Combination solutions for mobile phone base stations

Currently, operators of mobile telephony are faced daily with the need to expand the capacity of radio networks to provide voice and data service to their increasingly demanding customers.

In their attempts to confront the increasingly strong opposition from neighboring communities in enabling the installation of antennas on their roofs or nearby. The antennas are absolutely necessary to provide this service.
Operators optimize their antenna systems using multiple antennas connectors, usually 2 to GSM 870-960MHz (+ and -45 º), 2 x DCS (1710-1880Mhz) and 2 x UMTS (1920-2170MHz). The climb from the radio booth equipment to the antenna also try to perform with the minimum number of wires.


Combination
For both the combination and for multiplexing are rarely used any of the following elements, order of increasing complexity:

1. 3dB couplers: allow diplexión (sum) of several porta-economic Doras even intrabanda. Physically they are com-posed of two coupled magnetic lines near opponent.
2. Crossovers: adders are based on resonant cavities. They are more complex but have better isolation between inputs and less losses.
3. Triplexores: also based on cavity. Diplex allow 3 bands: GSM900, GSM1800 (or DCS) and UMTS.
4. Intra-band controllers. They are the most appropriate systems for medium and high power for its low insertion loss, high isolation and good VSWR (ROE). Avoid problems that appear to diplexer: blocking channels in recepctores, out of band spurious emissions from the transmitter and intermodulation levels within limits.
5. Splitters (distributors). Widely used in indoor coverage, are also suitable for sharing or receiving antennas as mounts. SPINNER has a proprietary model (BN 81 82 89) 2, 3, or 4 outputs operating between 330-2700MHz and only 134mm long.

Table 1 shows a summary of these solutions.
Not directly related to the combination but with the protection of radio equipment, and unloaders are used DC-BLOCKS that are usually tri-band, quarter-wave and / or gas. The intimate quality of a passive device is manifested in their specification of PIM.
(Intermodulation caused by the device itself). A 160dBc level (160 dB of power gap between injected and generated on the device) guarantees us the whole operation away from any problem.
Figure 2 shows the internal schema of a combiner intrabanda for UMTS. It consists of two diplexers rewards type antenna and a duplexer. The dual combiner includes two sets as above. They are therefore relatively sophisticated devices.
Allows diplexión intrabanda with very low loss, 1.4 dB maximum.
Figure 3 shows the frequency response of the controller above. The frequencies used in UMTS in Spain are:

Orange: 1935.3 to 1950.1 MHz / 2125.3 to 2140.1 MHz
Telefonica: 1964.9 to 1979.7 MHz / 2154.9 to 2169.7 MHz
Yoigo: 1920.5 to 1935.3 MHz / 2110.5 to 2125.3 MHz
Vodafone: 1950.1 to 1964.9 MHz / 2140.1 to 2154.9 MHz

SPINNER combinators noted for their low insertion loss, high frequency decoupling between close and very low intermodulation values.
Both for as triplexores diplexers and combiners are also available in intrabanda Rackeable version. SPINNER calls this solution MNCS (Mobile Network Combining System).
They inherit all the features of the components that comprise, in addition to allowing easy and convenient maintenance, expansion or monitored for signs that they are processed.

A successful case: The Paris Metro
The Paris Metro is one of the longest and most boisterous of the world. About 9 million passengers passing it daily which is 2,500 million passengers a year.
RATP, the company that manages, employs some 50,000 people that manage and maintain this vast network of railways. Also, RATP provides mobile coverage for 3 of their lines.

The operators are:

- Bouygues Telecom GSM 900 /
/ 1800/UMTS.
- SFR GSM 900/1800/UMTS.
- Orange GSM 900/1800/UMTS.

Los operadores suministran los equipamientos de la BTS/Nodo B. Todos ellos son combinados en un equipo customizado SPINNER como el de la Figura 5. La infraestructura de radio que había sido instalada en 2000 fue sustituida por otra con este tipo de combinadores en 2007.
Ese mismo año se terminó el despliegue de cobertura TETRA en la red. Los combinadores fueron proporcionados también por SPINNER.

A SPINNER's challenge
The proposed system should be integrated with other communications without compromise existing TETRA and analogue. The solution was led by France and SPINNER SPINNER Munich, first over one year to overcome the technical skills among SPINNER, RATP and the Operators. It was shown that our solution contained fewer components, was superior in performance and provided many added benefits: easy future expansion (and ultimately did not need to get UMTS) no maintenance and high reliability.
RATP pass a levy on operators by the use of infrastructure plus a percentage of calls that are made. It is also responsible for designing and implementing the network. The main reason for replacing the old network by the new charter SPINNER combiner top benefits and coverage achieved.
The commercial benefits were immediate when users began to feel more comfortable.

 

Author: German Gómez Beltrán, Senior Commercial Engineer SPINNER ELECTRÓTÉCNICA, S.L. Madrid