AU4748399A - A repetition apparatus for a cellular mobile telecommunication system - Google Patents
A repetition apparatus for a cellular mobile telecommunication system Download PDFInfo
- Publication number
- AU4748399A AU4748399A AU47483/99A AU4748399A AU4748399A AU 4748399 A AU4748399 A AU 4748399A AU 47483/99 A AU47483/99 A AU 47483/99A AU 4748399 A AU4748399 A AU 4748399A AU 4748399 A AU4748399 A AU 4748399A
- Authority
- AU
- Australia
- Prior art keywords
- tunnel
- antenna
- leakage coaxial
- coaxial cable
- repeater
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/24—Cell structures
- H04W16/26—Cell enhancers or enhancement, e.g. for tunnels, building shadow
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/155—Ground-based stations
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
- H04W88/08—Access point devices
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Near-Field Transmission Systems (AREA)
- Mobile Radio Communication Systems (AREA)
- Radio Relay Systems (AREA)
Description
P/00/011 28/5/91 Regulation 3.2
AUSTRALIA
Patents Act 1990
ORIGINAL
COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Actual Inventor Address for service is: Samsung Electronics Co, Ltd Ki-Hoon Choo WRAY ASSOCIATES 239 Adelaide Terrace Perth, WA 6000 Attorney code: WR Invention Title: A Repetition Apparatus For A Cellular Mobile Telecommunication System" The following statement is a full description of this invention, including the best method of performing it known to me:- -2-
TITLE
A Repetition Apparatus For A Cellular Mobile Telecommunication System FIELD OF THE INVENTION This invention relates to a repetition apparatus for a cellular mobile telecommunication system to extend mobile telecommunication services to the inside of a tunnel. More specifically, this invention relates to a repetition apparatus for offering telecommunication services inside a tunnel having an intense curve and a long length.
BACKGROUND ART Fig. 1 shows a conventional cellular system using code division multiple access (CDMA) technology. As illustrated in Fig. 1, the conventional cellular system comprises a mobile telephone (MT) 10 for providing a call service to a user, a base station (BS) 20 for providing the call service to the mobile telephone by radio frequency signals, a mobile switching centre (MSC) 30 for connecting the BS 15 to another MSC 40 and a public switched telephone network (PSTN) When the mobile telephone is located in a shadow area such as behind a building or inside a tunnel, the radio frequency signals can not reach the mobile telephone.
Consequently, call services are unavailable in the shadow area.
A repetition apparatus is a device for offering telecommunication services such as call services to mobile telephones in a shadow area. The repetition apparatus o .amplifies the radio frequency signals received from the base station or the mobile telephone and thereafter transmits the amplified signal to the mobile telephone or the base station, respectively.
Known repetition apparatus comprise a booster which receives radio frequency signals and transmits the received signal through an antenna after amplification.
However, the signal transmitted from the antenna can not reach inside a tunnel having an intense curve and a long length, so the inside of the tunnel remains a shadow area.
-3- Fig 2 shows a prior art repetition apparatus which uses a leakage coaxial cable for offering telecommunication services to the shadow area inside a tunnel 100.
As illustrated, the repetition apparatus comprises a first antenna 110 located at a position spaced from an entrance (point a) of the tunnel 100 for receiving and transmitting radio frequency signals. A first repeater 120 is connected to the first antenna 110, and a leakage coaxial cable 140 is provided in the tunnel 100 and connected at one end to the first repeater 120 by a first feeder line 130. A second antenna 150 is located at a position spaced from an entrance (point d) on the other side of a tunnel 100 for receiving and transmitting radio frequency signals.
A second repeater 160 is connected to the second antenna 150, and a second feeder line 170 connects the second repeater to the other end of the leakage coaxial cable 140.
The leakage coaxial cable 140 transmits radio frequency signals received from the antennas 110 and 150 to mobile telephones in the tunnel 100. The leakage coaxial cable 140 also receives radio frequency signals from the mobile telephones and communicates them to the antennas 110 and 150 via the S• repeaters 120 and 160.
