WO2016141569A1

WO2016141569A1 - Apparatus and methods for network counter based performance tuning and irat parameter optimization

Info

Publication number: WO2016141569A1
Application number: PCT/CN2015/074004
Authority: WO
Inventors: Alvin Siu-Chung Ng; Long Duan; Salil Sawhney; Zeng Tao LI; Jianming PENG; Guiyin ZHOU; Mustafa SAHIN; Liang MEI
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2015-03-11
Filing date: 2015-03-11
Publication date: 2016-09-15
Anticipated expiration: 2017-09-11

Abstract

Aspects of the disclosure are directed to a UE, an RNC, an eNB or an application operable in wireless communications networks and methods in which an apparatus for wireless communication is configured to perform inter-radio access technology (IRAT) handover, including determining if a call setup success rate (CSSR) is below a CSSR threshold, if an IRAT handover success rate is below an IRAT success threshold, or if a packet switch (PS) voice quality is below a voice quality threshold; and if at least one of CSSR, IRAT handover success rate or PS voice quality is below its respective threshold, increasing a reference signal power threshold, if none, estimating an achievable throughput, and comparing the achievable throughput against a throughput threshold (TH_TPut), and if the achievable throughput is greater/equal to the TH_TPut, continue network monitoring, or if the achievable throughput is less than the TH_TPut, decrease the reference signal power threshold.

Description

APPARATUS AND METHODS FOR NETWORK COUNTER BASED PERFORMANCE TUNING AND IRAT PARAMETER OPTIMIZATION

TECHNICAL FIELD

Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to handover of a user equipment between different radio access networks.

BACKGROUND

Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on.Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN) . The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS) , a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP) . UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (WCDMA) , Time Division–Code Division Multiple Access (TD-CDMA) , and Time Division–Synchronous Code Division Multiple Access (TD-SCDMA) . UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA) , which provides higher data transfer speeds and capacity to associated UMTS networks.

As the demand for mobile broadband access continues to increase, research and development continue to advance the wireless communication technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications. An example of an emerging telecommunication standard is the evolved UTRAN (eUTRAN) , also sometimes referred to as Long Term Evolution (LTE) . LTE is a set of enhancements to the UMTS mobile standard promulgated by Third Generation Partnership Project (3GPP) . It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL) , SC-FDMA on the uplink (UL) , and multiple-input multiple-output (MIMO) antenna technology. Therefore, it is desirable that a user equipment is operable in multiple radio access networks, for example, the UTRAN as well as the eUTRAN.

In an Inter-Ratio Access Technology (IRAT) handover process from one wireless technology to another, a method is a comparison of a received power measurement (e.g., reference signal received power (RSRP) for 4G and/or received signal code power (RSCP) for 3G) against a preconfigured threshold. As the received power decreases at the edge of 4G coverage, the data throughput is automatically reduced accordingly until the RSRP drops below the threshold and handover to 3G coverage begins, when there is a sharp reduction in data throughput (due to the limited bandwidth in 3G relative to that of 4G) . Additionally, the method may also include handover from 3G to 2G, as appropriate, using the preconfigured threshold as the point of handover. But, there needs to be a balance between throughput and quality of service (QoS) .

SUMMARY

The following presents a simplified summary of one or more aspects of the present disclosure, in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated features of the disclosure, and is intended neither to identify key or critical elements of all aspects of the disclosure nor to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in a simplified form as a prelude to the more detailed description that is presented later.

Aspects of the present disclosure are directed to a user equipment (UE) , a radio network controller (RNC) , or a remote server operable in a wireless communications network and methods in which packet drops may be avoided or reduced during the handover of the UE from one radio access technology (RAT) to another RAT (hereafter Inter-RAT handover or IRAT handover) .

In various aspects, the disclosure provides a method for inter-radio access technology (IRAT) handover including: receiving, through a receiver, a plurality of receive signals with at least one metric associated with the plurality of receive signals； performing at least one of the following: a) determining if a call setup success rate (CSSR) is below a CSSR threshold (Th_CSSR) ； b) determining if an IRAT handover success rate is below an IRAT success threshold (Th_IRAT) ； and c) determining if a packet switch (PS) voice quality is below a voice quality threshold (TH_voice) ； wherein one or more of the CSSR, the IRAT handover success rate and the PS voice quality is derived from the at least one metric； and determining that at least one of the CSSR, the IRAT handover success rate or the PS voice quality is below its respective threshold and increasing a reference signal power threshold by a predetermined increment to yield an updated reference signal power threshold； or determining that none of the CSSR, the IRAT handover success rate or the PS voice quality is below its respective threshold, estimating an achievable throughput and comparing the achievable throughput against a throughput threshold (TH_TPut) , and if the achievable throughput is greater or equal to the TH_TPut, continuing network monitoring, or if the achievable throughput is less than the TH_TPut, decreasing the reference signal power threshold by a predetermined decrement to yield the updated reference signal power threshold.

In various aspects, the disclosure provides a method for an inter-radio access technology (IRAT) handover, including: receiving, through a receiver, a plurality of receive signals with at least one metric associated with the plurality of receive signals； applying a first weighted factor to a call setup success rate (CSSR) to obtain a weighted CSSR； applying a second weighted factor to an IRAT handover success rate to obtain a weighted IRAT handover success rate； applying a third weighted factor to a packet switch (PS) voice quality to obtain a weighted PS voice quality, wherein one or more of the CSSR, the IRAT handover success rate and the PS voice quality is derived from the at least one metric； applying a fourth weighted factor to an achievable throughput to obtain a weighted achievable throughput； combining the weighted CSSR, the weighted IRAT handover success rate, the weighted PS voice quality and the weighted achievable throughput to obtain a check parameter； comparing the check parameter with a predetermined threshold T (P) to yield a comparison； and adjusting a reference signal power threshold for the IRAT handover based on the comparison.

In various aspects, the disclosure provides an apparatus for an inter-radio access technology (IRAT) handover, including: a receiver to receive a plurality of receive signals； a storage medium coupled to the receiver to store at least one metric associated with the plurality of receive signals； and a processing circuit coupled to the receiver, wherein the processing circuit is configured to perform one or more of the following: determine if a call setup success rate (CSSR) is below a CSSR threshold (Th_CSSR) ； determine if an IRAT handover success rate is below an IRAT success threshold (Th_IRAT) ； and determine if a packet switch (PS) voice quality is below a voice quality threshold (TH_voice) ； wherein one or more of the CSSR, the IRAT handover success rate and the PS voice quality is derived from the plurality of receive signals； and wherein the processing circuit is further configured to perform the following: determine that at least one of the CSSR, the IRAT handover success rate or the PS voice quality is below its respective threshold and increase a reference signal power threshold by a predetermined increment to yield an updated reference signal power threshold, or determine that none of the CSSR, the IRAT handover success rate or the PS voice quality is below its respective threshold, estimate an achievable throughput, and compare the achievable throughput against a throughput threshold (TH_TPut) , and if the achievable throughput is greater or equal to the TH_TPut, continue network monitoring, or if the achievable throughput is less than the TH_TPut, decrease the reference signal power threshold by a predetermined decrement to yield the updated reference signal power threshold, wherein one or more of the CSSR, the IRAT handover success rate and the PS voice quality is derived from the at least one metric.

In various aspects, the disclosure provides an apparatus for an inter-radio access technology (IRAT) handover, including: a receiver to receive a plurality of receive signals； a storage medium coupled to the receiver to store at least one metric associated with the plurality of receive signals； and a processing circuit coupled to the receiver, wherein the processing circuit is configured to perform the following: apply a first weighted factor to a call setup success rate (CSSR) to obtain a weighted CSSR； apply a second weighted factor to an IRAT handover success rate to obtain a weighted IRAT handover success rate； apply a third weighted factor to a packet switch (PS) voice quality to obtain a weighted PS voice quality, wherein one or more of the CSSR, the IRAT handover success rate and the PS voice quality is derived from the at least one metric； apply a fourth weighted factor to an achievable throughput to obtain a weighted achievable throughput； combine the weighted CSSR, the weighted IRAT handover success rate, the weighted PS voice quality and the weighted achievable throughput to obtain a check parameter； compare the check parameter with a predetermined threshold T(P) to yield a comparison； and adjust a reference signal power threshold for the IRAT handover based on the comparison.

In various aspects, the disclosure provides an apparatus for an inter-radio access technology (IRAT) handover, including: a receiver to receive a plurality of receive signals； a storage medium associated with the receiver to store at least one metric associated with the plurality of receive signals； means for determining if a call setup success rate (CSSR) is below a CSSR threshold (Th_CSSR) ； means for determining if an IRAT handover success rate is below an IRAT success threshold (Th_IRAT) ； means for determining if a packet switch (PS) voice quality is below a voice quality threshold (TH_voice) ； wherein one or more of the CSSR, the IRAT handover success rate and the PS voice quality is derived from the at least one metric； means for determining that at least one of the CSSR, the IRAT handover success rate or the PS voice quality is below its respective threshold and for increasing a reference signal power threshold by a predetermined increment to yield an updated reference signal power threshold； and means for determining that none of the CSSR, the IRAT handover success rate or the PS voice quality is below its respective threshold, for estimating an achievable throughput and for comparing the achievable throughput against a throughput threshold (TH_TPut) , and if the achievable throughput is greater or equal to the TH_TPut, for continuing network monitoring, or if the achievable throughput is less than the TH_TPut, for decreasing the reference signal power threshold by a predetermined decrement to yield the updated reference signal power threshold.

In various aspects, the disclosure provides an apparatus for an inter-radio access technology (IRAT) handover, including: a receiver to receive a plurality of receive signals； a storage medium associated with the receiver to store at least one metric associated with the plurality of receive signals； means for applying a first weighted factor to a call setup success rate (CSSR) to obtain a weighted CSSR； means for applying a second weighted factor to an IRAT handover success rate to obtain a weighted IRAT handover success rate； means for applying a third weighted factor to a packet switch (PS) voice quality to obtain a weighted PS voice quality, wherein one or more of the CSSR, the IRAT handover success rate and the PS voice quality is derived from the at least one metric； means for applying a fourth weighted factor to an achievable throughput to obtain a weighted achievable throughput； means for combining the weighted CSSR, the weighted IRAT handover success rate, the weighted PS voice quality and the weighted achievable throughput to obtain a check parameter； means for comparing the check parameter with a predetermined threshold T (P) to yield a comparison； and means for adjusting a reference signal power threshold for the IRAT handover based on the comparison.

In various aspects, the disclosure provides a computer-readable storage medium storing computer executable code, operable on a device comprising at least one processor； a storage medium to store at least one metric associated with a plurality of signals, the storage medium coupled to the at least one processor； a receiver coupled to the at least one processor, wherein the receiver is configured to receive the plurality of signals； and the computer executable code including: instructions for causing the at least one processor to determine if a call setup success rate (CSSR) is below a CSSR threshold (Th_CSSR) ； instructions for causing the at least one processor to determine if an IRAT handover success rate is below an IRAT success threshold (Th_IRAT) ； or instructions for causing the at least one processor to determining if a packet switch (PS) voice quality is below a voice quality threshold (TH_voice) , wherein one or more of the CSSR, the IRAT handover success rate and the PS voice quality is derived from the at least one metric； instructions for causing the at least one processor to determine that at least one of the CSSR, the IRAT handover success rate or the PS voice quality is below its respective threshold, and increasing a reference signal power threshold by a predetermined increment to yield an updated reference signal power threshold； or instructions for causing the at least one processor to determine that none of the CSSR, the IRAT handover success rate or the PS voice quality is below its respective threshold, estimating an achievable throughput, and comparing the achievable throughput against a throughput threshold (TH_TPut) , and if the achievable throughput is greater or equal to the TH_TPut, continue network monitoring, or if the achievable throughput is less than the TH_TPut, decrease the reference signal power threshold by a predetermined decrement to yield the updated reference signal power threshold.

