WO2016120660A1

WO2016120660A1 - Modulation quality based cell change

Info

Publication number: WO2016120660A1
Application number: PCT/IB2015/050580
Authority: WO
Inventors: Asif Ali KHAN; Muhammad Kazmi; Farshid Ghasemzadeh
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2015-01-26
Filing date: 2015-01-26
Publication date: 2016-08-04

Abstract

According to certain embodiments, a method for facilitating a cell change comprises determining a first observed modulation score based on a first radio signal from a first network node serving a first cell and a second observed modulation score based on a second radio signal from a second network node serving a second cell. The method additionally comprises obtaining a first reference modulation score at the first network node and a second reference modulation score at the second network node. The method further comprises determining a first relative modulation score based on the first, observed and reference modulation scores and a second relative modulation score based on the second observed and reference modulation scores. The method additionally comprises transmitting the first relative modulation score, The method also comprises adding the first and second relative modulation scores to a list comprising relative modulation scores. The method also comprises identifying the second cell as a target cell to which to change the wireless device based on the relative modulation scores.

Description

MODULATION QUALITY BASED CELL CHANGE

TECHNICAL FIELD

Embodiments presented herein relate to cell change fo wireless devices, and in particular to methods, network nodes, wireless devices, computer programs, or computer program products for modulation quality based cell change for wireless devices,

BACKGROUND

Mobile networks have traditionally been deployed in a singular fashion where mobile network operators deployed and provisioned a single Radio Access Technology (RAT). The rapid evolution of wireless technology and the proliferation of smart devices, including smart phones and tablets, generates a significant demand for data services which has motivated the mobile network operators to adapt the networks and deploy new RATs alongside the legacy deployed RATs.

A common example of multi-RAT (MR) deployment is the case where operators use GSM (Global System for Mobile cominumcation)/EDGE (Enhanced Data rates for GSM Evolution) and UMTS/LTE (Long Term Evolution) in an overlaid fashion to meet the data capacity demands within a particular geographical region. In an effort to minimize the operational expenditure and optimize the network deployments, the operators tend to deploy multiple RATs in a shared infrastructure. This means that different RATs may share certain network infrastructure components such as; sites, antennas, antenna masts, backhaul links, feeder cables, RF modulators, amplifiers, and power supplies,

In addition to the multi-RAT deployments, the operators tend to deploy network nodes, such as base stations (BSs), supporting multi-carrier operation to meet the increasing demand for capacity. A multi-carrier capable network node can simultaneously support and operate i more than one active channel, as opposed to the conventional single carrier operation. This leads to a rather complex deployment, where an operator maintains a multi-RAT deployment where a particular network node, belonging to one or more RAT(s) can support multi-carrier operation. Given the spectrum limitations, these RATs are often required to share the same available spectTiim, Thus, the resulting network deployment involves a multi-RAT multi-carrier operation within the same geographical region and a shared spectrum allocation (between the RATs),

Because the multi-RAT network deployments often share the same network infrastructure, they often also share equipment hardware. This type of a network node is called a Multi-Standard Radio (MSR) network node, and is distinguished by the property that both the transmitter (TX) and receiver (RX) are capable of simultaneously processing multiple carriers of different RATs in common active RF components such as power amplifiers, RF filters, antennas, etc. Despite the implementation complexity of the common active RE the MSR network node is a possible alternative for the operators because it facilitates the migration between different RATs and the operators can use the same equipment to support multiple RATs in the migration phase. Once the entire network is migrated to, for example, LTE, the operator can still use the same existing MSR network node, to provide LTE sendee in a single-RAT (SR) mode. Unfortunately the shared components of an MSR network node, such as an active RF block, may lead to components that are not optimized for a particular RAT and thus leave room for improved performance, even though a multi-carrier and multi-RAT network node can fulfil all standardized requirements. This performance shortcoming is due to the constraints placed by the simultaneous multi-carrier and multi-RAT operation where, depending on the RAT combination (e.g. GSM+LTE), the transmitted signal quality and/or received signal quality may be affected due to the shared components, including peak power reduction algorithms, between the RATs, SUMMARY

An object of embodiments herein is to provide improved cell change for wireless devices based on relative modulation quality scores.

According to certain embodiments, a method for facilitating cell change comprises determining a first observed modulation score based on a first modulation quality of a first radio signal from a first network node that is serving a first cell. The method further comprises determining a second observed modulation score based on a second modulation quality of a second radio signal from a second network node that is serving a second cel. The method additionally comprises obtaining a first reference modulation score at the first network node. The method also comprises obtaining a second reference modulation score at the second network node. The method further comprises determining a first relative modulation score based on the first observed modulation score and the first reference modulation score and determining a second relative modulation score based on the second observed modulation score and the second reference modulation score. The method additionally comprises transmitting at least the first relative modulation score from the first network node to the wireless device or the second network node. The method also comprises adding the first and second relative modulation scores to a list comprising relative modulation scores for a plurality of network nodes serving a plurality of cells. The method additionally comprises identifying the second cell as a. target cell to which to change the wireless device based on at least the first and second relative modulation scores in the list of relative modulation scores. The method also comprises facilitating a cell change of the wireless device from the first cell to the second cell based on the relative modulation scores.

According to some embodiments,, a method for facilitating a cell change comprises determining, at a first network node serving a first cell, an observed modulation score based on a modulation quality of a first radio signal. The method also comprises receiving, at the first network node, a reference modulation score. The method further comprises determining, at the first network node, a relative modulation score based on the observed modulation score and the reference modulation score. The method additionally comprises facilitating a cell change of a first wireless -device from the first cell to a second cell based on the relative modulation score,

According to particular embodiments, a metliod for facilitating a cell change comprises establishing a first wireless connection with a first network node serving a first cell. The method also comprises receiving from the first network node at least a relative modulation score based on at least a reference modulation score and an observed modulation score, the observed modulation score based on a fist radio signal associated with the first cell. The method further comprises facilitating a cell change from the first cell to a second cell based on the received relative modulation score.

According to certain embodiments, a network node configured to facilitate a cell change comprises a processor configured to determine an observed modulation score based on a modulation quality of a first radio signal associated with the network node, the network node serving a first celt The network node further comprises an interface coupled to the processor. The interface is configured to obtain a reference modulation score. The processor is further configured to determine a relative modulation score based on the observed modulation score and the reference modulation score. The processor is also configured to facilitate a cell change of a first wireless device from the first cell to a second cell based on the relative modulation score.

According to particular embodiments, a wireless device for facilitating a cell change comprises a wireless interface that is configured to establish a first wireless connection with a first network node serving a first cell. The interface is also configured to receive from the first network node at least^' a relative modulation score based on at least a reference modulation score and an observed modulation score. The observed modulation score is based on a first radio signal associated with the first cell. The wireless device also comprises a processor that is coupled to the interface and configure to facilitate a cell change from the first cell to second cell based on the received relative modulation score.

According to some embodiments, a network node for facilitating a cell change comprises a processor and computer readable storage media, the storage media containing instructions executable by the processor, whereb the network node, serving a first cell, is operative to determine an observed modulation score based on a modulation quality of a radio signal associated with the network node. The network node is further operative to receive a reference modulation score, The network node is also operative to determine a relative modulation score based on the observed modulation score and the reference modulation score. The network node is further operative to facilitate a cell change of a first wireless device from the first cell to a second cell based on the relative modulation score.

According to particular embodiments, a wireless device for facilitating a cell change comprises a processor and computer readable storage media, the storage media containing instructions executable by the processor, whereby the wireless device is operative to establish a first wireless connection with a first network node serving a first cell. The wireless device is further operative to receive from the first network node at least a relative modulation score based on at least: a reference modulation score and an observed modulation score. The observed modulation score is based on a first radio signal associated with the first cell. The wireless device is also operative to facilitate a cell change from the first cell to a second cell based on the received relative modulation score- According to certain embodiments, a network nod for facilitating. a cell change comprises a first determination module for determining an observed modulation score based on a modulation quality of a radio signal associated with the network node, where the network node serves a first cell. The network node also comprises a receiver module for obtaining a reference modulation score. The network node further comprises a second determination module for determining a relative modulation score based on the observed modulation score and the reference modulation score. The network node additionally comprises a cell change module for facilitating a cell change of a first wireless device from the first cell to a second cell based on the relative modulation score.

According to some embodiments, a wireless device for facilitating a cell change comprises a connection module for establishing a first wireless connection with a first network node serving a first cell. Hie wireless device also comprises a receiver module for receiving from the first network node at least a relative modulation score based on at least a reference modulation score and an observed modulation score. The observed modulation score is

5 based on a first radio signal associated with the first cell. The wireless device further comprises a cell change module for facilitating a ceil change from the first cell to a second cell based on the received relative modulation score.

Advantageously one or more embodiments provide improved cell change in which a relative modulation score is used in determining it where, o and when to facilitate a ceil change. Advantageously this allows for a better user experience through improved performance in the communications between the user's wireless device and the network node associated with the selected cell. It may also allow for better load balancing between different cells of a wireless network.