If the tunnel length is not too long, an antenna and repeater may only be present at one side of the tunnel. Otherwise if the length of the tunnel is too long for radio frequency signals to be received everywhere inside the tunnel, repeaters are .established at both ends of the tunnel.
The power of radio frequency signals received by the mobile station must be at .least equal to a minimum value in order to provide telecommunication services to mobile telephone. A typical figure for the minimum value is -85 dBm. The minimum value can be used to calculate the distance that coverage of the cellular system extends inside a tunnel.
For example, assuming: the strength of the radio frequency signal measured at point a is -75 dBm, the gain of the first antenna is 13 dB, -4the gain of the first repeater is 90 dB, the loss from the leakage coaxial cable to the mobile telephone when the cable is installed at a height of 3 m is -60 dB, and the attenuation of the leakage coaxial cable according to length is -5 dB per 100 m, the strength of the radio frequency signal measured at the end point of a leakage coaxial cable having a length of 1 km is -82 dBm. The coverage distance of the first antenna and the first repeater is 1050m, the point at which the strength of the received signal equals the minimum value of -85 dBm.
Further, assuming: the strength of the radio frequency signal measured at point b is -80 dBm, the gain of the second antenna is 13 dB, the gain of the second repeater is 90 dB, @0o 0 the loss from the leakage coaxial cable to the mobile telephone when the 15 cable is installed at a height of 3 m is -60 dB, and o.
the attenuation of the leakage coaxial cable according to length is -5 dB per 100 m, the strength of the radio frequency signal measured at the end point of a leakage coaxial cable having a length of 1 km is -87 dBm. The coverage distance of the second antenna and the second repeater is 1025 m, resulting in a total coverage distance of 2075 m.
Accordingly, if the tunnel length is over 2075 m, a mobile telephone located in near the centre of the tunnel can not receive radio frequency signals having sufficient strength from the leakage coaxial cable. As a result, when a mobile telephone that is making a call moves into the centre of the tunnel, the call will be dropped.
DISCLOSURE OF THE INVENTION Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
In accordance with a first aspect of this invention, there is provided a repetition apparatus for a cellular mobile telecommunication system to provide services to a mobile station in a tunnel via radio frequency (RF) signals, comprising: a first antenna provided outside of the tunnel; a repeater connected to said first antenna; a leakage coaxial cable provided in the tunnel and connected to said repeater through a feeder line; and a second antenna provided in the tunnel and connected to an end of said leakage coaxial cable, the leakage coaxial cable and the second antenna 15 transmitting and receiving RF signals in the tunnel.
Preferably, said second antenna is provided at a position where a power level of the RF signal transmitted from said leakage coaxial cable corresponds with a minimum value for providing services to the mobile station.
Preferably, the minimum value is -85 dBm.
20 Preferably, the leakage coaxial cable is positioned in the tunnel such that it commences substantially commensurate with a point where a power level of the RF signal transmitted from said second antenna corresponds with the minimum S. •value.
•DO*
Preferably, said second antenna comprises a Yagi antenna.
In accordance with a second aspect of this invention, there is provided a repetition apparatus for a cellular mobile telecommunication system to provide services to a mobile station in a tunnel via radio frequency (RF) signals, comprising: -6a first antenna and a second antenna, the first antenna provided outside of a first end of the tunnel and the second antennas provided outside of a second end of the tunnel; a first repeater and a second repeater connected the first antenna and the second antenna, respectively; a first leakage coaxial cable provided in the tunnel adjacent the first end thereof and connected to the first repeater through a first feeder line; a second leakage coaxial cable provided in the tunnel adjacent the second end thereof and connected to the second repeater through a second feeder line; a third antenna provided in the tunnel and connected to an end of said first leakage coaxial cable; and a fourth antenna provided in the tunnel and connected to an end of said second leakage coaxial cable, the first and second leakage coaxial cables 15 and the third and fourth antennas transmitting and receiving RF signals in the tunnel.
o •o •eo° i Preferably, said third and fourth antennas are provided at positions where a power level of the RF signal transmitted from the first and second leakage coaxial cables corresponds with a minimum value for providing services to the mobile station, respectively.
