Cellular Network Infrastructure » Radio Access Network » OsmoBSC

[[PageOutline]]

= Motorola Horizon macro BTS =

The Motorola Horizon macro BTS is a BTS model manufactured by Motorola in the late 1990ies.

It can support up to 6 TRX, typically in a configuration of 3 sectors.

There is currently no support for it in OpenBSC, but we are working on it.

== Hardware ==

[[Image(horizonmacro_cabinet_door_open.jpg, 50%)]]

[[Image(horizonmacro_cabinet_top.jpg, 33%)]]

=== CTU ===

The up to 6 CTU modules are the individual transceivers (TRX) of the BTS cabinet.  

They plug into the SURF RF backplane and have a front-accessible

DB9 serial port, as well as a SMA connector for the TX PA output.

This TX PA output is normally wired using a ~10cm semi-rigid SMA cable to the TX input port of a combiner/duplexer.

The CTU is of course fully shielded. But if you remove the shielding cover, it looks like this:

[[Image(horizonmacro_ctu_pcb.jpg, 50%)]]

You can see

 * two diversity receivers in the top left part

 * digital section in the top right part

 * transmit section (exciter) in the center

 * RF power amplifier in the bottom right part

==== digital part ====

The CTU digital part has the following connections

 * backplane connector for

  * power supply (27V DC)

  * two redundand 2048 Mbps TDM links with MCUF, manchester-encoded, 32 timeslots

 * three coaxial backplane connectors with SURF

  * Rx side A (diversity)

  * Rx side B (diversity)

  * Rx loopback (for transmitting into Rx path, loopback testing)

The CTU digital part consists of three main processors:

 * RSS (Radio Subsystem)

  * communicates with MCUF via dedicated 64kbps timeslots in TDM link

  * communicates via dual-ported ram with CCCP

  * Flash EEPROM for boot loader and 8 MByte DRAM

 * EQCP (Equalizer and Control Processor)

  * DSP for radio control and channel equalization

  * alarm management

  * downlink burst building and modulator control

  * tx power control

  * synthesizer channel control

  * rf frequency hopping

  * receiver front-end and remote tune combiner control

  * uplink synchronziation and equalization

  * diversity receiver control

  * automatic gain control

  * receiver signal sthrength calculation

 * CCCP (Channel Coder Control Processor)

  * DSP for channel coding, data routing and baseband hopping

  * uplink channel decoding

  * downlink channel encoding

  * A5 encryption

  * baseband frequency hopping

  * TRAU frame collection and synchronization

The CTU has a three serial consoles routed to the same DB-9 plug. We describe it in [wiki:Motorola_Horizon_macro/CTU_Console]

=== Combiner ===

The combiner / duplexer combines the TX signal of two CTU and duplexes it with the Rx path in order to be able to have two TRX attached to one antenna

=== MCUF ===

The MCUF is a full-size digital board and contains the BTS controller

[[Image(horizonmacro_mcuf_pcb_top.jpg, 33%)]]

[[Image(horizonmacro_mcuf_front.jpg, 33%)]]

=== NIU ===

The NIU is a E1 interface card for up to two E1 lines.  Multiple NIU boards can be plugged into the rack

[[Image(horizonmacro_niu_pcb.jpg, 50%)]]

=== BPSM ===

The BPSM is a small power supply for the NIU, MCUF and other digital boards

[[Image(horizonmacro_bpsm_pcb.jpg, 50%)]]

=== ALARMS ===

The ALARMS board is monitoring FAN and other alarms in the cabinet.

[[Image(horizonmacro_alarms_pcb.jpg, 50%)]]

=== A-bis interface ===

The A-bis interface is via classic E1 lines.  The Horizon indoor cabinet supports up to 6 E1 ports.

Each NIU module serves 1 or 2 E1 ports.

The E1 ports are physically routed to the BIB (Balanced Interface Board) module on top of the cabinet.

The pinout of the 37pin D-Sub connector on top of the BIB board has been reversed as:

||Pin   ||Transformer||Usage||

||1     ||T1.1  ||NIUA0 Port 0 (Tx)||

||2     ||T2.1  ||NIUA0 Port 0 (Rx)||

||3     ||GND   ||

||4     ||T4.1  ||

||5     ||T5.1  ||

||6     ||GND   ||

||7     ||T7.1  ||

||8     ||T8.1  ||

||9     ||GND   ||

||10    ||T10.1 ||

||11    ||T11.1 ||

||12    ||GND   ||

||13    ||T13.1 ||

||14    ||T14.1 ||

||15    ||GND   ||

||16    ||T16.1 ||

||17    ||T17.1 ||

||18    ||GND   ||

||19    ||GND   ||

||20    ||T1.8  ||NIUA0 Port 0 (Tx)||

||21    ||T2.8  ||NIUA0 Port 0 (Rx)||

||22    ||      ||      

||23    ||T4.8  ||

||24    ||T5.8  ||

||25    ||      ||

||27    ||T7.8  ||

||28    ||T8.8  ||

||29    ||T10.8 ||

||30    ||T11.8 ||

||31    ||      ||

||32    ||T13.8 ||

||33    ||T14.8 ||

||34    ||      ||

||35    ||T16.8 ||

||36    ||T17.8 ||

== Software ==

=== MCUF ===

There is a 20MByte Intel Series2 Flash PCMCIA card inside the MCUF.  It contains software + configuration for the BTS.

[[Image(horizonmacro_pcmcia_iflash2.jpg, 33%)]]

There once has been a mtd_iflash2.c driver for Linux 2.4.x, but apparently it has never been merged mainline before the

big CardServices API redesign happened in 2.6.x.  So unfortunately it's not straight-forward to read them out :(

The MCUF is able to run without the PCMCIA card.  In this case, it will download all software + config via E1 from the BSC.

The MCUF has a very extensive command line interface (MMI), for more information check [wiki:Motorola_Horizon_macro/MCUF_Console]

=== CTU ===

It is assumed that the CTU only contains a boot loader to download the real software from the MCUF.

== Further reading ==

 * Motorola BSS11 Base Station Operational Aspects (Describes BTS hardware)

  * http://wenku.baidu.com/view/da379c82d4d8d15abe234e32.html

 * Motorola SYS01 GSM SYSTEM INTERFACES (Chapter 5: Mobis)

  * http://read.pudn.com/downloads61/ebook/212957/SYS01.pdf