JP2001203633A - Data transmission system and its base station and satellite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data transmission system whose polling efficiency is enhanced. SOLUTION: A base station of a mobile phone network has a control unit that generates a series of data packets to be sent to all mobile phones through a common downlink. Each data packet has a header including a 1st selection phone identification flag, polls the phones identified by the flag and allows the phones to return to the base station through a common channel. The header also includes a 2nd selection phone identification flag and an identification ID and a time slot, polls the phones identified by the flag and allows the mobile phones to return to the base station through a common channel thereby attaining to poll at least two phones. The control unit polls each phone twice for each polling cycle, one polling includes the identification ID of a 2nd standby uplink channel and a time slot with respect to the channel and the other polling does not include them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to data transmission systems and, more particularly, to mobile telephone networks employing such systems and to ground stations and communication satellites for use in such systems.

[0002]

2. Description of the Related Art In a mobile telephone network, there are a number of base stations serving different areas. Each base station is configured to communicate with multiple mobile phones in its associated area.

[0003] These base stations perform communication with mobile telephones at discrete frequency (discrete number of channel f) values.
requencies). The mobile telephones are typically arranged in groups having base stations, and along the common downlink channel having one eigenfrequency assigned to the group from the base station to all telephones that make up the group. A signal is transmitted. The base station transmits from each mobile phone in the group an uplink station having a different natural frequency assigned to the group.
Receive signals along the channel.

In operation, the base station transmits data along a common downlink channel to all of the mobile phones in each group in a series of data packets. Each data packet is composed of two parts. The first part is called the header, a code ID that identifies the selected mobile telephone in the group and the uplink state that activates the mobile telephone so that it returns a data packet to the base station. The second part contains the payload of the data that the mobile phone will download and use as needed. The header is "transparent". That is, the header is readable by all mobile phones in the group. The payload is encrypted and its ID can be read and downloaded only by the mobile phone contained in the header. These packets are typically 20ms
When a particular telephone downloads a packet that includes its uplink status flag, the telephone immediately downloads the data packet along the common uplink channel after receiving the packet. It will be returned to the base station.

[0005]

In the conventional system,
If only one uplink status flag is received (i.e., polled) during each cycle of successive data packets transmitted from the base station at each mobile phone, the mobile phone will receive 20ms
There is a problem that data can be transmitted to the base station only during the interval and polling efficiency is low.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a data transmission system capable of improving polling efficiency, and in particular, to a mobile telephone network using such a system and a ground station and satellite for use in such a system. The purpose is to provide.

[0007]

According to one aspect of the present invention, a base station having a radio transmitter and receiver, a plurality of satellites each having a radio transmitter and receiver, and transmission of the base station. And the satellite's receiver are all tuned to the same downlink channel, and the satellite's transmitter and the base station's receiver have a common uplink channel and at least one spare uplink channel. The base station cyclically generates a series of data packets,
Control means for transmitting them to said plurality of satellites,
When each data packet is received by the first selected satellite, first poll only that satellite so that the satellite returns the data packet along the uplink channel to the base station. A header having a first section containing a first uplink status flag relating to the selected satellite, and polling only that satellite when received by the second selected satellite to receive the second selected satellite. Is paired with an identification ID of the spare uplink channel and a time slot for that channel that causes data packets to be transmitted along the spare uplink channel to the base station in the time slot. A second section containing a second uplink state flag identifying the second selected satellite being located; The number of packets in a cycle matches the number of satellites, appears once in the first section of the header during each cycle, and in the second section of another header during the same cycle. Appear once, thereby causing each satellite to respond twice during each cycle, once in response to the uplink status flag in the first section of the header, and once in the uplink in the second section of another header. A data transmission system comprising, in response to the link status flag, an uplink status flag related to being polled.

In accordance with another aspect of the present invention, a base station having a radio transmitter and receiver for communicating with a plurality of satellites, wherein the transmitter is tuned to a predetermined downlink channel; The receiver of the base station has a predetermined uplink
The base station is tuned to at least one spare uplink channel and includes control means for the base station to cyclically generate a series of data packets for transmission to the satellite. A first section containing a first uplink state flag associated with a first selected satellite, a first section identifying the spare uplink channel and paired with a time slot for that channel. And a second section containing a second uplink state flag identifying two selected satellites, wherein the number of packets in each cycle matches the number of said satellites, and during each cycle the number of packets in said header. Occurs once in the second section and in the second section of another header during the same cycle.
Times, so that the base station has 2
Times, once in response to an uplink status flag in a first section of the header, and once in response to an uplink status flag in a second section of another header,
An uplink status flag for polling each satellite.

