It also provides a similar link between the mobile station and the rest of the networks. The BTS provides on interface for the digital baseband signals used by the land based networks and the GSM radio signals used by mobile station. Telecommunication functions: which manage the transfer of traffic and control data between the BTS and Mobile Station. Support function: which provides a logical and physical environment in which the BTS functions can be realized. Other method of Abis Interface connection can be used for BTS, where the installation of the dedicated cabling in not possible.
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Passing on and copying of this document, use and communication of its contents not permitted without written authorization. Present edition considers only the new Twin TRX module. Thanks to on-air combining and diversity gain, this mode is equivalent to a very high TX power up to W in dense urban and GSM , assuming a diversity gain of 2. For the uplink path, either 2 way optionally with TMA or 4 way Receive Diversity can be used in order to balance the link budget.
These more compact configurations need less floor space thus reducing rental cost and consume less power. The main base station control functions performed are as follows: - Generating the clocks for all other BTS modules; the clocks can be either synchronized to an external clock reference - e. A-bis link, another BTS - or generated in a pure free-run mode by an internal frequency generator. A common interface for all modules has been defined. No dedicated locations within the subrack for each module are pre-assigned; the module location within the BTS is defined by the engineering rules, easy front cabling, optimization of thermal dissipation, easy assembly, dismounting and extensions on site.
Each basic module supports hot insertion and extraction. No service interruption is thus necessary during most maintenance interventions. A connection area is provided on the top of the indoor cabinet so as to link all external connections to the BTS A-bis, power supply, external alarms, etc. The BTSs have been designed in such a way, that an easy disassembling for recycling is possible. All modules are fixed in the sub-racks with Cam-Locks, which can be fastened and unfastened very quickly without need for specific tools.
To fulfill strong vibration requirements some heavy weight modules in outdoor BTS are additionally fastened with screws. Snap-In technology is used as much as possible as e. This can be made easier in terms of time intervention and outage if the necessary antenna coupling devices are already pre-equipped, - The selection of a BTS cabinet type depends only on the maximum number of TRXs to be provided in future; it is not linked to the BTS configuration, e.
The half-rate, enhanced full-rate and adaptive multi-rate functioning requires that the BSS software release and the other network elements also support these codecs. The modulation and the Tx power can change dynamically on a per time-slot basis. In coverage mode, i. This value results from the combined effects of: - an oustanding single-branch RX sensitivity of dBm for FR speech channels, without TMA; this value is guaranteed in all propagation environments and all frequency bands, independently from the number of combiner levels; it is 7dB better than 3GPP specification requirements.
Synchronization The clocks can be - generated in a pure free-run mode by an internal frequency generator, - synchronized to an external clock reference: - A-bis link PCM-synchronized , - Another BTS slave mode , previous BTS generation may be used; Transmission Two physical A-bis interfaces, allowing a flexible connection of base stations to the BSC in star, chain or loop configuration, are realized according to ITU-T recommendations G.
It addresses highest traffic demands and allows IP over Ethernet on the Abis link in the corresponding software release supporting those functions. In addition, Alcatel supports a signal attenuation on A-bis of up to 36 dB, which allows that base stations can be connected with increased transmission distances without any repeater.
For A-bis termination impedance value, two standards exist : 75 or The Base Station accepts the two values. It is configured on site, during commissioning, to the value used by the operator.
The exact number of IDUs that can be used depends on the mechanical and electrical characteristics of these IDUs, and possibly on the use of other additional equipment e. NTL for PCM line termination that would use the same resources inside the Mounting Frame for 19" equipment, power supply connectors, power dissipation limit, power consumption limit, As far as microwaves are concerned, the required DDF is 3U high at least the standard one proposed for Ohm transmissions ; IDUs are typically 1U high each; this allows to assess the maximum number of IDU that can be used.
In order to ensure de-correlated propagation, both signals are sent with a short time delay in-between, optimized to take maximum advantage of the MS equalizer. This leads to an additional diversity gain of up to 3dB.
TX Diversity works with all types of Mobile stations since it is fully transparent to the receiver; this feature takes advantage of the MS equalizer which can already handle multiple paths with different times of arrival.
Consequently, the equivalent TX output power is very high, up to 6dB above the nominal TX output power, which improves the coverage and reduces the number of sites needed to cover a given area, provided the link budget remains balanced or downlink-limited The table below provides the typical gains achieved thanks to TX Diversity and the equivalent TX output power that can be considered for link budget calculations.
Note that such gains are environment-dependent since they are highly related to the level of de-correlation between paths. No significant gains are expected. This is one way of doing smart antennas, An algorithm to reduce interference: this mitigates the influence of interferers by steering a null beam in the direction of the main interferer the phase difference between the two antennas for the strongest interfering signal is estimated and then this interfering signal is strongly attenuated by summing the signals with an inversed phase.
In interference-limited environments, beam-forming algorithms will provide a much greater diversity gain compared to traditional maximum ratio combining. The above mentioned algorithms are working together in a way to combat spatial interferer signals while keeping optimal sensitivity perfomance for undisturbed but week reception.
The table below provides the typical gains achieved thanks to 2RX enhanced Diversity and the equivalent Rx sensitivity that can be considered for link budget calculations. This feature is provided as a standard feature for all configurations i. It uses exactly the same algorithms as for 2Rx diversity, i.
The table below provides the typical gains achieved thanks to 4RX enhanced Diversity and the equivalent Rx sensitivity that can be considered for link budget calculations. The diagram below shows that 4RX Diversity requires two Antenna Network modules per sector, thereby needing either 4 vertical-polarized or 2 cross-polarized antennas. TX1 RX1.
Evolium 9100 BTS Product Description