Patent Application
20130257673
The present invention relates to mobile communication antenna coverage technology and more particularly, relates to a mobile communication coverage distribution system in corridor and a coupled radiation unit applied thereto.
With high speed development of mobile communication technology and national economy, people have higher and higher requirement for coverage quality of mobile communication. Mobile communication operators have tried their best to provide excellent mobile communication services for people anytime and anywhere. To this end, at one hand, the mobile communication operators have given their strength on optimization of base station network and at the other hand; they provide signal coverage in specific environments where coverage blind spot occurs. However, in actual environment, various corridor environments are trouble regions to be covered by network. These corridor environments may include tunnels, subway, lift shaft, narrow passageway in urban village and room which can be divided into a corridor. Currently, corridor is covered by following manners:
1. Tunnels and Subway
As shown in
(1) For a train with high speed, attenuation of train body is greater than a traditional one and the attenuation is about 24 dB. However, leaky cable has weak radiation level, thus leading to bad coverage effect and in some extreme instances, failing to realize network coverage.
Presently, China Railway High speed trains have been developed in many cities of China. It has been testified by experiments that robust train body causes attenuation of about 24 dB which is about 10 dB higher than a traditional one. In high speed train running tunnel environment, conventional leaky cable has poor coverage effect and in some cases, it may fail to meet network coverage.
(2) Leaky cable in particular abroad imported leaky cable is very expensive, thus resulting networking cost of the operator.
(3) Installation of leaky cable is difficulty. Arrangement of leaky cable in tunnel requires large and cumbersome vehicle to transport the leaky cable into the tunnel and it can't be finished by human labor. Meanwhile, in order not to affect the radiation performance of the leaky cable, the leaky cable should be installed so as to be distanced sufficiently from the tunnel wall, hence requiring numerous holding brackets and this further increasing installation difficulty and cost.
2. Lift Shaft and Narrow Passageway in Urban Village
Generally, there are two kinds of coverage solutions.
One solution is to employ leaky cable, suffering from disadvantages (2) and (3) as described above.
The other solution is to employ directional antenna coverage for example Yagi antenna or Log Periodic Antenna. The antenna radiation pattern features single direction radiation. Due to path attenuation in coverage region, the power level difference between near radiation region and far radiation region is almost up to tens of dB, thus causing uneven radiation level. At the same time, due to influence of the walls, the main-lobe radiation will biased away from the corridor direction and accordingly, the coverage distance is shortened. In addition, interference to other directions may be resulted. Furthermore, a conventional directional antenna is used to cover urban village. As a great number of independent and non-integrated splitters and couplers are used to balance and distribute power, serious problems such as “back line” during construction process. This not only increases loss of feed line but also increases burden on routing.
A main object of the invention is to provide a more comprehensive and efficient mobile communication coverage solution for various narrow corridors and therefore, a mobile communication coverage distribution system in corridor is proposed which improves coverage effect, reduces construction difficulty and cost of corridor coverage engineering.
Another object of the invention is to provide a coupled radiation unit adaptive to the aforementioned system.
To realize the above objects, the following technical solution is provided.
The mobile communication coverage distribution system in corridor according to the invention is used for mobile communication signal coverage in corridor environment. The system includes: a radio frequency (RF) cable arranged along longitudinal direction of the corridor and intended for signal transmission and having a plurality of spaced access nodes; a T/R model for transmitting signal to the RF cable or receiving signal from the RF cable; a number of coupled radiation unit corresponding to each access node and used to realize signal coverage in a limited range near the access node, said signal being transmitted across the RF cable.
The coupled radiation unit includes: a bidirectional radiation antenna for realizing bidirectional signal coverage in space; and a directional coupler for signal coupling between the bidirectional radiation antenna and RF cable. The bidirectional radiation antenna and directional coupler are integrated onto a metal base plate.