In various aspects, the disclosure provides a computer-readable storage medium storing computer executable code, operable on a device comprising at least one processor； a storage medium to store at least one metric associated with a plurality of signals, the storage medium coupled to the at least one processor； a receiver coupled to the at least one processor, wherein the receiver is configured to receive the plurality of signals； and the computer executable code including: instructions for causing the at least one processor to apply a first weighted factor to a call setup success rate (CSSR) to obtain a weighted CSSR； instructions for causing the at least one processor to apply a second weighted factor to an IRAT handover success rate to obtain a weighted IRAT handover success rate； instructions for causing the at least one processor to apply a third weighted factor to a packet switch (PS) voice quality to obtain a weighted PS voice quality, wherein one or more of the CSSR, the IRAT handover success rate and the PS voice quality is derived from the at least one metric； instructions for causing the at least one processor to apply a fourth weighted factor to an achievable throughput to obtain a weighted achievable throughput； instructions for causing the at least one processor to combine the weighted CSSR, the weighted IRAT handover success rate, the weighted PS voice quality and the weighted achievable throughput to obtain a check parameter； instructions for causing the at least one processor to compare the check parameter with a predetermined threshold T (P) to yield a comparison； and instructions for causing the at least one processor to adjust a reference signal power threshold for an IRAT handover based on the comparison.

These and other aspects of the present disclosure will become more fully understood upon a review of the detailed description, which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram conceptually illustrating an example of a telecommunications system.

FIG. 2 is a conceptual diagram illustrating an example of a hardware implementation for a user equipment (UE) employing a processing system.

FIG. 3 is a conceptual diagram illustrating an example of a hardware implementation for an RNC employing a processing system.

FIG. 4 is a conceptual diagram illustrating an example of a hardware implementation for an eNode B (eNB) employing a processing system.

FIG. 5 is a drawing conceptually illustrating an example of a radio access network (RAN) .

FIG. 6 is a diagram illustrating a multimode user equipment (UE) located in an area serviced by two or more RATs in accordance with aspects of the disclosure.

FIG. 7 is a diagram illustrating an example of a third generation (3G) radio protocol architecture.

FIG. 8 is a diagram illustrating an example of a fourth generation (4G) radio protocol architecture.

FIG. 9 is a flow chart illustrating an example of a scalable checking procedure in serial order for IRAT threshold adjustment.

FIG. 10 is a flow chart illustrating an example of a first use case of the scalable checking procedure of FIG. 9 in serial order for IRAT threshold adjustment.

FIG. 11 is a flow chart illustrating an example of a second use case scalable checking procedure of FIG. 9 in serial order for IRAT threshold adjustment.

FIG. 12 is a flow chart illustrating an example of a scalable checking procedure in parallel order for IRAT threshold adjustment.

FIG. 13 is a flow chart illustrating an example of a first use case scalable checking procedure of Fig. 12 in parallel order for IRAT threshold adjustment.

FIG. 14 is a flow chart illustrating an example of a second use case scalable checking procedure of Fig. 12 in parallel order for IRAT threshold adjustment.

FIG. 15 illustrates an example pseudocode with an associated example flow chart for a scalable checking procedure for IRAT threshold adjustment.

FIG. 16 is a flow chart illustrating a first example of inter-radio access technology (IRAT) handover.

FIG. 17 is a flow chart illustrating a second example of inter-radio access technology (IRAT) handover.

FIG. 18 is a conceptual diagram illustrating a simplified example of a hardware implementation for an apparatus employing a processing circuit that may be configured to perform one or more functions disclosed herein.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. It will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

According to various aspects of this disclosure, a user equipment (UE) may include hardware and/or software for supporting one or more radio access technologies (RATs) . For example, a UE may include hardware and/or software for accessing UMTS/HSPA and Long Term Evolution (LTE) networks. When the UE moves between (i.e., handover) different RATs (e.g., from LTE to UMTS/HSPA) while user data is being transferred between the UE and a remote terminal or network entity, packets may be dropped at one of the network nodes such as a radio network controller (RNC) . The dropped packets may impact the performance of packet-based applications and undesirably affect user experience. In various illustrative examples described herein, UE based and/or network based techniques are utilized to improve throughput performance when the UE is moved from a LTE network to a UMTS/HSPA network. The described techniques may also be applicable to other types of Inter-RAT handovers (e.g., WiMAX to LTE, EV-DO to HSPA, EV-DO to HSPA, LTE to HSPA, etc.)

According to various aspects of this disclosure, Inter-RAT handover (e.g., LTE to HSPA) may be triggered by various events or conditions such as, for example, based on data transferred (e.g., data volume triggers in a period of time) . In addition to data volume triggers, other types of triggers may be used. For example, Inter-RAT handover may be triggered if one of the network’s coverage/quality is better than a certain threshold. It should be noted that other examples for triggering Inter-RAT handover in other implementations may be used.

According to various aspects of this disclosure, potential enhancements to Inter-RAT handover may include using an adaptive threshold for received power measurements. These enhancements will be described in more detail infra. The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards.

FIG. 1 is a block diagram conceptually illustrating a telecommunications system 100 including a UTRAN and an eUTRAN according to an example of the disclosure. Referring now to FIG. 1, the telecommunications system 100 may include UMTS/HSPA and long term evolution (LTE) network access to a user equipment (UE) 101. In various examples, the telecommunications system 100 has an evolved packet core (EPC) , a UTRAN 102, and an eUTRAN 110. Among several options available for the UTRAN 102, in this example, the illustrated UTRAN 102 may employ a WCDMA air interface for enabling various wireless services including telephony, video, data, messaging, broadcasts, and/or other services. The UTRAN 102 may include a plurality of Radio Network Subsystems (RNSs) , each controlled by a respective Radio Network Controller (RNC) such as an RNC 104. For reasons of clarity, only the RNC 104 is shown in FIG. 1. The RNC 104 is an apparatus responsible for, among other things, assigning, reconfiguring, and releasing radio resources within an RNS. The RNC 104 may be interconnected to other RNCs (not shown) in the UTRAN 102 through various types of interfaces such as a direct physical connection, a virtual network, or the like using any suitable transport network.

The geographic region covered by the RNS may be divided into a number of cells, with a radio transceiver apparatus serving each cell. A radio transceiver apparatus is commonly referred to as a Node B in UMTS applications, but may also be referred to by those skilled in the art as a base station (BS) , a base transceiver station (BTS) , a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS) , an extended service set (ESS) , an access point (AP) , or some other suitable terminology. For clarity, one Node B 106 is shown in the UTRAN 102； however, each RNS may include any number of wireless Node Bs. The Node B 106 provides wireless access points to a core network for any number of mobile apparatuses (e.g., UE 101) . Examples of a mobile apparatus include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a notebook, a netbook, a smartbook, a personal digital assistant (PDA) , a satellite radio, a global positioning system (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player) , a camera, a game console, or any other similar functioning device. The mobile apparatus is commonly referred to as user equipment (UE) in UMTS and LTE applications, but may also be referred to by those skilled in the art as a mobile station (MS) , a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT) , a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. The UE 101 may further include a universal subscriber identity module (USIM) (not shown) , which contains a user's subscription information to a network. For illustrative purposes, one UE 101 is shown in communication with the Node B 106. The downlink (DL) , also called the forward link, refers to the communication link from the Node B 106 to the UE 101, and the uplink (UL) , also called the reverse link, refers to the communication link from the UE 101 to the Node B 106.

The telecommunications system 100 may include a serving GPRS support node (SGSN) 109 to provide packet-data services. The SGSN 109 provides a packet-based connection for the UTRAN 102 to the EPC 108.

As shown, an evolved packet core (EPC) 108 can interface with one or more radio access networks, such as the UTRAN 102 and an evolved UTRAN (eUTRAN) 110. As those skilled in the art will recognize, the various concepts presented throughout this disclosure may be implemented in other suitable radio access networks, to provide UEs with access to types of core networks other than UMTS and LTE networks. The eUTRAN 110 may include an eNode B (eNB) 112 and other eNBs (not shown) . The eNB 112 provides user and control plane protocol terminations toward the UE 101. The eNB 112 may be connected to the other eNBs via an X2 interface (i.e., backhaul) . The eNB 112 may also be referred to by those skilled in the art as a base station, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS) , an extended service set (ESS) , or some other suitable terminology. The eNB 112 provides an access point to the EPC 108 for the UE 101.

The EPC 108 includes a Mobility Management Entity (MME) 114, other MMEs (not shown) , a Serving Gateway (S-GW) 116, and a Packet Data Network (PDN) Gateway (P-GW) 118. The MME 114 is the control node that processes the signaling between the UE 101 and the EPC 108. Generally, the MME 114 provides bearer and connection management. User IP packets are transferred through the S-GW 116, which itself is connected to the P-GW 118. The P-GW 118 provides UE IP address allocation as well as other functions. The P-GW 118 is connected to Operator’s IP Services 120. The Operator’s IP Services may be provided by one or more remote servers. The terms Operator’s IP Services and remote server (s) may be used interchangeably herein. The Operator’s IP Services 120 may include the Internet, the Intranet, an IP Multimedia Subsystem (IMS) , and a PS Streaming Service (PSS) . One example, the Operator’s IP Services 120 include a TCP server. The telecommunications system 100 may include a Home Subscriber Server (HSS) 122 that presents the registers, covering functionalities such as the Home Location Register (HLR) and contains, for example, user-specific information on service priorities, data rates, etc. The S-GW 116 and P-GW 118 handle tasks related to the mobility management inside the eUTRAN 110, as well as the UTRAN 102. As shown in FIG. 1, the SGSN 109 is operatively connected to the gateways (S-GW 116 and P-GW 118) , thus handling the Gateway GPRS Support Node (GGSN) functionalities of the UTRAN network.

FIG. 2 is a conceptual diagram illustrating a hardware implementation for the UE 101 according to an example of the disclosure. Components of the UE 101 generally known in the art are not shown for reasons of clarity and comprehensibility. As shown in FIG. 2, the UE 101 generally includes a processing circuit 202 coupled to or placed in electrical communication with a communications interface 204 and a storage medium 206.

The processing circuit 202 is arranged to obtain, process and/or send data, control data access and storage, issue commands, and control other desired operations. The processing circuit 202 may include circuitry adapted to implement desired programming provided by appropriate media in at least one example. For example, the processing circuit 202 may be implemented as one or more processors, one or more controllers, and/or other structures configured to execute executable programming. Examples of the processing circuit 202 may include a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic component, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may include a microprocessor, as well as any conventional processor, controller, microcontroller, or state machine. The processing circuit 202 may also be implemented as a combination of computing components, such as a combination of a DSP and a microprocessor, a number of microprocessors, one or more microprocessors in conjunction with a DSP core, an ASIC and a microprocessor, or any other number of varying configurations. These examples of the processing circuit 202 are for illustration and other suitable configurations within the scope of the present disclosure are also contemplated.

