1. Field
The present application relates generally to wireless communications, and more specifically to methods and systems for handling transitions between different wireless systems, such as, for example, from 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems to 3rd Generation Partnership Project 2 (3GPP2) systems.
2. Background
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-in-single-out, multiple-in-signal-out or a multiple-in-multiple-out (MIMO) system.
With the deployment of a multitude of wireless technologies worldwide and support for these technologies in mobile multimode devices or user equipment, there is a growing need for seamless system selection toward the goal of global roaming Furthermore, any particular geographic region may support mixed technologies and networks, such as 3GPP and 3GPP2 technologies.
A mobile multimode device that supports mixed technologies may include multiple databases that are used in selecting optimal networks within a technology. As an example, for 3GPP2 technologies, such as certain CDMA2000 (Code Division Multiple Access 2000) networks, a Preferred Roaming List (PRL) database which is stored at the mobile device provides information about which system/network from 3GPP2 technologies is preferred in a geographic region for that device. Whether predetermined or programmed via over-the-air (OTA) Management protocols, the PRL contains information about the preferred networks and the order in which they should be selected for the user. PRLs for 3GPP2 technologies may be structured to have a table associated with each geographical region, which in turn contains a list of system descriptions keyed by system identifier/network identifier (SID/NID) pairs and associated with an acquisition index. The acquisition index is used as a pointer to an acquisition table AT which contains an indexed list of RF channels for channel acquisition purposes in the related system.
On the other hand, for 3GPP technologies, such as Global System for Mobile (GSM) and UMTS Terrestrial Radio Access (UTRA), a differently structured database list of preferred networks, termed Public Land Mobile Networks (PLMNs), is stored in a Subscriber Identity Module (SIM) or Universal Subscriber Identity Module (USIM) of the mobile device. The PLMNs in the database include a Mobile Network Code (MNC) that is used in combination with a Mobile Country Code (MCC) (also known as a “MCC/MNC tuple”) to uniquely identify a service operator using a 3GPP technology, such as GSM and UMTS public land mobile networks.
In addition, a new class of small base stations has emerged, which may be installed in a user's home and provide indoor wireless coverage to mobile units using existing broadband Internet connections. Such a base station is generally known as an Access Point (AP) base station, but may also be referred to as Home Node B (HNB) unit, Home evolved Node B unit (HeNB), femto cell, femto Base Station (fBS), base station, or base station transceiver system. Typically, the AP base station is connected to the Internet and the mobile operator's network via a Digital Subscriber Line (DSL), cable internet access, T1/T3, or the like, and offers typical base station functionality, such as Base Transceiver Station (BTS) technology, radio network controller, and gateway support node services. This allows an Access Terminal (AT), also referred to as a cellular/mobile device or handset, or User Equipment (UE), to connect to the AP base station and utilize the wireless service. ATs can include, for example, cellular phones, smart phones, laptops, handheld communication devices, handheld computing devices, satellite radios, navigational devices, Personal Digital Assistants (PDAs), or any other suitable device for communicating over a wireless communication system.
In a heterogeneous wireless access environment that includes a plurality of radio access technologies, as well as macro base stations and femto base stations, there is a need for ATs that are equipped to handle idle and in-traffic transitions between different networks in a seamless manner. For example, such technologies would make it possible to support Single Carrier Radio Transmission Technology (1×RTT) and High Rate Packet Data (HRPD) neighbor lists over LTE. The embodiments described in detail below enable, for example, efficient scans for 3GPP2 neighbors with minimal interruption to the LTE operations both when idle or when in-traffic.