Preferably, the minimum value is -85 dBm.
*se Preferably, the first and second leakage coaxial cables are positioned in the tunnel such that they commence substantially commensurate with a point where a power level of the RF signal transmitted from the first and second antennas corresponds with the minimum value, respectively.
Preferably, said third and fourth antennas each comprise a Yagi antenna.
-7- BRIEF DESCRIPTION OF THE DRAWINGS This invention will now be described with reference to two embodiments thereof and the accompanying drawings, in which: FIG. 1 shows a conventional cellular system using CDMA technology; FIG. 2 shows a prior art repetition apparatus; FIG. 3 shows a repetition apparatus according to a first preferred embodiment of this invention; FIG. 4 shows a repetition apparatus according to a second preferred embodiment of this invention; and FIG. 5 is a flow chart of a method of installing a repetition apparatus according to this invention.
BEST MODE(S) FOR CARRYING OUT THE INVENTION The first embodiment is illustrated in figure 3 and is directed towards a repetition apparatus for a cellular mobile telecommunication system provided at one end of :15 a tunnel 200.
As shown in figure 3, the repetition apparatus of the first embodiment comprises a first external antenna 210 located at a position spaced from an entrance (point A) of the tunnel 200 for receiving and transmitting radio frequency signals. A first repeater 220 is connected to the first external antenna 210. A first leakage coaxial cable 240 is provided in the tunnel 200 and is connected to the first repeater 220 by a first feeder line 230. The first leakage coaxial cable 240 is connected to the first feeder line 230 at a position (point B) spaced from the S. entrance (point A) of the tunnel 200. A first internal antenna 250 is provided at the other end (point C) of the first leakage coaxial cable 240.
25 The first external antenna 210 receives radio frequency signals from a base station. The first repeater 220 amplifies the received signal and transmits it to the first leakage coaxial cable 240 via the first feeder line 230. The first leakage coaxial cable 240 transmits the amplified signal in the tunnel 200 and provides a -8portion of the signal to the first internal antenna 250. The first internal antenna 250 amplifies the radio frequency signal according to its gain value and transmits the signal within the tunnel 200. In the embodiment, the first internal antenna 250 is a Yagi antenna.
If the minimum value of power received by a mobile telephone in order to receive telecommunications services is -85dBm, the coverage distance of the repetition apparatus can be measured. Assuming the following parameters: The strength of the radio frequency signal measured at point A and point B are and -85dBm, with point B 50m from point A, the gain of the first external antenna is 13 dB, the gain of the first repeater is 90 dB, the loss from the leakage coaxial cable to the mobile telephone when the cable is installed at a height of 3 m is -60 dB, and the attenuation of the leakage coaxial cable according to length is -5 dB per 100 m.
The strength of the radio frequency signal measured at the end (point C) of the first leakage coaxial cable having a length of 1km is -82dBm without the first o°internal antenna 250.
With the first internal antenna 250 in position, the strength of the radio frequency 20 signal measured at point C is -72dBm, assuming the first internal antenna 250 has a gain of 10 dB.
With the first internal antenna 250 in place, the coverage distance of the repetition apparatus is 1,300m, with the coverage distance of the first leakage coaxial cable 240 and the first internal antenna 250 being 950m and 350m, respectively.
25 To provide the telecommunication services as far into the tunnel 200 as possible, the leakage coaxial cable 240 is spaced as far as possible from the entrance (point This is determined according to the point (point B) at which the strength -9of the radio frequencies signals measured inside the tunnel without the leakage coaxial cable 240 reaches the minimum value of The second embodiment is shown in figure 4. Like reference numerals are used to denote like parts to those used in the first embodiment. The second embodiment is also directed towards a repetition apparatus for a cellular mobile telecommunications system. The tunnel 200 in the second embodiment is assumed to be sufficiently long and curved that adequate coverage within the tunnel 200 can not be achieved using a repeater at one end only of the tunnel.