The processing circuit 202 is adapted for processing, including the execution of programming, which may be stored on the storage medium 206. As used herein, the term “programming” shall be construed broadly to include without limitation instructions, instruction sets, data, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

The communications interface 204 is configured to facilitate wireless communications of the UE 101. For example, the communications interface 204 may include circuitry and/or programming adapted to facilitate the communication of information bi-directionally with respect to one or more network nodes. The communications interface 204 may be coupled to one or more antennas (not shown) , and includes wireless transceiver circuitry, including at least one receiver circuit 208 (e.g., one or more receiver chains) and/or at least one transmitter circuit 210 (e.g., one or more transmitter chains) .

The storage medium 206 may represent one or more computer-readable, machine-readable, and/or processor-readable devices for storing programming, such as processor executable code or instructions (e.g., software, firmware) , electronic data, databases, or other digital information. The storage medium 206 may also be used for storing data that is manipulated by the processing circuit 202 when executing programming. The storage medium 206 may be any available media that can be accessed by a general purpose or special purpose processor, including portable or fixed storage devices, optical storage devices, and various other mediums capable of storing, containing and/or carrying programming. By way of example and not limitation, the storage medium 206 may include a computer-readable, machine-readable, and/or processor-readable storage medium such as a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip) , an optical storage medium (e.g., compact disk (CD) , digital versatile disk (DVD) ) , a smart card, a flash memory device (e.g., card, stick, key drive) , random access memory (RAM) , read only memory (ROM) , programmable ROM (PROM) , erasable PROM (EPROM) , electrically erasable PROM (EEPROM) , a register, a removable disk, and/or other mediums for storing programming, as well as any combination thereof.

The storage medium 206 may be coupled to the processing circuit 202 such that the processing circuit 202 can read information from, and write information to, the storage medium 206. That is, the storage medium 206 can be coupled to the processing circuit 202 so that the storage medium 206 is at least accessible by the processing circuit 202, including examples where the storage medium 206 is integral to the processing circuit 202 and/or examples where the storage medium 206 is separate from the processing circuit 202 (e.g., resident in the UE 101, external to the UE 101, and/or distributed across multiple entities) .

Programming stored by the storage medium 206, when executed by the processing circuit 202, causes the processing circuit 202 to perform one or more of the various functions and/or process steps described herein. For example, the storage medium 206 may include a handover routine 212 that may be executed by the processing circuit 202 (e.g., a handover circuitry 216) to handle Inter-RAT handovers. Thus, according to one or more aspects of the present disclosure, the processing circuit 202 is adapted to perform (in conjunction with the storage medium 206) any or all of the processes, functions, steps and/or routines for any or all of the UEs described herein (e.g., UE 101) . As used herein, the term “adapted” in relation to the processing circuit 202 may refer to the processing circuit 202 being one or more of configured, employed, implemented, and/or programmed to perform a particular process, function, step and/or routine according to various features described herein.

FIG. 3 is a conceptual diagram illustrating a hardware implementation of the RNC 104 according to an example of the disclosure. Components of the RNC 104 generally known in the art are not shown for reasons of clarity and comprehensibility. As shown, the RNC 104 includes a processing circuit 302 coupled to or placed in electrical communication with a communications interface 304 and to a storage medium 306. The processing circuit 302 is arranged to obtain, process and/or send data, control data access and storage, issue commands, and control other desired operations. The processing circuit 302 may include circuitry adapted for processing, including the execution and implementation of programming provided by appropriate media, including media stored on the storage medium 306 in at least one example. Examples and implementations for the processing circuit 302 may include any of the various examples and implementations of the processing circuit 202 described above with reference to FIG. 2. The examples of the processing circuit 302 including those set forth with reference to the processing circuit 202 in FIG. 2 are for illustration, and other suitable configurations within the scope of the present disclosure are also contemplated.

The communications interface 304 is configured to facilitate wired and/or wireless communications of the RNC 104. For example, the communications interface 304 may include circuitry and/or programming adapted to facilitate the communication of information bi-directionally with respect to one or more UEs, as well as one or more other network nodes. The communications interface 304 may be coupled to one or more antennas (not shown) , and includes wireless transceiver circuitry, including at least one receiver circuit 308 (e.g., one or more receiver chains) and/or at least one transmitter circuit 310 (e.g., one or more transmitter chains) .

The storage medium 306 may represent one or more computer-readable, machine-readable, and/or processor-readable devices for storing programming, such as processor executable code or instructions (e.g., software, firmware) , electronic data, databases, or other digital information. The storage medium 306 may also be used for storing data that is manipulated by the processing circuit 302 when executing programming. The storage medium 306 may be any available media that can be accessed by a general purpose or special purpose processor, including portable or fixed storage devices, optical storage devices, and various other mediums capable of storing, containing and/or carrying programming. Examples of the storage medium 306 may include any of the examples included in the description of the storage medium 206 set forth above with reference to FIG. 2.

The storage medium 306 may be coupled to the processing circuit 302 such that the processing circuit 302 can read information from, and write information to, the storage medium 306. That is, the storage medium 306 can be coupled to the processing circuit 302 so that the storage medium 306 is at least accessible by the processing circuit 302, including examples where the storage medium 306 is integral to the processing circuit 302 and/or examples where the storage medium 306 is separate from the processing circuit 302 (e.g., resident in the RNC 104, external to the RNC 104, and/or distributed across multiple entities) .

Programming stored by the storage medium 306, when executed by the processing circuit 302, causes the processing circuit 302 to perform one or more of the various functions and/or process steps described herein. For example, the storage medium 306 may include an Inter-RAT routine 312, and the processing circuit 302 may include a handover circuitry 316 that is adapted to perform various functions in accordance with the Inter-RAT routine 312. The various functions of the Inter-RAT routine 312 will be described in more detail infra. Thus, according to one or more aspects of the present disclosure, the processing circuit 302 is adapted to perform (in conjunction with the storage medium 306) any or all of the processes, functions, steps and/or routines for any or all of the RNC 104 described herein. As used herein, the term “adapted” in relation to the processing circuit 302 may refer to the processing circuit 302 being one or more of configured, employed, implemented, and/or programmed to perform a particular process, function, step and/or routine according to various features described herein.

FIG. 4 is a conceptual diagram illustrating a hardware implementation of the eNB 112 according to an example of the disclosure. Components of the eNB 112 generally known in the art are not shown for reasons of clarity and comprehensibility. As shown, the eNB 112 includes a processing circuit 402 coupled to or placed in electrical communication with a communications interface 404 and to a storage medium 406. The processing circuit 402 is arranged to obtain, process and/or send data, control data access and storage, issue commands, and control other desired operations. The processing circuit 402 may include circuitry adapted for processing, including the execution and implementation of programming provided by appropriate media, including media stored on the storage medium 406 in at least one example. Examples and implementations for the processing circuit 402 may include any of the various examples and implementations of the processing circuit 202 described above with reference to FIG. 2. The examples of the processing circuit 402 including those set forth with reference to the processing circuit 202 in FIG. 2 are for illustration, and other suitable configurations within the scope of the present disclosure are also contemplated.

The communications interface 404 is configured to facilitate wired and/or wireless communications of the eNB 112. For example, the communications interface 404 may include circuitry and/or programming adapted to facilitate the communication of information bi-directionally with respect to one or more UEs, as well as one or more other network nodes. The communications interface 404 may be coupled to one or more antennas (not shown) , and includes wireless transceiver circuitry, including at least one receiver circuit 408 (e.g., one or more receiver chains) and/or at least one transmitter circuit 410 (e.g., one or more transmitter chains) .

The storage medium 406 may represent one or more computer-readable, machine-readable, and/or processor-readable devices for storing programming, such as processor executable code or instructions (e.g., software, firmware) , electronic data, databases, or other digital information. The storage medium 406 may also be used for storing data that is manipulated by the processing circuit 402 when executing programming. The storage medium 406 may be any available media that can be accessed by a general purpose or special purpose processor, including portable or fixed storage devices, optical storage devices, and various other mediums capable of storing, containing and/or carrying programming. Examples of the storage medium 406 may include any of the examples included in the description of the storage medium 206 set forth above with reference to FIG. 2.

The storage medium 406 may be coupled to the processing circuit 402 such that the processing circuit 402 can read information from, and write information to, the storage medium 406. That is, the storage medium 406 can be coupled to the processing circuit 402 so that the storage medium 406 is at least accessible by the processing circuit 402, including examples where the storage medium 406 is integral to the processing circuit 402 and/or examples where the storage medium 406 is separate from the processing circuit 402 (e.g., resident in the eNB 112, external to the eNB 112, and/or distributed across multiple entities) .

Programming stored by the storage medium 406, when executed by the processing circuit 402, causes the processing circuit 402 to perform one or more of the various functions and/or process steps described herein. For example, the storage medium 406 may include an Inter-RAT routine 412, and the processing circuit 402 may include a handover circuitry 416 that is adapted to perform various functions in accordance with the Inter-RAT routine 412. The various functions of the Inter-RAT routine 412 will be described in more detail infra. Thus, according to one or more aspects of the present disclosure, the processing circuit 402 is adapted to perform (in conjunction with the storage medium 406) any or all of the processes, functions, steps and/or routines for any or all of the eNB 112 described herein. As used herein, the term “adapted” in relation to the processing circuit 402 may refer to the processing circuit 402 being one or more of configured, employed, implemented, and/or programmed to perform a particular process, function, step and/or routine according to various features described herein.

FIG. 5 is a drawing conceptually illustrating an example of a radio access network (RAN) 500 supporting multiple RATs (e.g., UTRAN and eUTRAN) that may be utilized in accordance with the present disclosure. The RAN 500 includes multiple cellular regions (cells) , including

cells

502, 504, and 506, each of which may include one or more sectors. Cells may be defined geographically (e.g., by coverage area) and/or may be defined in accordance with a frequency, scrambling code, etc. That is, the illustrated geographically-defined

cells

502, 504, and 506 may each be further divided into a plurality of cells

In a cell that is divided into sectors, the multiple sectors within a cell can be formed by groups of antennas with each antenna responsible for communication with UEs in a portion of the cell. For example, in cell 502,

antenna groups

512, 514, and 516 may each correspond to a different sector. In cell 504,

antenna groups

518, 520, and 522 may each correspond to a different sector. In cell 506,

antenna groups

524, 526, and 528 may each correspond to a different sector.

The

cells

502, 504, and 506 may include several UEs that may be in communication with one or more sectors of each

cell

502, 504, or 506. For example,

UEs

530 and 532 may be in communication with Node B/eNB 542,

UEs

534 and 536 may be in communication with Node B/eNB 544, and

UEs

538 and 540 may be in communication with Node B/eNB 546. Here, each Node B/

eNB

542, 544, and 546 may be configured to provide an access point to a EPC 108 (see FIG. 1) for the

UEs

530, 532, 534, 536, 538, and 540 in the

respective cells

502, 504, and 506. In various examples, each of the Node B/

eNB

542, 544, and 546 may include a Node B 106, an eNB 112, or both. In some examples, a Node B and an eNB of the same cell may be at the same location or different locations. That is, a coverage area of a Node B (e.g., 504a) and that of a corresponding eNB (e.g., 504b) may overlap each other, partially overlap each other, or do not overlap. Therefore, the RAN 500 may support multiple radio access networks such as the HSPA and LTE standards.

