is sent to the satellite in the X band and repeated in the L band of one of the three downlinks. The output level is equal to the downlink TDM signal generated by the processing payload. Thus, a technique for providing digital transmission of all information services (such as voice, music, data, images, and multimedia information that can be obtained from the Internet) according to the invention described herein is transparent payload and processing. It can be applied to both payloads. Processing such as routing performed at satellite 20 may occur at terrestrial stations when using transparent payloads.

FIG. 4 illustrates relocation of the prime rate channel on the satellite from the uplink frequency division multiple access channel to the downlink MCPC / TDM channel of the processing payload of satellite 20 in FIG. The total uplink capacity is preferably 288 to 384 prime rate channels 116 per 16 kbps. 96 prime rate channels 118 are selected for transmission in each downlink beam 30 and time division multiplexed into one carrier having a bandwidth of about 2.5 MHz as indicated by reference numeral 120. Each uplink channel may be routed with all or some downlink beams or not at all. The order and placement of the prime rate channels in the downlink beam may be selected from telemetry, audible distance and control (TRC) facility 38 via the command link, as shown in FIG.

In order to allocate the space segment of the uplink beam 28 to the satellite 20, software is preferably provided to the broadcasting station 26, and if there is more than one broadcasting station 26 in the system 10, local broadcasting control. It is preferably provided to facility (RBCF) 39. The RBCF 39 is preferably connected to the TRC facility 38 via a communication link. The software optimizes the use of the uplink spectrum by assigning PRC carriers whenever there is a spare in the 48 channel groups. Carriers associated with a particular broadcast channel need not be contiguous within a group of 48 carrier channels and need not be assigned to the same group of 48 carrier channels.

The carrier frequency of each downlink beam 30 is different to enhance beam to beam isolation. Each TDM downlink channel operates in a satellite payload in saturation and represents the maximum possible output efficiency in connection performance. The use of single carriers in transponder operation can achieve maximum efficiency when using satellite communication payloads for solar conversion to radio frequency outputs. This is more efficient than techniques requiring simultaneous amplification of multiple TDM carriers. The system produces high reception margins suitable for fixed and mobile reception indoors and outdoors.

The system 10 of the present invention performs audio source encoding using MPEG 2.5, Layer 3, which represents the corresponding quality at bit rates of 16, 32, 64, and 128 kbps, and also performs 8 kbps encoding. have. Image coding is done using the JPEG standard. The error rate of the system is less than 10 ^-10 and is therefore suitable for high quality digital image and data transmission for multimedia services. MPEG 2.5, Layer 3 encoding provides better bit rate efficiency than previous MPEG 2.1, layer 2 (musicam) or MPEG 2 standards for sound quality. In audio broadcasting, the digitally coded source bit rate is as follows.

◆ utility mono voice: 8 kbps

◆ non-general mono voice: 16 kbps

◆ FM music close to mono quality: 32 kbps

◆ FM music near stereo quality: 64 kbps

◆ CD stereo music close to sound quality: 128 kbps

In a preferred implementation of a satellite direct radio broadcast system, each satellite has the ability to transmit a total of 3072 kbps per beam, including two TDM carriers for each of the processing payload and the transparent payload, thereby all of the above described. Combinations of audio services are possible. This is equal to the capacity per beam below.

◆ 192 mono audio channels; or

◆ 96 mono music channels; or

◆ 48 stereo music channels; or

◆ 24 CD stereo music channels; or

◆ any combination of the above signal qualities

Since the system 10 of the present invention provides a direct digital channel for the digital transmission of broadcast services, any type of data, images, video and other such as information from the Internet and multimedia sources, as well as voice and music, can be obtained. Multimedia data may also be broadcast via the satellite 20. According to one aspect of the present invention, the system 10 of the present invention can provide push internet information or the like that is transmitted to the user terminal 22 without being acknowledged by the user.

