WO2007110746A2

WO2007110746A2 - Apparatus, method and computer program product providing 3.9g mobile-assisted cell change

Info

Publication number: WO2007110746A2
Application number: PCT/IB2007/000768
Authority: WO
Inventors: Lars Dalsgaard; Jarkko T. Koskela
Original assignee: Nokia Corporation; Nokia, Inc.
Priority date: 2006-03-27
Filing date: 2007-03-26
Publication date: 2007-10-04
Also published as: EP2008491A2; US8000707B2; EP2008491A4; WO2007110746A3; US20070224992A1

Abstract

Disclosed herein are apparatus, method and computer program product providing 3.9G mobile-assisted cell change. During an active state of user equipment, it is determined whether at least one trigger condition exists. If at least one trigger condition is determined to be present, the user equipment performs an autonomous cell change. Alternatively, if at least one trigger condition is determined not to be present, the user equipment performs a cell change under network control (non-autonomous).

Description

APPARATUS, METHOD AND COMPUTER PROGRAM PRODUCT PROVIDING 3.9G MOBILE-ASSISTED CELL CHANGE

TECHNICAL FIELD: The exemplary and non-limiting embodiments of this invention relate generally to wireless communications systems, methods, computer program products and devices and,

more specifically, relate to hand over or hand off (HO) procedures executed when a user equipment (UE) changes cells.

BACKGROUND:

The following abbreviations are herewith defined:

3GPP Third Generation Partnership Project

AT Allocation Table

DL Downlink (Node B to UE)

DRX Discontinuous Reception

GSM Global System for Mobile Communication

IMS Instant Messaging Service

LTE Long Term Evolution

Node B Base Station

RNC Radio Network Control

RRC Radio Resource Control

SIB System Information Block

UE User Equipment

UL UpHnIc (UE to Node B) UMTS Universal Mobile Telecommunications System

UTRAN UMTS Terrestrial Radio Access Network E-UTRAN Evolved UTRAN

In 3.9G (E-UTRAN) it has been agreed that the mobility principle for a UE in the

Active state will be network controlled handover. This means that when the UE is in the Active state the UE is expected to provide the network with measurement reports for

providing the network with information to assist it in making a HO decision. UE performed measurements, which form the basis of the measurement reports send by the UE to the network, are normally performed when the UE is active for transmission and/or reception of data. A current general view in 3.9G is that data transmission and/or reception is linked to the DRX scheme of the UE. The DRX scheme basically pertains to

when the UE wakes up from an inactive period (sleep) in order to receive information as

to whether any UL or DL resources have been assigned for the UE. In 3.9G the resource assignment is proposed to be done through ATs.

It has been realized that combining Active state mobility through network

controlled HO may not be fully compatible with another 3.9G requirement concerning optimized power saving possibilities for those UEs in the Active state. Enhanced power

saving possibilities may have the side effect of introducing long delays in the measurements performed by the UE, and thus in the measurements reports sent to the

network from the UE. This delay from the UE side in providing the measurement reports

to the network can be expected to introduce an overall delay in the HO decision made by

the network, thereby delaying the overall HO procedure and adversely affecting the

mobility of the UE. In a worst case the delay in making a HO decision in the network

may cause increased inter-cell interference and possibly a loss of service. The GSM system uses HO when in the dedicated mode (circuit switched mode), otherwise cell reselection is performed as either network assisted or stand-alone. The

UTRAN system supports both HO and cell reselection as well.

In a 3GPP 3.9G study item the problem stated above been has been

acknowledged, and various proposals have been made.

A first proposal would keep the UE in the Active state only for very short periods

of time (10 - 20 Seconds) and let the transition to the idle state be done without signaling between the network and the UE (e.g. timer based). However, a problem with this

proposal is the handling of error cases when the UE and the network are unsynchronized concerning the UE state (Active or Idle), which has the potential to introduce

unacceptable behavior.