Recently, many existing networks have been upgraded to support UMTS and LTE. Therefore, a UE 101 configured to support multiple RATs may move from one RAT to another RAT (Inter-RAT handover) in the middle of an ongoing communication. When the UE 101 moves from one RAT to another RAT, data packets may be dropped at one or more of the network nodes (e.g., a network controller such as RNC 104) . This can impact certain applications such as TCP-based applications. Aspects of this disclosure describe UE-based and network-based techniques that may enhance performance of TCP and other data applications when the UE 101 is moved from one RAT to another RAT, by way of example, from HSPA to LTE

In a wireless telecommunications system, the communication protocol architecture may take on various forms depending on the particular application. For example, in a 3GPP UMTS network, the signaling protocol stack is divided into a Non-Access Stratum (NAS) and an Access Stratum (AS) . The NAS provides the upper layers, for signaling between the UE 101 and the core network, and may include circuit switched and packet switched protocols. The AS provides the lower layers, for signaling between the UTRAN/eUTRAN and the UE 101, and may include a user plane and a control plane. Here, the user plane (also referred to herein as the data plane) carries user traffic, while the control plane carries control information (i.e., signaling) .

FIG. 6 is a diagram illustrating a multimode UE 602 located in an area serviced by two or more RATs such as a first RAT 604 (first cell) and a second RAT 606 (second cell) in accordance with aspects of the disclosure. In one non-limiting example, the first RAT 604 may be W-CDMA, and the second RAT 606 may be LTE. The first RAT 604 is associated with a first base station 608, and the second RAT 606 is associated with a second base station 610. In some examples, the first base station and second base station may be the same base station. In other examples, the UE 602 may be located in an area serviced by multiple second RATs (e.g., GSM, W-CDMA, LTE, etc.) . However, only one second RAT 606 is shown in FIG. 6 for clarity. The coverage areas of the first RAT 604 and second RAT 606 may be partially overlapped or completely overlapped.

FIG. 7 is a diagram illustrating an example of a radio protocol architecture operational in a UMTS network. Turning to FIG. 7, the AS is shown with three layers: Layer 1, Layer 2, and Layer 3. Layer 1 is the lowest layer and implements various physical layer signal processing functions. Layer 1 will be referred to herein as the physical layer 706. The data link layer, called Layer 2 708, is above the physical layer 706 and is responsible for the link between the UE 101 and Node B 106 over the physical layer 706.

At Layer 3, the RRC layer 716 handles the control plane signaling between the UE 101 and the Node B 106. RRC layer 716 includes a number of functional entities for routing higher layer messages, handling broadcasting and paging functions, establishing and configuring radio bearers, etc.

In the illustrated air interface, the L2 layer 708 is split into sublayers. In the control plane, the L2 layer 708 includes two sublayers: a medium access control (MAC) sublayer 710 and a radio link control (RLC) sublayer 712. In the user plane, the L2 layer 708 additionally includes a packet data convergence protocol (PDCP) sublayer 714. Although not shown, the UE 101 may have several upper layers above the L2 layer 708 including a network layer (e.g., IP layer) that is terminated at a PDN gateway on the network side and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.) .

The PDCP sublayer 714 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 714 also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between Node Bs.

The RLC sublayer 712 generally supports an acknowledged mode (AM) (where an acknowledgment and retransmission process may be used for error correction) , an unacknowledged mode (UM) , and a transparent mode for data transfers, and provides segmentation and reassembly of upper layer data packets and reordering of data packets to compensate for out-of-order reception due to a hybrid automatic repeat request (HARQ) at the MAC layer. In the acknowledged mode, RLC peer entities such as an RNC and a UE may exchange various RLC protocol data units (PDUs) including RLC Data PDUs, RLC Status PDUs, and RLC Reset PDUs, among others. In the present disclosure, the term “packet” may refer to any RLC PDU exchanged between RLC peer entities.

The MAC sublayer 710 provides multiplexing between logical and transport channels. The MAC sublayer 710 is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer 710 is also responsible for HARQ operations.

FIG. 8 is a diagram illustrating an example of a radio protocol architecture operable in an LTE network. Turning to FIG. 8, the radio protocol architecture for communication between the UE 101 and the eNB 112 is shown with three layers: Layer 1, Layer 2, and Layer 3. Layer 1 is the lowest layer and implements various physical layer signal processing functions. Layer 1 will be referred to herein as the physical layer 806. Layer 2 (L2 layer) 808 is above the physical layer 806 and is responsible for the link between the UE 101 and eNB 112 over the physical layer 806. In the user plane, the L2 layer 808 includes a media access control (MAC) sublayer 810, a radio link control (RLC) sublayer 812, and a packet data convergence protocol (PDCP) sublayer 814, which are terminated at the eNB 112 on the network side. Although not shown, the UE 101 may have several upper layers above the L2 layer 808 including a network layer (e.g., IP layer) that is terminated at the P-GW 118 (see FIG. 1) on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.) .

The PDCP sublayer 814 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 814 also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between eNBs. The RLC sublayer 812 provides segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARQ) . The MAC sublayer 810 provides multiplexing between logical and transport channels. The MAC sublayer 810 is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer 810 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE 101 and eNB 112 is substantially the same for the physical layer 806 and the L2 layer 808 with the exception that there is no header compression function for the control plane. The control plane also includes a radio resource control (RRC) sublayer 816 in Layer 3. The RRC sublayer 816 is responsible for obtaining radio resources (i.e., radio bearers) and for configuring the lower layers using RRC signaling between the eNB and the UE.

Hereinafter, various aspects of the disclosure are described in the following nonlimiting examples in which the UE 101 may include hardware and/or software for supporting multiple RATs. By way of example, and not limited thereto, the UE 101 may include hardware and/or software for supporting HSPA and LTE standards. When the UE 101 moves from HSPA to LTE, packets may be dropped at one of the network nodes (e.g., the RNC 104) . Therefore, according to aspects of the present disclosure, UE based and network based techniques are used to enhance the performance of data application (e.g., TCP applications) when the UE 101 is moved from HSPA to LTE. The below described techniques may also be applicable to other types of Inter-RAT handovers (e.g., WiMAX to LTE, EV-DO to HSPA, EV-DO to HSPA, LTE to HSPA, etc.)

FIG. 9 is a flow chart illustrating an example of a scalable checking procedure in serial order for IRAT threshold adjustment. In various examples, the IRAT threshold is a reference signal power threshold. The procedure balances PS throughput and overall quality of service (QoS) performance metrics. The IRAT threshold is adaptively adjusted to meet overall QoS performance criteria such as call setup success rate (CSSR) (e.g., LTE RRC connection success rate) , IRAT handover success rate, PS voice quality, etc. while maximizing PS throughput. The scalable checking procedure is applicable for any IRAT transition, for example, 4G to 3G, 4G to 2G, etc. In addition, the procedure is scalable for additional threshold checking.

One overall QoS performance metric is the call setup success rate (CSSR) . For example, in a circuit switched fallback (CSFB) mobile originated/mobile terminated (MO/MT) call, a UE may establish a RRC Connection Setup message before redirecting to a 3G network (e.g., UMTS, CDMA 1X) or a 2G network. In addition, for a CSFB MT call, the reliability of a LTE page message may be a consideration as well. For example, the CSSR may depend on the IRAT threshold. The CSSR will generally improve with a higher IRAT threshold. The CSSR is relevant during call initiation while in the 4G network (e.g. LTE network) where for a MT call, a MT page sent to the UE is successfully received, and for a MO call, a RRC Connection Setup message carrying an extended service request (ESR) sent to the network is successfully received. The selection of IRAT threshold may be performed on a per cell basis with a different IRAT threshold for each cell. For example, the selection of IRAT threshold may be a tradeoff between increasing the CSSR by increasing the IRAT threshold versus prolonging the coverage with the 4G network by decreasing the IRAT threshold, and perhaps degrading the IRAT handover success rate.

Another overall QoS performance metric is the IRAT handover success rate. For example, some cells may experience more IRAT handovers than others while some cells may experience a lower CSSR (i.e., more CSFB failures) than others. The IRAT threshold is selected to maximize the CSSR to fulfill user expectations. Conversely, a radio link failure on a data call may be more tolerable due to lower user expectations. For example, the IRAT threshold may be selected (e.g. by the network operator) to match user expectations: a voice-dominated network may select the IRAT threshold to result in a higher voice call success rate (i.e. higher CSSR) while a data-dominated network may select the IRAT threshold to result in a higher PS throughput.

Another overall QoS performance metric is the PS voice quality. PS voice quality is relevant in a voice-dominated network. For example, voice over LTE (VoLTE) is a voice over Internet Protocol (IP) /IP multimedia system (a.k.a., VoIP/IMS) based call using a LTE network. For example, single radio voice call continuity (SRVCC) is a handover of a VoIP/IMS based call from a PS domain to a CS domain. An example of a PS domain is LTE. Examples of CS domain are GSM/UMTS, CDMA 1x, etc. PS voice quality (e.g. for VoLTE or SRVCC) may be assessed using several metrics such as packet loss, jitter, latency (delay) , etc. For example, the IRAT threshold may be selected (e.g. by the network operator) to match the user expectations: a voice-dominated network may select the IRAT threshold to result in a higher CSSR (e.g. for VoIP/IMS) and/or a higher voice quality (e.g. packet loss rate, jitter, latency, etc.) while a data-dominated network may select the IRAT threshold to result in a higher PS throughput.

Other sets of overall QoS performance metrics may be power headroom, PDCCH block error rate (BLER) , uplink negative acknowledgement (NACK) rate, uplink signal to interference and noise ratio (SINR) , internal base station metrics (e.g. eNodeB metrics) , etc. In various examples, one or more of these QoS performance metrics is checked to determine if they are below a performance threshold. The performance threshold is application dependent and thus is also configurable accordingly. One skilled in the art would understand that the list of QoS performance metrics presented herein is not exclusive or limiting. Thus, other QoS performance metrics not listed herein may be used and be within the scope and spirit of the present disclosure.

In various examples, the scalable checking procedure maximizes the PS throughput while balancing the overall QoS performance metrics described above. For example, a lower IRAT threshold may prolong the coverage duration in a 4G cell (e.g. LTE cell) . In various examples, the PS throughput is balanced against one of the QoS performance metrics, for example, the IRAT handover success rate. A first consideration is that the optimum IRAT threshold may be determined as the point where the PS throughput of the 4G system becomes less than the PS throughput of the 3G system, for example, when the following equation is true:

PS throughput (4G) @X dBm of RSRP

<PS throughput (3G) @Y dBm of RSCP eqn (1)

where:

PS throughput (4G) is the PS throughput (Mbps) for the 4G system (e.g. LTE) ,

PS throughput (3G) is the PS throughput (Mbps) for the 3G system (e.g. UMTS) ,

X dBm of RSRP refers to the point where the power level of RSRP is X dBm, and

Y dBm of RSCP refers to the point where the power level of RSCP is Y dBm.

Additionally, a second consideration for the optimum IRAT threshold is the attainment of an IRAT handover success rate such that the IRAT threshold is selected to attain at least a minimum IRAT handover success rate (i.e., IRAT handover success rate is not degraded by a prolonged coverage duration in a 4G cell) to balance the PS throughput.

In various examples, a 4G PS throughput estimator is used to obtain an estimation of the 4G PS throughput which may be based on a filtered average of a reported receive power measurement, e.g. LTE RSRP in the event B2 sent by UEs, or by direct RSRP threshold value set in the event B2. The filtered average may be implemented by a weighted moving average (MA) , a fixed time domain average, a finite impulse response (FIR) digital filter, an infinite impulse response (IIR) digital filter, etc. In various examples, when using the filtered average of the reported receive power measurement, the 4G PS throughput may be estimated by any combination of: the filtered average of reported receive power measurement, a proprietary table lookup of RSRP to 4G PS throughput mapping, and/or target network serving probability. In various examples, the RSRP to 4G PS throughput mapping may be based on a table lookup generated from a proprietary PS throughput versus RSRP curve which graphs 4G PS throughput in, for example, Mbps, on the vertical axis and RSRP in, for example, dBm, on the horizontal axis. In other examples, usage of serving probability may provide another loading factor in the RSRP to 4G PS throughput mapping, by multiplying the serving probability to the mapping.