5 It is to be noted that any feature of any of the above embodiments may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments ma apply to the other embodiments, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, o attached claims, and drawings.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explidtiy defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. Hie steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. BRIEF DESCRIPTION OF THE DRAWINGS

Particular embodiments are now described, by way of example, with reference to the accompanying drawings, in which:

Figure i is a diagram illustrating a wireless communication network comprising multiple cells, according to particular embodiments;

Figure 2 is a block diagram illustrating certain components of a wireless device and a network node, according to particular embodiments;

Figures 3-5 are block diagrams of three different wireless network architectures, according to particular embodiments;

Figure 6 is a flowchart illustrating a method, including various optional steps, according to particular embodiments;

Figure 7 is a signalling diagram depicting signalling and actions, including optional signalling and actions, according to particular embodiments; and

Figure 8 is a schematic block diagram illustrating the functional modules used in modulation quality based cell change, according to particular embodiments.

DETAILED DESCRIPTION

Some of the embodiments contemplated by the claims will now be described more fully hereinafter with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the claims and the claims should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will felly convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description,

Figure i illustrates an example wireless communications system 2 in which components associated with a Global System for Mobile communication (GSM) architecture are illustrated. In particular, a plurality of wireless devices (WDs) 10 (sometimes called endpoints, mobile terminals, user equipments (UEs), etc.) are located in a geographical sendee area covered by cells Ci through C6. Base stations (BSs) 4 (also sometimes called base transceiver stations (BTSs)) are positioned within the geographic area covered by the ceils Ci through C6 and act as an interface between wireless devices 10 and wireless communications system 2. Base stations 4 are connected to base station controller (BSC) 6, which in turn is connected to one or more core network nodes or network subsystems like a mobile switching center (MSG), a serving GSM support node (SGSN), etc, A network node, as used herein, may comprise one of the two BSs 4 and the BSC 6, Accordingly, Figure i comprises two network nodes, a first network node comprising a first BS 4 (BS 4 serving cells C1-C3) and BSC 6; and a second network node comprising a second BS 4 (serving cells C4-C6) and BSC 6. BSC 6 may be connected to other BSCs and/or other BSs, and the core network node(s) are usually coupled to external networks like a public switched telephone network (PSTN) 8 and/or the Internet. In some instances, one or more of the hardware components of base station 4 or BSC 6 may be used to support more than one radio access technology (e.g., High Speed Packet Access (HSP ), universal terrestrial radio access (UTRA), GSM, LTE) and/or more than one earlier of different RATs. As one of WD 10 moves within, or between ceils, the quality and strength of the wireless signal between WD 10 and the corresponding base station 4 may change. At some point it may become desirable for WD 10 to change from its current cell to a new cell. Depending on the embodiment, a ceil change may include a handover from one base station 4 to another, a radio resource control (RRC) connectio release with redirection, RRC connection re-establishment, serving cell change (e.g. primary cell (PCell) change, cell selection in RRC idle state, cell reselection in RRC idle state, primary component carrier PCC change, secondar cell (SCell) change, secondary component carrier SCC change etc.), etc.

In determining whether or not to initiate a cell change, and in identifying the target cell, particular embodiments may use one or more relative modulation scores, in addition to traditional metrics used to measure signal strength (e.g., RSRP, CPICH received signal code powe (RSCP), path loss etc) or signal quality (e.g., RSEQ, CPICH Ec No (energy per chip/noise spectral density), signal to interference plus noise ratio (SI R), signal to noise ratio (SNR), etc.). For example, in some embodiments, WD 10 may compare the signal strength and the signal quality of the current cell with their respective thresholds, and also compare the signal strength and the signal quality of a target cell with their respective thresholds. Using the comparisons and the relative modulation scores, WD 10 ma decide whether or not to facilitate a cell change from the curren cell to the target cell. Including the relative modulation scores in the cell change decision allows for a more informed, and therefore more accurate, cell change decision. For example, consider the scenario in which a particular WD 10 is within range of two different base stations 4 in which the signal strength and/or signal quality (both as measured using traditional metrics) with the current base station 4 are lower than the signal strength and/or signal quality from the target base station 4. Further consider that the current base station 4 is a dedicated LTE system while the target base station 4 was designed as a GSM system but had LTE functionality added to it. If ail that was considered was signal strength or signal quality, WD 10 may be handed over to the target base station 4 because of the better signal strength or signal quality. However, doing so may actually degrade the user experience, despite the stronger signal, because of losses in the quality of the modulation of the wireless signal caused by the use of non-dedicated equipment. By also considering relative modulation scores, WD 10 may determine it is better off remaining with its current BS 4.

Figure 2 illustrates a wireless network comprising a more detailed view of network node 200 and WD 210, in accordance with a particular embodiment. For simplicity, Figure 2 only depicts network 220, network nodes 200 and 200a, and WD 210. Network node 200 comprises processor 202, storage 203, interface 201, and antenna 201a. Similarly, WD 210 comprises processor 212, storage 213, interface 211 and antenna 211a. These components may work together in order to provide network node and/ or wireless device functionality, such as providing wireless connections in a wireless network and making cell change decisions using relative modulatio scores. In different embodiments, the wireless network may comprise any number of wired or wireless networks, network nodes, base stations, controllers, wireless devices, relay stations, and/or any other components that, may facilitate or participate in the communication of data and/or signals whether via wired or wireless connections.

Network 220 may comprise one or more ΪΡ networks, public switched telephone networks (PSTNs), packet data networks, optical networks, wide area networks (WANs), local area networks (LANs), wireless local are networks (WLANs), wired networks, wireless networks, metropolitan area networks, and other networks to enable communication between devices.

Network node 200 comprises processor 202, storage 203, interface 201, and antenna 201a. These components are depicted as single boxes located within a single larger box. In practice however, a network node may comprises multiple different physical components that make up a single illustrated component (e.g., interface 201 may comprise terminals for coupling wares for a wired connection and a radio transceiver for a wireless connection). Similarly, network node 200 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, a BTS component and a BSC component, etc.), which may each have their own respective processor, storage, and interface components. In certain scenarios in which network node 200 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single C may control multiple NodeB's. In such a scenario, each unique NodeB and BSC pair, may be a separate network node. In some embodiments, network node 200 may be configured to support multiple RATs. In such embodiments, some components may be duplicated (e.g., separate storage 203 for the different RATs) and some components may be reused (e.g., the same antenna aoiamay be shared by the RATs).

Processor 202 may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in conjunction with other network node 200 components, such as storage 203, network node 200 functionality. For example, processor 202 may execute instructions stored in storage 203. Such functionality may include providing various wireless features discussed herein to a wireless devices, such as WD 210, including any of the steps or methods disclosed herein.

In certain embodiments, processor 202 ma be used to identify a target cell to which to change a wireless device based on at least a relative modulation score. Processor 202 may also be used to determine observed modulation scores based on the modulation quality of any wireless connections established with network node 200 and/or any other radio signals or other wireless signals transmitted by network node 200. Processor 202 may use these modulation quality scores determined from the wireless connections (hereinafter, observed modulation scores) along with, for example, a reference modulation score to determine a relative modulation score. Processor 202 may then use the relative modulation score to identify a wireless device wi thin a first ceil for which a cell change may be advantageous and/or identify a second cell to which to change the wireless device. Processor 202 may, if applicable, further facilitate in handing the wireless device over to the identified cell.

Storage 203 may comprise any form of volatile or non-volatile computer readable memory including, without limitation, persistent storage, solid state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), removable media, or any other suitable local or remote memory component. Storage 203 ma store any suitable instructions, data or information, including software and encoded logic, utilized by network node 200. In some embodiments, storage 203 may store one or more reference, observed or relative modulation scores and information related t the various wireless connections and cells associated with network node 200 and/or 200a, The modulation scores may be maintained in a list, database, or other organization of data useful for identifying target cells to which to change the WDs wirelessly connected to network node 200 and/or WDs wirelessly connected to other network nodes, such as network node 200a,

Network node 200 also comprises interlace 201 which may be used in the wired or wireless communication of signalling and/or data between network node 200, network 220, and/or WD 210. For example, interface 201 may perform any formatting, coding, or translating that may be needed to allow network node 200 to send and receive data from network 220 over a wired connection. Interface 201 may also include a radio transmitter and/or receiver that may be coupled to or a part of antenna 201a. The radio may receive digital data that is to be sent out to other network nodes or WDs via a wireless connection. The radio may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters. The radio signal ma then be transmitted via antenna 20 ta to the appropriate recipient (e.g., WD 210).

In some embodiments, interface 201 ma receive modulation scores (e.g., reference modulation scores or relative modulation scores from other network nodes and/or cells) that may be used in determining a relative modulation score. The received modulation scores may be received at any of a variety of different times from and from any of a variet of different 1.3 sources, including a network operator, from nearby network nodes (e.g., network node 200a), wireless devices (e.g., WD 210), network controllers, or any other wired or wireless source connected (or connectable) to network node 200. Similarly, interface 201 may be able to transmit, modulation scores, For example, interface 201 may transmit the relative modulation score calculated by processor 202.