The coupled radiation unit further includes a double frequency multiplexer for multiplexing signals of two frequency bands. The bidirectional radiation antenna includes two radiation elements of different frequency bands. When signals are uplinked, signals from space are received by two radiation elements of the bidirectional radiation antenna, and then are coupled by the coupler. Next, the signals are multiplexed by the multiplexer and finally are transmitted to the RF cable. When signals are down-linked, the signals from the RF cable are split by the multiplexer and then are coupled to the two radiation elements of the bidirectional antenna and finally, they are transmitted to space through the two radiation elements.
The coupler is formed on the metal base plate. One side of the coupler is provided with the double frequency multiplexer formed on the metal base plate, while the other side thereof is provided with an erected dielectric substrate. The bidirectional radiation antenna is printed on the dielectric substrate.
The coupled radiation unit has a suspension member suspended on a periphery wall of the corridor.
Preferably, the plurality of access nodes is distributed equidistantly. The coupling coefficient of the directional coupler is proportional to the distance of the directional coupler from the signal source. The signal source may be any one of repeater, macro base station, micro base station and radio remote unit. The two frequency bands range from 790-960 MHz and 1710-2700 MHz respectively. The number of the signal sources is two and two signal sources are arranged on two ends of the RF cable respectively for bidirectional transmission of signals.
Compared with conventional technology, the present invention has the following advantages. The design of the invention is simple. For example, the RF cable is combined with a standalone coupled radiation unit, thus replacing conventional leaky cable, significantly reducing cost, and being able to get great commercial success. In addition, as weight of the RF cable is much less than leaky cable and the RF cable can be installed piece by piece, construction process is simplified. Moreover, coverage ability of the system becomes more even and better by reasonably designing distance between the access nodes. Furthermore, the integrated coupled radiation unit can be formed together with walls and therefore, low wind resistance is generated.
The present invention is further described in conjunction with accompanied drawings and embodiments.
With reference to
The signal source 2 may be any kind of replying devices such as repeater, macro base station, micro base station or radio remote unit (RRU) for transmitting to the RF cable 4 downlink signals coming from a mobile communication system base station or receiving from the RF cable 4 uplink signals coming from a mobile station and then transmitting the signals to the base station.
The RF cable 4 is divided into multiple segments. In present embodiment, it is divided into multiple segments with equidistance. For example, each segment may be 250 meters long and an access node P is defined between two segments for transmitting uplink or downlink signals.
The coupled radiation unit 3 may be designed to adapt either to single frequency band or to double frequency band.
As shown in
As shown in
Reference is made to
By the same token, uplink signals are transmitted from the mobile station inside the corridor and are received by the bidirectional radiation antenna 33. Next, the signals are coupled into the RF cable 4 by the directional coupler 32. After that, the signals are further up-linked to the signal source 2 through pieces of RF cable 4. Finally, the signals are transferred to the base station of the mobile communication system by the signal source 2 such that the signals will be further processed.
Referring to
Considering that attenuation will occur when the signals directly pass through the entire piece of RF cable 4, the coupling coefficient of each directional coupler 32 is adjusted in order to compensate attenuation. Specifically, during construction process, based on attenuation characteristics of the RF cable 4 and distance between the access nodes P, the coupling coefficient of the directional coupler 32 is measured and set up. The detailed measure method is well known in the art.
The RF cable 4 of the invention is preferably a coaxial cable which is less expensive than leaky cable.
Referring to
To adapt to influence of high speed trains on signals, two ends of the RF cable 4 may be equipped with a signal source (
Summarily, the mobile communication coverage distribution system in corridor according to the invention has simple structure, low cost, is convenient in construction and has reliable performance.
Though various embodiments of the invention have been illustrated above, a person of ordinary skill in the art will understand that, variations and improvements made upon the illustrative embodiments fall within the scope of the invention, and the scope of the invention is only limited by the accompanying claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201010578679.4 | Dec 2010 | CN | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CN11/81470 | 10/28/2011 | WO | 00 | 6/12/2013 |