In various examples, a 3G PS throughput estimator is used to obtain an estimation of the 3G PS throughput which may be based on a filtered average of a reported receive power measurement, e.g. 3G RSCP in the event B2 sent by UEs, or by direct RSCP threshold value set in the event B2. The filtered average may be implemented by a weighted moving average (MA) , a fixed time domain average, a finite impulse response (FIR) digital filter, an infinite impulse response (IIR) digital filter, etc. In various examples, when using the filtered average of the reported receive power measurement, 3G PS throughput may be estimated by any combination of: the filtered average of reported receive power measurement, a proprietary table lookup of RSCP to 3G PS throughput mapping, and/or target network serving probability. In various examples, the RSCP to 3G PS throughput mapping may be based on a table lookup generated from a proprietary PS throughput versus RSCP curve which graphs 3G PS throughput in, for example, Mbps, on the vertical axis and RSCP in, for example, dBm, on the horizontal axis. In other examples, usage of serving probability may provide another loading factor in the RSRP to 4G PS throughput mapping, by multiplying the serving probability to the mapping.

In various examples, the serving probability is an assumed value, between 0 and 1, that serves as an input to the 4G PS throughput estimator or the 3G PS throughput estimator. The serving probability may account for scheduling loading, event loading, interference loading, etc. The serving probability may be a cell-based value with a different value for each cell, e.g. indoor vs. outdoor cell. The serving probability may have a different value at different time of day, e.g., 1.0 for a non-busy hour and/or 0.25 for a busy hour. The serving probability may be calculated over a period of time based on the percentage of average resource block (RB) assignment to UE at poor RF conditions.

The IRAT threshold adjustment may account for the service mix between voice and data traffic. For example, the IRAT threshold for a data service may be different than the IRAT threshold for a voice service. In addition, the IRAT threshold may be RSRP threshold-based, reference signal received quality (RSRQ) threshold-based, or a combination of the two. The IRAT handover between 4G and 3G, for example, may consider different service scenarios, such as, data only, data+circuit switched (CS) voice, data+packet switched (PS) voice, etc. The IRAT threshold may be based on an adjusted throughput when a voice radio access bearer (RAB) is added. The IRAT threshold may also be based on a combination of multi-RAB throughput and voice quality metrics, e.g. packet loss, jitter, latency, etc. The IRAT threshold may be adjusted on a periodic basis (e.g., per a predetermined schedule) or on a real-time basis (e.g., near-instantaneously) . The IRAT threshold may be adjusted using weights for various performance metrics. For example, in the case of a voice-dominated network, more weight may be applied toward the CSSR check than to the PS throughput check. The IRAT threshold may be based on, for example, the LTE B1 event threshold, the LTE B2 event threshold, and/or a combination of both thresholds. Moreover, the B1 event or B2 event threshold may be applied to a single UE (e.g. on a per call basis) or to multiple UEs (e.g. on a cell basis or a system basis) .

In other aspects, the IRAT threshold adjustment may consider the offload of a WiFi network when QoS is important. For example, the IRAT threshold adjustment may be based on a QoS metric. The IRAT threshold adjustment may also consider a particular application, for example, video, so that application-specific quality metrics, e.g. video quality metrics, may be considered. Moreover, the IRAT threshold adjustment may depend on application and/or system characteristics such as a frequency division duplex (FDD) system with symmetric uplink and downlink that favors voice or a time division duplex (TDD) system which favors data on either the downlink or uplink. Although some of the examples are described as handovers between 4G and 3G, the disclosed procedures and associated features may be equally applicable to other IRAT handovers.

In block 910, increment the network monitoring packet switched/circuit switched (PS/CS) statistics for iteration n. For example, the iteration n is an integer ranging from n＝1 to n＝N. For example, the PS/CS statistics include call setup success rate (CSSR) , IRAT handover success rate, packet switched (PS) voice quality, and PS throughput.

In the following description, a particular serial order is presented as an example. The serial order may be altered, for example, according to choice (s) made by a network operator and/or a system operator. In this description, the CSSR, IRAT handover success rate and PS voice quality are assumed to have a higher priority over the PS throughput. For example, the PS voice quality may include packet loss, jitter and/or latency (delay) . One skilled in the art would understand that in other cases, the PS throughput may have a higher priority over one or more of the CSSR, IRAT handover success rate or PS voice quality.

The IRAT threshold may be adjusted depending on the particular performance criteria utilized. For example, the IRAT threshold may be increased to improve the CSSR, IRAT handover success rate and PS voice quality. The IRAT threshold may be decreased to improve the PS throughput. For example, if the CSSR, IRAT handover success rate and PS voice quality all exceed their respective thresholds, that is, they all meet their respective key performance indicator (KPI) , the IRAT threshold may be decreased to improve the PS throughput.

In other examples, if the IRAT handover success rate is the primary performance criterion, then the serial order may be revised accordingly. In this case, the IRAT handover success rate may be checked first, the PS voice quality next, followed by CSSR and PS throughput. In other examples, if the PS throughput is the primary performance criterion, then the serial order may be revised accordingly. In this case, the PS throughput may be checked first, then PS voice quality next, followed by IRAT handover success rate and CSSR. In other examples, if the circuit switched fallback (CSFB) capability is the primary performance criterion, then the serial order may be revised accordingly. In this case, the CSSR may be checked first, then PS throughput next, followed by PS voice quality and IRAT handover success rate. One skilled in the art would understand that although specific orders for checking the CSSR, IRAT handover success rate, PS voice quality and PS throughput are presented herein as examples, these specific orders may be varied without departing from the scope and spirit of the present disclosure.

In block 920, check if a call setup success rate (CSSR) for increment n is below a CSSR threshold. If yes, proceed to block 990. If no, proceed to block 930. In block 930, check if an IRAT handover success rate for increment n is below a success rate threshold. If yes, proceed to block 990. If no, proceed to block 940. In block 940, check if the packet loss for increment n is less than a packet loss threshold. If yes, proceed to block 990. If no, proceed to block 950. In block 950, check if the jitter for increment n is less that a jitter threshold. If yes, proceed to block 990. If no, proceed to block 960. In block 960, check if the latency for increment n is less than a latency threshold. If yes, proceed to block 990. If no, proceed to block 970. In block 970, check if an additional parameter for increment n is less than an additional parameter threshold. If yes, proceed to block 990. If no, proceed to block 980. In block 980, check if a PS throughput (a.k.a. an achievable throughput) for increment n is less than a PS throughput threshold (a.k.a. a throughput threshold (TH_TPut) ) . If yes, proceed to block 990. If no, return to block 910 and increment network monitoring packet switched/circuit switched (PS/CS) statistics for iteration (n+1) .

In block 990, adjust an IRAT threshold by either increasing or decreasing the IRAT threshold, depending on which preceding block passes its threshold check. For example, if the CSSR is below the CSSR threshold, then increase the IRAT threshold by X1 in dB. The value of X1 may depend on one or more of system application, system design, operator choice and/or user choice, etc. In various examples, X1＝1 dB. For example, if the IRAT handover success rate is below the IRAT handover success rate threshold, then increase the IRAT threshold by X2 in dB. The value of X2 may depend on one or more of system application, system design, operator choice and/or user choice, etc. In various examples, X2＝1 dB. For example, if the PS voice quality is below the PS voice quality threshold, then increase the IRAT threshold by X3 in dB. The value of X3 may depend on one or more of system application, system design, operator choice and/or user choice, etc. In various examples, X3＝1 dB. For example, if the PS throughput is below the PS throughput threshold, then decrease the IRAT threshold by Y1 in dB. The value of Y1 may depend on one or more of system application, system design, operator choice and/or user choice, etc. In various examples, Y1＝1 dB.

In block 995, update the IRAT threshold (a.k.a. the reference signal power threshold) according to the adjustment determined in block 990 to yield an updated IRAT threshold (a.k.a. an updated reference signal power threshold) . Subsequently, return to block 910 and increment network monitoring packet switched/circuit switched (PS/CS) statistics for iteration (n+1) .

FIG. 10 is a flow chart 1000 illustrating an example of a first use case of the scalable checking procedure of FIG. 9 in serial order for IRAT threshold adjustment. In block 1010, increment the network monitoring packet switched/circuit switched (PS/CS) statistics for iteration n. In this example, CSSR (block 1020) , IRAT handover success rate (block 1030) and PS throughput (block 1080) are the performance criteria utilized in the procedure in serial order for IRAT threshold adjustment (block 1090) . In various examples, the PS throughput check utilizes an estimated 3G PS throughput for the PS throughput threshold.

In block 1095, update the IRAT threshold (a.k.a. the reference signal power threshold) according to the adjustment determined in block 1090 to yield an updated IRAT threshold (a.k.a. an updated reference signal power threshold) . Subsequently, return to block 1010 and increment network monitoring packet switched/circuit switched (PS/CS) statistics for iteration (n+1) .

FIG. 11 is a flow chart 1100 illustrating an example of a second use case scalable checking procedure of Fig. 9 in serial order for IRAT threshold adjustment. In block 1110, increment the network monitoring packet switched/circuit switched (PS/CS) statistics for iteration n. In this example, PS voice quality (

blocks

1140, 1150, 1160) and PS throughput (block 1180) are the performance criteria utilized in the procedure in serial order for IRAT threshold adjustment (block 1190) . In various examples, the PS voice quality check utilizes serial checks of packet loss (block 1140) , jitter (block 1150) and latency (block 1160) , in that order. In other examples, the serial checks of these three metrics may be performed in any order. In various examples, the PS throughput check utilizes an estimated 3G PS throughput for the PS throughput threshold.

In block 1195, update the IRAT threshold (a.k.a. the reference signal power threshold) according to the adjustment determined in block 1190 to yield an updated IRAT threshold (a.k.a. an updated reference signal power threshold) . Subsequently, return to block 1110 and increment network monitoring packet switched/circuit switched (PS/CS) statistics for iteration (n+1) .

The discussions relating to the features in FIG. 9 are applicable to FIGs. 10 and 11 and are therefore not repeated here. In various examples, the scalable checking procedure in serial order for IRAT threshold adjustment as depicted in FIG. 10 would be suitable in a circuit switched (CS) voice dominated network where a circuit switched fallback (CSFB) call to 3G performance is being monitored. In various examples, the scalable checking procedure in serial order for IRAT threshold adjustment as depicted in FIG. 11 would be suitable in a packet switched (PS) voice dominated network where VoIP over LTE or VoLTE call performance is being monitored.

A scalable checking procedure for IRAT threshold adjustment may also be performed in parallel order (i.e. scalable checking procedure in parallel order for IRAT threshold adjustment) . In various examples, it may be possible that different IRAT thresholds may be selected using weighting factors for different types of traffic. For example, for VoLTE only traffic, the IRAT threshold may be adjusted to meet the VoLTE single radio voice call continuity (SRVCC) key performance indicator (KPI) . For PS data only traffic, the IRAT threshold may be adjusted to yield the highest PS throughput. In other examples, for a mix of PS data and VoLTE traffic, the IRAT threshold may be chosen to balance the performance for both traffic types by using, for example, a weighted factor approach.