Accordingly, the second embodiment is directed towards a repetition apparatus in which repeaters are used at both ends of the tunnel 200.
As shown in figure 4, the repetition apparatus of this embodiment further comprises a second external antenna 310 located at a position spaced from the other end (point F) of the tunnel 200 for receiving and transmitting radio frequency signals. A second repeater 320 is connected to the second external antenna 310.
A second leakage coaxial cable 340 is provided in the tunnel 200 and connected to the second repeater 320 via a second feeder line 330. A second internal antenna 350 is provided at a remote end (point E) of the second leakage coaxial cable 340. The second antenna 310, the second repeater 320, the second leakage coaxial cable 340, and the second internal antenna are configured in a 20 similar manner to that described in relation to the first embodiment. The second internal antenna 250 comprises a Yagi antenna.
In a similar manner to that described in the first embodiment, if the minimum value of the strength of the radio frequency signals received by a mobile telephone is assumed to be minus 85dBm in order to provide telecommunication services to the mobile telephone, the coverage distance of the repetition apparatus of the second embodiment can be calculated as follows. Firstly, assuming the same parameters as described above in relation to the first embodiment, the coverage distance of the first repeater 220, the first leakage coaxial cable 240 and the first l. internal antenna 250 is the same as that calculated in the first embodiment, namely 1,300 metres. Further, assuming: The strength of the radio frequency signal measured at point F and E are and -85dBm, respectively, where point E is 25m from point F, the gain of the second external antenna is 13 dB, the gain of the second repeater is 90 dB, the loss from the leakage coaxial cable to the mobile telephone when the cable is installed at a height of 3 m is -60 dB, and the attenuation of the leakage coaxial cable according to length is -5 dB per 100 m.
The strength of the radio frequency signal measured at the end (point D) of the second leakage coaxial cable 240 having a length of 0.9 km is -82dBm, if the second internal antenna 350 is not present.
If the second internal antenna 350 is installed, the strength of the radio frequency signal measured at point D is -72dBm assuming the second internal antenna 350 has a gain of 10 dB. The coverage distance of the second repeater 320, the second leakage in coaxial cable 340 and the second internal antenna 350 is 1225m, composed of the coverage distance of the second leakage coaxial cable 340 and the second internal antenna 350 of 875m and 350m, respectively.
As a result, the total coverage distance of the repetition apparatus of the second embodiment is 2525m, which is sufficient to offer telecommunication services inside a tunnel having a length of 2500m or less. Further, it is possible to sustain the signal level over the minimum value of -85dBm in the tunnel.
O.*
Figure 5 is a flow chart illustrating a method of installing a repetition apparatus according to the first or second embodiments.
The first step is to determine the internal radio state of the tunnel. This is achieved by measuring the strength of a radio frequency signal transmitted from 25 the base station, the strength of a pilot signal from the base station and the strength of radio frequency signals transmitted by a mobile telephone. The strengths of the signals are measured and recorded at the entrance and inside the tunnel close to the entrance. This is preferably performed at both entrances even -11 if the length of the tunnel should permit the use of a repeater at one entrance only.
If the tunnel permits the use of a repeater at one entrance only, it is preferable to select the entrance having the better radio characteristics of the two entrances.
The length, height and width of the tunnel are also determined, which can be used to determine how the feeder line and the leakage coaxial cable will be installed in the tunnel.
Once the best entrance of the two entrances is determined, an external antenna and a repeater are installed in a position spaced from the selected entrance.
Where repeaters are required at both entrances, two external antennas and two repeaters are installed, one of each at each of the entrances. This is shown in figure 2 at step s120.