Another proposal also would keep the UE in the Active state only for very short

periods of time (10 - 20 Seconds), but would then let the transition be accomplished using, e.g., RRC signaling between network and UE. A potential problem with this

proposal is that a UE which performs frequent IP transfers (e.g,. e-mail, TCP/IP keep

alive, IMS keep alive) may cause excessive signaling to be performed due to the frequent RRC state transfers.

Another proposal introduces pull-mode/re-active HO in the Active state (which

resembles cell reselection). Prior to this invention, no completely satisfactory solution has been proposed to

the problems discussed above.

SUMMARY OF THE INVENTION

The foregoing and other problems are overcome, and other advantages are

realized, in accordance with the following embodiments of the invention.

A first embodiment of the invention is a method. In the method it is detected that user equipment is in an active state. Then, it is determined whether at least one trigger

condition is satisfied. If the at least one trigger condition is satisfied, the user equipment performs autonomous cell change to a neighboring cell. If the at least one trigger

condition is not satisfied, the user equipment performs cell reselection under network

control.

A second embodiment of the invention is user equipment operative in a wireless communications network comprising a transceiver configured to bi-directionally

communicate; at least one memory configured to store a computer program configured to control the user equipment when executed; and digital processing apparatus coupled to the transceiver and to the memory. When the computer program is executed by the

digital processing apparatus the user equipment is configured to receive an indication

whether at least one trigger condition allowing autonomous cell change to a neighbor cell is satisfied; to perform autonomous cell autonomous cell change to the neighbor cell if

the at least one trigger condition is satisfied; and to perform cell change under network control if the at least one trigger condition is not satisfied.

A. third embodiment of the invention is user equipment operative in a wireless communication network. The user equipment comprises transceiver means for

bidirectionally communicating with the wireless communications network; memory means for storing program means, the program means for controlling the user equipment

when executed; and digital processing means coupled to the transceiver means and the

memory means, the digital processing means for executing the program means. When the program means is executed by the digital processing means the user equipment is

configured to receive a message from the wireless communication network allowing the user equipment to perform an autonomous cell change from a serving cell to a neighbor cell; and to effect the autonomous cell change from the serving cell to the neighbor cell.

A fourth embodiment of the invention is a computer program product comprising a computer readable memory medium, the computer readable memory medium storing a

computer program, the computer program configured to be executed by digital processing

apparatus of a device operative in a wireless communications network. When executed, the computer program is configured to determine whether at least one trigger condition is

satisfied for user equipment operative in the wireless communications network, wherein

when the trigger condition is satisfied the user equipment is permitted to perform an

autonomous cell change from a serving cell to a neighbor cell; and to allow the user

equipment to perform the autonomous cell change when the trigger condition is satisfied.

A fifth embodiment of the invention is a network access node operative in a wireless communications network, the network access node comprising: a transceiver configured to bidirectionally communicate with user equipment accessible in the wireless communications network; at least one memory configured to store a computer program

configured to control the user equipment when executed; and digital processing apparatus

coupled to the transceiver and to the memory, the digital processing apparatus configured

to execute the computer program. When the computer program is executed by the digital processing apparatus the network access node is configured to determine whether at least one trigger condition is satisfied for a user equipment operative in the wireless communications network; and to communicate to the user equipment that it is authorized

to perform autonomous cell change if the at least one trigger condition is satisfied.

A sixth embodiment of the invention is an integrated circuit for use in a device

operative in a wireless communications network, the integrated circuit configured to

detect whether a particular user equipment is in an active mode; to determine whether at

least one trigger condition is satisfied; if the at least one trigger condition is satisfied, to cause the user equipment to perform a cell change to a neighbor cell; and if the at least

one trigger condition is not satisfied, to cause the use equipment to perform cell change to

a neighbor cell under network control.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects of these teachings are made more evident in the

following Detailed Description of the Invention, when read in conjunction with the

attached Drawing Figures, wherein: FIG. 1 is a block diagram depicting a wireless communications network in which

exemplary embodiments of the invention may be practiced;

FIG.2 is a chart depicting a situation where the DRX time period is greater than a

pre-determined time;

FIG. 3 is a flow chart depicting the decision process for allowing autonomous cell

change when the DRX time is greater than a predetermined period, all in accordance with the invention;