Antenna 201a may be any type of antenna capable of transmitting and receiving data and/or signals wirelessly. in some embodiments, antenna 201a may comprise one or more omnidirectional, sector or panel antennas operable to transmit/receive radio signals between, for example, 2 GHz and 66 Gliz. An omni-directional antenna may be used to transmit/receive radio signals in any direction, a sector antenna may be used to transmit/receive radio signals from devices within a particular area, and a panel antenna ma be a line of sight antenna used to transmit/receive radio signals in a relatively straight line.

WD 210 may be any type of wireless endpoint, mobile station, mobile phone, wireless local loo phone, smartphone, user equipment, desktop computer, PDA, cell phone, tablet, laptop, VoIP phone or handset, which is able to wirelessly send and receive data and/or signals to and from a network node, such as network node 200. WD 210 comprises processor 212, storage 213, interface 211, and antenna 211a, Like network node 200, the components of WD 210 are depicted as single boxes located within a single larger box, however in practice a wireless device may comprises multiple different physical components that make up a single illustrated component (e.g., storage 213 may comprise multiple discrete microchips, each microchip representing a portion of the total storage capacity).

Processor 212 may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in combination with other WD 210 components, such as storage 213, WD 210 functionality. Such functionality may include providing various wireless features discussed herein, including any of the steps or methods disclosed herein. For example, in some embodiments, processor 212 may facilitate a cell change based on one or more modulation scores, such as two relative modulation scores, or a relative modulation score and a threshold modulation score or value. In doing so, processor 212 may compare relative modulation scores from two or more network nodes (e.g., network nodes 200 and 200a). In some embodiments, processor 212 may be configured to determine a score or metric associated with wireless connection 230 and wireless signal 240, Processor 212 may then compare the scores or metrics and use the comparison, along with the modulation scores to determine which cell, if any, to which to change WD 210,

Storage 213 may be any form of volatile or non-volatile memory including, without limitation, persistent storage, solid state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memoiy (ROM), removable media, or any other suitable local or remote memory component. Storage 213 may store any suitable data, instructions, or information, including software and encoded logic, utilized b WD 210. In some embodiments storage 213 may maintain a list, database, or other organization of data (e.g. modulation scores) useful for identifying target ceils to which to change wireless devices, such as WT) 210.

Interface 211 may be used in the wireless communication of signalling and/or data between WD 210 and network node 200, For example, interface 211 ma perform any formatting, coding, or translating that may be needed to allow WD 2iO to send and receive data from network node 200 over a wireless connection. Interface 211 ma also include a radio transmitter and/or receiver that may be coupled to or a part of antenna 211a. The radio may receive digital data that is to be sent out to network node 20 i via a wireless connection. The radio may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters. The radio signal may then be transmitted via antenna 211a to network node 200.

Antenna 211a may be any type of antenna capable of transmitting and receiving data and/or signals wirelessly. In some embodiments, antenna ana may comprise one or more omni -directional, sector or panel antennas operable to transmit/receive radio signals between 2 GHz and 66 GHz. For simplicity, antenna 211a may be considered a part of interface 211 to the extent that a wireless signal is being used.

In some embodiments, interface 211 may establish wireless connection 230 with network node 200. Interface 211 may then receive an observed modulation score, a reference modulation score and/or a relative modulation score from network node 200 via wireless connection 230. In some embodiments, wireless device 210 may use interface 211 to then transmit the received modulation scores to another network node, such as network node 200a. Interface 211 may also be able to receive determined, reference, and/or relative modulation scores from the other network node (e.g., network node 200a). In some embodiments, interface 211 may receive the modulation scores from different sources, such as from WD 210 or network 250,

Figures 3~5 are block diagrams of three different wireless network architectures, according to particular embodiments. The illustrated architectures highligh some of the component and equipment differences in network nodes between architectures. In particular, WDs 3ioa-3iOc, 410a- 410c, and sioa-sioc, and core networks 340, 440, and 540 provide similar functionality as they relate to cell change based on modulation scores. WDs 3ioa~3ioc, 4ioa-4ioc, and 5103-5100 may comprise any type of wireless device capable of communicating, with a network nodeor other WDs using a wireless signal (e.g., via radio signals). The WDs may be any one or more of radio communication devices, device to device (D2D) WDs, machine type WDs or WDs capable of machine to machine communication (M2M), sensors equipped with wireless communication capabilities, iPADs, tablets, mobile terminals, smart phone, laptop embedded equipment (LEE), laptop mounted equipment (LME), USB dongles, customer premises equipment (CPE) etc.

Similarly, the term network node, as used herein, may refer to a single node or component, such as network nodes 520a and 520b which are evolved node B (eNode B or eNB) network nodes of an LTE architecture, or it may refer to multiple nodes or components, such as network nodes 320a and 320b which include Node B nodes and NC nodes of an HSPA architecture or network nodes 420a and 420b which include BTS nodes and BSC nodes of a GSM architecture. Although three different types of network nodes are depicted in Figures 3-5, a network node may include any kind of network node configured to provide wireless access and/ or manage the wireless access of other network nodes including, but not limited to, base stations (BSs), radio base stations ( BSs), BTSs, base station controllers, network controllers, eNode Bs, Node Bs, relay nodes, access points, radio access points, remote radio units (RRUs), remote radio heads (RRHs), multi- standard radio base stations (MSRBSs), etc.

In some scenarios, such as with an MR network node, a single network node may include components from different architectures. For example, a single network node may include eNode B components along with BTS components and BSC components. The components within the network node may even share, hardware or equipment (amplifiers, filters, antennas, etc.). The sharing of components, while providing power consumption benefits, can have a negative impact on the transmitted signal quality and/ r received signal quality. The degradation in signal quality may not he immediately present using traditional metrics used in pairing wireless devices to cells or network nodes.

Regardless of the component breakdown, depending on the embodiment, cell change may be facilitated through the use of modulation scores. The modulation quality of a wireless signal from a network node, such as network node 320a, can affect the reception quality and/or the quality of service experienced by the wireless devices, such as WD 310a. The modulation quality of a modulated signal may be evaluated using any type of performance metric suited for such a task. For example, some possible metrics include Error Vector Magnitude (EVM), frequency error, time alignment between signals from different antennas etc. EVM is a measure of the difference between the ideal symbols and the measured, symbols after equalization. The EVM result is typically defined as the square root of the ratio of the mean error vector power to the mean reference power expressed in percent^'. Depending on the embodiment, the EVM may be different for different types of transmitted physical channels (e.g., Physical Downlink Shared Channel (PDSCH) etc) and physical signals (e.g. CRS etc). In certain embodiments, in addition to modulation quality, other wireless signal related measurements may be used in making a cell change decision. The measurements may be made during a low activity state (e.g., RRC idle state operation) for cell selection or ceil reseleclion (e.g., between different networks such as evolved universal terrestrial radio access networks (E-UTRAN), or between diifereiit RATs), and minimization of drive test (MDT), The measurements may also be used during a high activity state (e.g. RE.C connected state operation) for cell change (e.g. hand-over between E~ UTRANs or hand-over between different RATs). Some of the measurements that may be made, depending on the embodiment, include Reference Signal Receive Quality (RSRQ) in LTE, Reference Signal Receive Power (RSRP) in LTE, the Common Pilot Channel (CPICH) measurements in HSPA and GSM, carrier Received Signal Strength Indicator (RSSI) in GSM/GSM EDGE Radio Access Network(GERAN)/EDGE. In some embodiments, a cell change may comprise handover, cell selection in RRC idle state, cell reselection in RRC idle state, an RRC connection release with redirection, RRC re-establishment, change of serving cell or serving carrier (e.g. PCell, PCC, SCeli SCC etc.) for a WD configured with carrier aggregation (CA) alca UE multi-carrier operation.

In certain embodiments, a target network node, such as network node 420b, may transmit a relative modulation score to one or more ofWDs 410a- 410c or network node 420a. The recipient of the relative modulation score may use the information to identify a cell to which to change one or more of WDs 4ioa-4ioc. The relative modulation score may be based on a combination of an observed modulation score and a reference modulation score. The observed modulation score ma be determined using an of a variety of metrics for determining a modulation quality of a wireless signal. The reference modulation score may be a common or known score (e.g., among other network nodes so as to provide consistent scores) that is used in combination with the observed modulation score to generate a relative modulation score. Depending on the embodiment, the reference modulation score may be based on a hypothetical or ideal network node, it may be a value provided by a carrier responsible for network node 420b, it may be provided by networ node 420a, or it may be provided by any of a variety of other means. In some embodiments, network node 420b may simply send the observed modulation score and leave it to the recipient to determine the relative modulation score.

