US20150105083A1

US20150105083A1 - Modified Measurement Procedures for User Equipments

Info

Publication number: US20150105083A1
Application number: US14/578,826
Authority: US
Inventors: Christopher Peter Callender; Tao Chen
Original assignee: Broadcom Corp
Current assignee: Avago Technologies International Sales Pte Ltd
Priority date: 2012-01-24
Filing date: 2014-12-22
Publication date: 2015-04-16
Also published as: US20130189971A1; GB201201125D0; US9094882B2; GB2498721A; WO2013111056A1; GB2498721B

Abstract

A network sends to a user equipment UE downlink signaling indicating at least one frequency which is subject to special handling. In response the UE measures and reports neighbor cells operating on any of that/those frequencies without regard to a threshold signal strength of a serving cell which is configured for reporting neighbor cells. In more specific examples, if the neighbor cells operating on any of that/those frequencies is considered a first set of neighbor cells, then the network also sends a second set of neighbor cells in other downlink signaling. Measuring and reporting on the first set of neighbor cells is less frequent than for the second set of neighbor cells, when measurements of the second set is required. Measuring and reporting on the second set is dependent on measured signal strength of a serving cell being greater than the configured threshold signal strength of the serving cell.

Description

TECHNICAL FIELD

The exemplary and non-limiting embodiments of this invention relate generally to wireless communication systems, methods, devices and computer programs, and more specifically relate to user equipment UE measurements of neighbor cells.

BACKGROUND

Abbreviations used in this description and/or in the referenced drawings are defined below following the Detailed Description section.
Inter-frequency mobility procedures for LTE have been designed primarily so that UE remains in coverage. With the deployment of heterogeneous network (hetnet) network elements such as pico-cells, slightly different procedures for inter-frequency measurements could be considered which would better meet the needs of handover to capacity hotspots.
FIG. 1 illustrates a hetnet showing one possible hotspot scenario, specifically scenario 4 for carrier aggregation detailed at 3GPP TS 36.300v11.0.0 informative annex J.1. The eNB 101 provides macro coverage on frequency f1 110 and a number of remote radio heads 102 a, 102 b are deployed on frequency f2 120 in areas of high traffic such as railway stations, airports, shopping malls, etc. Alternatively, dedicated pico eNBs may be deployed in place of the remote radio heads to provide the hotspot coverage.
With this scenario in mind, now consider the conventional neighbor cell measurement procedures in LTE. The network provides to the UE in the MeasConfig information element a parameter s-Measure which is a threshold for the PCell (macro cell in FIG. 1) that controls whether or not the UE is required to perform neighbor cell measurements. If the serving cell reference signal received power RSRP measured by the UE is greater than the s-Measure parameter, the UE does not measure other cells. There is only one value for s-Measure at any given time for a UE, meaning that same value controls intra-frequency, inter-frequency and inter-RAT measurements. The network can disable this by setting the value “0” for the s-Measure parameter.
The assumption behind this conventional use of the s-Measure parameter is that if the serving cell is good enough, no neighbor cells need to be measured. This makes sense for a coverage-based handover. But the hetnet scenario of FIG. 1 contemplates also capacity-based handovers to a hotspot which may be located within an area of strong macro coverage. In a capacity-based handover, the macro cell 101 is not handing over to assure continuous coverage for the UE as is typical if the RSRP is trending lower, but in order to offload the UE's traffic from the macro cell's f1 frequency layer 110 to the pico cell's f2 frequency layer 120 due to congestion on the macro cell's f1 frequency layer 110. Such a capacity-based handover may be to a hotspot which is located within an area of strong macro cell coverage, and the conventional s-Measure parameter is not very effective for this purpose. The only way in current specifications to ensure that the UE searches for pico cell hotspots 120 that may continuously lie in good macro cell coverage 110 would be to disable s-Measure. One exemplary disadvantage of this technique is that disabling the s-Measure parameter precludes its use for intra-frequency and inter-RAT measurements as well as for any coverage based inter-frequency measurements.
Inter-frequency measurements, either with or without measurement gaps, are assumed to be shared equally between all configured inter-frequency/inter-RAT component carriers, and the current measurement performance requirements are strict since the intention is to avoid dropping a call if the UE reaches the edge of coverage on its current serving frequency/frequencies.
Co-owned U.S. patent application Ser. No. 13/023,675 concerns measuring inter-frequency and inter-RAT neighbor cells and describes that the UE's measurement occasions are used for different neighbor cells depending on whether the UE has good or marginal coverage with its serving cell. It describes a priority re-selection algorithm in the E-UTRAN system by which the network can prioritize measurements of either a frequency layer or a RAT over another, so as to more efficiently use the available measurement occasions depending on the strength of the serving cell.
Co-owned U.S. patent application Ser. No. 13/251,363 detail selecting different sets of entries from the prioritized neighbor cell list depending on whether the UE is searching for purposes of maintaining coverage or for obtaining enhanced services, and the coverage/services distinction is determined at least in part based on the UE's received signal strength or signal quality of its serving cell.
What is needed in the art is a way to distinguish when the UE should do coverage-based neighbor cell measurements and when it should do capacity-based neighbor cell measurements.