FIG. 4 is a block diagram depicting an establishment request being issued by a UE

to the Network;

FIG. 5 is a flowchart depicting whether to allow autonomous cell change based on anestablishment request, all in accordance with the invention;

FIG. 6 is another chart depicting trigger situations for allowing autonomous cell

selection, all in accordance with the invention;

FIG. 7 is a flowchart depicting a decision whether to allow autonomous cell

change base on a difference between characteristics of serving cell connection and a

potential connection with a neighbor cell, all in accordance with the invention;

FIG. 8 is flowchart depicting a decision whether to allow autonomous cell change based on the delay in receiving an HO command, all in accordance with the invention;

FIG. 9 is a diagram depicting uplink synchronization status for UE;

FIG. 10 is a flow chart depicting a decision whether to allow autonomous cell

change based on uplink synchronization status, all in accordance with the invention; and

FIG. 11 is a flow chart depicting in general terms methods in accordance with the

invention.

DETAILED DESCRIPTION OF THE INVENTION

By way of introduction, the exemplary embodiments of this invention relate to mobility behavior and definitions in 3.9G (also known as LTE or as E-UTRAN). Of

particular interest herein is 3.9G UE Active state mobility, as well as Active state

mobility rules and triggers for Active state mobility. Although particularly well suited for

use in and with 3.9G network Active state mobility environments, the exemplary embodiments of this invention may also find utility in other types of mobile

communication systems.

The exemplary embodiments of this invention pertain at least in part to the above

mentioned pull-mode/re-active HO in the Active state proposal, and provide an intelligent

method of controlling UE reselection using this type of active state mobility handling.

Reference is made first to Figure 1 for illustrating a simplified block diagram of various electronic devices that are suitable for use in practicing the exemplary

embodiments of this invention. In Figure 1 a wireless network 100 is adapted for communication with a UE 110 via a Node B (base station) 120. The network 100 may

include a RNC 140, or other radio controller function, which may be referred to as a

serving RNC (SRNC). The UE 110 includes a data processor (DP) 112, a memory (MEM) 114 that stores a program (PROG) 116, and a suitable radio frequency (RF)

transceiver 118 for bidirectional wireless communications with the Node B 120, which also includes a DP 122, a MEM 124 that stores a PROG 126, and a suitable RF

transceiver 128. TheNodeB 120 is coupled via a data path 130 (Iub) to the RNC 140 that

also includes a DP 142 and a MEM 144 storing an associated PROG 146. The RNC 140

may be coupled to another RNC (not shown) by another data path 150 (Iur). At least one of the PROGs 116, 126 and 146 is assumed to include program instructions that, when executed by the associated DP, enable the electronic device to operate in accordance with

the exemplary embodiments of this invention, as will be discussed below in greater

detail.

Shown in Figure 1 is also a second Node B 120', it being assumed that the first

Node B establishes a first cell (Cell 1) and the second Node B establishes a second cell

(Cell 2), and that the UE 110 is capable of a HO from one cell to another. In Figure 1 the Cell 1 may be assumed to be a currently serving cell, while Cell 2 may be a neighbor or

target cell to which HO may occur. Note that the Node Bs could be coupled to the same

RNC 140 (as shown), or to different RNCs 140. Note that while shown spatially separated, Cell 1 and Cell 2 will typically be adjacent and/or overlapping, and other cells

will typically be present as well. The exemplary embodiments of this invention may be implemented by computer

software executable by the DP 112 of the UE 110 and the other DPs, such as in cooperation with a DP in the network, or by hardware, or by a combination of software

and/or firmware and hardware.

In general, the various embodiments of the UE 110 can include, but are not

limited to, cellular telephones, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication

capabilities, image capture devices such as digital cameras having wireless

communication capabilities, gaming devices having wireless communication capabilities,

music storage and playback appliances having wireless communication capabilities,

Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions.