Depending on how the received (or determined) relative modulation score of a potential target cell served by, for example, network node 420b, compares to the relative modulation score of the current cell, WD 410a may stay with network node 420a or it may change to the cell served b network node 420b. By including the relative modulation score in determining if, and where, to change cells, the resulting ceil change is more likely to result in performance improvements (e.g., more likely to meet, or improve upon, target bit rates because throughput is impacted by the transmitted and/or received modulation quality of a signal) for WD 410a, than if WD 410a was handed over based only on traditional signal strength or signal qualit metrics (e.g., RS Q, SINK, etc.).

In some embodiments, the relative modulation scores may be used in load balancing a wireless network composed of several network nodes within a geographical area. For example, wireless devices requiring higher bit rates may be directed to network nodes with better modulation quality.

In certain embodiments, the relative modulation score (Qrel) is a function of an observed modulation score (Qmod) of a radio signal of a network node (e.g., network node 520a) and a reference modulation score (Qref). Depending on the embodiment, the observed modulation score can be a pre-defined value based on, for example, the characteristics of the wireless signal (e.g. EVM of 8% for 64 QAM in the downlink (DL)) or it can be based on measured parameters of the wireless signal. Depending on the embodiment, the reference modulation score may be a pre-defined and/or pre-loaded value (e.g., by the carrier or operator responsible for the base statin) or it can be configured by, and/or received from, another network node (e.g., b another network node), by the carrier or operator responsible for the network node (e.g., by the carrier's or operator's Operations and Management function or Operations Support System function), or by any other node, entity, or function responsible for determining or providing a reference modulation score. In some embodiments, the reference modulation score may correspond to the modulation quality of a signal transmitted or received by a network node with a certain type of reference radio architecture. An example reference radio architecture may be one of a network node with a single RAT, or with a single RAT and a single carrier.

In some embodiments, the relative modulation score can be obtained separately for an uplink signal received at the network node (Qrel__ul) and for a downlink signal transmitted by the network node (Qrel.„dl). I particular embodiments, the relative modulation score ma be obtained separatel for each type of signal or as a combined score for two or more different types of wireless signals. Examples of wireless signals are physical signals and physical channels. The physical channels differ from physical signals in that the former carry higher layer information e.g. data/traffic, RRC signaling etc. Examples of DL physical signals in LTE are primary synchromzation signal (PSS), secondary synchronization signal (SSS), cell-specific reference signal (CRS), channel state information-reference signals (CSI-RS), demodulation reference signal (DMRS), multicast broadcast single frequency network reference signals (MBSFN RS), etc. Examples of DL physical channels in LTE are PDSCH, physical downlink control channel (PDCCH), extended PDCCH (E-PDCCH), physical control format indicator channel (PCFICH) physical hybrid ARQ indicator channel (PHICH) etc. Examples of uplink (UL) physical signals in LTE are DMRS, sounding reference signal (SRS), etc. Examples of UL physical channels in LTE axe physical uplink shared channel (PUSCH), physical uplink control channel (PUCCH), random access channel (RACH), etc.

In certain embodiments, the relative modulation score may be obtained separately for each carrie frequency or frequency band. In some embodiments, the relative modulation score may be obtained as a combined metric for two or more carriers or two or more frequency bands. I particular embodiments, the relative modulation score may be obtained separately for each type of modulated signals (e.g. separate values for QPSK, 16QAM, 64QAM, 256QAM etc} or as a combined metric of two or more types of modulated signals. Depending on the embodiment, the relative modulation score may be expressed in an of a variety of different types of scales (e.g., linear scale, log scale, percentage etc.). In certain embodiments, the relative modulation score may be expressed i the general form:

Qrel = f(Qmod, Qref) (i)

In which Qrel may relate to Qmod and Qref by a specific function or operation such as ratio or a difference. Another example of a generalized function expressing the relative modulation score is as follows:

Qrel - f(Qmod, Qref, a) (2)

In equation (a), a is a scaling factor to scale or adjust the Qrel value within a predetermined range or margin. For example, a may be used to scale Qmod or Qref or both Qmod and Qref values. Below are a few examples of the many ways in which the relative modulation score may be determined from the observed modulation score and the referenced modulation.

Qrel - Qraod/Qref (3)

Qrel = Qref/Qraod (4)

Qrel - Qmod-Qref [dB] (5)

Qrel - Qref-Qmod [dB] (6)

Qrel = Qmod-Qref + a [dB] (7)

Qrel = aCQmod/QrefFioo [%] C8)

Where Qmod and Qref in (5X7) are expressed, in lo scale.

In certain embodiments, the network node may store several different functions by which to determine the relative modulation score. The network node may select one of the functions based on an instruction from, for example, another network node or the operator or carrier responsible for the network node. In some embodiments, the network node may receive both an instruction on how to calculate the relative modulation score along with a reference modulation score to use in determining the relative modulation score. In some embodiments, the network node may retrieve a stored value of the reference modulation score from memory (e.g., storage 203 depicted in Figure 2).

In some embodiments, the network node may store two or more relative modulation scores (e.g., Qrel„..ul_s QreL„dl_? Qrel for DL PDSCH in LTE etc.). The stored value of the relative modulation score can he based on any one or more characteristics and expressions described herein. In certain embodiments, the network node may derive the relative modulation score using a reference modulation score received from another network node, or some other component of the network, in which the received reference modulation score is based on the measured quality of a wireless signal from the network node sending the reference modulation score.

In some embodiments, any of the relative, reference, or observed modulation scores may be shared with other network nodes or wireless devices either directly or indirectly (e.g., network node 320a may transmit relative modulation scores to network node 320b via one or more of wireless devices 310), depending on the network architecture. The modulation scores may be transmitted periodically, upon request (e.g., a target network node ma request a particular modulation scores from the current network node), on the occurrence of an event, or on the periodic, or threshold number of occurrences, of an event. In those embodiments in which a network node transmits modulation scores to a wireless device, the transmission may be done using a specific channel associated with a specific wireless device (e.g. PDSCH in LTE) and/or transmitted to multiple wireless devices, for example as system information sent via a broadcast channel (e.g., physical broadcast channel (PBCH), PDSCH in LTE etc.).

Depending on the embodiment, a cell change may be based on the relative modulation score of at least a target cell, the relative modulation score of the current cell, and radio or wireless signal measurements by the network node and/or the wireless devices. Assume for purposes of this example that wireless device 410a is operating in a first cell served by network node 420a and network node 420a is evaluating whether to change WD 410a to a second cell served by network node 420b. In this example, network node 420a may compare at least the relative modulation score obtained from network node 420b with a relative modulation score threshold. Based on the comparison, network node 420a may decide whether or not to perform the cell change. In some embodiments, the comparison may include considering a threshold difference between the relative modulation scores of the two network nodes. The threshold may he based on a required bit rate or throughput in the UL and/or the I>L for WD 4^'ioa. The threshold may also be independently chosen depending upon required throughput for WD 410a in the UL and the DL. For example, if the quality of service for WD 410a requires higher throughput (e.g. 70% or above maximum throughput) then network node 410a may use a larger threshold value compared to the case when a lower throughput (e.g. 30% or below maximum throughput) is sufficient, if a cell change is determined to be advantageous, network node 420a may send, for example, a hand-over command or message (such as hand-over command, RRC reconfiguration message etc.) to wireless device 410a.

Depending 011 the embodiment, network node 420a may compare the modulation scores from the DL, UL, or both when deciding whether to perform a cell change. In some embodiments in which both DL and UL modulation scores are used, the network node may decide to perform a cell change when at least one of the DL or UL relative modulation scores is above its respective threshold, or when both the DL and the UL relative modulation scores are above their respective threshold.

In some embodiments, in addition to the modulation scores, network node 520a may also obtain and consider one or more wireless signal measurements (e.g., SINE, LTE RSRF, LTE RSRQ, etc.) performed by one or more of WD 510 on the wireless signals transmitted by network node 520a and/or one or more neighboring network nodes (e.g., network node 520b). Network node 520a may then compare one or more wireless signal measurements with their respective thresholds. Based on this comparison, and any of the modulation score comparisons discussed herein, network node 520a may decide whether or not to perform a cell change for WD 510a. For example, network node 520a may decide to initiate a cell change if the relative modulation score is above the threshold modulation score and if the RSRP measurement is also above an RSRP threshold. In another example, the cell change may be performed if the relative modulation score is above a modulation threshold and if both the RSRP and. RSRQ measurements are above their respective thresholds. In another example, a cell change may be performed if the modulation score is above its respective threshold and the RSRP measured for the wireless signal from the target cell is above its respective threshold while the RSRP measured for the wireless signal from the serving cell is below its respective threshold.