According to yet another aspect of the present invention, a satellite having a unique identification ID, having control means and a radio transmitter and receiver for communicating with a base station, and a receiver of the satellite having a predetermined ID. Is tuned to the downlink channel of
The satellite's transmitter is tuned to a predetermined uplink channel and at least one spare uplink channel, and the satellite is arranged to receive a series of data packets from the base station; Each data packet includes a first uplink state flag having an identification ID of a first selected satellite, and if the identification ID matches the unique identification ID, the control means causes the transmitter to A first section for causing a data packet to be sent back along the uplink channel to the base station, and an identification ID of the spare uplink channel and a time slot for that channel. A second uplink status flag having the identification ID of the second selected satellite,
A header having a second section that causes the control means to return a data packet within the time slot to the base station along the spare uplink channel if the ID matches the unique identification ID; , One in the first section of the header during each cycle
The unique identifier that appears twice and once in the second section of another header during the same cycle
So that the satellite has twice during each cycle,
A satellite is provided comprising an uplink status flag for returning data to the base station.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG.
A radio transmitter 4 for transmitting data simultaneously to four satellites or mobile telephones M1 to M4 along a downlink channel of frequency f2, and a receiver 6 for receiving data mainly along an uplink channel of frequency f1 And

The base station 2 generated by the control unit 8
Is composed of a series of data packets, each having a duration of 20 ms.

As shown in FIG. 2, each data packet includes a fixed length header H. The header H comprises, for example, a first uplink status flag slot 12 containing an uplink status flag USF1 for the mobile telephone M1 and a second uplink status flag slot containing an uplink status flag USF2 for the mobile telephone M2, for example. 14 is included. Following the second uplink status flag slot 14, there is a time slot 16 and a frequency slot 18, which define, for example, a spare uplink channel whose time slot T3 is frequency f3. Then, there is a payload P. Next, "General Packet Radio Service and Medium Access Control" (General Packet
Radio Service Medium Access Control (GPRS MAC) For compatibility with the standard, the three other slots 20, 22, and 24 are each "auxiliary polling."
(Supplementary Polling; SP) Data, "Relative Reserve Block Period; RRB"
P) Provided for data and payload data. These data are all transmitted in the uplink state flag U
It is associated with the mobile telephone identified by SF1 and slot 2.

In operation, when mobile telephone M1 receives a packet, it transmits a data packet along the default uplink channel at frequency f1 in response to an uplink status flag USF1. Mobile phone M2 has the same data
Upon receiving the packet, the mobile phone M2 responds to the uplink status flag USF2 with a specific time
The data packet in slot TS3 is transmitted along a spare uplink channel at frequency f3.

In this way, the base station can receive two data packets from two mobile telephones in response to the same data packet transmitted along the downlink channel.

Although the standby uplink channel is defined as having a frequency of f3, it is clear that the base station can have several other different frequency channels that can be used as standby uplink channels. Will. Therefore, the base station has the availability (availabilit
Different reserve uplink channels can be selected in different cases according to y).

The length of the improved MAC (medium access control) header shown in FIG. 2 is 2 bytes, that is, 8 bits, longer than the standard MAC (medium access control) header. Of these 8 bits, 3 bits are speculative (specul
USF2, which is an uplink status flag of the mobile telephone M2 polled atively), where 5 bits are a subfield 16 to which a time slot of 3 bits is allocated and a subfield to which a frequency slot of 2 bits is allocated. 18 is a reply field including a reply field.

The effect of the increased header length is:
It can be absorbed by removing most of the duplicates from the Voice GPRS coder. Alternatively, another lower bit rate voice coder may be employed.

It is important to generate accurate polling patterns to achieve efficient polling. Since mobile phones polled in slot 12 always have a dedicated uplink (UL) response channel, all mobile phones in any group will have an uplink status flag appearing in slot 12 of the header once every polling cycle. It is important to be polled with Also during each polling cycle, the uplink status flag for each mobile phone should appear in slot 14 of the header.