The MEMs 114, 124 and 144 may be of any type suitable to the local technical

environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical

memory devices and systems, fixed memory and removable memory. The DPs 112, 122

and 142 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors,

digital signal processors (DSPs) and processors based on a multi-core processor

architecture, as non-limiting examples.

Having thus introduced one suitable but non-limiting technical context for the practice of the exemplary embodiments of this invention, the exemplary embodiments

will now be described with greater specificity.

The exemplary embodiments of this invention enable permission to be granted for

the UE 110 to perform an autonomous cell change in the Active state if certain conditions

are fulfilled.

As was mentioned above, the current understanding in 3GPP concerning Active state mobility is that in the Active state the primary mobility option is defined by network

controlled, mobile assisted HO. However, in order to assure support for good power

saving possibilities in the UE Active state, the exemplary embodiments of this invention

provide that an autonomous cell change may be performed (or permitted) if conditions

(set by network or by a predefined specification) are fulfilled.

As described earlier the measurements and mobility capabilities for a 3.9 G UE

110 depend on the DRX cycle of the UE 110. If an optimum power saving is to be

achieved it would not be efficient to require the UE 110 to wake up from sleep between the scheduled DRX cycles just to perform a mobility measurement. However, the

currently proposed 3.9G Active mobility concept may unfortunately require this to occur

due to the fact that only network controlled HO is supported. The exemplary

embodiments of this invention remove the need for interrupting UE 110 inactivity (sleep)

periods due to a need to perform mobility measurements.

The use of the exemplary embodiments of this invention enhances the currently proposed 3.9G Active state HO based mobility to include a UE 110 executed autonomous cell change in Active state if one or more network or specification-defined conditions are fulfilled.

The exemplary embodiments of this invention can be supported by specification

in several different ways. Non-limiting examples of conditions of which one or more should or could be fulfilled for triggering UE 110 based autonomous cell change in the Active state include (in a non-prioritized order) the following.

A. A first condition is if the DRX period is longer than a specified time. This time

limit may be set by the network or it may be determined by other means. One example

may be if the next scheduled DRX is further in the future than the UE 110 would

normally require to autonomously change cells and initiate cell update/association/registration (in the new/target cell). Reference with regard to this first

condition can be made to FIGS. 2 - 3. In this situation, after performing neighbour cell

measurements the UE 110 checks cell change condition, such as Quality level, Time period and/or DRX time as shown at step 310 in FIG. 3. hi a next step at 320, a

consideration is made of:

(Cell change time + SIB reception time + Access time in new cell) < defined time.

If this expression evaluates as true, the UE 110 autonomously changes cells at

step 330, otherwise the UE 110 does not autonomously change cells as shown at step

340. B. A second condition is if the quality level of the serving cell decreases below a certain pre-defined level (e.g., camping criteria is no longer fulfilled) for some specified

length of time. Reference with regard to this condition 630 can be made to FIG. 6.

C. Another condition relates to a basic power or quality level offset between the

serving cell and a neighbor cell (for some specified length of time). The value used may

be one of many system-specific values. Reference with regard to this condition can also

be made to FIG. 6 at 630.

FIG. 7 is a flowchart depicting a method operating in accordance with this

exemplary embodiment. User equipment 110 at step 710 determines a difference in level

associated with a connection parameter between a serving and a neighbor cell and the

time duration at the difference level. Assuming the difference is greater than a predetermined threshold; at 720 the user equipment 110 determines whether the duration

at the difference level is greater than a pre-determined time. If it is greater than a predetermined time at 730 the user equipment 110 performs an autonomous cell change to a

neighbor cell. If it is less than the pre-determined time, the user equipment at 740 uses network-controlled (non-autonomous cell change). In the alternative, the user equipment

can wait until threshold time condition for performing autonomous cell change is satisfied.

D. Another condition relates to a HO command delay being so long that the

serving cell power or quality (or other measurement quantity or quantities) becomes less than some threshold limit (for some specified length of time). Alternatively, the decisions

to perform autonomous cell change can be made when the delay in receiving the HO

command exceeds a pre-determined time limit as shown at 620 in FIG 6.