In some embodiments, serving network node 320a may use combination of relative modulation scores, wireless signal measurements made by WDs 310, and one or more network node measurements. The network node measurements may be performed b any of network nodes 320, The network node measurements may be based on the number, type, or other characteristic of the wireless signals they have established with WDs, the load on the network interfaces, or resource or processor usage in the network node. For example, in some embodiments, one or more of transmit power or power utilization (e.g., a percentage of used power), physical channel usage (e.g., physical resource block (PRB) usage,, etc), received interference, transport network interface load, hardware load, etc. may be included as part of the cell change decision. In certain embodiments, a joint metric comprising one or more relative modulation scores, one or more RSRP measurements, one or more power utilization measurements, and one or more PRB utilization measurements may be used by network node 320a for deciding whether or not to perform a cell change. The PRB utilization measurements may provide information about the traffic load of the target network node (e.g., network node 320b) and the congestion in the corresponding ceil. This in turn may provide information about delays experienced by WD 310c being served by target network node 320b (e.g., queuing delay, FTP delay, scheduling delays, etc.) and thus may affect the throughput tor WD 310a if it were to change from network node 320a to network node 320b. Similarly, the power utilization of potential target network nodes may provide information about the transmit power available at the respective network node. As an example, a network node may facilitate a cell change if the following conditions are met: (1) the relative modulation score of the target ceil is above a threshold; (2) the RSRP measurements of the target cell are above a threshold; (3) the PRB utilization in the target cell is below a threshold; and (4} power utilization in the target cell is below a threshold,

In particular embodiments, network nodes 420a. and 420b may store modulation scores in a list. The modulation scores may be relative modulation scores received, either directly or indirectly, from neighboring cells, as well as its own relative modulation score. For example, network node 420a may store one or more relative modulation scores associated with neighboring network nodes in the form of a mapping table, which maps at least the relative modulation scores with their respective cell IDs. In some embodiments, network node 420a may create and maintain a separate list of relative modulation scores for UL and DL, for different types of signals, and/or for composite, combined or common types of signals. In certain embodiments, the list may store multiple modulation scores for a single entit or network node (e.g._> relative modulation scores reported by a network node over a particular period of time).

In some embodiments, the WDs, for example WD 510a, may obtain relative modulation and autonomously decide whether or not to perform a cell change. This may be useful, for example, where WD 510a is operating in low activity IIRC state (e.g., idle state, CELL„PCH state, URA... PCH state etc.). The cell change in a low activity state may correspond to ceil reselection or a cell selection (e.g., an initial cell selection). WD 510a may use DL and/or UL relative modulation scores and/or their respective thresholds for determining whether or not to perform a cell change. In some embodiments, WD 510a may use a pre-defined rule, an instruction from a network node (e.g., network node 520a), or an autonomous decision (e.g., based 011 a desired bit rate in the DL and/or UL) to decide whetlier to use DL and/or UL relative modulation scores.

In certain embodiments, WD 510a may obtain the relative modulation scores for multiple cells from one or more network nodes (e.g., network nodes 520a and 520b). In some embodiments, in addition to relative modulation scores, WD 510a may obtain other relevant information from the one or more network nodes such as modulation thresholds, reference modulation scores, observed modulations scores, etc. The values may he received from, the current serving network node (e.g., network node 520a), and or neighboring network nodes (e.g., network node 520b), In some embodiments, WD 510a may receive one or more lists comprising the values to be used by WD 510a in deciding whether or not to initiate a cell change. In some embodiments, WD 510a may receive the relative modulation score of the cell associated with network node 520a through the system information contained in the broadcast channel(s) transmitted by network node 520a. For example, before determining whether to facilitate a cell change, WD 510a may read the broadcast channel of network node 520b (the target network node) which may contain a relative modulation score. WD 510a may then use the relative modulation score to decide whether a cell change would be advantageous. In some embodiments, WD 510a may also use one or more wireless signal measurements (e.g. RSRP, RSRQ etc) made on the wireless signals from network nodes 5,10a and 510b.

In some embodiments, WD 510a may compare an acquired relative modulation score from network node 520b with threshold value, and based on the comparison decide whether to facilitate a cell change. In particular embodiments, WD 510a may also compare at. least, one wireless signal measurement (e.g. RSRP) with a corresponding threshold value. In certain embodiments, WD 510a may also compare an RSRP measurement with a corresponding threshold.

In some embodiments, WD 510a may assist network node 520a in obtaining relative modulation scores (or any other data used in making a cell change decision) from one or more neighboring cells. More particularly, WD 510a may receive relative modulation scores from neighboring ceils (e.g., from the cell associated with network node 520b) by reading system information contained in the broadcast channel(s) of that cell, WD 510a may then report the acquired relative modulation scores from one or more neighboring cells to network node 520a, its serving cell, as part of its radio measurement reports. This may be useful when WD 510a is operating in a high activity RRC state and relies on the network nodes (e.g., for the serving cell) to make the cell change decision. Figure 6 is a flowchart illustrating a method, including various optional steps, according to particular embodiments. The flowchart begins at step 600. At step 605, a wireless connection is established between a first network node and a wireless device via a radio signal. For purposes of this flowchart, the first network node selves a first cell The process of establishing the wireless connection may vary depending on the underlying RAT (e.g., LTE, GSM, UTRA, HSPA, etc.) used by the first network node and the wireless device. In some embodiments, the first network node may support multiple different RATs, however the wireless connection with the wireless device will be associated with a single RAT.

At step 610 , a first observed, modulation score is determined. The first observed modulation score may, for example, be based on a modulation quality of the radio signal and/or the wireless connection established between the first network node and the wireless device, hi some embodiments, the first observed modulation score may be an observed modulation score based on an average modulation quality of some, or all, of the wireless connections established with the first network node, or associated with the first cell. Depending on the embodiment, the first observed modulation score may be calculated by the first network node and/or the wireless device.

At step 615, a second observed modulation score is determined. The second modulation score may, for example, be an observed modulation score based on a modulation quality of one or more wireless connections established with a second network node. For purposes of this flowdiart, the second network node may be serving a second cell. In some embodiments, the second observed modulation score may be based on a wireless signal, a radio signal, or potential wireless connection, between the second network node and the wireless device (currently connected to the first, network node). Depending on the embodiment, the second observed modulation score ma be calculated by the second network node and/or the wireless device.

At step 620, a firs reference modulation score is obtained by the first network node. The first reference modulation score may, for example, be based on any one of, or combination of, several different factors including modulation quality in theoretical or ideal conditions (e.g., single RAT, clear line of sight, no interference, etc.), a target or goal modulation quality, the actual or observed modulation qualify of a specific network node within the network, etc. The reference modulation quality may be obtained from any of a variety of sources, including other network nodes (e.g., the second network node may transmit a reference modulation score to the first network node), from wireless devices, or it may he stored in the first network node (e.g., from a previous cell change, from installation or manufacture of the network node, At step 625, a second reference modulation score is obtained by the second network node. In some embodiments, the first and second reference modulation scores may comprise d e same score. This may allow for consistent results when the first and second relative modulation scores are compared,

At step 630, a first relative modulation score is determined. The first relative modulation score may be based on the first observed modulation score and the first reference modulation score. The first relative modulation score may be determined using, for example, any of the equations or functions listed herein (e.g., any of equations (i)-(8)). Any other equations or functions may be used which provide a way to express an observed modulation quality in terms of how it relates to a reference modulation quality.

At step 635, a second relative modulation score is determined. The second relative modulation score may be based on the second observed modulation score and second reference modulation score. The second relative modulation score may be determined in the same fashion as the first relative modulation score. This may allow for consistent results when the first and second relative modulation scores are compared.

Depending on the embodiment, steps 630 and 635 may be performed by the same network node (or network node component) or by different network nodes. For example, in some embodiments, the first network node may determine the first relative modulation score, and the second network node may determine the second relative modulation score. As another example, in certain embodiments the wireless device, or a single network node, may determine both the first and second relative modulation scores.

At step 640, the first relative modulation score is transmitted from the first network node. Depending 011 the embodiment, the first relative modulation score may be transmitted to the wireless device connected to the first network node, to the second network node, to another node in the network, or to some, or all, of the wireless devices connected to the first network node or associated with the first cell. In some embodiments, the first relative modulation score may be transmitted to the wireless device from the first network node and then the wireless device may transmit it to the second network node (and/or one or more neighbouring network nodes). For purposes of this flowchart, it will be assumed that, the second network node received the transmitted relative modulation score.

At step 645, the first and second relative modulatio scores are added to a list comprising relative modulation scores fo a plurality of network nodes associated with a plurality of cells. The list may comprise relative modulation scores associated with some, or all, of the neighbouring network nodes and some, or all, of the wireless devices within the cells associated with the neighbouring network nodes. For example, if there are three network nodes to which, or from which, a wireless device may change, and there are four wireless devices connected to the three network nodes, there may be at least 12 relative modulation scores stored in the lis in some embodiments, the list may contain multiple entries for a single network node/wireless device pair (e.g., different relative modulation scores over time, a best and a worst relative modulation score, etc.) or a single entry (e.g., the most recent, an average of prior modulation scores, etc.). In some embodiments, the list may comprise separate entries for UL and DL relative modulation scores. In certain embodiments_., the list may also comprise signal strength scores, modulation threshold values and/or signal strength threshold values.