Thus, with a group of three mobile telephones, the control unit 8 would generate three packets in each cycle. Slot 12 in the header of the first packet and slot 14 in the header of the third packet will contain the uplink state flag USF1 for mobile phone M1. Slot 14 of the header in the first packet and slot 12 of the header in the second packet will contain the uplink status flag USF2 for mobile phone M2. Slot 14 in the header of the second packet and slot 1 in the header of the third packet
2 would include the uplink status flag USF3 for mobile phone M3. Therefore, this cycle is repeated endlessly.

This polling pattern, shown in FIG. 3, is for a number of groups 1-3, 4-6, 7-9, 10-12 and 13-1 of three mobile telephones each.
5 is shown. Each group has a different uplink
Time slots (Ti
me Slot; TS). Each packet is 20 ms long with each cycle repeated once every 60 ms. From FIG. 3 the notation 1/2 of the 20 ms column is the mobile telephone M1 in slot 12 of the header of the first packet.
And represents the uplink status flag of mobile phone M2 in slot 14.

The use of the polling pattern of FIG. 3 has the advantage that during a normal polling period, if the "speculatively" polled mobile phone fails the first time, it will be captured a second time. Yes. This is especially important for real-time traffic as access delays must be minimized. Using this method, it is possible to poll three mobile phones twice in 60 ms. Thus, the polling group includes three mobile phones. Another advantage of this polling method is that it allows the system to send RR (Radio Resource) messages to initially specified and inferentially polled mobile telephones, and Expected response (Packet Control Acknowledgement) because the order of the uplink status flags in the Media Access (MAC) header is swirled
It is possible to assert the validity of

The subsequent behavior when the polling pattern shown in FIG. 3 is adopted is as follows. When those mobile phones are polled and this polling is successfully accomplished,
That is, when both mobile phones have what to transmit, the default channel (uplink (UL) time slot of the uplink status flag USF1) and the answering channel are occupied.
If the polling of the uplink status flag USF1 fails, during the polling period (by the system,
It will be polled again (after 40-80 ms). If the polling of the uplink status flag USF2 fails, it will be polled again in the next time slot. The response described in FIG. 3 is the uplink status flag USF2 with the data to be transmitted.
Early capture of mobile phones.

When each group contains four mobile phones, the polling cycle is increased to 80 ms. The polling is performed speculatively, so that each mobile phone appears at least once in slot 12 of the header, an uplink status flag that appears once every four packet cycles, and a header slot 14 FIG. 4 shows polling that cannot be used for four packets of different groups, with an uplink status flag occurring at least once in the same and also once every four packet cycles. It is a table.

When the polling pattern shown in FIG. 4 is adopted, there is no early capture in the case of data transmitted from a speculatively polled mobile telephone. However, further mobile phones are added to the polling group and RRs in the media access (MAC) header by reversing the ordering of those uplink status flags having the media access (MAC) header.
(Radio resource) Enables scheduling and response to messages.

[0025]

According to the present invention, a data transmission system capable of improving polling efficiency, in particular, a mobile telephone network using such a system and a ground station for use in such a system, A satellite is obtained.

Reference numerals described in the claims are for the purpose of facilitating the understanding of the invention, and should not be understood to limit the scope of the claims.

[Brief description of the drawings]

FIG. 1 is a block diagram of a base station in communication with a number of mobile phones.

FIG. 2 is a diagram showing a configuration of a header of a data packet.

FIG. 3 is a table showing the order of polling when there are three mobile telephones in each group.

FIG. 4 is a table showing the order of polling when four mobile telephones exist in each group.

[Explanation of symbols]

 2 Base Station 4 Radio Transmitter 6 Receiver 8 Control Unit 12 First Uplink Status Flag Slot 14 Second Uplink Status Flag Slot 16 Time Slot 18 Frequency Slot

 ──────────────────────────────────────────────────続 き Continuation of the front page (71) Applicant 596077259 600 Mountain Avenue, Murray Hill, New Jersey 07974-0636 U.S.A. S. A. (72) Inventor Constantine Ias Thornford Drive 48, Swindon, UK 48 (72) Constantine Samaras U.K., Swindon, Rodbourne, Montag Street 53 (72) Inventor Louis Gin Samuel U.K., Swindon, Abbey Meads, Standen Way 82 (72) Inventor Fiona Claire Angarad United Kingdom, Bass, Millbrook Place, Millbrook Court, Flat 4 (72) Inventor Jan Jun Woo England, Reading, Hunting Ton Close 32 (72) Inventor Run- Hong Yang UK, SN7 7SS, Fallington, Kings Lane, Hawthorne