SUMMARY

In a first exemplary embodiment of the invention there is a method comprising: receiving downlink signaling indicating at least one frequency which is subject to special handling; and in response, measuring and reporting neighbor cells operating on any of the at least one frequency without regard to a threshold signal strength of a serving cell which is configured for reporting neighbor cells.
In a second exemplary embodiment of the invention there is an apparatus comprising at least one processor and at least one memory storing a set of computer instructions. In this embodiment the at least one processor is arranged with the memory storing the instructions to cause the apparatus to perform: receiving downlink signaling indicating at least one frequency which is subject to special handling; and in response, measuring and reporting neighbor cells operating on any of the at least one frequency without regard to a threshold signal strength of a serving cell which is configured for reporting neighbor cells.
In a third exemplary embodiment of the invention there is a computer readable memory tangibly storing a set of instructions which, when executed on a communicating apparatus causes the apparatus to perform at least: receiving downlink signaling indicating at least one frequency which is subject to special handling; and in response, measuring and reporting neighbor cells operating on any of the at least one frequency without regard to a threshold signal strength of a serving cell which is configured for reporting neighbor cells.
In a fourth exemplary embodiment of the invention there is an apparatus for communicating, comprising means for receiving downlink signaling indicating at least one frequency which is subject to special handling; and means for measuring and reporting neighbor cells operating on any of the at least one frequency without regard to a threshold signal strength of a serving cell which is configured for reporting neighbor cells. For example, the means for receiving may be a radio receiver or an input node of one or more components of a user equipment which receives the downlink signaling from another component of the user equipment; and the means for measuring and reporting may be a processor executing a program stored in a memory that causes a receiver of the user equipment to measure signaling from the neighbor cells.
In a fifth exemplary embodiment of the invention there is a method comprising: arranging neighbor cells into a first list for offloading traffic and a second list for maintaining coverage; and providing downlink signaling to indicate special handling for measuring and reporting neighbor cells in the first list, and a threshold signal strength upon which measuring and reporting neighbor cells in the second list is conditional.
In a sixth exemplary embodiment of the invention there is an apparatus comprising at least one processor and at least one memory storing a set of computer instructions. In this embodiment the at least one processor is arranged with the memory storing the instructions to cause the apparatus to perform: arranging neighbor cells into a first list for offloading traffic and a second list for maintaining coverage; and providing downlink signaling to indicate special handling for measuring and reporting neighbor cells in the first list, and a threshold signal strength upon which measuring and reporting neighbor cells in the second list is conditional.
In a seventh exemplary embodiment of the invention there is a computer readable memory tangibly storing a set of instructions which, when executed on a communicating apparatus causes the apparatus to perform at least: arranging neighbor cells into a first list for offloading traffic and a second list for maintaining coverage; and providing downlink signaling to indicate special handling for measuring and reporting neighbor cells in the first list, and a threshold signal strength upon which measuring and reporting neighbor cells in the second list is conditional.
In an eighth exemplary embodiment of the invention there is an apparatus for communicating, comprising means for arranging neighbor cells into a first list for offloading traffic and a second list for maintaining coverage; and means for providing downlink signaling to indicate special handling for measuring and reporting neighbor cells in the first list, and a threshold signal strength upon which measuring and reporting neighbor cells in the second list is conditional. For example, the means for arranging may be a processor executing a program stored on a memory to store two separate lists of neighbor cells (frequencies), which may be received from a higher network node or which may be parsed by an access node itself. The means for providing downlink signaling may be a transmitter or it may be the processor and the program stored on the memory for directing a transmitter to send the special handling indication and the threshold signal strength.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a prior art schematic diagram illustrating scenario 4 for carrier aggregation from 3GPP TS 36.300 v11.0.0 showing pico cells within larger macro cells, and illustrates an example environment in which some embodiments of these teachings may be practiced to advantage.