The overall satellite direct radio broadcast system transmits digital signals with a bit error rate (BER) of 10 ^-4 or lower, thereby providing the various quality of service described above. For each of the L-band downlink beams 30 transmitted by the satellite, the Edge of Coverage EIRP of the TDM carrier is 49.5 dBW. This EIRP uses a baseline radio receiver antenna with specific forward error correction (FEC) to ensure a 9 dB minimum margin of 10 ⁻⁴ BER. This margin helps to combat the signal loss due to obstructions in the path between the satellite 20 and the receiver of the user terminal 22, providing perfect reception quality within the desired service area.

The user terminal 22 in an obstacle-blocked area may be connected to a high gain antenna or an antenna installed in an obstacle-free area. For example, reception in a large building would require a common roof antenna with internal retransmissions for the entire building or a separate receiving antenna near the window. Where the 4 dB down on the ground service area, and has a margin channels are calculated to 10dB with respect to power density (power density) needed to represent the bit error rate of ^10-4. This margin at the center of the beam is 14 dB.

The operating margin of a direct radio broadcast system does not change because of its high bit rate. Within the 4 dB contour, most user terminals 22 look at the satellite at an elevation angle of 60 Hz or more, so that there is practically no interference due to the structure. In some beams, the elevation angle to the satellite in the 8 dB range is greater than 50 dB and sometimes experiences interference from reflections and blocking from the structure. A line of sight reception at small elevations (10 Hz to 50 Hz) is also always possible using a small 8 dBi gain antenna with some beams oriented towards the horizon.

As described above, the direct radio broadcast system includes one baseband processing payload of satellite 20. Baseband processing enables the system cost improvement for uplink and downlink connection costs, broadcast station management, and downlink signal control. 5 shows a satellite signal processing process of a satellite direct radio broadcasting system. The coded prime rate uplink carrier is received at the X band receiver 122. One multiphase demultiplexer / demodulator 124 receives 288 individual FDMA signals (48 signals in the form of six groups) and six analog signals in which the data of 288 signals are divided into six time multiplexed streams. Is generated to perform demodulation of serial data on each stream. One routing switch / modulator 126 modulates three downlink L-band TDM signals with or without routing individual channels of serial data to all or some of the three downlink signals each having 96 channels. . The traveling wave tube amplifier 128 amplifies the output of the three downlink signals, which are sent to the earth by the L band transmit antenna 130. The transparent payload also consists of one demultiplexer / downconverter 50 and one amplifier group 52, which are known for frequency converting uplink TDM / MCPC signals for retransmission in the L band. It consists of a bent pipe signal path.

The satellite 20 is operated by one terrestrial control sector (e.g., software available on a single broadcaster or software available on the RBCF serving multiple broadcasters), and during the orbital lifetime the traffic is transmitted by the mission control sector. traffic is managed according to the needs. The bit rate and hence the quality of service are mixed in order to meet the service demand in any range. The bit-rate / quality nature of a service can be easily changed by orders from the ground and can also vary over time. In a preferred embodiment, the channel assignment can be changed hourly by a preset program schedule 24 hours in advance. However, of course, channel assignments can change from time to time often and sometimes rarely.

2, within each QPSK modulation block 86, one individual QPSK modulator modulates each prime rate channel to one intermediate frequency. Upconverter 88 shifts the individual prime rate channels to the FDMA uplink band, and the upconverted channels are transmitted via amplifier 90 and antenna 91. The uplink broadcasting station preferably uses a VSAT signal using a small antenna having a diameter of 2 to 3 m in transmitting a 16 kbps base channel.

Prime rate uplink channels are transmitted to satellite 20 on separate FDMA carriers. As described above, up to 288 uplink prime rate carriers may be transmitted to the satellite 20 via the global uplink beam. A small station terrestrial station with a parabola X-band antenna of 2.4 m in diameter and a 25-watt amplifier is a branch in the country that has programmed a program channel of 128 kbps per second (with eight prime rate channels). From satellite to satellite 20 can be easily transmitted. Instead, the program channel may be connected to the shared uplink terrestrial terminal via a rented PSTN terrestrial link network. By having its own satellite radio broadcast channel, the system has adequate uplink capacity to cover countries around the world.

