Location Tracking Schemes for Broadband Wireless Networks

Abstract

In order to enable the delivery of last mile wireless broadband access, the IEEE 802.16-2004 standard (IEEE Std 802.16-2004, 2004) for the wireless metropolitan area networks (WMAN) is designed to fulfill various demands for higher capacity, higher data rate, and advanced multimedia services. Furthermore, the IEEE 802.16e standard (IEEE Std 802.16e-2005, 2006) enhances the original IEEE 802.16-2004 specification by addressing the mobility issues for the mobile stations (MSs). Recently, the IEEE 802.16-2009 standard (IEEE Std 802.16-2009, 2009) has been specified as an integrated version of the IEEE 802.16 specification by the IEEE 802.16 maintenance task group. The IEEE 802.16-2009 standard is as known as the revision of IEEE 802.16-2004 and consolidates material from IEEE 802.16e-2005, IEEE 802.16-2004/Cor12005, IEEE 802.16f-2005, and IEEE 802.16g-2007. In order to fulfill the requirement of the E911 phase II requirement advanced by Federal Communications Commission, the location-based services (LBSs) (Perusco & Michael, 2007) are considered one of the key functions of the IEEE 802.16-2009 standard. Moreover, for fulfilling the resource management purpose, location update is also essential to other numerous functions such as the paging processes. Based on the IEEE 802.16 standard, it is required to provide satisfactory location estimation performance under a wide-range of MS’s moving speeds. Location tracking is designed as one of the options to provide feasible estimation performance in order to trace the MS’s moving behaviors. However, there are several issues required to be considered before enabling the location tracking scheme within IEEE 802.16 system. It is noted that timing information, i.e., the time-difference-of-arrival (TDOA) measurements, from at least four base stations (BSs) is required to perform a two-dimensional location estimation and tracking for an MS. With the stringent synchronization requirement for the IEEE 802.16 OFDMA-based system, the frequent TDOA measurements with other neighbor (a.k.a. non-serving) BSs can be timeconsuming and impractical processes for location estimation and tracking. It is a waste of the bandwidth to scan for the neighbor BSs frequently, especially under broadband wireless communication. In this book chapter, two location tracking schemes are proposed to alleviate the problem that requires frequent connections between the MS and the neighbor BSs. The kinematics-assisted location tracking (KLT) scheme adopts the kinematic relationship to estimate the MS’s location at the time instant with unavailable neighbor BSs; while the geometry-assisted location tracking (GLT) algorithm utilizes the geometric constraints for the prediction of MS’s position. The two schemes are proposed to interpolate the location of an MS between two direct 32