 be updated due to the new requirement situation: either there are new requirements such as 4.2.2.1.1 LTE drivers and philosophy the spectrum flexibility or there are requirements that no The 3GPP LTE is intended to be a mobile-communication longer are valid such as the support of ISDN services. system that can take the telecom industry into the The technology advancement in the cellular area has, of 2020s. The philosophy behind LTE standardization is course, also influenced the design choice of LTE. that the competence of 3GPP in specifying mobile- communication systems in general and radio interfaces 4.2.2.1.2 HSPA evolution drivers and in particular shall be used, but the result shall not be restricted by previous work in 3GPP. Thus, LTE do not philosophy need to be backward compatible with WCDMA and WCDMA, HSDPA, and soon also HSPA are in com- HSPA. mercial operation throughout the world. This means that Leaving the legacy terminals behind, not being re- the infrastructure for HSPA is already in place with the stricted by designs of the late 1990s, makes it possible to network node sites, especially the base-station sites with design a radio interface from scratch. In the LTE case, the their antenna arrangements and hardware. This equip- radio interface can be purely optimized for IP trans- ment is serving millions of terminals with different missions not having to support ISDN traffic: that is, there characteristics and supported 3GPP releases. These ter- is no requirement for support of GSM circuit-switch minals need to be supported by the WCDMA operators services, a requirement that WCDMA had. Further- for many more years. more, LTE also has the opportunity to maximize the The philosophy of the HSPA Evolution work is to commonality of FDD and TDD operations, a situation continue to add new and fancier technical features, and that did not exist in 3GPP before LTE. at the same time be able to serve the already existing Instead new requirements have arisen, for example terminals. This is the successful strate