FIG. 12 is a flow chart 1200 illustrating an example of a scalable checking procedure in parallel order for IRAT threshold adjustment. In block 1210, increment the network monitoring packet switched/circuit switched (PS/CS) statistics for iteration n. The procedure balances PS throughput and overall quality of service (QoS) performance metrics. The IRAT threshold is adaptively adjusted to meet overall QoS performance criteria such as call setup success rate CSSR (e.g., LTE RRC connection success rate) (block 1220) , IRAT handover success rate (block 1230) , PS voice quality (

blocks

1240, 1250, 1260) , etc. while maximizing PS throughput (block 1280) . The scalable checking procedure is applicable for any IRAT transition, for example, 4G to 3G, 4G to 2G, etc. In addition, the procedure is scalable for additional threshold checking (block 1270) .

In block 1295, update the IRAT threshold (a.k.a. the reference signal power threshold) according to the adjustment determined in block 1290 to yield an updated IRAT threshold (a.k.a. an updated reference signal power threshold) . Subsequently, return to block 1210 and increment network monitoring packet switched/circuit switched (PS/CS) statistics for iteration (n+1) .

In FIG. 12, several performance criteria, e.g. CSSR, IRAT handover success rate, PS voice quality, other parameter (s) and PS throughput are checked in parallel against their respective thresholds, rather than serially, as in Fig. 9. For example, the IRAT threshold adjustment may be based on a weighted combination of several performance criteria with the following definitions:

weighted factor w (i) ＝ {w (1) , w (2) , w (3) , w (4) , …} eqn (2)

where w (i) may be in the range [0.0, 1.0] , and may be greater than 1.0 if applicable.

y (i) ＝ {y (1) , y (2) , y (3) , y (4) , …} eqn (3)

where

y (1) ＝CSSR delta＝CSSR target-CSSR current KPI value

y (2) ＝IRAT HO success rate delta＝IRAT HO success rate target-IRAT HO success rate current KPI value

y (3) ＝PS voice quality delta

＝ (packet loss target-packet loss current KPI value) + (jitter target-jitter current KPI value) /jitter target+(latency target-latency current KPI value) /latency target

y (4) ＝PS throughput delta

＝ (PS throughput target-PS throughput current KPI) /PS throughput target

P is a check parameter defined as the weighted summation (using weighted factor w (i) ) of QoS performance metric delta y (i) :

P＝∑w (i) y (i) , eqn (4)

T (P) a predetermined threshold for check parameter P. T (P) may be a configurable threshold such that:

If P<T (P) , increase the IRAT threshold by X dB； and

if P≥T (P) , decrease the IRAT threshold by Y dB. eqn (5)

In various examples, the values of the IRAT threshold increment (X dB or Y dB) may be 0.5 dB, 1 dB or 2 dB. The value of the IRAT threshold increment (X dB or Y dB) may depend on whether the IRAT threshold is reference signal received power (RSRP) based or reference signal received quality (RSRQ) . In various examples, for RSRP based, an example dynamic range is from-44 dBm to-140 dBm. In various examples, the dynamic range should have a sensitively level of at least as high as-120 to-124 dBm. In various examples, for RSRQ based, an example dynamic range is-3 dB to-19.5 dB.

The weights w (i) may be selected to emphasize certain performance criteria over others. For example, if CSSR is more important, w (1) may be selected with a value near 1.0 while w (2) and w (3) may be selected with values near 0.0 to maximize the CSSR KPI value. The weights w (i) may be selected to balance the KPI values and may be selected according to various factors such as an operations model, cost model, etc.

FIG. 13 is a flow chart 1300 illustrating an example of a first use case scalable checking procedure of Fig. 12 in parallel order for IRAT threshold adjustment. In block 1310, increment the network monitoring packet switched/circuit switched (PS/CS) statistics for iteration n. In this example, CSSR (block 1320) , IRAT handover success rate (block 1330) and PS throughput (block 1380) are the performance criteria utilized in the procedure in parallel order for IRAT threshold adjustment (block 1390) . In various examples, the PS throughput check utilizes an estimated 3G PS throughput for the PS throughput threshold.

In block 1395, update the IRAT threshold (a.k.a. the reference signal power threshold) according to the adjustment determined in block 1390 to yield an updated IRAT threshold (a.k.a. an updated reference signal power threshold) . Subsequently, return to block 1310 and increment network monitoring packet switched/circuit switched (PS/CS) statistics for iteration (n+1) .

FIG. 14 is a flow chart 1400 illustrating an example of a second use case scalable checking procedure of Fig. 12 in parallel order for IRAT threshold adjustment. In block 1410, increment the network monitoring packet switched/circuit switched (PS/CS) statistics for iteration n. In this example, PS voice quality (

blocks

1440, 1450, 1460) and PS throughput (block 1480) are the performance criteria utilized in the procedure in serial order for IRAT threshold adjustment (block 1490) . In various examples, the PS voice quality check utilizes parallel checks of packet loss (block 1440) , jitter (block 1450) and latency (block 1460) , in that order. In various examples, the PS throughput check utilizes an estimated 3G PS throughput for the PS throughput threshold.

In block 1495, update the IRAT threshold (a.k.a. the reference signal power threshold) according to the adjustment determined in block 1490 to yield an updated IRAT threshold (a.k.a. an updated reference signal power threshold) . Subsequently, return to block 1410 and increment network monitoring packet switched/circuit switched (PS/CS) statistics for iteration (n+1) .

The discussions relating to the features in FIG. 9 are applicable to FIGs. 12-14 and are therefore not repeated here.

FIG. 15 illustrates an example pseudocode with an associated example flow chart 1500 for a scalable checking procedure for IRAT threshold adjustment. In this example, CSSR, IRAT HO success rate and PS throughput are checked in serial order. The example pseudocode shown represents any suitable programming language which implements the scalable checking procedure for IRAT threshold adjustment. One skilled in the art would understand that the example pseudocode and associated flow chart presented in FIG. 15 are merely examples and that other pseudocode and flow chart implementations may be used for the scalable checking procedure.

FIG. 16 is a flow chart 1600 illustrating a first example of inter-radio access technology (IRAT) handover. In block 1610, receive a plurality of receive signals through a receiver and perform at least one of the following:

a) determine if a call setup success rate (CSSR) is below a CSSR threshold (Th_CSSR) .

b) determine if an IRAT handover success rate is below an IRAT success threshold (Th_IRAT) ； and

c) determine if a packet switch (PS) voice quality is below a voice quality threshold (TH_voice) .

In various examples, the plurality of receive signals includes at least one metric and one or more of the CSSR, the IRAT handover success rate and the PS voice quality is derived from the at least one metric associated with the plurality of receive signals. In various examples, the at least one metric may include one or more of the following: receive power level (e.g., received signal strength indicator (RSSI) which is a measurement of the power present in the plurality of received signals.) , bit error rate (BER) , packet loss rate, chip error rate, log likelihood ratio (LLR) , etc. One skilled in the art would understand that the metrics listed herein are examples only and other metrics associated with the plurality of received signals may be used to derive one or more of the CSSR, the IRAT handover success rate and the PS voice quality.

In various examples, the

receiver

208, 308, 408 (shown in the devices illustrated in FIGs. 2, 3, 4) may be used to receive the plurality of receive signals. The plurality of receive signals (once received) and any associated metric may be stored within the

storage medium

206, 306, 406 (of the respective devices illustrated in FIGs. 2, 3, 4) .

In various examples, the CSSR is for a circuit switched fallback (CSFB) call. In various examples, the PS voice quality includes at least one of packet loss, jitter and latency. In various examples, the determining the call setup success rate (CSSR) , the determining the IRAT handover success rate, and the determining the packet switch (PS) voice quality are performed in parallel order. In various examples, in lieu of one or more or in addition to the CSSR, the IRAT handover success rate and the PS voice quality, one or more of the following performance metrics: a power headroom, a block error rate, an uplink negative acknowledgement (NACK) rate, an uplink signal to interference and noise ratio (SINR) or internal base station metrics may be determined if it is below a corresponding performance threshold. And, the resulting determination may be used as a factor in adjusting (e.g., increasing) a reference signal power threshold (a.k.a., an IRAT threshold) .

In block 1620, determine if at least one of the CSSR, the IRAT handover success rate or the PS voice quality is below its respective threshold. If yes, proceed to block 1630. If no, proceed to block 1640. In block 1630, increase a reference signal power threshold by a predetermined increment to yield an updated reference signal power threshold. In various examples, the reference signal power threshold is a reference signal received power (RSRP) threshold. From block 1630, proceed to block 1680. In block 1640, estimate an achievable throughput. In various examples, the achievable throughput is a 4G throughput (i.e., the throughput of a 4G network) and the throughput threshold is a 3G throughput (i.e., the throughput of a 3G network) . In various examples, the estimating an achievable throughput is based on a filtered average of a reported receive power measurement. The filtered average may be implemented by a weighted moving average (MA) , a fixed time domain average, a finite impulse response (FIR) digital filter, or an infinite impulse response (IIR) digital filter. In various examples, the estimating the achievable throughput is based on a table lookup and uses a serving probability as a loading factor.

In block 1650, compare the achievable throughput against a throughput threshold (TH_TPut) . If the achievable throughput is greater or equal to the TH_TPut, proceed to block 1660. If the achievable throughput is less than the TH_TPut, proceed to block 1670. In various examples, the CSSR threshold (Th_CSSR) , the IRAT success threshold (Th_IRAT) , the voice quality threshold (TH_voice) and the throughput threshold (TH_TPut) are based on a B1 event, a B2 event or a combination of B1 event and B2 event. In various examples, the comparing the achievable throughput against the throughput threshold (TH_TPut) is performed in parallel order with the determining the CSSR, the determining the IRAT handover success rate, and the determining the PS voice quality.

In block 1660, continue network monitoring. In block 1670, decrease the reference signal power threshold by a predetermined decrement to yield the updated reference signal power threshold. In block 1680, use the updated reference signal power threshold to trigger an IRAT handover. In various examples, the IRAT handover success rate is for the IRAT handover from a 4G network to a 3G network. In various examples, components in any of the devices of FIGs. 2-4 may be used to perform any of the steps in blocks 1610 through 1680, for example but not limited to, the

processing circuit

202, 302, 402 and the

handover circuitry

216, 316, 416.

FIG. 17 is a flow chart 1700 illustrating a second example of inter-radio access technology (IRAT) handover. In block 1710, receive a plurality of receive signals through a receiver and apply a first weighted factor w (1) to a call setup success rate (CSSR) to obtain a weighted CSSR. In block 1720, apply a second weighted factor w (2) to an IRAT handover success rate to obtain a weighted IRAT handover success rate. In block 1730, apply a third weighted factor w (3) to a packet switch (PS) voice quality to obtain a weighted PS voice quality.

In block 1740, apply a fourth weighted factor w (4) to an achievable throughput to obtain a weighted achievable throughput. In block 1750, combine the weighted CSSR, the weighted IRAT handover success rate, the weighted PS voice quality and the weighted achievable throughput to obtain a check parameter P. In block 1760, compare the check parameter P with a predetermined threshold T (P) to yield a comparison.