FIG. 2 illustrates one non-limiting example of a Measurement Object Information Element adapted according to these teachings to include a flag indicating whether the frequency referred to by this measurement object is used for capacity-based neighbor cell measurement reporting.

FIG. 3A-B are logic flow diagrams that illustrates, from the perspective of the UE and the network access node, the operation of a method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with the exemplary embodiments of this invention.

FIG. 4 is a non-limiting example of a simplified block diagram of the UE in communication with a wireless network illustrated as an eNB and a MME/S-GW, which are exemplary electronic devices suitable for use in practicing the exemplary embodiments of this invention.

DETAILED DESCRIPTION

While the examples below are in the context of the LTE system with a UE operating in a carrier aggregation deployment of a hetnet, these are non-limiting examples only. The specific examples used in these teachings are readily extendable for other RATs (radio access technologies) such as UTRAN (universal terrestrial radio access network) and UMTS (universal mobile telecommunications system), whether or not those other RATs are deployed with carrier aggregation.
The background section above discusses different reasons for handovers; namely coverage-based handovers which are conventional to assure the UE stays within coverage in order to avoid dropped calls, and the more recently relevant capacity-based handovers in which the network seeks to offload some traffic to another cell/frequency layer in order to relive network congestion. Recall the FIG. 1 scenario and the network's need for sufficient information to decide whether to make a capacity-based handover of a UE. From the UE's perspective, to reduce power consumption any measurements of neighbor cells for capacity-based handover purposes should be less frequency. Dispensing with the conventional protocol of sharing the UE's measurement opportunities equally among the different neighbor cells helps ensure that the impact of making capacity-based measurements will minimize any adverse effects on the UE's measurements of carriers needed for coverage purposes, since the capacity-based measurements may not need to be as frequent as the coverage-based measurements in typical deployments.
According to an embodiment of these teachings the eNB indicates to the UE which frequencies are used for hotspots. For those indicated hotspot frequencies the UE will ignore the s-Measure parameter even if it is enabled. This means that for this particular embodiment the UE searches and measures those hotspot frequencies which the macro network may use for additional capacity even when the UE's signal reception from the serving (macro) cell is strong.
For those indicated hotspot frequencies, there are in one embodiment of these teachings more relaxed measurement performance requirements. This means the indicated hotspot (capacity) frequencies can be searched more infrequently than the coverage-based frequencies or the inter-RAT neighbor cells.
According to one non-limiting embodiment, the indication of which frequencies are hotspot frequencies is a flag added to a measurement object information element. Such a flag indicates that the frequency referred to by this measurement object is to be measured by the UE for capacity based handover purposes. In the LTE system, the Measurement Configuration information element (which includes the parameter s-Measure as noted in the background section above) gives the UE specifics for how to conduct its measurements and reporting while the objects/neighbor cells to be measured are identified in all the configured Measurement Object information elements.
One example implementation of such a flag is shown at FIG. 2, which is a conventional E-UTRAN Measurement Object information element 200 with an added flag 202 indicating whether this frequency is a hotspot 204 (the frequency referred to by the measurement object is a capacity frequency if the flag 202 is set) in use in the area by pico cells or remote radio heads (assuming the environment of FIG. 1). The name of this flag 202 in the FIG. 2 example is “freqUsedForCapacity’, but other embodiments may use different terminology for similar functionality in the Measurement Object information element 200. Other implementations may not indicate whether signaled frequencies are hotspots 204 in that Measurement Object 200 itself but instead signal the same substantive information to the UE in different downlink signaling, such as in the Master Information Block MIB on the broadcast channel, or in System Information in the PDCCH as non-limiting alternatives.
The indication 202, 204 of the hotspot frequencies can be used to enable the UE to perform more infrequent measurements (reduced measurement occasions/requirements) when those measurements are for capacity purpose, rather than the more urgent coverage-based case. But such frequency indications 202, 204 can also be used for a variety of other purposes, instead of or in addition to distinguishing cells that are most appropriate for capacity-based handovers from cells that are most appropriate for coverage-based handovers. Therefore a more generic term for this indication 202, 204 for all the measurement objects is an indication of what frequencies are subject to special handling as compared with conventional mobility procedures which are more optimized for coverage-type handovers. For the capacity-based handover scenarios the special handling is for the UE to ignore the s-Measure parameter and to measure on a more infrequent basis than other neighbor cell frequencies which are reported in dependence on the s-Measure parameter.
