MC-TRX / MC-RRH in Converged RAN
_________________________________________________________________________________________ Document Issue: v5 Document Status: Released. Date of Issue: July/2010 _________________________________________________________________________________________
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External Document Alcatel-Lucent MC-TRX and MC-RRH in Converged RAN
1
June 2010
Introduction
1.1 Operator Challenges The current operator challenge is to protect past investments (GSM installed Base Stations) while improving the flexibility of the network to answer end-user expectations for Broadband & Wireless. Operators need to leverage on their existing RAN equipment by introducing agility in their networks, to be able to easily evolve from GSM to W-CDMA or to LTE according to their strategy and spectrum constraints. Networks operations need to be kept as simple as possible and with a cost as low as possible.
SDR CONVERGED BS
Alcatel-Lucent Converged RAN BS
1.2 Benefits of Alcatel-Lucent Multi-Carrier Power Amplifier (MCPA) solution First it is backward compatible: the MC-TRX has the same form factor as previous generations of transmitters (TWIN TRX, single TRX). It can be plugged in all Alcatel-Lucent BTS cabinets and can be mixed with existing TRX modules. Second to improve GSM scalability inside the Base Station: one MC-TRX module can replace several single carrier GSM modules as it can be configured with up to 6 carriers: 3 TWIN TRX modules of a sector can be replaced by one MC-TRX module. In addition with MC-TRX in a pure GSM configuration, the use of one Power Amplifier for up to 6 carriers in parallel allows to suppress the wideband combiner stage (3 dB loss = 50% of RF power loss) required to feed antenna, resulting in a better power efficiency. Third to be future proof with multi-standard agility. Agility is the result of Software Define Radio (SDR) concepts developed by Bell Labs – Alcatel-Lucent R&D: in multi-mode, the MC-TRX/MC-RRH modules allows for parallel operation of GSM+W-CDMA or GSM+LTE to achieve a smooth migration from 2G to 3G and 4G networks. This multi-standard hardware is a perennial investment even with the final target to switch off the GSM carriers and replace them by W-CDMA or LTE carriers depending on customer needs. The MC-TRX and MC-RRH are both MIMO capable; it ensures the best performances when activating W-CDMA or LTE carriers on these modules. It brings confidence to an operator to deploy the right product in the network. If the majority of wireless subscribers are using GSM, the MC-TRX/MC-RRH will be configured in GSM mode. If the subscribers are moving towards WCDMA or LTE, it is just a matter of allocating more power to W-CDMA or LTE by simple software reconfiguration.
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External Document Alcatel-Lucent MC-TRX and MC-RRH in Converged RAN
2
June 2010
Alcatel-Lucent solution
MC-TRX and MC-RRH are the core building block of the Alcatel-Lucent Converged Radio Access Network. This new generation of Multi-Carrier transceiver based on SDR is able to handle carriers from 2 different technologies simultaneously. Both Radio modules are based on the same MCPA technology described below: MC-TRX is the classical macro transceiver form factor MC-RRH is a repackaging of the MCPA technology that fits with a distributed BTS solution. An Alcatel-Lucent GSM Base Station is easily upgradeable to a Multi-standard Base station by software activation on MC-TRX/MC-RRH to operate in multi-mode (GSM+W-CDMA or GSM+LTE).
2.1 Multi-Carrier TRX (MC-TRX) plug-in module The new generation of Alcatel-Lucent transceiver “MC-TRX” is an ultracompact TRX module that can be used in all Alcatel-Lucent BTS cabinets (indoor and outdoor). MC-TRX is a stand-alone module and contains 1 up to 6 GSM carriers with one power amplifier.