A method to handle this situation is shown in FIG. 8. User equipment 110 at 810

determines a delay in receiving an HO command. Then, at 820, the user equipment

determines whether the delay in receiving the HO command is greater than a predetermined value. If the delay is greater than the pre-determined value, the UE 110

performs autonomous cell change. If it is less, the user equipment 110 uses network-

controlled (non-autonomous) cell change at 840. In the alternative, the user equipment waits to perform the cell change until the delay in receiving the HO command exceeds

the predetermined value.

E. Another possible condition may be related to a specific network setting, as

illustrated in Figure 4. In this case the UE 110 sends an establishment request 410 to the network 120 requesting resources for a certain connection type. The network evaluates

the requested connection type and requirements (e.g. delay, jitter) at 420 and sends an establishment confirm message 430 to the UE 110 including, among other information, whether the UE 110 shall use one of network-controlled HO for mobility or autonomous

cell change for mobility.

An exemplary method for performing this aspect of the invention is depicted in

FIG. 5. In step 510, the network receives an establishment request from user equipment.

Then, at step 520, the user equipment evaluates connection type and requirements. Next, at 530, the network determines whether under current conditions autonomous cell change

is feasible. If so, at 540 the network sends an establishment confirmation message to UE allowing autonomous cell change to a neighbour cell. If not, at 550 the network sends

establishment confirmation message to UE requiring network-controlled (non-

autonomous) cell change.

F. Another possible condition may be related to a connection type (depending on parameters such as, but not limited to, delay and/or jitter), is generally depicted illustrated

in FIG. 9, where synchronization state is provided as one example of a parameter.

G. Another possible condition may be related to a history of past services that the UE 10 has used.

H. Another possible condition relates to mobility behavior based on UL

synchronization status, as depicted in Figure 9. hi this case the UE 110, when in the

Active state, makes a determination as to whether the UL is synchronized or unsynclironized. If in the UL synchronized state, only HO is permitted and no

Autonomous reselection is permitted, while if not in the UL synchronized state then UE 10 autonomous cell reselection or HO is permitted.

A method for performing this aspect of the invention is depicted in FIG. 10. At step 1010, the UE 110 determines active state uplink synchronization status. Then, at

1020, the UE 110 determines whether uplink synchronization is present. If not, at step

1040, the UE 110 can use network-controlled or autonomous cell change. If uplink synchronization is present, at step 1030 the UE 110 uses network-controlled (non-

autonomous) cell change to a neighbor cell.

The trigger for performing the mobile assisted cell change may be a combination of any of the conditions listed above and/or other conditions. As a non-limiting example,

the autonomous UE 110 cell change trigger may be based on the DRX time being longer than the specified time, and the level of a measured quantity is found to be below some threshold.

The UE 110 autonomous cell change procedure may be protected against an occurrence of a ping-pong cell change effect by the use of different protection

mechanisms that include, but need not be limited to, one or more of: a timer whereby the

UE 110 may not reselect back to the former cell for some certain amount of time; an

additional offset that is applied to the former cell, thereby biasing the selection against the former cell; and/or the use of a counter, where the UE 110 offset/timer depends on a counted number of cell changes.

As non-limiting implementation examples:

1 ) If the DRX period is greater than X (X being defined in a specification) the UE

110 may/shall perform autonomous mobility through a cell change (see FIGS. 2, 3).

2) During a connection setup the network informs, based on the

nature/requirement of the connection such as delay, jitter and possible other settings, that the UE 110 should use autonomous mobility through a cell change (see FIGS. 4, 5).

3) The UE 110 knows from network settings (or through signaling, such as RRC

signaling) that autonomous mobility through cell change shall be used if the serving cell

quality level falls below a defined threshold. Another input parameter to the UE 110 may

be a currently used DRX cycle length (see FIGS. 6 - 8).

Figure 11 is a logic flow diagram that illustrates in summary terms the operation

of the UE of Figure 1 in accordance with exemplary embodiments of this invention. At

Block 1110 the UE 110 enters the Active state. At Block 1120 the UE 110 evaluates one or more of the conditions discussed above to determine if at least one trigger condition is

satisfied to enable Autonomous HO to a neighbor cell. If at least one trigger is generated,

the UE 110 makes an Autonomous cell change (Block 1130), otherwise the UE 110 uses a network-controlled cell change trigger (Block 1140).