For inbound mobility from the macro cell 101 to the overlaid small/pico cell 102 a, the inter-frequency searching for the pre-defined hotspots is activated with a low searching rate. The capacity-driven handover may need to take into account the load of the target cell to improve the performance or balance the load between cells. In this respect according to an exemplary embodiment of these teachings there is also a capacity indicator which the different cells indicate to one another, such as across the X2 interface 23 shown at FIG. 4. In one embodiment the pico cell 102 a informs the macro cell 101 of the pico cell's capacity to handle additional traffic, and the macro cell 101 similarly informs the pico cell 102 a of the macro cell's capacity to handle additional traffic.
The above capacity indication communicated directly between the pico cell 102 a and the macro cell 101 would result in the UE still taking and reporting measurements on the pico cell 102 a even when the macro cell 101 has sufficient capacity and/or when the pico cell 102 a has little or none. To address this issue, in another embodiment the pico cell 102 a broadcasts a capacity indication, or the macro cell 101 broadcasts a capacity indication on behalf of the pico cell 102 a, which allows the UE to measure and report this particular pico cell 102 a whose frequency is in the list 204 only if the pico cell's broadcast capacity indicator indicates the pico cell 102 a is not at or near full capacity. In this regard the pico cell's capacity indicator (which may be broadcast by the macro or the pico cell) may be a simple overload indicator; as little as a single bit indicating overload or not. The overload indication can alternatively be more than one bit and carry more than only binary overload/no-overload information, such as some gradations of relative capacity remaining in the pico cell 102 a.
In one embodiment the macro cell 101 can also be informed of capacity/overload indicator and semi-statically remove from the list 204 that particular pico cell's frequency. In one embodiment the macro cell 101 removes such a frequency under two conditions: that particular pico cell's indicator indicates overload, and no other hotspots/cells in the area are using the same frequency.
To configure the neighbor cell list the network operator will consider whether a frequency in the neighbor list is used for coverage purposes or for capacity purposes. The macro eNBs of the system are then configured (for example, by the network operator's operations and maintenance systems) with the appropriate setting of the flag 202 for each frequency in the eNB neighbor list. Those frequencies with the flag set (capacity purpose cells) are indicated for special handling 204, and together all the frequencies having the flag set form a list which may be considered to represent a first set of neighbor cells, and all those frequencies without the flag set (for example, neighbor macro eNBs) are put in the conventional neighbor cell list which may be considered a second neighbor cell list which the UEs measure and report with regard to the s-Measure parameter. For those instances where the flag 202 is not set for any measurement object, the eNB 101 has found no neighbor cells which are classified as being for capacity handover purposes. The first set of neighbor cells is empty and the UE's behavior as far as measuring and reporting neighbor cells is no different from conventional practice; it will only measure and report on the second set of neighbor cells and according to the conventional measurement gap practice. For those frequencies for which the flag 202 is set the UE will ignore the s-Measure parameter as to those frequencies indicated for special handling 204 and measure and report those cells (in the first neighbor cell list) on a more infrequent basis than those on the conventional neighbor cell list (the second neighbor cell list).
In one embodiment for mobility inbound from the macro cell 101 to the overlaid small/pico cell 102 a, this hotspot frequency can be defined for the UE which is under the macro cell as its serving cell. This list for capacity enhancement is in some embodiments orthogonal to the conventional inter-frequency neighbor cell list which is used for coverage-based handovers. According to the above examples these two lists are defined separately, with different searching rates and trigger configurations. In an embodiment the network can override the initial low searching rate for the special handling frequencies and signal the UE to change the measurement and reporting rate, but the default condition (absent specific signaling) is for a searching/reporting rate for the special handling cells to be lower than that for the cells in the conventional neighbor cell list.
In one embodiment for mobility outbound from the small/pico cell 102 a to the overlaid large/macro cell 101, this is a coverage-based handover and so the hotpot frequency list 204 may not be necessary in this embodiment, and typically may not be activated unless possibly there is a still smaller cell within the area of the pico cell 102 a for capacity enhancement as a further part of a hierarchical cell structure. For this typical outbound mobility case there would be no capacity-driven cell searching list, or if there is the typical case would be that the special handling searching/reporting by UEs under control of a pico/femto cell is deactivated.