At step 650, a first signal strength score associated with the radio signal from the first network node is determined. The signal strength score may be determined using any of a variety of metrics or techniques (e.g., SI R, RSRQ, RSRP, CPICH, RSSI, etc). Depending on the embodiment, the signal strength ma be determined at fee first network node, the wireless device, or both.

At step 655, a second signal strength score associated with a radio signal from the second network node is determined. The signal strength score may be determined using any of a variety of metrics or techniques (e.g., 5INR, RSRQ, RSRP, CPICH, RSSI, etc.). Depending on the embodiment, the signal strength may be determined at the second network node, the wireless device, or both.

At step 66o, the wireless device associated with the first cell having a wireless connection with the first network node is identified as a potential candidate for a cell change. The wireless device may be identified because of any of a number of factors depending on the embodiment. For example, the modulation score arid/or signal strength score for the wireless connection between the wireless device and the first network node may be below a threshold. As another example, the modulation score and/or signal strength score for the wireless signal between the wireless device and the second network node may be above a threshold. As yet another example, the difference between the modulation scores and/or signal strength scores between the wireless device and the first network node and the second network node may be above a threshold. In some embodiments, the wireless device ma be identified in response to a need for the network to balance the load being handled by the first and second network nodes.

At step 665, the first and second relative modulation scores are compared. At step 670, the firs!; and second signal strength scores are compared. Depending on the embodiment, the comparison may be based on any of a variety of different metrics, functions, or other methods of making comparisons. In some embodiments, the relative modulation scores and the signal strength scores may be compared together. For example, the relative modulation score and the signal strength score may be combined into a single combined score and then the combined scores may compared. As another example, the relative modulation scores may be compared and the signa strength scores may be compared, and then the differences from the two comparisons may he combined into a single comparison score. In other embodiments, the modulation scores and the signal strength scores may be compared separately or independently. In some embodiments, the scores may be compared in connection with, the respective threshold values.

At step 675, the second cell, served by the second network node, is identified as a cell to which to change the wireless device. The second cell may be identified based on at least the first and second relative modulation scores. In some embodiments, such as the one described in this flowchart, the second cell may further be identified based on the signal strength scores. The second cell may be identified (or not identified) based on any of a variety of different techniques. Some of the many possible techniques include:

(1) the relative modulation score and/ or the signal strength score associated with the second network node is above a respective threshold;

(2) the difference between the relative modulation score and/or the signal strength score associated with the first network node and the second network node are above a respective threshold;

(3) the difference between the relative modulation score and/or the signal strength score associated with the first network node and the second network node is greater than the difference between the relative modulation score and/ or the signal strength score associated with the first network node and any other candidate network node; and

{4) the difference between the relative modulation scores combined with the difference between the signal strength scores associated with the first network node and the second network node is above a particular threshold.

At step 680, the first and second network nodes and the wireless device facilitate in changing the wireless device from the first cell, served by the first network node, to the second cell served by the second network node. This may comprise transmitting a hand-over message. How the cell change is implemented may vary depending on, among other things, the RAT being used. At step 685, the wireless device is changed from the first cell to the second cell, and at step 690 the flowchart ends.

The steps described above are merely illustrative of certain embodiments. It is not required that all embodiments incorporate all the steps above nor that the steps be performed in the exact order depicted in Figure 6. For example, in some embodiments, the signal strength scores ma not be considered in making a cell change decision. Furthermore, some embodiments may include steps not illustrated in Figure 6. For example, in some embodiments, a third network node may make the cell change decision, and the wireless device may transmit the signal strength scores to the third network node.

The steps illustrated in Figure 6, and described above, may be performed through a computer program product that may, for example, he executed, by the components and equipment illustrated in Figure a. For example, storage 203 may comprise computer readable means on which a computer program can be stored. The computer program may include instructions which cause processor 202 (and any operative^ coupled entities and devices, such as interface 201 and storage 203) to execute methods according to embodiments described herein. The computer program and/or computer program product may thus provide means for performing any steps herein disclosed.

Figure 7 is a signalling diagram depicting signalling and actions, including optional signalling and actions, according to particular embodiments. The depicted embodiment includes network node 700, having wireless device 703 connected thereto, and network node 709 having wireless device 706 connected thereto. The signalling diagram includes various actions and signals, Action 712 comprises network node 700 computing an observed modulation score. The observed modulation score may comprise the modulation quality of a wireless connection with at least wireless device 703, In some embodiments, network node 700 may also compute the observed modulation score for a wireless signal with wireless device 706.

Action 715 comprises network node 700 obtaining a reference modulation score. The reference modulation score may be obtained in a variety of different ways. For example, the reference modulation score may have been stored on internal memory within network node 700. As another example, the reference modulation score may have been received from another network node (e.g., in response to a request from network node 700), Action 718 comprises network node 700 determining a relative modulation score. The relative modulation score may foe determined using a combination of the observed modulation score, the reference modulation score and/or one or more modifiers (e.g., a constant).

Signals 721 and 724 comprise messages sent by network node 700 containing one or more of the observed, reference, and relative modulation scores. Although the signalling diagram depicts network node 700 transmitting both signals. In certain embodiments, network node 700 ma onl transmit one of the signals 721 or 724or it may transmit a single broadcast signal that is received by both network node 709 and wireless device 703.

In addition to wireless device 703 receiving one or more modulation scores from network node 700, action 730 comprises wireless device 703 receiving one or more of observed, reference, and relative modulation scores from neighbouring network nodes (e.g., network node 709). Action 727 comprises wireless device 703 using the received modulation scores to select a cell to which to change. In some embodiments, wireless device 703 may use other information, such as signal strengtli or signal quality, in selecting a new cell to which to change.

Similar to action 730a, action 730b comprises wireless device 706 receiving one or more of observed,_, reference, and relative modulation scores from neighbouring network nodes (e.g., network node 700). However, in this instance, rather than use the modulation scores to select a cell, wireless device 706 uses signal 733 to send the modulation scores to network node 709 so that network node 709 can make the cell change decision. If network node 709 determines that wireless device 706 should change cells, then wireless device 706 may receive signal 751 comprising a hand-over instruction specifying the selected target cell to which wireless device 706 is to change.

Action 736 comprises network node 709 creating a list of modulation scores (e.g., one or more of relative, reference, and observed modulation scores). The list, is created regardless of whether network node 709 receives modulation scores from wireless device 706, via signal 733, or from network node 700, via signal 724, The list may be constructed in any of a variety of ways and may include any of the information disclosed herein.

Action 739 comprises network node 709 computing one or more observed modulation scores. The observed modulation scores may be computed using any of a variety of techniques, including any of the techniques disclosed herein. In some embodiments, the observed modulation scores may then be added to the list of modulation scores created in action 736,

Action 742 comprises network node 709 obtaining a reference modulation score. The reference modulation score may be obtained in a variety of different ways. For example, the reference modulation score may have been stored on internal memory within network node 709. As another example, the reference modulation score may have been received from another network node (e,g«, in response to a request from network node 709).

Action 45 comprises network node 709 determining a relative modulation score. The relative modulation score may be determined using a combination of the observed modulation score, the reference modulation score and/or one or more modifiers (e.g., a constant). In some embodiments, the relative modulation score may be added to the list

Action 748 comprises network node 709 selecting a cell to which to change wireless device 706. The target cell ma be selected for any of a variety of reasons, including any of the reasons discussed herein. For example, based on the relative modulation scores, network node 709 may determine that wireless device 706 will likely receive a better experience (e.g., better bit rate or data throughput) if it was in the cell served by network node 700, rather than the cell served by network node 709.

Signal 751 comprises the hand-over instructions for wireless device 706. The hand-over instructions may include the selected ceil to which wireless device 706 is to hand over. In other embodiments, a different instruction may be sent indicating wireless device 706 is to change cells.

The depicted signalling diagram is just an example of the possible actions and signals that may be involved in basing cell change decisions, at least in part, on relative modulation scores. Other embodiment or other scenarios may include more, fewer, or different signals and actions. For example, wireless device 703 may, after receiving signal 721, forward the information on to network node 709.

Figure 8 is a schematic block diagram illustrating the functional modules used in modulation quality based cell change, according to particular embodiments. In particular, there is depicted the functional modules of a particular wireless device 800 and network node 810. Other embodiments may include more, fewer, or different functional modules. Moreover, a single depicted module may represent multiple similar modules. For example, determination module 811, may comprise two determination modules, each determination module responsible for a different function or task. The modules may comprise software, computer programs, subroutines, libraries, source code, or any other form of executable instructions that are run by, fo example, a processor. In this Figure 8, wireless device 800 comprises connection module 801, receiver module 802, cell change module 803, transmitter module 804, comparator module 805 and determination module 806; and network node 810 comprises determination module 811, receiver module 812, cell change module 813, transmitter module 814, list module 815, and identification module 816.