Next, at step s130, a leakage coaxial cable is installed in the tunnel for each repeater. Each leakage coaxial cable is positioned so that it commences in the tunnel at a point where the strength of the radio frequency signals measured at step s110 correspond with the minimum value required to provide telecommunication services (for example, -85dBm). The leakage coaxial cable has a length according to its attenuation characteristics per unit length, so that for a given gain of the antenna and repeater, the strength of radio frequency signals ****°received from the end of the leakage coaxial cable will correspond with the 20 minimum value.
Generally, the leakage coaxial cable is installed at the centre of the ceiling of the tunnel. However, the height of the tunnel, the greater the attenuation from the •.•leakage coaxial cable to the mobile telephone. For example, if the height of the tunnel is halved, the loss is decreased by 6 dB.
In some circumstances, it may be preferable to install the leakage coaxial cable on a side wall of the tunnel if the height is too high. However, if the leakage coaxial cable is positioned on a side wall of the tunnel, consideration must be given as to whether the width of the tunnel is too wide for radio frequency signals from the leakage coaxial cable to reach the other side of the tunnel. In such situations, it may be necessary to install the leakage coaxial cable in the centre of -12the ceiling.
Next, the leakage coaxial cable is connected to the repeater using a feeder line at step s140.
Finally, the internal antenna is established at the end of the leakage coaxial cable atstep s150.
A final check is performed by applying power to the repetition apparatus. The repeater then transmits radio frequency signals to the leakage coaxial cable and the internal antenna. Measurements are taken to determine whether the signal strength is sufficient along the length of the tunnel. If the measurements show that there are areas where the strength of the receive signal is less than the minimum value, it is preferred that the gain of the repeater is increased until the shadow areas disappear.
As illustrated in the embodiments, the invention provides a repetition apparatus for cellular mobile telecommunication systems which extend the coverage distance by combining a leakage coaxial cable with an internal antenna.
It should be appreciated that the scope of this invention is not limited to the S:particular embodiments described above.
*..oe e*
Claims (11)
1. A repetition apparatus for a cellular mobile telecommunication system to provide services to a mobile station in a tunnel via radio frequency (RF) signals, comprising: a first antenna provided outside of the tunnel; a repeater connected to said first antenna; a leakage coaxial cable provided in the tunnel and connected to said repeater through a feeder line; and a second antenna provided in the tunnel and connected to an end of said leakage coaxial cable, the leakage coaxial cable and the second antenna transmitting and receiving RF signals in the tunnel.
2. The apparatus as set forth in claim 1, wherein said second antenna is provided at a position where a power level of the RF signal transmitted from said leakage coaxial cable corresponds with a minimum value for providing services to the mobile station.
3. The apparatus as set forth in claim 2, wherein the minimum value is -85 dBm. o..
4. The apparatus as set forth in claim 2 or 3, wherein the leakage coaxial cable is positioned in the tunnel such that it commences substantially commensurate with a point where a power level of the RF signal transmitted from said second 20 antenna corresponds with the minimum value.
The apparatus as set forth in any one of the preceding claims, wherein said second antenna comprises a Yagi antenna.
6. A repetition apparatus for a cellular mobile telecommunication system to •provide services to a mobile station in a tunnel via radio frequency (RF) signals, comprising: a first antenna and a second antenna, the first antenna provided outside of a first end of the tunnel and the second antennas provided outside of a -14- second end of the tunnel; a first repeater and a second repeater connected the first antenna and the second antenna, respectively; a first leakage coaxial cable provided in the tunnel adjacent the first end thereof and connected to the first repeater through a first feeder line; a second leakage coaxial cable provided in the tunnel adjacent the second end thereof and connected to the second repeater through a second feeder line; a third antenna provided in the tunnel and connected to an end of said first leakage coaxial cable; and a fourth antenna provided in the tunnel and connected to an end of said second leakage coaxial cable, the first and second leakage coaxial cables and the third and fourth antennas transmitting and receiving RF signals in the tunnel.