Ⅳ. User terminal

A block diagram of one of the user terminals 22 of FIG. 1 is shown in FIG. 6. The user terminal 22 receives and modulates the L band signal from the satellite 20, extracts useful audio, data and image signals from the TDM stream and reproduces them with desired audio and image information. The user terminal can be equipped with a small patch antenna with virtually no orientation and with a gain of about 4-6 dBi. The user terminal 22 is automatically tuned to the selected channel.

As described above, time division multiplexed, multiple-channel-per-carrier (MCPC / TDM) technology is used for downlink transmission to user terminal 22. Each prime rate channel has its own time slot in the time division stream. These prime rate channels are combined to transmit program channels that range from 16 to 128 kilobits per second. The use of digital technology enables additional services for the radio, including the use of slow video, call, mail, fax and flat screen outputs or serial data interfaces. This data and information may be multiplexed within an audio digital signal channel. In addition, the prime rate channel may carry screens for display on a user terminal (eg, a home page on the WWW) and program channels, which are data downloaded for storage and printing, with or without an audio program. have.

Each user terminal 22 may be tuned to one of the TDM carriers transmitted to one of the beam coverage areas. As shown in FIG. 6, the user terminal 22 includes one digital broadcast receiver 21, one antenna 136, and one computer 29. The receiver 21 can be connected to the serial port of the computer 29, for example. One Internet service providing device, such as the system gateway 23 of FIG. 1, may be operated in one, two or both of the beam service zones of the three satellites 20. The system 10 of the present invention provides information on the satellite 20 via the FDM uplink 28 assigned to one Internet service providing device and one or more downlink beams 30 via software and telemetry control. You can change how root is routed.

In the digital broadcast terminal 21, one low noise amplifier 138 amplifies the satellite signal, and the amplified signal is received by one front end / QPSK demodulator 140. The output of the RF front end / QPSK demodulator 92 is a first time division demultiplexer 142 that recovers audio prime rate channels (PRCs), and a prime rate that carries data including image information. One second time division demultiplexer 144 may be connected to restore the channel.

After n PRCs of the received broadcast channel are rearranged, the symbols of each PRC are remultiplexed using blocks 142 and 144 into one FEC-coded broadcast channel. The output of block 142 is one baseband digital signal for transmitting audio information, and the output of block 144 is one baseband digital signal for transmitting data.

This reconstructed recombined, coded program channel is decoded and deinterleaved to recover the original baseband prime rate bit stream entering the system of terrestrial broadcaster 26. In the case of audio data, the recovered bit stream is converted back to one analog signal by one audio decoder 146 and one digital-to-audio converter 146. The analog signal is amplified by the amplifier 146 and reproduced through the loudspeaker. The user terminal 22 can reproduce various audio quality from AM mono to CD stereo according to the program channel bit rate. In the case of data, the reconstructed bit stream may be converted into a format that can be output by the picture / image decoder 154. The received data may be stored or printed in the memory device in addition to the screen output.

The instructions necessary for the user terminal 22 to control the recombination of the coded prime channel into the coded program channel are engraved in the coded prime rate channel and the original prime rate bit stream (such as SCH or PRC preamble), respectively. It is preferably contained in an embedded control word. Receiver 21 is programmed to process instructions in control words.

By one embodiment of the present invention, one SCH 102 is provided in each BC as shown in FIG. Data from the data decoder 154, including the broadcast channel and the SCH, is provided to the computer 29 through one broadcast channel input / output (BCIO) port. Computer 29 stores data in disk drive 176 of FIG. The computer processes the data to inspect the packet. Packet information is compared with user selections made using keypad 170, mouse 174, or other input device connected to computer 29 to determine which storage packet to use depending on the output purpose. . The information identification data may be provided as part of the service control header 102, which identifies packets originating from the same internet source.