Connection module 801 is configured to establish wireless connections with network nodes. For example, connection module 8oi may establish a connection with network node 810, wherein network node 810 is serving a first cell.

Receiver moduie 802 is configured to receive one or more of relative modulation scores, reference modulation scores, aad observed modulation scores. The modulation scores may be received from network node 810, or any other neighbouring network node.

Cell change module 803 is configured to facilitate in changing wireless device 800 from the first cell to a second cell. The cell change from the first cell to the second cell is based, at least in part, on the relative modulation scores associated with the first and second cells. Depending on the embodiment, the decision to change cells may be made by wireless device

800, network node 8io, or some other network node. Transmitter module 804 is configured to transmit one or more of relative modulation scores, reference modulation scores, and observed modulation scores to the second network node associated with the second cell. The modulation scores may be all, or some, of the modulation scores received by wireless device 800,

Comparator module 805 is configured to compare relative modulation scores received from at least network node 810 and one or more additional relative modulation scores. Cell change module 803 may make the cell change decision based on the comparison of the relative modulation scores. In some embodiments, comparator module 805 may also be configured to compare signal strength scores, for example as determined by determination module 806. In such an embodiment, the cell change decision may further include the comparison of the signal strength scores in addition to the comparison of the relative modulation scores.

Determination module 806 is configured to determine one or more signal strength scores associated with the wireless connection with network node 810 and/or one or more other radio signals detected by wireless device 800.

Moving the discussion now to network node 810, determination module 811 is configured to determine at least an observed modulation score based on a modulation quality of the■wireless connection between network node 810 and wireless device 800. Determination module 8.1.1 may also he configured to determine a relative modulation score based on the aforementioned observed modulation score and a reference modulation score received by receiver module 812.

Receiver module 812 is configured to obtain a reference modulation score. In some embodiments, the reference modulation score ma be received upon request (e.g., network node 810 may request a reference modulation score), in certain embodiments, the reference modulation score may be received from another network node or from some other node or component within the network. In particular embodiments, the reference modulation score may be provided by the manufacturer, operator, or carrier associated with network node 810 The reference modulation score may be received during the manufacture or assemble of network node Sio, during initial configuration or deployment of network node 810, during maintenance of the network node 810, upon request or other triggering event, or any other means which may he desired (e.g., a carrier may offer its customers a new data plan, and may then adjust the reference modulation score to account for the changes in the new data plan).

Cell change module 813 is configured to facilitate a cell change for wireless device 800 changing wireless device 800 from the first cell served by network node 810 to a second cell. The cell change may be based, at least in part, on the relative modulation score determined by determination module 811.

Transmitter module 814 is configured to transmit at least the relative modulation score to wireless device 800 or a second network node.

list module 815 is configured to add, and store, the relative modulation score to a list of modulation scores. The list of modulation scores may comprise one or more relative modulation scores, one or more reference modulation scores, and/or one or more observed modulation scores. The various modulation scores may come from a plurality of network nodes associated with a plurality of ceils. In some embodiments, list module 815 may also be configured to store one or more signal strength scores and/or signal quality scores in addition to the modulation scores.

Identification module 8.16 is configured to identify wireless devices, such as wireless device 800 within the first cell, for which a cell change would be advantageous. Identification module 816 may also be configured to identify a targe cell to which to change wireless device 800. Both the identification of wireless device 800 and the second cell may be done based on at least the relative modulation scores. In some embodiments, the identification may be based on signal strength, and/or signal quality, as well as relative modulation scores,

Figure 8 schematically illustrates, in terms of a number of functional modules, the components of wireless device 800 and network node 810, according to particular embodiments. In general terms, each functional module depicted therein may be implemented in hardware and/or in software. Preferably, one or more or all functional modules may be implemented by processors 212 and/or 202, possibly in cooperation with storage 213 and/or 203. Processors 212 and/or 202 and storage 213 and/ or 203 may thus be arranged to allow processors 212 and/or 202 to fetch instructions from storage 213 and/or 203 and execute the fetched instructions to allow the respective functional module to perform any steps or functions disclosed herein. The illustrated modules may further be configured to perform other functions or steps not explicitly described with respect to the respective module, including providing any features or functions disciosed with respect to any of the other figures. For example, the transmitter modules (804 and 814} may be configured to transmit data not related to signal strength or modulation quality (e.g., the contents of a web page).

In view of the above disclosure, at least some of the herein disclosed embodiments may be summarized as providing improved cell change by considering relative modulation scores when making cell change decisions. Certain aspects of the inventive concept have mainl been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, embodiments other than the ones disclosed above are equally possible and within the scope of the inventive concept, as defined by the appended claims. For example, although Figures 3-5 depicted the architectures for three particular RATs, the inventive concept equall applies to other RATs, and their corresponding architectures. Similarly, while a number of different combinations of modulation scores, wireless signal measurements, and network node measurements have been discussed, all possible combinations have not been disclosed. One skilled in the art would appreciate that other combinations exist and are within the scope of the inventive concept. Moreover, as is understood by the skilled person, the herein disclosed embodiments are as such applicable also to other standards and communication systems and any feature from a particular figure disclosed in connection with other features may be applicable to any other figure and or combined with different features.

Claims

CXAIMS

1. A method for facilitating a cell change comprising:

determining a first observed modulation score based on a first modulation quality of a first radio signal from a first network node, the first network node serving a first cell;

determining a second observed modulation score based on a second modulation quality of a second radio signal from a second network node, the second network node serving a second cell;

obtaining a first reference modulation score at the first network node; obtaining a second reference modulation score at the second network node;

determining a first relative modulation score based on the first observed modulation score and the first reference modulation score;

determining a second relative modulation score base on the second observed modulation score and the second reference modulation score;

transmitting at least the first relative modulation score from fee first network node to a wireless device associated with the first cell or the second network node;

adding the first and second relative modulation scores to a list comprising relative modulation scores for a plurality of network nodes serving a plurality of cells;

identifying the second cell as a target cell to which to change the wireless device based on at least the first and second relative modulation scores in the list of relative modulation scores; and

facilitating a cell change of the wireless device from the first cell to the second cell based on the relative modulation scores.

2. A method for facilitating a cell change comprising:

determining, at a first network node serving a first cell, an observed modulation score based on a modulation quality of a first radio signal^*

obtaining, at the first network node, a reference modulation score; determining, at the first network node, a relative modulation score based on the observed modulation score and the reference modulation score; and

facilitating, at the first network node, a cell change of a first wireless device from the first cell to a second cell based on the relative modulation score.

3. The method of Claim 2, further comprising transmitting at least the relative modulation score to the first wireless device or a second network node.

4. The method of Claim 2, further comprising storing, at the first: network node, the relative modulation score in a list comprising relative modulation scores from a plurality of network nodes serving a plurality of cells.

5. The method of Claim 4, furtlier comprising:

identifying a first wireless device associated with the first cell and having a wireless connection with the first network node; and

identifying the second cell as a target cell to which to change the first wireless device based on at least the relative modulation scores in the list of relative modulation scores.

6. The method of Claim 2, wherein the reference modulation score is based on a modulation quality of a radio signal of a reference network node.

7. The method of Claim 2, wherein the first network node comprises two physically separate components and the second network node comprises two physical separate components.

8. The method of Claim 2, farther comprising:

obtaining a modulation threshold value;

comparing the relative modulation score to the modulation threshold value; and

facilitating the cell change of the first wireless device from the first cell to the second cell further based on the comparison of the relative modulation score and the modulation threshold value.

9. A method for facilitating a cell change comprising:

establishing a first wireless connection with a first network node_; the first network node serving a first cell;

receiving from the first network node at least a relative modulation score based on at least a reference modulation score and an observed modulation score, wherein the observed modulation score is based on a first radio signal associated with the first cell; and

facilitating a cell change from the first cell to a second ceil based on the received relative modulation score.

10. The method of Claim 9, further comprising transmitting the relative modulation score to a second network node serving the second cell,

11. The method of Claim 9, further comprising:

receiving one or more additional relative modulation scores, the additional relative modulation scores comprising at least a relative modulation score associated with a second network node serving the second cell; and

comparing the relative modulation score received from the first network node with the one or more additional relative moduiation scores.

12. The method of Claim 9, farther comprising:

determining a first signal characteristic based on at least one of:

a first signal strength score associated with the first radio signal; and

a first signal quality score associated with the first radio signal; determining a second signal characteristic Tbased on at least one of:

a second signal strength score associated with a second radio signal associated with the second cell; and

a second signal quality score associated with the second radio signal;

comparing the first and second signal characteristics based, on at least one of:

the first signal strength score to the second signal strength score; the first signal quality score to the second signal quality score; the first signal strength score to a first signal strength threshold; the second signal strength score to a second signal strength threshold;

the first signal qualit score to a first signal quality threshold; the second signal quality score to a second signal quality threshold; and

wherein facilitating the cell change is farther based on the at least one comparison of the first and second signal characteristics.

