The migration from second-generation to third-generation mobile systemsis one of the core issues facing the industry as it enters into the new tele-coms world. Ericsson is committed to making this migration as seamlessas possible for the operator. One of Ericsson’s cornerstone products is anew, indoor macro-base station—the RBS 2206.

The RBS 2206—A flexible ticket to third-generation wireless systems

Per Wilén

Ericsson Review No. 2, 2000 93

Twice the capacity, samefootprint

The RBS 2206 is a successor to the RBS 2202, which is the world’s most de-ployed GSM base station. A new doubletransceiver unit (dTRU) in the RBS 2206gives it unsurpassed capacity: with room forsix dTRUs, it can serve as a 12-transceiverbase station, which is twice the capacity ofthe RBS 2202. Nonetheless, the footprintof the two models is exactly the same, whichis an important point—today, many basestation sites host two RBS 2202 units. Ifthese units were replaced with the RBS2206, the extra space gained at the site couldbe used for a second unit, say, one that sup-ports third-generation standards (Figure 2).Thus, operators can build a third-generationnetwork using existing sites. This is goodnews, since site space is a valuable operatorasset.

True bridge from 2G to 3G When an operator decides to implementthird-generation technology, the RBS 2206can provide coverage quickly. Indeed, theRBS 2206 is a true bridge from second- tothird-generation systems. Full support forenhanced data rates for global evolution(EDGE) is achieved by adding one or moreplug-in transceiver units in the cabinet’stransceiver slots; support for widebandcode-division multiple access (WCDMA) isachieved by adding a plug-in WCDMAtransceiver unit (WTRU) and a remote radiounit (RRU). The RBS 2206, which repre-sents a flexible, low-cost ticket to third-generation capabilities, is especially suitedto sites where space is a premium (urbanareas) or where coverage is the main priori-ty (rural areas).

Plug-in WTRU and remote radio unitAs mentioned above, the RBS 2206 can be

expanded to support WCDMA using aplug-in WTRU, which contains basebandfunctionality (Figure 3). A remote radiounit, which can be placed anywhere betweenthe cabinet and the antenna, contains radiofunctionality and power amplification. Theconnection between the base station and theremote unit is made by means of a fiber opticcable, making installation flexible and easy.Up to three RRUs can be deployed, de-pending on the number of sector configura-tions (one, two or three).

Figure 1Photograph of the RBS 2206. Dimensionsin mm (height x width x depth): 1900 x 600 x 400.

Generation 2.5In the interim before third-generation sys-tems are introduced, the RBS 2206 can aptlyfulfill several roles, since it provides full sup-port for the technologies that pave the wayfor third-generation systems. The RBS 2206is• fully prepared for GSM data services, in-

cluding 14.4 kbit/s time slots, high-speedcircuit-switched data (HSCSD), and gen-eral packet radio service (GPRS); and

• equipped with a powerful distributionswitch unit (DXU) and fast internalbuses, which guarantee full EDGE sup-

port on all time slots. Moreover, the DXUis prepared for Internet protocol-based(IP) A-bis transmission.

Immediate benefitsThe RBS 2206 also offers several immedi-ate benefits to present-day GSM networks.Apart from having twice the capacity of itspredecessor, the RBS 2206 also gives im-proved radio performance. For example, inaddition to standard, two-branch diversity,it supports four-branch receiver diversity,which improves the uplink with up to 4 dB.

94 Ericsson Review No. 2, 2000

WCDMA RBS 3202

RBS 2206RBS 2202 RBS 2202

Figure 2The footprint of the RBS 2206 is one-halfthat of the RBS 2202. Thus, by upgradingto the RBS 2206, operators have spaceover for, say, a second unit that supportsthird-generation standards.