One advantage of the less frequent measurements of those special handling cells is that it reduces the dependency on measurement gaps for performing measurements. There are a limited number of measurement gaps during which the UE can re-tune its receiver to a frequency other than its serving cell's in order to measure a neighbor cell. Fewer instances of measuring the special handling cells means more of those gaps are available for measuring those neighbor cells which are available for coverage-based handovers, which would continue to be measured and reported as is conventional with reference to the serving cell's RSRP/RSRQ.
The FIG. 1 environment assumes a carrier aggregation system, in which the hotspot frequency/pico cell is configured as a secondary component carrier. For UEs capable of operating on multiple component carriers at once, in case the network has not configured a secondary component carrier for the UE it can use its additional RF capability for taking measurements of the special handling cells even without using measurement gaps allowed by its serving cell 101 (these example assume the serving cell is a macro cell 101 but this is a non-limiting feature).
For UEs not capable of carrier aggregation operation, measurements of the special handling cells may be done with an additional “measurement” RF (radio-frequency) receive chain. The advantage enabled by the above non-limiting examples is that measuring the special handling cells would not occupy any measurement gaps, and aspects of the performance of this additional RF chain such as receiver sensitivity may not need to be as good as the main reception RF chain in order to reduce its additional cost. For example, there is no need to detect capacity cells at the lowest signal levels. LTE Release 8 specifications even allow for UEs which have such an additional RF chain and do not need gaps for measurements. For UEs without any additional RF receive chain, the macro eNB 101 may provide infrequent gaps in a separate gap pattern, different from the conventional measurement gaps which allow for coverage-based measurements and reporting, which allows the UE to search and measure the capacity frequency layer(s) indicated for special handling 204. Or such a UE can instead autonomously decide when to measure the special handling cells regardless of the measurement gap pattern the network configures for it. For example, this UE might notice a brief interruption to the serving cell's 101 transmissions and the serving cell 101 might notice a brief interruption to the UEs transmission during which time the UE can measure the special handling cells.
The conventional measurement gaps configured by the eNB for neighbor cell measurements may be used for measuring the special handling cells, but with a lesser share of those measurement gaps being used for the special handling cells which represent the capacity-based frequency layers, and a larger share being used for the conventional neighbor cell list which represents the coverage-based frequency layers.
To more smoothly handle integration with legacy UEs such as those capable only of LTE Release 8 operation, some embodiments of these teachings also employ a new s-Measure parameter. In this specific case, the network can set the old s-Measure parameter to zero so that the legacy/Release 8 UEs will measure and report on all the cells in their conventional neighbor cell list for any measured signal strength of their serving cell (since the threshold s-Measure against which they compare the serving cell measured signal strength is zero). Then the newer UEs would ignore the old Release 8 s-Measure parameter and use only the new one, for example s-Measure1, whenever it is provided. The use would be as detailed above for the conventional neighbor cell list and to ignore the s-Measure1 value for each frequency indicated for special handling 204.
One technical advantage of these teachings is that they enable coverage and capacity measurements to be optimized according to their different needs. The coverage performance is less impacted by the measurement of capacity frequencies since the latter measurements can be performed less frequently. The parameter s-Measure (or the new parameter s-Measure1) can be configured to inhibit measurements of coverage frequencies/RATs without inhibiting measurements of capacity frequencies. This may improve the UE's power consumption on two counts; because the parameter s-Measure (or s-Measure1) is able to be configured to limit measurement activities on coverage carriers/cells that don't need to be measured when the serving cell is strong, and/or because there is reduced measurement activity on the capacity carriers as compared to simply measuring them just as often as measuring the capacity cells.
FIGS. 3A-B are logic flow diagrams which summarize some example embodiments of the invention. FIG. 3A describes from the perspective of the UE and FIG. 3B describes from the perspective of the macro eNB, and each of those Figures may be considered to illustrate the operation of a method, and a result of execution of a computer program stored in a computer readable memory, and a specific manner in which components of an electronic device are configured to cause that electronic device to operate, whether such an electronic device is the UE, the eNB or other network access node, or one or more components thereof such as a modem, chipset, or the like.