The main components of the computer 29 are one microprocessor 156, one real-time clock and one screen controller 166 with adequate RAM 160 and ROM 162 capacity. It includes. Screen controller 166 controls the formatting of image data (eg, web page data) to screen 168. The microprocessor 156 is also preferably connected with one keypad 170, one printer / plotter 172, one mouse 174 and one disk drive 176. One microprocessor input / output (I / O) interface 158 is shown to represent the serial and parallel ports of the microprocessor 156. As shown in FIG. 6, the data decoded by the receiver 21 is sent to the computer 29 through one serial port connection device. The keypad 170 and the mouse 172 are used to select a broadcast program, control sound quality, and select a menu. Menus and screens may be created on screen 168 in accordance with program code of microprocessor 156 or a received web page. In addition to showing data on screen 168, printer / plotter 172 allows a user to have a printed copy of all received data, including images. Finally, disk drive 176 allows data or programs to be loaded into computer 29, and allows computer 29 to store received data such as web pages for later viewing, listening, and printing. Another function of the disk drive 176 is that, for example, the computer 29 may receive an image or other data received in real-time from an existing data stored on a magnetic diskette, or may be digital broadcast receiver 21. You can use) to merge. This is useful for allowing existing images or other data to be updated, for example, simply by sending new or modified information without retransmitting the existing images or data.

The elements of FIG. 6 may be incorporated into one single device designed for portable or mobile use. Instead, as shown in FIG. 1, the receiver 21 can be a portable device connected to one individual computer 29. At this time, power is supplied by a battery, a solar cell, or a generator operated by a spring motor, a hand crank, or the like. When the user terminal 22 is used in a vehicle such as a ship, an airplane, a vehicle, the user terminal 22 supplies power to a power supply device of the vehicle. Instead of accommodating all the components of the user terminal 22 in one single case, a network or system of individual components interconnected with appropriate cables may be constructed.

FIG. 7 is a flow diagram summarizing a series of basic operations performed by the user terminal 22 of FIG. 5 when audio or data programs are received. It can be seen from this flowchart that the user terminal 22 can simultaneously receive and play audio programs and data due to the TDM format of the downlink channels 30. Thus, the user does not have to interrupt the audio program being listened to in order to receive an image or other type of data. As a result, for example, a user who wants to obtain selected data from the Internet can simultaneously obtain the data while listening to the audio program of the audio program channel.

Referring now to the logic sequence shown in FIG. 7, the first step in the program is to power on and initialize the receiver 21 and the computer 29 (block 180). Receiver 21 is adjusted to receive one of three TDM downlinks 30 (block 182). The receiver demultiplexes, decodes the prime rate channel from the received downlink 30 and remultiplexes the channels into one broadcast channel including the SCH 102. The broadcast channel may include one real-time audio and video program. The user terminal initiates audio program playback to speaker 152 and video program output to screen 168 (block 184). The broadcast channel may also include Internet information stored on disk drive 176 for non real-time use. Computer 29 creates screen 220 on screen 168 as shown in FIG. 8 (block 186). Screen 220 is an initial browser screen that provides a user with a list of different information topics obtained from an internet broadcast.

The screen 220 may provide a single icon and a corresponding name of the title of information such as news, weather, stock quotes, product catalogs, maps, and the like. The user can select one of the desired subjects using the keypad 170, the mouse 174, or some other input device (block 188).

According to a preferred embodiment of the present invention, stored information identifying the type of packet data obtained from the SCH 102 is processed by the computer 29 to select and display the type of Internet information selected by the user (block 190). And 192). As shown in the packet matching check block 194 and the packet matching branch of the packet ignore block 196, the computer extracts a packet corresponding to the user's selection, and displays the packet according to the packet. Create a screen (block 198). For example, the packets may comprise one web page, or one simple computer screen with text but no graphics, or data for displaying video data. In addition, some packets may include one sound byte that may be provided to an auxiliary speaker 178 that is directly connected to the computer. If the selected data has one sound byte, the playback of the audio program through the speaker 152 may occur simultaneously with the playback of the sound byte. Packets whose information identification data do not correspond to user selections on screen 220 are ignored by computer 29 (block 196).

