vesolutions. CHAPTER Multi-Carrier Operation INTRODUCTION The World Radio Conference (WRC) 2007 identified new frequency bands for International Mobile Telecommunications (IMT) systems (which consist of both IMT-2000 and IMT-Advanced), some of which are Region 1 specific 450-470 MHz globally; 698-806 MHz in Region 2 and nine countries in Region 3; 790-862 MHz in Region 3 and part of Region 1 countries; 2.3-2.4 GHz globally; 3.4-3.6 GHz in a large number of countries in Regions 1 and 3. The intention was that the bands previously identified in the radio regulations for IMT-2000 are now applicable to the IMT systems. The work on the frequency arrangement is ongoing in ITU-R Working Party (WP) 5D and finalization of the band plans is expected in February 2011 [33]. Spectrum, and more recently carrier aggregation, have become particularly important for the successful deployment and adoption of IMT-Advanced systems. The concept of spectrum aggre- gation consists of exploiting multiple, small spectrum fragments simultaneously to deliver a wider band service (i.e., not otherwise achievable when using a single spectrum fragment). Spectrum aggregation can be useful when an operator's dedicated band is not continuous; rather it is split into two or more segments. In addition, spectrum aggregation can happen in scenarios in which an operator accesses both a dedicated band, and a spectrum sharing band which is separated in frequencies from the dedicated operator's band. Spectrum aggregation allows new high data rate wireless communication systems to coexist with their legacy systems when deployed in the same spectrum. This is also valid for the inter-operator scenario. In this context, it can be very beneficial to explore the scenarios for joint use of spectrum aggregation techniques and radio resource management in radio access networks [33]. Support of wider bandwidths up to 100 MHz is one of the distinctive features of IMT- Advanced systems [3,4]. The IMT-Advanced systems target a peak data rate up to 1 Gbps for low mobil