Such blocks and the functions they represent are non-limiting examples, and may be practiced in various components such as integrated circuit chips and modules, and that the exemplary embodiments of this invention may be realized in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this invention.
Such circuit/circuitry embodiments include any of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) combinations of circuits and software (and/or firmware), such as: (i) a combination of processor(s) or (ii) portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone/UE, to perform the various functions summarized at FIG. 3) and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. This definition of ‘circuitry’ applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term “circuitry” would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term “circuitry” also covers, for example, a baseband integrated circuit or applications processor integrated circuit for a mobile phone/UE or a similar integrated circuit in a server, a cellular network device, or other network device.
Now consider FIG. 3A from the perspective of the UE. At block 302 the UE receives downlink signaling indicating at least one frequency which is subject to special handling, and in response at block 304 the UE measures and reports neighbor cells operating on any of the at least one frequency without regard to a threshold signal strength of a serving cell which is configured for reporting neighbor cells. Where the functions described by FIG. 3A are practiced by one or more components for a UE, such components may be configured to receive the downlink signaling as an input from a receiver of the UE or some other element of the UE's receive RF chain and also configured to control the measuring and the reporting as said in block 304.
The remainder of FIG. 3A illustrates more specific implementations. Block 306 characterizes the neighbor cells operating on any of the at least one frequency as a first set of neighbor cells, and the UE receives a second set of neighbor cells in other downlink signaling. In this case the UE's measuring and reporting on the first set of neighbor cells may be less frequent than the UE's measuring and reporting on the second set of neighbor cells, when measurements of the second list is required by s-Measure/s-Measure 1 (e.g., s-Measure/s-Measure 1 is not disabled). Block 308 gives further detail that the measuring and reporting on the second set of neighbor cells is dependent on measured signal strength of a serving cell being greater than the configured threshold signal strength of the serving cell.
Block 310 details the specific example above in which the configured threshold signal strength of the serving cell is a parameter s-Measure indicated in a Measurement Configuration information element, and the downlink signaling indicating the at least one frequency comprises, for each of the at least one frequencies, a Measurement Object information element comprising a flag indicating capacity-based measurement reports and the at least one frequency associated with the flag.
And finally at block 312 the UE additionally receives a downlink capacity indicator from a particular neighbor cell (one of the neighbor cells noted in block 304) operating on the at least one frequency; and in this case the UE's measuring and reporting of that particular neighbor cell is conditional on the capacity indicator indicating that the particular cell is not overloaded.
FIG. 3B summarizes some embodiments from the perspective of a network access node such as the eNB of the macro cell 101. At block 352 the eNB arranges neighbor cells into a first list for offloading traffic and a second list for maintaining coverage; and at block 354 the eNB provides downlink signaling to indicate special handling for measuring and reporting neighbor cells in the first list, and a threshold signal strength upon which measuring and reporting neighbor cells in the second list is conditional. Where the functions described at FIG. 3B are practiced by one or more components for an eNB, such components may be configured to store in a local memory of the eNB the first and second list if such lists are actually compiled by some other network element or other component of the eNB, and practicing component(s) execute block 354 by outputting the downlink signaling to a transmitter or other element of a transmit RF chain of the eNB.
The remainder of FIG. 3B illustrates more specific implementations. Block 356 provides that the special handling comprises measuring and reporting neighbor cells in the first list without regard to the threshold signal strength, in which the threshold signal strength is of a serving cell, and block 358 provides that the special handling further comprises measuring and reporting neighbor cells in the first list less frequently than measuring and reporting neighbor cells in the second list, when measurements of the second list is required (by s-Measure/s-Measure1 in the above non-limiting examples).
Block 360 more closely reflects some of the specific examples above, in which the downlink signaling comprises a Measurement Configuration information element and a Measurement Object information element. In this case the threshold signal strength of the serving cell comprises a parameter s-Measure whose value is indicated in the Measurement Configuration information element, and the Measurement Object information element comprises a flag indicating capacity-based measurement reports and a list of frequencies corresponding to the first list of neighbor cells.