As previously discussed, the check parameter P is defined as the weighted summation (using weighted factor w (i) ) of QoS performance metric delta y (i) , as shown by P＝∑w (i) y (i) . Also previously discussed and repeated herein are:

w (i) ＝ {w (1) , w (2) , w (3) , w (4) , …}

y (i) ＝ {y (1) , y (2) , y (3) , y (4) , …}

where

y (1) ＝CSSR delta＝CSSR target-CSSR current KPI value

y (3) ＝PS voice quality delta

＝ (packet loss target-packet loss current KPI value) + (jitter target-jitter current KPI value) /jitter target+ (latency target-latency current KPI value) /latency target

y (4) ＝PS throughput delta

＝ (PS throughput target-PS throughput current KPI) /PS throughput target

As discussed previously, T (P) is the predetermined threshold for the check parameter P, and T (P) may be configurable such that if P<T (P) , increase the IRAT threshold by X dB； and if P≥T (P) , decrease the IRAT threshold by Y dB. In block 1770, adjust a reference signal power threshold (a.k.a. an IRAT threshold) for the IRAT handover based on the comparison.

In various examples, components in any of the devices of FIGs. 2-4 may be used to perform any of the steps in blocks 1710 through 1770, for example but not limited to, the

processing circuit

202, 302, 402 and the

handover circuitry

216, 316, 416. In various examples, the

receiver

208, 308, 408 (shown in the devices illustrated in FIGs. 2, 3, 4) may be used to receive the plurality of receive signals. The plurality of receive signals (once received) , any associated metric and/or any of the weighted factors (the first weighted factor w (1) , the second weighted factor w (2) , the third weighted factor w (3) , the fourth weighted factor w (4) ) may be stored within the

storage medium

206, 306, 406 (of the respective devices illustrated in FIGs. 2, 3, 4) .

FIG. 18 is a conceptual diagram 1800 illustrating a simplified example of a hardware implementation for an apparatus employing a processing circuit 1802 that may be configured to perform one or more functions disclosed herein. In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements as disclosed herein may be implemented utilizing the processing circuit 1802. The processing circuit 1802 may include one or more processors 1804 that are controlled by some combination of hardware and software modules. Examples of processors 1804 include microprocessors, microcontrollers, digital signal processors (DSPs) , field programmable gate arrays (FPGAs) , programmable logic devices (PLDs) , state machines, sequencers, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. The one or more processors 1804 may include specialized processors that perform specific functions, and that may be configured, augmented or controlled by one of the software modules 1816. The one or more processors 1804 may be configured through a combination of software modules 1816 loaded during initialization, and further configured by loading or unloading one or more software modules 1816 during operation.

In the illustrated example, the processing circuit 1802 may be implemented with a bus architecture, represented generally by the bus 1810. The bus 1810 may include any number of interconnecting buses and bridges depending on the specific application of the processing circuit 1802 and the overall design constraints. The bus 1810 links together various circuits including the one or more processors 1804, and storage 1806. Storage 1806 may include memory devices and mass storage devices, and may be referred to herein as computer-readable media and/or processor-readable media. The bus 1810 may also link various other circuits such as timing sources, timers, peripherals, voltage regulators, and power management circuits. A bus interface 1808 may provide an interface between the bus 1810 and one or more transceivers 1812. A transceiver 1812 may be provided for each networking technology supported by the processing circuit. In some instances, multiple networking technologies may share some or all of the circuitry or processing modules found in a transceiver 1812. Each transceiver 1812 provides a means for communicating with various other apparatus over a transmission medium. Depending upon the nature of the apparatus, a user interface 1818 (e.g., keypad, display, speaker, microphone, joystick) may also be provided, and may be communicatively coupled to the bus 1810 directly or through the bus interface 1808.

A processor 1804 may be responsible for managing the bus 1810 and for general processing that may include the execution of software stored in a computer-readable medium that may include the storage 1806. In this respect, the processing circuit 1802, including the processor 1804, may be used to implement any of the methods, functions and techniques disclosed herein. The storage 1806 may be used for storing data that is manipulated by the processor 1804 when executing software, and the software may be configured to implement any one of the methods disclosed herein.

One or more processors 1804 in the processing circuit 1802 may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, algorithms, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside in computer-readable form in the storage 1806 or in an external computer-readable medium. The external computer-readable medium and/or storage 1806 may include a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip) , an optical disk (e.g., a compact disc (CD) or a digital versatile disc (DVD) ) , a smart card, a flash memory device (e.g., a “flash drive, ” a card, a stick, or a key drive) , a random access memory (RAM) , a read only memory (ROM) , a programmable ROM (PROM) , an erasable PROM (EPROM) , an electrically erasable PROM (EEPROM) , a register, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer. The computer-readable medium and/or storage 1806 may also include, by way of example, a carrier wave, a transmission line, and any other suitable medium for transmitting software and/or instructions that may be accessed and read by a computer. Computer-readable medium and/or the storage 1806 may reside in the processing circuit 1802, in the processor 1804, external to the processing circuit 1802, or be distributed across multiple entities including the processing circuit 1802. The computer-readable medium and/or storage 1806 may be embodied in a computer program product. By way of example, a computer program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system. Additionally, one skilled in the art would recognize that the term computer-readable medium and computer-readable storage medium may be used interchangeably and that a computer-readable storage medium may store computer executable code operable on a device.

The storage 1806 may maintain software maintained and/or organized in loadable code segments, modules, applications, programs, etc., which may be referred to herein as software modules 1816. Each of the software modules 1816 may include instructions and data that, when installed or loaded on the processing circuit 1802 and executed by the one or more processors 1804, contribute to a run-time image 1814 that controls the operation of the one or more processors 1804. When executed, certain instructions may cause the processing circuit 1802 to perform functions in accordance with certain methods, algorithms and processes described herein.

Some of the software modules 1816 may be loaded during initialization of the processing circuit 1802, and these software modules 1816 may configure the processing circuit 1802 to enable performance of the various functions disclosed herein. For example, some software modules 1816 may configure internal devices and/or logic circuits 1822 of the processor 1804, and may manage access to external devices such as the transceiver 1812, the bus interface 1808, the user interface 1818, timers, mathematical coprocessors, and so on. The software modules 1816 may include a control program and/or an operating system that interacts with interrupt handlers and device drivers, and that controls access to various resources provided by the processing circuit 1802. The resources may include memory, processing time, access to the transceiver 1812, the user interface 1818, and so on.

One or more processors 1804 of the processing circuit 1802 may be multifunctional, whereby some of the software modules 1816 are loaded and configured to perform different functions or different instances of the same function. The one or more processors 1804 may additionally be adapted to manage background tasks initiated in response to inputs from the user interface 1818, the transceiver 1812, and device drivers, for example. To support the performance of multiple functions, the one or more processors 1804 may be configured to provide a multitasking environment, whereby each of a plurality of functions is implemented as a set of tasks serviced by the one or more processors 1804 as needed or desired. In one example, the multitasking environment may be implemented utilizing a timesharing program 1820 that passes control of a processor 1804 between different tasks, whereby each task returns control of the one or more processors 1804 to the timesharing program 1820 upon completion of any outstanding operations and/or in response to an input such as an interrupt. When a task has control of the one or more processors 1804, the processing circuit is effectively specialized for the purposes addressed by the function associated with the controlling task. The timesharing program 1820 may include an operating system, a main loop that transfers control on a round-robin basis, a function that allocates control of the one or more processors 1804 in accordance with a prioritization of the functions, and/or an interrupt driven main loop that responds to external events by providing control of the one or more processors 1804 to a handling function.

Additionally, the components described in FIG. 18 may be implemented to perform some or all the blocks of the flow diagrams in FIGs. 9-18. Several aspects of a telecommunications system have been presented. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to various types of telecommunication systems, network architectures and communication standards.

Several aspects of a wireless telecommunications system have been presented with reference to a UTRAN/eUTRAN system. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards.

By way of example, various aspects may be extended to other UMTS systems such as TD-SCDMA and TD-CDMA. Various aspects may also be extended to systems employing Long Term Evolution (LTE) (in FDD, TDD, or both modes) , LTE-Advanced (LTE-A) (in FDD, TDD, or both modes) , CDMA2000, Evolution-Data Optimized (EV-DO) , Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Ultra-Wideband (UWB) , Bluetooth, and/or other suitable systems. The actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.

Within the present disclosure, the word “exemplary” is used to mean “serving as an example, instance, or illustration.” Any implementation or aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects of the disclosure. Likewise, the term “aspects” does not require that all aspects of the disclosure include the discussed feature, advantage or mode of operation. The term “coupled” is used herein to refer to the direct or indirect coupling between two objects. For example, if object A physically touches object B, and object B touches object C, then objects A and C may still be considered coupled to one another—even if they do not directly physically touch each other. For instance, a first die may be coupled to a second die in a package even though the first die is never directly physically in contact with the second die. The terms “circuit” and “circuitry” are used broadly, and intended to include both hardware implementations of electrical devices and conductors that, when connected and configured, enable the performance of the functions described in the present disclosure, without limitation as to the type of electronic circuits, as well as software implementations of information and instructions that, when executed by a processor, enable the performance of the functions described in the present disclosure.

One or more of the components, blocks, features and/or functions illustrated in the figures may be rearranged and/or combined into a single component, block, feature or function or embodied in several components, blocks, or functions. Additional elements, components, blocks, and/or functions may also be added without departing from novel features disclosed herein. The apparatus, devices, and/or components illustrated in the various drawings may be configured to perform one or more of the methods, features, or blocks described herein. The novel algorithms described herein may also be efficiently implemented in software and/or embedded in hardware.

It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited therein.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a； b； c； a and b； a and c； b and c； and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”

Claims

A method for an inter-radio access technology (IRAT) handover， comprising：

receiving， through a receiver， a plurality of receive signals with at least one metric associated with the plurality of receive signals；

performing at least one of the following：

a) determining if a call setup success rate (CSSR) is below a CSSR threshold (Th_CSSR) ；

b) determining if an IRAT handover success rate is below an IRAT success threshold (Th_IRAT) ； and

c) determining if a packet switch (PS) voice quality is below a voice quality threshold (TH_voice) ； wherein one or more of the CSSR， the IRAT handover success rate and the PS voice quality is derived from the at least one metric； and

determining that at least one of the CSSR， the IRAT handover success rate or the PS voice quality is below its respective threshold and increasing a reference signal power threshold by a predetermined increment to yield an updated reference signal power threshold； or

determining that none of the CSSR， the IRAT handover success rate or the PS voice quality is below its respective threshold， estimating an achievable throughput and comparing the achievable throughput against a throughput threshold (TH_TPut) ， and if the achievable throughput is greater or equal to the TH_TPut， continuing network monitoring， or if the achievable throughput is less than the TH_TPut， decreasing the reference signal power threshold by a predetermined decrement to yield the updated reference signal power threshold.
The method of claim 1， wherein the PS voice quality includes at least one of packet loss， jitter and latency.
The method of claim 1， further comprising using the updated reference signal power threshold to trigger the IRAT handover.
The method of claim 3， wherein the IRAT handover success rate is for the IRAT handover from a 4G network to a 3G network.
The method of claim 4， wherein the achievable throughput is a 4G throughput and the throughput threshold (TH_TPut) is a 3G throughput.
The method of claim 1， wherein the CSSR is for a circuit switched fallback (CSFB) call.
The method of claim 1， further comprising：

determining if one or more of the following： a power headroom， a block error rate， an uplink negative acknowledgement (NACK) rate， an uplink signal to interference and noise ratio (SINR) or internal base station metrics is below a performance threshold； and