As should be appreciated, a number of advantages can be realized by the use of

the exemplary embodiments of this invention. For example, the use of the exemplary

embodiments of this invention provide making Active state mobility in a 3.9G system more flexible such that it is not controlled only by network-controlled HO. Further by

example, UE failures in connection with the delays introduced by having long DRX

(measurement and reporting cycles) are minimized. The occurrence of certain severe

failures, such as loss of service, can be reduced. Further by example, the use of the

exemplary embodiments of this invention reduces interference caused by the UE 110 due

to a delayed HO procedure. Further by example, the use of the exemplary embodiments of this invention can aid in reducing the signaling load between the UE 110 and the Node

B 120. Further by example, the use of the exemplary embodiments of this invention reduces complexity in the network related to controlling Active-state mobility due to the reduced amount of directly controlled UEs. However, the network is still enabled to

directly control certain UEs, such as those engaged in high in data transmission activity.

The exemplary embodiments of this invention thus provide a method, a computer program product, and apparatus providing a permission-based UE 110 execution of an autonomous cell change in the Active state in response to a trigger being generated due to

the fulfillment of at least one criterion, hi an exemplary, but not limiting embodiment, the UE 110 operates in a 3.9G (LTE or E-UTRAN) network environment. The exemplary embodiments of this invention thus also provide a method, a computer program product,

and apparatus enabling a network node to grant permission to the UE 110 to execute an

autonomous cell change in the Active state in response to a trigger being generated due to the fulfillment of at least one criterion. The trigger may be generated in response to one or

more conditions being satisfied. The conditions may comprise, as non-limiting examples,

one or more of the DRX period being longer than a specified time, the quality level of

the serving cell decreasing below a certain pre-defined level, a basic power or quality level offset existing between the serving cell and a neighbor cell (for some specified

length of time), a HO command delay being so long that the serving cell power or quality

(or other measurement quantity or quantities) becomes less than some threshold limit (for

some specified length of time), a specific network setting, a connection type, a history of

past services that the UE 110 has used, and/or mobility behavior based on the UL

synchronization status. In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects

may be implemented in hardware, while other aspects may be implemented in firmware

or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the

invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems,

techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general

purpose hardware or controller or other computing devices, or some combination thereof. Embodiments of the inventions may be practiced in various components such as

integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a

logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

Programs, such as those provided by Synopsys, Inc. of Mountain View, California

and Cadence Design, of San Jose, California automatically route conductors and locate

components on a semiconductor chip using well established rules of design as well as libraries of pre-stored design modules. Once the design for a semiconductor circuit has

been completed, the resultant design, in a standardized electronic format (e.g., Opus,

GDSn, or the like) may be transmitted to a semiconductor fabrication facility or "fab" for

fabrication. Various modifications and adaptations may become apparent to those skilled in

the relevant arts in view of the foregoing description, when read in conjunction with the

accompanying drawings. However, any and all modifications of the teachings of this invention will still fall within the scope of the non-limiting embodiments of this

invention.

For example, while in certain exemplary embodiments above mention has been

made of time units of seconds or minutes it should be appreciated that other temporally-

related units could be employed, such as system frame number as one non-limiting example.

Furthermore, some of the features of the various non-limiting embodiments of this invention may be used to advantage without the corresponding use of other features. As

such, the foregoing description should be considered as merely illustrative of the

principles, teachings and exemplary embodiments of this invention, and not in limitation

thereof.

Claims

CLAIMSWE CLAIM:

1. A method comprising: detecting that a user equipment operative in a wireless communications network is in an active state;

determining whether at least one trigger condition is satisfied; if at least one trigger condition is satisfied, performing autonomous cell change to

neighbor cell; and

if no trigger condition is satisfied, performing network-controlled cell change.

2. A method as in claim 1 wherein the wireless communications network is a

3.9G network.