Reference is now made to FIG. 4 for illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing the exemplary embodiments of this invention. In FIG. 4 a wireless network (eNB 22 and mobility management entity MME and/or serving gateway S-GW 24) is adapted for communication over a wireless link 21A with an apparatus, such as a mobile terminal or UE 20, via a network access node such as a base station/eNB 22 or relay station. The network may include the MME/S-GW 24 which provides connectivity with further networks (e.g., a publicly switched telephone network PSTN and/or a data communications network/Internet).
The UE 20 includes processing means such as at least one data processor (DP) 20A, storing means such as at least one computer-readable memory (MEM) 20B storing at least one computer program (PROG) 20C, communicating means such as a transmitter TX 20D and a receiver RX 20E for bidirectional wireless communications with the network access node 22 via one or more antennas 20F. Also stored in the MEM 20B at reference number 20G is the UE's rules for special handling of the capacity frequency layer as distinguished from the coverage frequency layers as is detailed above with specificity.
The network access node 22 is in the position of the macro cell 101 in FIG. 1, and also includes processing means such as at least one data processor (DP) 22A, storing means such as at least one computer-readable memory (MEM) 22B storing at least one computer program (PROG) 22C, and communicating means such as a transmitter TX 22D and a receiver RX 22E for bidirectional wireless communications with the UE 20 via one or more antennas 22F. The access node 22 also includes at unit 22G the two distinct neighbor cell lists (NCLs) which it indicates different handling to the UE via the s-Measure (or s-Measure1) parameter and the special handling indication/flag. There is also a data and/or control path 25 coupling the eNB 22 with the MME/S-GW 24, and another data and/or control path 23 coupling the eNB 22 to other base stations/eNBs/access nodes such as the pico access node 26 which is in the position of one of the pico cells 102 a shown at FIG. 1. The UE 20 has a wireless link 21B with the pico eNB 26 for taking measurements thereof, and so that in a particular embodiment it can also receive the overload indicator which in the example above is broadcast by the pico eNB 26.
For completeness the pico eNB 26 is also illustrated as having a data processor (DP) 26A, storing means/computer-readable memory (MEM) 26B storing at least one computer program (PROG) 26C, and communicating means such as a transmitter TX 26D and a receiver RX 26E for bidirectional wireless communications with the UE 20 via one or more antennas.
Similarly, the MME/S-GW 24 includes processing means such as at least one data processor (DP) 24A, storing means such as at least one computer-readable memory (MEM) 24B storing at least one computer program (PROG) 24C, and communicating means such as a modem 24H for bidirectional wireless communications with the eNB 22 via the data/control path 25. While not particularly illustrated for the UE 20 or base station 22, those devices are also assumed to include as part of their wireless communicating means a modem which may be inbuilt on an RF front end chip within those devices 20, 22, 26 and which also carries the TX 20D/22D/26D and the RX 20E/22E/26E.
At least one of the PROGs 20C/20G in the UE 20 is assumed to include program instructions that, when executed by the associated DP 20A, enable the device to operate in accordance with the exemplary embodiments of this invention, as detailed above. The access node 22 (and the pico eNB 26) may also have software stored in its MEM 22B to implement certain aspects of these teachings as detailed above with respect to FIG. 3B. In this regard the exemplary embodiments of this invention may be implemented at least in part by computer software stored on the MEM 20B, 22B which is executable by the DP 20A of the UE 20 and/or by the DP 22A/26A of the access node(s) 22, 26, or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware). Electronic devices implementing these aspects of the invention need not be the entire UE 20 or eNB 22 (or 26), but exemplary embodiments may be implemented by one or more components of same such as the above described tangibly stored software, hardware, firmware and DP, modem, system on a chip SOC or an application specific integrated circuit ASIC.
In general, the various embodiments of the UE 20 can include, but are not limited to personal portable digital devices having wireless communication capabilities, including but not limited to cellular telephones, navigation devices, laptop/palmtop/tablet computers, digital cameras and Internet appliances.
Various embodiments of the computer readable MEMs 20B, 22B and 26B include any data storage technology type which is suitable to the local technical environment, including but not limited to semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, removable memory, disc memory, flash memory, DRAM, SRAM, EEPROM and the like. Various embodiments of the DPs 20A, 22A and 26A include but are not limited to general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and multi-core processors.
Some of the various features of the above non-limiting embodiments may be used to advantage without the corresponding use of other described features. The foregoing description should therefore be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.
The following abbreviations used in the above description and/or in the drawing figures are defined as follows:

- 3GPP third generation partnership project
- eNB evolved Node B (base station of an LTE system)
- E-UTRAN evolved UTRAN (also known as LTE)
- Hetnet heterogeneous network
- LTE long term evolution (also known as E-UTRAN)
- NCL neighbor cell list
- RAT radio access technology
- RF radio-frequency
- RSRP reference signal received power
- RSRQ reference signal received quality
- UE user equipment
- UTRAN universal terrestrial radio access network

Claims

We claim:

1. An apparatus for communicating, comprising:

at least one processor; and

a memory storing a set of computer instructions,

in which the at least one processor is arranged with the memory storing the instructions to cause the apparatus to perform:

arranging neighbor cells into a first list for offloading traffic and a second list for maintaining coverage;

providing downlink signaling to indicate special handling for measuring and reporting neighbor cells in the first list, and a threshold signal strength upon which measuring and reporting neighbor cells in the second list is conditional.

2. The apparatus according to claim 1, in which the special handling comprises measuring and reporting neighbor cells in the first list without regard to the threshold signal strength, in which the threshold signal strength is of a serving cell.

3. The apparatus according to claim 2, wherein the threshold signal strength of the serving cell is a non-zero value for a parameter s-Measure or s-Measure1.

4. The apparatus according to claim 2, in which the special handling further comprises measuring and reporting neighbor cells in the first list less frequently than measuring and reporting neighbor cells in the second list, when measurements of the second set is required.

5. The apparatus according to claim 1, in which the downlink signaling comprises a Measurement Configuration information element and a Measurement Object information element.

6. The apparatus according to claim 5, in which the threshold signal strength of the serving cell comprises a parameter s-Measure whose value is indicated in the Measurement Configuration information element.

7. The apparatus according to claim 6, in which the Measurement Object information element comprises a flag indicating capacity-based measurement reports for at least one frequency referred to by the measurement object.

8. The apparatus according to claim 1, in which the apparatus comprises a network access node.

9. A computer readable memory tangibly storing a set of instructions which, when executed on a communicating apparatus causes the apparatus to perform at least:

10. The computer readable memory according to claim 9, in which the special handling comprises measuring and reporting neighbor cells in the first list without regard to the threshold signal strength, in which the threshold signal strength is of a serving cell.

11. The computer readable memory according to claim 10, wherein the threshold signal strength of the serving cell is a non-zero value for a parameter s-Measure or s-Measure1.

12. The computer readable memory according to claim 10, in which the special handling further comprises measuring and reporting neighbor cells in the first list less frequently than measuring and reporting neighbor cells in the second list, when measurements of the second set is required.

13. The computer readable memory according to claim 9, in which the downlink signaling comprises a Measurement Configuration information element and a Measurement Object information element.

14. The computer readable memory according to claim 13, in which the threshold signal strength of the serving cell comprises a parameter s-Measure or s-Measure1 whose value is indicated in the Measurement Configuration information element.

15. The computer readable memory according to claim 14, in which the Measurement Object information element comprises a flag indicating capacity-based measurement reports for at least one frequency referred to by the measurement object.

16. The computer readable memory according to claim 9, in which the communicating apparatus comprises a network access node.

17. A method for operating a network access node, the method comprising:

compiling a plurality of information elements, each information element indicating for a respective neighbor cell one or more frequencies used by the respective neighbor cell, such that the plurality of information elements distinguish frequencies for offloading traffic from frequencies for maintaining coverage;

signaling to user equipments in a cell the plurality of information elements and a signal strength parameter, the signal strength parameter for use by the user equipments as a condition for measuring and reporting the frequencies for maintaining coverage but not for measuring and reporting the frequencies for offloading traffic.

18. The method according to claim 17, wherein each of the information elements is a Measurement Object information element, and the information elements having frequencies for offloading traffic are signaled separately from the information elements having frequencies for maintaining coverage.

19. The method according to claim 17, wherein the signal strength parameter is a non-zero value for s-Measure or s-Measure1, and the information elements having frequencies for offloading traffic are distinguished from the information elements having frequencies for maintaining coverage by presence or absence of a flag.

20. The method according to claim 19, wherein the network access node is a macro eNodeB operating in a heterogeneous network, and for each of the flags that is present the flag is a single bit per frequency and/or a single bit per information element.