2G Second-generation mobile/wirelesssystem

3G Third-generation mobile/wirelesssystem

CDU-F Combiner and distribution unit (F)CDU-G Combiner and distribution unit (G)dTRU Double transceiver unitDXU Distribution switch unitEDGE Enhanced data rates for global evo-

lution GPRS General packet radio serviceGSM Global system for mobile communi-

cationHSCSD High-speed circuit-switched dataRBS Radio base stationRRU Remote radio unitTRU Transceiver unitWCDMA Wideband code-division multiple

accessWTRU WCDMA TRU

BOX A, ABBREVIATIONS

Key features• Six double transceiver units (dTRU) for a total

of 12 transceivers • Hybrid combining one, two or three sectors in

one cabinet• Filter combining one, two or three sectors in

one cabinet• 35/16 W output power from cabinet (CDU-G)• 20 W output power from cabinet (CDU-F)• Synthesized and baseband frequency hop-

ping• Prepared for data: 14.4 kbit/s, HSCSD, GPRS• Prepared for two-slot WTDUs

• Supports 12 EDGE transceivers on all timeslots

• All speech codes: HR, FR, EFR• Dual-band (GSM 900/GSM 1800)• Extended range 121 km• Supports software power boost• Prepared for IP-based transmission• Prepared for four-branch receiver diversity• Prepared for GPS-assisted positioning ser-

vices

BOX B, THE RBS 2206

Technical specifications• Frequency band E-GSM 900, GSM 1800• Transmission (Tx) 925-960, 1805-1880 MHz• Reception (Rx) 880-915, 1710-1785 MHz• Dimensions 1900x600x400 mm• Weight (equipped) 230 kg• Power into

antenna feeder 35 W (GSM 900) 28 W (GSM 1800)

• Receiver sensitivity -110 dBm• Power supply 120 to 250 VAC, 50/60 Hz

-48 to –72 VDC+20 to +29 VDC

Ericsson Review No. 2, 2000 95

The combination of two unique features—Extended range 121 km, and four-branch re-ceiver diversity—gives almost immediaterural coverage at the lowest possible cost.

The RBS 2206 also comes with two newcombiners—the CDU-F and CDU-G—which when compared to the combiners ofthe RBS 2202, increase output power by 1 dB. Obviously, increased output powerimplies greater site-to-site distance. Thus,compared to the RBS 2202, networks builtwith the RBS 2206 require approximately15% fewer sites (Figure 4).

The CDU-G combiner can be configuredin either capacity or coverage mode. In cov-erage mode, its output power is increased by3 dB to 35 W, making it ideal for rural sitesor roll-outs where speed or cost is a key fac-tor.

Because it is fully compatible with Ericsson’s RBS 2202, the RBS 2206 canquickly and easily be implemented in pre-sent-day networks. The RBS 2206 will be-come commercially available during thefirst quarter of 2001. EDGE functionalitywill be introduced a few months later. Theplug-in WTRU will be offered for deploy-ment in 2002.

ConclusionThe RBS 2206 gives operators flexible entryinto the world of third-generation systems.Having the same footprint as the RBS 2202but double the capacity, the RBS 2206 frees

up 50% of the cabinet space currently oc-cupied at base station sites. Operators canuse this extra space to install a third-generation base station; for example, theWCDMA macro-base station/RBS 3202.

The RBS 2206 is fully prepared for EDGEand WCDMA. To add WCDMA function-ality, operators need only plug in aWCDMA transceiver unit and remote radiounit. Thus, because major site investmentscan be reused, the RBS 2206 gives operatorsrapid, low-cost roll-out of a third-generation network.

RRU RRU RRU

RBS 2206

WCDMA

EDGE

Figure 3The RBS 2206 can be expanded to sup-port WCDMA using a plug-in WTRU andremote radio unit.

RBS 2206

+ 15%

RBS 2202

Figure 4The increased site-to-site distance afford-ed by the CDU-F combiner means that—compared to the RBS 2202—networksbuilt with the RBS 2206 require approxi-mately 15% fewer sites.