3. A method as in claim 1 wherein the wireless communications network is an E-UTRAN network.

4. A method as in any of the preceding claims wherein the trigger condition

comprises the DRX period being longer than a specified time.

5. A method as in claim 4 wherein the specified time is set by the network.

6. A method as in claim 1 , 2 or 3 wherein the trigger condition corresponds to a quality level of the serving cell falling below a certain pre-defined level.

7. A method as in claim 1 , 2 or 3 wherein the trigger condition corresponds

to an offset between the serving cell and a neighbor cell of a connection characteristic

persisting for a predetermined period of time.

8. A method as in claim 7 wherein the connection characteristic corresponds

to power.

9. A method as in claim 7 wherein the connection characteristic corresponds to a signal quality measure.

10. A method as in claim 1 , 2 or 3 wherein the trigger condition corresponds to an HO command being delayed for a period of time during which a characteristic of a

serving cell becomes less than a threshold limit.

11. A method as in claim 1, 2 or 3 wherein the trigger condition further comprises the characteristic of a serving cell persisting at less than a threshold limit for a

predetermined period of time.

12. A method as in claim 1, 2 or 3 wherein the trigger condition concerns

requirements for a connection type.

13. A method as in claim 1 , 2 or 3 wherein the trigger condition is related to a

history of past services that the user equipment has used.

14. A user equipment operative in a wireless communications network comprising: a transceiver configured to bidirectionally communicate with the wireless

communications network;

at least one memory configured to store a computer program configured to control

the user equipment when executed; and digital processing apparatus coupled to the transceiver and to the memory, the

digital processing apparatus configured to execute the computer program, wherein when

the computer program is executed by the digital processing apparatus the user equipment

is configured to detect whether the user equipment is in active state; to determine whether at least one trigger condition is satisfied; if the at least one trigger condition is satisfied,

to perform autonomous cell change to neighbor cell; and if the at least one trigger

condition is not satisfied, to perform a cell change under network control.

15. A user equipment operative in a wireless communication network comprising:

transceiver means for bidirectionally communicating with the wireless communications network;

memory means for storing program means, the program means for controlling the

user equipment when executed; and digital processing means coupled to the transceiver means and the memory means, the digital processing means for executing the program means, wherein when the

program means is executed by the digital processing means the user equipment is

configured to receive a message from the wireless communication network allowing the user equipment to perform an autonomous cell change from a serving cell to a neighbor

cell; and to effect the autonomous cell change from the serving cell to the neighbor cell.

16. A computer program product comprising a computer readable memory medium, the computer readable memory medium configured to store a computer program, the computer program configured to be executed by digital processing apparatus

of a device operative in a wireless communications network, wherein when executed, the computer program is configured to determine whether at least one trigger condition is

satisfied for user equipment operative in the wireless communications network, wherein when the trigger condition is satisfied the user equipment is permitted to perform an

17. A computer program product as in claim 16 wherein the device operative in the wireless communications network comprises the user equipment.

18. A network access node operative in a wireless communications network

comprising: a transceiver configured to bidirectionally communicate with user equipment

accessible in the wireless communications network;

at least one memory configured to store a computer program configured to control the user equipment when executed; and digital processing apparatus coupled to the transceiver and to the memory, the digital processing apparatus configured to execute the computer program, wherein when

the computer program is executed by the digital processing apparatus the network access

node is configured to determine whether at least one trigger condition is satisfied for a

user equipment operative in the wireless communications network; and to communicate to the user equipment that it is authorized to perform autonomous cell change if the at

least one trigger condition is satisfied.

19. An integrated circuit for use in a device operative in a wireless communications network, the integrated circuit comprising memory and processing

apparatus, the integrated circuit configured to detect whether a particular user equipment

is in an active mode; to determine whether at least one trigger condition is satisfied; if the at least one trigger condition is satisfied, to cause the user equipment to perform an

autonomous cell change to a neighbor cell; and if the at least one trigger condition is not

satisfied, to cause the use equipment to perform cell change to a neighbor cell under

network control.