adjusting the reference signal power threshold based on determining that the one or more of the following： the power headroom， the block error rate， the uplink negative acknowledgement (NACK) rate， the uplink signal to interference and noise ratio (SINR) or the internal base station metrics is below the performance threshold.
The method of claim 1， wherein the reference signal power threshold is a reference signal received power (RSRP) threshold.
The method of claim 1， wherein the estimating an achievable throughput is based on a filtered average of a reported receive power measurement.
The method of claim 9， wherein the filtered average may be implemented by a weighted moving average (MA) ， a fixed time domain average， a finite impulse response (FIR) digital filter， or an infinite impulse response (IIR) digital filter.
The method of claim 1， wherein the estimating an achievable throughput is based on a table lookup and uses a serving probability as a loading factor.
The method of claim 1， wherein the CSSR threshold (Th_CSSR) ， the IRAT success threshold (Th_IRAT) ， the voice quality threshold (TH_voice) and the throughput threshold (TH_TPut) are based on a B 1 event， a B2 event or a combination of B 1 event and B2 event.
The method of claim 1， wherein the determining the call setup success rate (CSSR) ， the determining the IRAT handover success rate， and the determining the packet switch (PS) voice quality are performed in parallel order.
The method of claim 13， wherein the comparing the achievable throughput against the throughput threshold (TH_TPut) is performed in parallel order with the determining the CSSR， the determining the IRAT handover success rate， and the determining the PS voice quality.
A method for an inter-radio access technology (IRAT) handover， comprising：

receiving， through a receiver， a plurality of receive signals with at least one metric associated with the plurality of receive signals；

applying a first weighted factor to a call setup success rate (CSSR) to obtain a weighted CSSR；

applying a second weighted factor to an IRAT handover success rate to obtain a weighted IRAT handover success rate；

applying a third weighted factor to a packet switch (PS) voice quality to obtain a weighted PS voice quality， wherein one or more of the CSSR， the IRAT handover success rate and the PS voice quality is derived from the at least one metric；

applying a fourth weighted factor to an achievable throughput to obtain a weighted achievable throughput；

combining the weighted CSSR， the weighted IRAT handover success rate， the weighted PS voice quality and the weighted achievable throughput to obtain a check parameter；

comparing the check parameter with a predetermined threshold T (P) to yield a comparison； and

adjusting a reference signal power threshold for the IRAT handover based on the comparison.
An apparatus for an inter-radio access technology (IRAT) handover， comprising：

a receiver to receive a plurality of receive signals；

a storage medium coupled to the receiver to store at least one metric associated with the plurality of receive signals； and

a processing circuit coupled to the receiver， wherein the processing circuit is configured to perform one or more of the following：

determine if a call setup success rate (CSSR) is below a CSSR threshold (Th_CSSR) ；

determine if an IRAT handover success rate is below an IRAT success threshold (Th_IRAT) ； and

determine if a packet switch (PS) voice quality is below a voice quality threshold (TH_voice) ； wherein one or more of the CSSR， the IRAT handover success rate and the PS voice quality is derived from the plurality of receive signals； and

wherein the processing circuit is further configured to perform the following：

determine that at least one of the CSSR， the IRAT handover success rate or the PS voice quality is below its respective threshold and increase a reference signal power threshold by a predetermined increment to yield an updated reference signal power threshold； or

determine that none of the CSSR， the IRAT handover success rate or the PS voice quality is below its respective threshold， estimate an achievable throughput， and compare the achievable throughput against a throughput threshold (TH_TPut) ， and if the achievable throughput is greater or equal to the TH_TPut， continue network monitoring， or if the achievable throughput is less than the TH_TPut， decrease the reference signal power threshold by a predetermined decrement to yield the updated reference signal power threshold，

wherein one or more of the CSSR， the IRAT handover success rate and the PS voice quality is derived from the at least one metric.
The apparatus of claim 16， wherein the processing circuit is further configured to perform the following：

determine if one or more of the following： a power headroom， a block error rate， an uplink negative acknowledgement (NACK) rate， an uplink signal to interference and noise ratio (SINR) or internal base station metrics is below a performance threshold； and

adjust the reference signal power threshold based on that the one or more of the following： the power headroom， the block error rate， the uplink negative acknowledgement (NACK) rate， the uplink signal to interference and noise ratio (SINR) or the internal base station metrics is below the performance threshold.
The apparatus of claim 16， wherein the PS voice quality includes at least one of packet loss， jitter and latency.
The apparatus of claim 16， wherein the processing circuit is further configured to use the updated reference signal power threshold to trigger the IRAT handover.
The apparatus of claim 19， wherein the IRAT handover success rate is for the IRAT handover from a 4G network to a 3G network.
The apparatus of claim 20， wherein the achievable throughput is a 4G throughput and the throughput threshold (TH_TPut) is a 3G throughput.
An apparatus for an inter-radio access technology (IRAT) handover， comprising：

a receiver to receive a plurality of receive signals；

a storage medium coupled to the receiver to store at least one metric associated with the plurality of receive signals； and

a processing circuit coupled to the receiver， wherein the processing circuit is configured to perform the following：

apply a first weighted factor to a call setup success rate (CSSR) to obtain a weighted CSSR；

apply a second weighted factor to an IRAT handover success rate to obtain a weighted IRAT handover success rate；

apply a third weighted factor to a packet switch (PS) voice quality to obtain a weighted PS voice quality， wherein one or more of the CSSR， the IRAT handover success rate and the PS voice quality is derived from the at least one metric；

apply a fourth weighted factor to an achievable throughput to obtain a weighted achievable throughput；

combine the weighted CSSR， the weighted IRAT handover success rate， the weighted PS voice quality and the weighted achievable throughput to obtain a check parameter；

compare the check parameter with a predetermined threshold T (P) to yield a comparison； and

adjust a reference signal power threshold for the IRAT handover based on the comparison.
An apparatus for an inter-radio access technology (IRAT) handover， comprising：

a receiver to receive a plurality of receive signals；

a storage medium associated with the receiver to store at least one metric associated with the plurality of receive signals；

means for determining if a call setup success rate (CSSR) is below a CSSR threshold (Th_CSSR) ；

means for determining if an IRAT handover success rate is below an IRAT success threshold (Th_IRAT) ；

means for determining if a packet switch (PS) voice quality is below a voice quality threshold (TH_voice) ； wherein one or more of the CSSR， the IRAT handover success rate and the PS voice quality is derived from the at least one metric；

means for determining that at least one of the CSSR， the IRAT handover success rate or the PS voice quality is below its respective threshold and for increasing a reference signal power threshold by a predetermined increment to yield an updated reference signal power threshold； and

means for determining that none of the CSSR， the IRAT handover success rate or the PS voice quality is below its respective threshold， for estimating an achievable throughput and for comparing the achievable throughput against a throughput threshold (TH_TPut) ， and if the achievable throughput is greater or equal to the TH_TPut， for continuing network monitoring， or if the achievable throughput is less than the TH_TPut， for decreasing the reference signal power threshold by a predetermined decrement to yield the updated reference signal power threshold.
The apparatus of claim 23， further comprising means for using the updated reference signal power threshold to trigger the IRAT handover and wherein the IRAT handover success rate is for the IRAT handover from a 4G network to a 3G network.
The apparatus of claim 24， wherein the achievable throughput is a 4G throughput and the throughput threshold (TH_TPut) is a 3G throughput.
The apparatus of claim 23， wherein the CSSR is for a circuit switched fallback (CSFB) call.
The apparatus of claim 23， further comprising：

means for determining if one or more of the following： a power headroom， a block error rate， an uplink negative acknowledgement (NACK) rate， an uplink signal to interference and noise ratio (SINR) or internal base station metrics is below a performance threshold； and

means for adjusting the reference signal power threshold based on determining that the one or more of the following： the power headroom， the block error rate， the uplink negative acknowledgement (NACK) rate， the uplink signal to interference and noise ratio (SINR) or the internal base station metrics is below the performance threshold.
An apparatus for an inter-radio access technology (IRAT) handover， comprising：

a receiver to receive a plurality of receive signals；

a storage medium associated with the receiver to store at least one metric associated with the plurality of receive signals；

means for applying a first weighted factor to a call setup success rate (CSSR) to obtain a weighted CSSR；

means for applying a second weighted factor to an IRAT handover success rate to obtain a weighted IRAT handover success rate；

means for applying a third weighted factor to a packet switch (PS) voice quality to obtain a weighted PS voice quality， wherein one or more of the CSSR， the IRAT handover success rate and the PS voice quality is derived from the at least one metric；

means for applying a fourth weighted factor to an achievable throughput to obtain a weighted achievable throughput；

means for combining the weighted CSSR， the weighted IRAT handover success rate， the weighted PS voice quality and the weighted achievable throughput to obtain a check parameter；

means for comparing the check parameter with a predetermined threshold T (P) to yield a comparison； and

means for adjusting a reference signal power threshold for the IRAT handover based on the comparison.
A computer-readable storage medium storing computer executable code， operable on a device comprising at least one processor； a storage medium to store at least one metric associated with a plurality of signals， the storage medium coupled to the at least one processor； a receiver coupled to the at least one processor， wherein the receiver is configured to receive the plurality of signals； and the computer executable code comprising：

instructions for causing the at least one processor to determine if a call setup success rate (CSSR) is below a CSSR threshold (Th_CSSR) ；

instructions for causing the at least one processor to determine if an IRAT handover success rate is below an IRAT success threshold (Th_IRAT) ； or

instructions for causing the at least one processor to determining if a packet switch (PS) voice quality is below a voice quality threshold (TH_voice) ， wherein one or more of the CSSR， the IRAT handover success rate and the PS voice quality is derived from the at least one metric； and

instructions for causing the at least one processor to determine that at least one of the CSSR， the IRAT handover success rate or the PS voice quality is below its respective threshold， and increasing a reference signal power threshold by a predetermined increment to yield an updated reference signal power threshold； or

instructions for causing the at least one processor to determine that none of the CSSR， the IRAT handover success rate or the PS voice quality is below its respective threshold， estimating an achievable throughput， and comparing the achievable throughput against a throughput threshold (TH_TPut) ， and if the achievable throughput is greater or equal to the TH_TPut， continue network monitoring， or if the achievable throughput is less than the TH_TPut， decrease the reference signal power threshold by a predetermined decrement to yield the updated reference signal power threshold.
A computer-readable storage medium storing computer executable code， operable on a device comprising at least one processor； a storage medium to store at least one metric associated with a plurality of signals， the storage medium coupled to the at least one processor； a receiver coupled to the at least one processor， wherein the receiver is configured to receive the plurality of signals； and the computer executable code comprising：

instructions for causing the at least one processor to apply a first weighted factor to a call setup success rate (CSSR) to obtain a weighted CSSR；

instructions for causing the at least one processor to apply a second weighted factor to an IRAT handover success rate to obtain a weighted IRAT handover success rate；

instructions for causing the at least one processor to apply a third weighted factor to a packet switch (PS) voice quality to obtain a weighted PS voice quality， wherein one or more of the CSSR， the IRAT handover success rate and the PS voice quality is derived from the at least one metric；

instructions for causing the at least one processor to apply a fourth weighted factor to an achievable throughput to obtain a weighted achievable throughput；

instructions for causing the at least one processor to combine the weighted CSSR， the weighted IRAT handover success rate， the weighted PS voice quality and the weighted achievable throughput to obtain a check parameter；

instructions for causing the at least one processor to compare the check parameter with a predetermined threshold T (P) to yield a comparison； and

instructions for causing the at least one processor to adjust a reference signal power threshold for an IRAT handover based on the comparison.