7. The apparatus as set forth in claim 6, wherein said third and fourth antennas .are provided at positions where a power level of the RF signal transmitted from the first and second leakage coaxial cables corresponds with a minimum value for providing services to the mobile station, respectively. :°oooo
8. The apparatus as set forth in claim 7, wherein the minimum value is -85 dBm. 20
9. The apparatus as set forth in claim 7 or 8, wherein the first and second leakage coaxial cables are positioned in the tunnel such that they commence substantially commensurate with a point where a power level of the RF signal transmitted from the first and second antennas corresponds with the minimum value, respectively. 25
10.The apparatus as set forth in any one of claims 6 to 9, wherein said third and fourth antennas each comprise a Yagi antenna.
11.A repetition apparatus for a cellular mobile telecommunication system to provide services to a mobile station in a tunnel via radio frequency (RF) signals substantially as described herein with reference to figures 3 and 5 or figures 4 and 5 of the accompanying drawings. Dated this Nineth day of September 1999. Samsung Electronics Co, Ltd Applicant Wray Associates Perth, Western Australia Patent Attorneys for the Applicant S *o* *S S*
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR98-038066 | 1998-09-15 | ||
| KR1019980038066A KR20000019793A (en) | 1998-09-15 | 1998-09-15 | Repetition apparatus for mobile communication service in inside of tunnel and installation method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| AU4748399A true AU4748399A (en) | 2000-03-23 |
Family
ID=19550682
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU47483/99A Abandoned AU4748399A (en) | 1998-09-15 | 1999-09-09 | A repetition apparatus for a cellular mobile telecommunication system |
Country Status (3)
| Country | Link |
|---|---|
| KR (1) | KR20000019793A (en) |
| CN (1) | CN1250332A (en) |
| AU (1) | AU4748399A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU2003290499B2 (en) * | 2003-11-28 | 2007-12-13 | Consistel Pte Ltd | Wireless communication system and lift system having the same |
| KR100806825B1 (en) * | 2006-06-23 | 2008-02-22 | 컨시스텔 피티이 엘티디 | Wireless communication system and lift system having the same |
| CN114614847A (en) * | 2022-03-29 | 2022-06-10 | 中交第一航务工程局有限公司 | Immersed tube tunnel communication device and building method thereof |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20010099247A (en) * | 2001-09-14 | 2001-11-09 | 김의숙 | Accident preventing System of inner tunnel using radically leakage coaxial cable |
| KR100442132B1 (en) * | 2001-11-27 | 2004-07-30 | 에스케이 텔레콤주식회사 | Optical Distribution System for Tunnel in mobile communication network |
| KR100736116B1 (en) * | 2005-06-01 | 2007-07-06 | 한국전파기지국주식회사 | Terrestrial DMB service system for underground railway |
| JP4892962B2 (en) * | 2005-12-22 | 2012-03-07 | オムロン株式会社 | Communication relay device and communication processing device for RFID |
| KR101719955B1 (en) | 2016-02-12 | 2017-03-27 | 라온시스템즈 주식회사 | Repeating system using leakage coaxial cable and ics repeater in tunnel |
-
1998
- 1998-09-15 KR KR1019980038066A patent/KR20000019793A/en not_active IP Right Cessation
-
1999
- 1999-09-09 AU AU47483/99A patent/AU4748399A/en not_active Abandoned
- 1999-09-15 CN CN99121680A patent/CN1250332A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU2003290499B2 (en) * | 2003-11-28 | 2007-12-13 | Consistel Pte Ltd | Wireless communication system and lift system having the same |
| KR100806825B1 (en) * | 2006-06-23 | 2008-02-22 | 컨시스텔 피티이 엘티디 | Wireless communication system and lift system having the same |
| CN114614847A (en) * | 2022-03-29 | 2022-06-10 | 中交第一航务工程局有限公司 | Immersed tube tunnel communication device and building method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1250332A (en) | 2000-04-12 |
| KR20000019793A (en) | 2000-04-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MK5 | Application lapsed section 142(2)(e) - patent request and compl. specification not accepted |