The subject of the information currently stored in the disk drive 176 is output on the screen 22. Meanwhile, disk drive 176 may store a new set of Internet information that is currently being received so that the user can later retrieve it again. As such, the disk drive allows you to store new Internet information while searching and browsing already stored information. The computer can also store information for later use of real time materials such as distance learning.

The system 10 of the present invention is useful in providing remote users with digital delivery channels for broadcasting voice, music, other types of image and video data, and multimedia information. Therefore, a user terminal not connected to the Internet can also receive Internet broadcast information, that is, push Internet broadcast information, which does not require confirmation from a remote user. According to another aspect of the invention, the user terminal may be provided with a terrestrial network, such as a public switched telephone network connection, for communication with the information provider. For example, a user may receive an educational broadcast program including voice, text, and image information from a long distance learning center via satellite 20. The user can send a response to the training program via a PSTN link to a long distance learning center or elsewhere. This configuration is useful when the PSTN link does not have enough bandwidth to carry the program's voice, text, and image data.

Although the present invention has been described with reference to preferred embodiments, the invention is not limited to the details described. Various alternatives and variations have been described above, and others will be possible to those of ordinary skill in the art. All such alternatives and modifications should be considered to be within the scope of the invention as defined in the appended claims.

Summary of the Invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a satellite direct digital broadcasting system that broadcasts selected Internet information to a low cost user terminal in view of the problems and limitations described above. The selected internet information may be, for example, weather forecasts, news, stock quotes, product catalogs, etc., among other types of information.

Another object of the present invention is to broadcast a selected type of Internet information in the form of a packet of a broadcast channel. Internet packets are streamed through the broadcast channel of the satellite direct broadcast system. The broadcast channel may transmit one or more of the Internet information types such as news, weather, stock quotes, and the like. In addition, the Internet packet includes information necessary for selecting a specific page such as a category of Internet information by using a browser.

Another object of the present invention is to provide a low cost user terminal comprising a radio broadcast receiver adapted to be well connected to a multimedia device such as a PC.

It is still another object of the present invention to provide a user terminal with a user interface for selecting a type of broadcast Internet information to be stored for screen output on the user terminal. The user terminal uses the selection input through the user interface to inspect the stored packets, and retrieves the storage packet corresponding to the type of Internet information selected by the user. The packet is output to the screen or voice using a multimedia device.

The above and other objects of the present invention are incorporated by a broadcast receiver for receiving a satellite direct radio broadcast and a multimedia device for storing and outputting selection information from an Internet service providing device broadcast through the satellite direct radio broadcast system. Partly achieved by providing a user terminal to a remote user. The user terminal is programmed to convert the user information option indicative of the type of Internet information desired by the user into a control signal for instructing the multimedia device to extract a received packet corresponding to the user information option for voice and screen output. .

Thus, in one aspect of the present invention, an Internet service providing apparatus has a gateway configured to route selected multimedia data from the Internet / WWW to a broadcasting station. The broadcast station formats the Internet packet data into a broadcast program including the packet, and transmits the broadcast program to the satellite of the satellite direct digital broadcast system. The service providing apparatus supplies additional information for identifying a packet corresponding to different types of Internet information such as news in a broadcast program, a merchant catalog, an education program, and the like.

In another aspect, the present invention relates to a method for enabling a low-cost portable user terminal that can be accessed worldwide, and limited access to information services available through the Internet. The method comprises the steps of generating a screen prompt on a multimedia device, such as a PC, connected to a radio broadcast receiver. Screen prompts allow the user to choose between different types of Internet information broadcast via the satellite direct broadcast system. The receiver demultiplexes and decodes the data received from the satellite direct radio broadcast system to obtain a broadcast channel. The user's response to the screen prompt is processed by the computer to allow the computer to extract selected packets of the broadcast channel that make up the broadcast program containing the Internet information. The multimedia device first stores the packet from the broadcast channel in a mass storage device such as a disk drive for later access by the user.

