Shu (Marloon) Wang

One key feature of any mobile communication system is to provide a mobility mechanism for mobiles to do fast and seamless switching between serving cells. There are many different handover mechanisms for achieving this goal. They include soft handover, which is mostly used for voice services, and hard handover, which is designed for data services. Hard handovers can be further classified as network-controlled handovers and mobile-based handovers. The interesting thing is if you look at the basic handover or handoff procedures I will explain in the next, you may feel a long-time debate on which entity , base stations or mobiles, should control handover or handoff. Traditionally there is no standardized direct connection between two BTS's, even they both belong to the same BSC. Therefore, there usually are a long outage for a mobile do hard handover. For example, the default forward traffic channel MAC handover scheme of CDMA2000 EV-DO Rev. 0 usually results in 100~200ms ou...

One advanced feature of 3GPP LTE-Advanced is carrier aggregation. It is an essential mechanism for LTE Release 10/11 to meet the peak-data rate, 1Gbps, requirement of IMT-Advanced of ITU-R. Beside this, it also helps LTE maintain backward compatibility, support symmetric/asymmetric operation modes and contiguous/non-contiguous aggregations. All these features help enable a variety of network deployment scenarios, such as hot-spot operations and flexible duplex. Historically carrier aggregation is not something brand-new in standards.  On 3GPP2 side, the IS-2000 standard supports a multi-carrier operation, Spreading Rate 3 or 3x. Spreading 3 is used when higher data rates are desired with more bandwidth available. Spreading 3 of multi-carrier operation can make IS-2000 not only is backward compatible with its IS-95 predecessor but also satisfies the requirements set forth by IMT-2000/3G at that time. With adding additional guard band, IS-2000 can...