“You can support GSM and UMTS functions in one basestation? In the same hardware? In the same time? It’s crazy, no no it’s magic.”
--Aug. 2007, Office of an Indian Telecommunication Operator

“This SDR is the best equipment I have seen today, tell me when it can be launched.”
--Feb. 2008, 3GSM Congress Barcelona. A CEO of a European Operator

“ZTE is considered to be among the pioneers for SDR in telecom networks…the only vendors that support dual mode GSM/UMTS operation in their base stations, ZTE having released the platform firs.”
--Dec. 2008, Informa report: ‘Overview of SDR Market’

These are a little evaluation for ZTE SDR (Software Defined Radio) basestation. ZTE also won the InfoVision award for the SDR in BBWF in this October. And won CSL, TATA contracts to swap and build a new network by SDR (CSL is the biggest operator in HongKong and TATA is the 2nd place CDMA operator in India).

And there are more stories with this SDR. So what is SDR? It just likes a magic rack to meet your wish when you say “please change to another RAT basestation”. SDR is a kind of intelligent basestation that radio in which some or all the physical layer functions are software defined.

If a GSM network need be changed to UMTS, this is also a challenge to the operators which goes with huge new investment, scrapping current network equipment and headache, then what is the easiest and cheapest way? Replace it with NodeB? Change all the hardware inside of the rack? And the same problem unfolded in the sight of the 3G network operator is how to upgrade the 3G network to 3.75G or 4G. The best answer is that built the GSM or 3G network with SDR. Of cause SDR is not only can support GSM and UMTS but also can support most of the 2G 3G 3.75G RAT such as CDMA, CDMA2000, TD-SCDMA, WiMAX, HSPA+ and LTE.

Source: Informa Telecom & Media

In emerging countries the 3G services haven’t been provided in large scale, while the 2G especially GSM subscribes are increased sharply just like China and India. SDR could be used to build a new 2G network, and then the network can be evolved to 3G and LTE in a comfortable way.

In developed market, both 2G and 3G network are running and most of the 2G networks were deployed 5 – 10 years ago. These equipments could not provided new service just like EDGE or E-EDGE, and even are going to out of lifecycle. SDR is suitable to replace these equipments to provide the same and the farther services; also it can make sure that the evolution will be more smoothly than the current 3G network.

Is SDR really a so powerful panacea? Perhaps we can get the answer by a deeper exploring. The SDR network structure is like below graphic. The SDR RRU is the Remote Radio Unit and it will be the same for different RAT at all when they are working at the same frequency band. And in tomorrow the RRU could support wider frequency band such like that 1800M/2100M together. Therefore the operator can keep this RRU when the network is upgrading to 3G or LTE, if the frequency point is no change. And the bandwidth of the Power Amplifier is 20MHz also ready for the HSPA+ and LTE. Today the high cost efficiency and newest technology services like a cake which you can have it and eat it.

Note: The transmission methods in interfaces are only examples. NetNumen is the O&M system

For the BBU, baseband unit, the MicroTCA architecture ensures the SDR’s control part, transmission part, power part could be shared by the different RAT. Use different BP cards (baseband process) to provide GSM or UMTS or any other service is what ZTE can provide, that means the BS upgrading cost is only the BP cards adding or changing. And next step, a kind of universal BP card can make this SDR as pure software defined BS. The universal BP card is a card can support different RATs when it loads corresponding software. For ZTE SDR BBU, 2U height equipment could provide 60 TRX for GSM or 15CS for UMTS. The capacity is bigger than the traditional BS.

Consider of the whole wireless access sub-system, the BS controller and O&M system are also the important parts in the network investment. The software defined BS controller could make the operator & maintenance easier and reduce the transmission cost. And ZTE use one OMCR server, NetNumen, for all kinds of radio access network and also including core network. Hereby the SDR RAN just need one set equipment to deploy two or more system network , so the operation and maintenance cost will be saved in many fields, such as O&M, software version management , spare part, human-resource, etc.

So the SDR could be reconfigured and could evolved to future easily and provide big capacity. Beside all of these, SDR also can adjust the service balance It is easily to realize the service balance by multi-mode base station. It can direct the UMTS voice to GSM to fulfill the GSM network and then more resource of the UMTS network can be used for data service.

And SDR is coordinated. If two sets of equipments are employed, the growth of their scales shall be far beyond user growth, leading to resources waste. In this case, SDR shall be helpful since two networks can be well coordinated, and its network growth rate will match with user growing. Even consider of the frequency resource limitation SDR is also a suitable solution that only by adding new frequency RRU to deploy a new BS in a new frequency band.

For the power consumption SDR use the multi-carriers PA with the unique digital predistortion (DPD) and Doherty PA technology to reach a PA efficiency of 45% at present and 50% in future. The higher PA power efficiency go with the low BS power consumption but the SDR RAN also could save transmission and maintenance server’s quantity which also are big parts of the whole power consumption.

ZTE is one of the biggest telecommunication venders and provides GSM/UMTS, CDMA/CDMA200, WiMAX, Fixed telecommunication network, WiFi, TD-SCDMA, LTE and so on. With significant R&D investment on 2G/3G integrated networks, ZTE has gained experience in delivering total 2G/3G network interoperation solutions ranging from business platform, core networks and access networks to terminals, as well as comprehensive and versatile end-to-end infrastructure technologies. Its unified core network, HLR, dual-mode BBU/RRU are widely deployed globally, while PLMN, NMP and 2G/3G interoperable technologies have been implemented in more than 20 countries in Western Europe, South Asia and Africa. ZTE’s SDR products are fully compatible with legacy network equipment.

SDR perhaps is not a kind of panacea, but it’s still a better solution for most operators than the traditional RAN solutions for the SDR could bring a single RAN to the operators and save the TCO. And ZTE SDR with powerful R&D center, manufacture ability, engineering experts and efficiency globe after-sale groups could bring you a dream network with one RAN by SDR