Claims (10)

One receiver; Is configured to receive a broadcast channel comprising packets comprising information relating to at least one of the plurality of headings and comprising data indicating which of the plurality of headings corresponds to which of the plurality of headings, One satellite operative to transmit the broadcast channel to the receiver; One processing device coupled to the receiver; A user input device connected to the processing device; A screen output device connected to the processing device; The processor may be programmed to display one screen on the display device to allow a user to select one of the plurality of headings, and the receiver may be operated to provide the packet to the processor. And when the user makes a selection using the screen, processes the one input signal made using the user input device and examines the data to determine which of the packets corresponds to the input signal. Provide the user terminal with information from at least one telecommunications network, wherein the processing device is operable to control and the screen output device is controlled by the processing device to output the information corresponding to the input signal. System. The method of claim 1, further comprising a multimedia device connected to the receiver, wherein the information comprises at least one of data, graphics, still images, moving images, text, audio, web pages, and videos. The multimedia apparatus outputs the data, the graphic, the still image, the video, the text, the audio, the web page, and the video according to the input signal, and performs at least one of a plurality of operations of reproducing the audio. A system that can be operated to perform. The apparatus of claim 1, further comprising: at least one of an Internet service providing computer and one system gateway connected to the telecommunication network; Further comprising the broadcast station receiving the information from at least one of the one Internet service providing apparatus and the one system gateway and indicating which of the plurality of headings corresponds to the packets. And format the information with data into the broadcast channel, and transmit the broadcast channel to the satellite. 4. The system of claim 3, further comprising a hub for connecting the broadcast station to the system gateway. Formatting a broadcast channel comprising a plurality of headings for transmission to user terminals and packets of said internet information relating to identification data identifying which of said plurality of headings are packets of internet information; Transmitting the broadcast channel to the user terminal through a satellite; Receiving the broadcast channel at a plurality of the user terminals; Creating a menu using the multimedia device to enumerate the plurality of headings; Determining one user input signal corresponding to a selection of one of the plurality of headings from the menu; Determining which of the packets corresponds to the user input signal using the identification data; Outputting the packets corresponding to the user input signal using the multimedia apparatus; A method of broadcasting information from an internet service providing apparatus to a user terminal including a receiver and a multimedia device through a satellite without a backhaul link between the user terminal and the service providing apparatus. 6. The method of claim 5, wherein the formatting step comprises formatting the internet information comprising at least one of news, weather forecasts, stock quotes, educational programs and customer information. The method of claim 6, wherein the menu generation step; Using the multimedia device as menu options to identify at least one of the news, the weather forecast, the stock quote, the educational program, and the customer information, Providing a prompt for a user to select one of the menu options. 6. The method of claim 5, wherein the formatting step further comprises formatting program information indicating the plurality of headings and corresponding broadcast time for reception at the user terminal. The method of claim 8, wherein the user terminal is programmed to update the menu using the program information. Multiple receivers; At least one broadcast station for transmitting one broadcast channel comprising packets of different types of internet information and which of the packets identifies which of the other types of internet information; One satellite for receiving the broadcast channel and transmitting the broadcast channel to the plurality of receivers; It is made, including At least one of the plurality of receivers receives the broadcast channel, The receiver comprises one multimedia device, The multimedia device, A memory device for storing packets obtained from the broadcast channel; One output device for reminding the user to select one from a plurality of different types of Internet information; An input device that allows a user to make the selection; One processor programmed to retrieve the selected packets stored in the memory device corresponding to the selection and to provide the selected packets to the output device, Satellite broadcasting communication system for broadcasting internet information.