Claims (8)

[Claims] 1. A data transmission system, comprising: a base station (2) having a radio transmitter and a receiver; a plurality of satellites each having a radio transmitter and a receiver; Receivers are all tuned to the same downlink channel, and the satellite transmitter and the base station receiver are tuned to a common uplink channel and at least one auxilialy uplink channel Control means (8) for said base station to cyclically generate a series of data packets and transmitting them to said satellites, each data packet being received by said first selected satellite. The first selected satellite when the satellite is polled and the satellite returns a data packet along the uplink channel to the base station. A first containing a first uplink state flag
A header having a section, and, when received by the second selected satellite, poll only that satellite so that the second selected satellite passes a data packet in the time slot along the spare uplink channel. ID of the backup uplink channel to be transmitted to the base station
ty) and a second section containing a second uplink state flag identifying the second selected satellite paired with the time slot for that channel; and wherein the number of packets in each cycle is Match, appear once in the first section of the header during each cycle and once in the second section of another header during the same cycle, so that each satellite Twice in the cycle, one time in response to the uplink status flag in the first section of the header,
An uplink status flag related to being polled, once in response to the uplink status flag in a second section of another header. 2. The system of claim 1, wherein the number of satellites is three, and the satellites are polled twice during each cycle of three packets. 3. For any two consecutive packets of data, the second of the header of the first occurring packet
Uplink state flag identification ID whose section content is the same as the first section of the header of the immediately following packet
3. The system according to claim 2, comprising: 4. The number of said satellites is four, and for any two consecutive packets of data, four sections of said two headers have said four uplink states associated with said four satellites. The system of claim 1, wherein each of the flags is occupied by a flag. 5. A base station having a radio transmitter and receiver for communicating with a plurality of satellites, wherein the transmitter is tuned to a predetermined downlink channel, wherein the base station receiver A series of data tuned to an uplink channel and at least one spare uplink channel for transmission by the base station to the satellite;
Control means for cyclically generating packets, each data packet comprising a first data packet associated with a first selected satellite.
A first section containing an uplink status flag;
A second section containing a second uplink status flag identifying the spare uplink channel and identifying a second selected satellite paired with the time slot for that channel. Wherein the number of packets in each cycle matches the number of satellites, appears once in the second section of the header during each cycle, and during the same cycle the second section of another header Once, whereby the base station responds twice during each cycle, once in response to the uplink status flag in the first section of the header and once in the second A base station responsive to polling each satellite in the section. 6. The control means polls three satellites twice during each cycle of the three packets, and for any two consecutive packets of data, the first of the first occurring packet. The base station according to claim 5, characterized in that the content of the second section of the header is programmed to include the same uplink state flag identification ID as the first section of the header of the immediately following packet. . 7. The control means polls four satellites, and for any two consecutive packets of data, four sections of the two headers have four sections associated with the four satellites. The system of claim 5, wherein the system is programmed to be occupied by individual flags of an uplink status flag. 8. A satellite having a unique identification ID and having control means and a radio transmitter and receiver for communicating with a base station, wherein the satellite's receiver is tuned to a predetermined downlink channel. The satellite's transmitter is tuned to a predetermined uplink channel and at least one spare uplink channel, and the satellite is arranged to receive a series of data packets from the base station. And each data packet includes a first uplink status flag having an identification ID of a first selected satellite, and if the identification ID matches the unique identification ID, the control means transmits A first section for returning a data packet along the uplink channel to the base station via a transceiver, and the spare uplink Identification ID of the channel
And a second uplink state flag having an identification of the second selected satellite paired with the time slot for that channel, if the identification matches the unique identification. A header having a second section for causing the control means to return a data packet within the time slot along the backup uplink channel to the base station; and a first section of the header during each cycle. Having the unique identification ID appearing once in a section and once in the second section of another header during the same cycle, such that the satellite
A satellite comprising an uplink status flag for transmitting data back to the base station.