The upgrade of the Alcatel-Lucent BTS cabinets will result in up to 9 MC-TRX modules in MBI5/MBO2E cabinets and up to 6 MC-TRX modules in MBI3/MBO1E cabinets. One of the main MC-TRX benefits is the full backward compatibility with existing Alcatel-Lucent BTS cabinets: Reuse of existing SUM control boards and Antenna Network modules (ANC) Mixed configurations with previous transceiver generations and MC-TRX
2.1.1 MC-TRX General Characteristics An MC-TRX is designed to work in a specific GSM frequency band: the MC-TRX900 is addressing the whole GSM 900MHz band and the MC-TRX1800 is addressing the whole GSM 1800MHz band. Their characteristics are shown in the table below:
Working frequency bands
MC-TRX 900MHz
MC-TRX 1800MHz
880-915 MHz / 925-960 MHz
1710-1785 MHz / 1805-1880 MHz
Size / Weight
Same size and weight as a TWIN TRX
Rx Sensitivity (typical)
GSM: -112 dBm W-CDMA: -125.5 dBm
Instantaneous bandwidth MTBF
20 MHz* 144 180 h
* With enlarged spectrum frequency span feature, GSM spectrum spread among the complete 900MHz band (35 MHz) can be addressed with 2 MC-TRX modules (B12 candidate feature)
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External Document Alcatel-Lucent MC-TRX and MC-RRH in Converged RAN
June 2010
2.1.2 MC-TRX architecture The MC-TRX is based on a single Multi-Carrier Power Amplifier as shown below. The different carriers are built at the digital stage, and then amplified through a single multi-carrier power amplifier as show on the picture below:
MCPA architecture D i g i N TRX PA t a l
to the antenna
The multi-carrier technology brings a great flexibility and provides new exciting possibilities:
Due to the de facto removal of wideband combining of GSM carriers in the path to the antenna the overall power efficiency of a GSM BTS is increased. Radio power is simply not lost in the combiner stages anymore.
A module provides a certain amount of physical output power. Its capability to distribute the total output power to all carriers gives operators the highest flexibility to convert the radio transmitted power to coverage or capacity, and this is done by SW adaptation only from OMC. This power may be distributed over a high number of carriers to provide capacity, focused on a less number of carriers with higher power per carrier to provide coverage, or it could be shared between two different radio standards.
It is possible to emit two radio technologies simultaneously, e.g. GSM+W-CDMA or GSM+LTE on the same HW module and in the same frequency band (900 MHz or 1800 MHz). This allows a smooth transition to the next radio technology.
Same hardware
Ref
0
dBm
* Att
20
dB
* RBW
30
* VBW
300
kHz
* SWT
100
kHz ms
0 A
-10 1 RM * VIEW
-20
-30
-40
SDR multi-mode module
-50
-60
-70
W-CDMA
-80
GSM
GSM
or
GSM LTE
GSM 3G
GSM
-90
-100
Center
2.14
GHz
3
MHz/
Span
30
MHz
Configure several technologies within a single module
SDR capabilities of MC-TRX
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External Document Alcatel-Lucent MC-TRX and MC-RRH in Converged RAN
June 2010
2.1.3 MC-TRX performances 2.1.3.1
MC-TRX Output power
MC-TRX output power depends on the number of carriers configured per module. The following tables describe the output power values in case of pure GSM and Multi-mode configurations.
GSM Carriers
GMSK Output power @ ToC class2
GMSK Output power @ TOC class2 W/ moderate overbooking
8-PSK Output power @ ToC class2
1 Carrier
67W
67W
45W
2 Carriers
33W
33W
22W
3 Carriers
22W
25W
15W
4 Carriers
17W
21W
11W
5 Carriers
12W
19W
8W
6 Carriers 8W 16W MC-TRX GSM only performances with all carriers at full power Assumes in average 1.3dB loss compared to module level
5W
For LTE only 1 carrier SISO between 40W and 60W per MC-TRX, MIMO implementation requires 2 MCTRXs. The table below is not exhaustive, but gives some configurations that would make sense on the field when introducing one or several W-CDMA/LTE carriers. The MC-TRX module has the full flexibility to support other mixed configuration in the limit of the Power Amplifier capacity. W-CDMA GSM + W-CDMA GSM + LTE
Output power @ module
GMSK Output Power Class 2
1 W-CDMA 2 W-CDMA
1x40W
3 W-CDMA
3x20W
GMSK Output power Class 2 with Power Overbooking
2x20W
1 GSM + 1 W-CDMA
1x21W + 1x54W 1x45W + 1x27W
1x16W + 1x40W 1x32W + 1x20W
1x16W + 1x40W 1x32W + 1x20W
2 GSM + 1 W-CDMA
2x21W + 1x27W
2x16W + 1x20W
2x16W + 1x20W
3 GSM + 1 W-CDMA 4 GSM + 1 W-CDMA
3x12W+ 1x27W 4x10W+ 1x27W
3x10W + 1x20W 4x8W + 1x20W
3x11W + 1x20W 4x10W + 1x20W
1 GSM + 2 W-CDMA
1x21W + 2x27W
1x16W + 2x20W
1x16W + 2x20W
1 GSM + 1 W-CDMA
MIMO 2x2 (Requires 2 MC-TRX)
1 LTE Carrier w/MIMO (2x40W) 2x32W + 1 LTE Carrier w/MIMO (2x20W) 2x16W + 1 LTE Carrier w/MIMO (2x40W)
LTE only 2 GSM + 1 LTE (1 GSM Carrier per MC-TRX) 2 GSM + 1 LTE (1 GSM Carrier per MC-TRX)
2x32W + 1 LTE Carrier w/MIMO (2x20W) 2x16W + 1 LTE Carrier w/MIMO (2x40W)
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External Document Alcatel-Lucent MC-TRX and MC-RRH in Converged RAN 4 GSM + 1 LTE (2 GSM Carrier per MC-TRX)
2.1.3.2
June 2010
4x16W + 1 LTE Carrier w/MIMO (2x20W) MC-TRX multi-mode performances
4x16W + 1 LTE Carrier w/MIMO (2x20W)
MC-TRX Power consumption
Several factors influence power consumption of a radio module for entire day: Overall output power configured per sector; Traffic load around the day; Activation of features such as DTX, Power Control that reduce the power consumption.
