by Caroline Gabriel, Rethink Wireless
T-Mobile International is the first operator to conduct extensive interoperability tests between femtocell equipment from different vendors, which will take place over the next six months in its labs in Germany, using kit from Ubiquisys and Huawei.
When new standards start to be commercialized in multiple suppliers’ products, there is usually a division of the interoperability testing between industry organizations and carriers. In some markets, like Wi-Fi, the balance has been almost entirely with the former, in that case the Wi-Fi Alliance; in others, like 3G, most of the work has been done on a network-by-network basis by operators, with even fully standard devices having to be further certified for a carrier’s system.
The WiMAX Forum aimed to reduce cost and time to market, compared to 3G, by adopting a centralized approach similar to Wi-Fi’s, but most providers with networks of any complexity conduct their own tests in parallel. The femtocell market is also moving into a middle ground – the Femto Forum plans its first official plugfests next year, but confidence in the new standards will be boosted in the shorter term by operator activities like T-Mobile’s.
The main standard at issue here is Iuh, the open interface recently standardized by the 3GPP, for linking femtocells to femto gateways in the carrier’s core network. The tests by T-Mobile – which has trialled miniature base stations from several suppliers in its various markets and invests in Ubiquisys – will see a femtocell from that UK start-up communicating with a Huawei gateway over Iuh. In future, IP/IMS is likely to become the main standard for femtocell connections to the core, and some operators – notably Softbank in Japan and some CDMA carriers – are adopting this approach from day one.
T-Mobile and its two suppliers have signed a memorandum of understanding that is intended to “pave the way for operators to select standards-based femtocells and femto gateways from multiple vendors, in the knowledge that they will be fully compatible with each other and their core networks”. Jürgen Krath of T-Mobile told Mobile Europe: “These interop tests will demonstrate for the first time that femtocell interoperability is becoming a reality.”