13. A network node configured to facilitate cell change comprising: a processor configured to determine an observed modulation score based on a modulation quality of a first radio signal associated with a network node that is ser ing a first cell; and

an interface coupled to the processor and configured to obtain a reference modulation score;

wherein the processor is further configured to:

determine a relative modulation score based 011 the observed modulation score and the reference modulation score; and

facilitate a cell change of a first wireless device f om the first cell to a second cell based on the relative modulation score.

14. The network node of Claim 13. wherein the interface is further configured to transmit the relative modulation score to the first wireless device or a second network node.

15. The network node of Claim 13, further comprising a computer readable medium coupled to the processor and configured to store the relative modulation score in a list comprising relative modulation scores from a plurality of network nodes serving a plurality of cells.

16. The network node of Claim 15, wherein the processor is farther configured to:

identify the first wireless device, die first wireless device associated with the first cell and having a wireless connection with the first network node; and

identify the second cell as a target cell to which to change the first wireless device based on the relative modulation scores in the list of relative modulation scores.

17. The network node of Claim 13, wherein the reference modulation score is based 011 a modulation quality of a radio signal of a reference network node.

18. The network node of Claim 13, wherein:

the network node comprises two physically separate locations; and the interface is further configured to facilitate communication between the two physically separate locations of the network node.

19. The method of Claim 13, wherein;

the interface is further configured to obtain a modulation threshold value; nd.

the processor is further configured to:

compare the relative modulation score to the modulation threshold value; and

facilitate the cell change of the first wireless device from the first cell to the second cell further based on the comparison of the relative modulation score and the modulation threshold value.

20. A wireless device for facilitating a cell change comprising;

a wireless interface configured to:

establish a first wireless connection with a first network node serving a first cell; and.

receive from the first network node at least a relative modulation score based on at least a reference modulation score and an observed modulation score, wherein the obseived modulation score is based on a first radio signal associated with the first cell; and

a processor coupled to the interface and configured to facilitate a cell change from the first cell to a second cell based on the received relative modulation score.

21. The wireless device of Claim 20, wherein the wireless interface is further configured to transmit the relative .modulation score to a second network node serving the second cell.

22. The wireless device of Claim 20, wherein:

the wireless interface is further configured to receive one or more additional relative modulation scores, the additional relative modulation scores comprising at least a relative modulation score associated with a second network node serving the second cell; and

the processor is further configured to compare the relative modulatio score received from the first network node with the one or more additional relative modulation scores.

23, The wireless device of Claim 20, wherein the processor is farther configured to:

determine a first signal characteristic based on at least one of:

a first signal strength score associated with the first radio signal; and

a first signal quality score associated with the first radio signal; determine a second signal characteristic based on at least one of;

a second signal quality score associated with the second radio signal;

compare the first and second signal characteristics based on at least one of

the first signal quality score to a first signal quality threshold; the second signal quality score to a second signal quality threshold; and

wherein the cell change is further based on the at least one comparison of the first and second signal characteristics.

24. A network node for facilitating a cell change comprising a processor and computer readable storage media, the storage media containing instructions executable by the processor, whereby the network node is operative to:

determine an observed modulation score based on a modulation quality of a first radio signal established with. ^'the network node, the network node serving a first cell;

obtain a reference modulation score;

determine a relative modulation score based on the observed modulation score and the reference modulation score; and

facilitate a cell change of a first wireless device from the first cell to a second cell based on the relative modulation score.

25. The network node of Claim 24, wherein the network node is further operative to transmit at least the relative modulation score to the first wireless device or a second network node,

26. The network node of Claim 2.4, wherein the network node is further operative to store the relative modulation score in a list comprising relative modulation scores from a plurality of network nodes serving a plurality of cells.

27. The network node of Claim 26, wherein the network node is further operative to:

identify die first wireless device, the first wireless device associated with the first cell and. having a wireless connection with the first network node; and

identity the second cell as a target cell to which to change the first wireless device based on at least the relative modulation scores in the list of relative modulation scores.

28. The network node of Claim 24, wherein the reference modulation score is based on a modulation quality of a radio signal of a reference network node,

29. The network node of Claim 24, wherein the network node is located in two physically separate locations, each comprising its own respective processor and computer readable storage media, each storage media containing instructions executable b the respective processor.

30. The network node of Claim 24, wherein the network node is further operative to:

obtain a modulation threshold value;

compare the relative modulation score to the modulation threshold value; and

facilitate the cell change of the first wireless device from the first cell to the secood cell further based on the comparison of the relative modulation score and the modulation threshold value.

3.1. A wireless device for facilitating a cell change comprising a processor and computer readable storage media, the storage media containing instructions executable by the processor, whereby the wireless device is operative to:

establish a first wireless connection with a first network node serving a first cell;

receive from the first network node at least a relative modulation score based on at least a reference modulation score and an observed modulation score, wherein the observed modulation score is based on a first radio signal associated with the firs ceil; and

facilitate a cell change from the first cell to a second cell based on the received relative modulation score.

32, The wireless device of Claim 31, wherein the wireless device is further operative to transmit the relative modulation score to a second network node serving the second cell

33. The wireless device of Claim 31, wherein the wireless device is further operative to*

receiv one or more additional relative modulation scores, the additional relative modulation scores comprising at least: a relative modulation score associated with a second network node serving the second cell and

compare the relative modulation score received from the first network node with the one or more additional relative modulation scores.

34, The wireless device of Claim 31, wherein the wireless device is further operative to:

determine a first signal characteristic based on at least one of:

a first signal strength score associated with the first radio signal; and

a second signal quality score associated with the second radio signal;

compare the first and second signal characteristics based on at least one of:

the first signal strength score to the second signal strength score; the first signal quality score to the second signal quality score; the first sig al strength score to a first signal strength threshold; the second signal strength score to a second signal strength threshold;

35. A network node for facilitating a cell change, the network node comprising:

a first determination module for determining an observed modulation score based o a modulation quality of a first radio signal associated with the network node, the network node serving a first cell;

a receiver module for obtaining a reference modulation score;

a second determination module for determining a relative modulation score based on the observed modulation score and the reference modulation score; and

a cell change module for facilitating a cell change of a first wireless device from the first cell to a second cell based on the relative modulation score,

36, The network node of Claim 35, further comprising a transmitter module for transmitting at least the relative modulation score to the first wireless device or a second network node,

37. The network node of Claim 35, further comprising a list module for storing the relative modulation score in a list comprising relative modulation scores from a plurality of network nodes serving a plurality of cells.

38, The network node of Claim 37, further comprising:

a first identification module for identifying the first wireless device, the first wireless device associated with the first ceil and having a wireless connection with the first network node; and

a second identification module for identifying the second cell as a target cell to which to change the first wireless device based on at least the relati ve modulation scores in the list of relative modulation scores.

39, The network node of Claim 35, wherein the reference modulation score is based on a modulation quality of a radio signal of a reference network node,

40, The network node of Claim 35, wherein the network node is located in two physically separate locations, each comprising its own respective set of modules.

41, The network node of Claim 35 further comprising;

a second receiver module for obtaining a modulation threshold value; a third determination module for comparing the relative modulation score to the modulation threshold value; and

a second cell change module for facilitating the cell change of the first wireless device fro the first cell to the second cell further based on the comparison of the relative modulation score and the modulation thresboM value.

42. A wireless device for facilitating a cell change, the wireless device comprising:

a connection module for establishing a first wireless connection with a first network node serving a first cell;

a. receiver module for obtaining from the first network node at least relative modulation score based on at least a reference modulation score and an observed modulation score, wherein the observed modulation score is based on a first radio signal associated with the first cell; and

a cell change module for facilitating a cell change from the first cell to a second ceil based on the received relative modulation score.

43. The wireless device of Claim 42, further comprising a transmitter module for transmitting the relative modulation score to a second network node serving the second cell,

44. The wireless device of Claim 42, further comprising:

a second receiver module for receiving one or more additional relative modulation scores, the additional relative modulation scores comprising at least a relative modulation score associated with a second network node serving the second ceil; and

a comparator module for comparing the relative modulation score received from the first network node with the one or more additional relative modulation scores,

45. The wireless device of Claim 42, further comprising:

a first determination module for determining a first signal characteristic based on at least one of:

a first signal strength score associated with the first radio signal; and

a first signal quality score associated with the first radio signal; a second determination module for determining a second signal characteristic based on at least one of;

a second signal quality score associated with the second radio signal;

a comparator module fo comparing the first and second signal characteristics based on at least one of:

the first signal strength score to the second signal strength score; the first signal qualit score to the second signal quality score; the first signal strength score to a first signal strength threshold; the second signal strength score to a second signal strength threshold;

the first signal quality score to a first signal quality threshold; the second signal qualit score to a second signal quality threshold; and

wherein the cell change is further based on the at least one comparison of the first and second signal characteristics,