The table below shows power consumption of some configurations with MC-TRX in GSM only mode:
20% load
Indoor
3x5 MBI-3 DC
3x6
BTS
MBI-3 DC
Outdoor BTS
3x5 MBO-1 DC
3x6 MBO-1 DC
50% load
80% load
100% load
599 W
635 W
701 W
737 W
554 W
590 W
623 W
662 W
624 W
660 W
726 W
762 W
579 W
615 W
648 W
687 W
The above table provides MC-TRX power consumption values computed with the following features activated: DTX (50% voice inactivity), Power Control (3dB below BCCH TRX level for non-BCCH TRX), Adjust Power Voltage (new MC-TRX feature to increase the power efficiency) Power overbooking activated Indoor MBI3 BTS and outdoor MBO1 outdoor BTS with DAC @ 25°C in the 900 MHz frequency band MCBTS class 2 GMSK output power @ ToC: 17W per carrier with 5 carriers per sector, 14W per carrier with 6 carriers per sector.
The typical power consumption values for MC-TRX 900 MHz in GSM + W-CDMA modes are summarized in the following table:
20% load 3x1 GSM + 3x1 W-CDMA MBI-3 DC
3x2 GSM + 3x1 W-CDMA MBI-3 DC
50% load
80% load
100% load
809 W
872 W
936 W
980 W
818 W
884 W
950 W
992 W
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External Document Alcatel-Lucent MC-TRX and MC-RRH in Converged RAN
June 2010
The above table provides MC-TRX power consumption values computed with the following features activated: Indoor MBI3 BTS with d2U in the 900 MHz frequency band Activation of Downlink DTX (50% inactivity), Downlink Power Control (-3dB on non BCCH TS) and Adjust Power Voltage Output power @ ToC: 16W per GSM carriers, 20W for UMTS carrier.
2.1.3.3
Power consumption efficiency comparison of MC-TRX vs.TWIN TRX
The conventional approach via single carrier power amplifier needs 4 x 45W = 180W of RF output power on the module side to provide 4 GSM carriers in one sector. Due to the loss in the necessary wideband combiner the output at Top of Cabinet is 4 x 16W =64W of RF power in this sector. To reach the same result a MC-TRX needs 4x21W=84W of RF output power on the module side. Because there is no combining needed the desired RF output power of 4x16W=64W is also reached at Top of Cabinet. This is illustrated by the figure below:
4x45W = 180W @module output
4x16W = 64W @TOC
G S M
4x21W = 84W @module output
4x16W
2x16W
G S M
AN
2 TWIN
4x16W = 64W @TOC
GSM
2x16W MC-TRX
AN
AN AN
MC-TRX benefits come with large GSM configurations, usually configurations with more than 3 TRXs per sector and very high load. The next table summarizes a comparison of MC-TRX versus TWIN TRX modules for different configurations and load:
Configuration
S333
S444
S666
20% load
3%
-7%
-35%
50% load
-6%
-17%
-47%
80% load
-17%
-26%
-56%
Load
100% load
-23% -32% MC-TRX900 vs. TWIN TRX900 power consumption gain
-59%
2.1.4 Multi-Standard configuration with MC-TRX in Macro BTS When operator is willing to deploy W-CDMA or LTE technologies in the same frequency band as the GSM band (900MHz or 1800MHz) the most appropriate solution is to consider the MC-TRX module as a shared hardware between both technologies.
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