WO2017162276A1 - Mitigating system capacity loss in high speed scenario - Google Patents
Mitigating system capacity loss in high speed scenario Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/32—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0009—Control or signalling for completing the hand-off for a plurality of users or terminals, e.g. group communication or moving wireless networks
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/32—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data
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Abstract
A wireless communication device (201) is assigned to a group (261) comprising at least one other wireless communication device with similar movement or travel pattern. Serving cell (211) reception status is obtained from wireless communication devices in this group and, based on the obtained serving cell reception status, a prediction is made of when the first wireless communication device will not be able to receive the serving cell anymore. The wireless communication device is then subjected to prohibitive scheduling when determined that it is out of sufficient serving cell coverage, thereby minimizing wasting of radio resources (and hence avoids decreasing system throughput) by only scheduling the wireless communication device when it can receive the serving cell.
Description
MITIGATING SYSTEM CAPACITY LOSS IN HIGH SPEED SCENARIO
TECHNICAL FIELD
Embodiments herein relate to wireless communication and more specifically to uplink signal processing control in a scenario where wireless communication devices are moving at high speeds.
BACKGROUND
Wireless communication systems, i.e. systems that provide communication services to wireless communication devices such as mobile phones, smartphones (often denoted by UE that is short for user equipment) as well as machine-type communication (MTC) devices, have evolved during the last decade into systems that must utilize the radio spectrum and other system resources in the most efficient manner possible. A reason for this is the ever increasing demand for high speed data communication capabilities in terms of, e.g., bitrate and to provide these capabilities at any given time, at any geographical location and also in scenarios where the wireless communication device is moving at a high speed, e.g., on board a high speed train.
To meet this demand, within the third generation partnership project (3GPP) work is being done regarding possible enhancements to radio resource management, RRM, performance in high speed train (HST) environments. The justification is that there are railways such as Japan Tohoku Shinkansen (running at 320km/h), German ICE
(330km/h), AGV Italo (400km/h), and Shanghai Maglev (430km/h) at which vehicles travel at greater speed than 300km/h and where there is demand for using mobile services.
While it is necessary to handle such HST scenarios, it is still necessary for wireless communication devices to operate as energy efficient as possible, for example by minimizing the use of radio circuitry when little radio transmission and reception is expected. One way of dealing with this issue has been specified since long in the 3GPP standard specifications, namely discontinuous reception (DRX). DRX is specified such that a wireless communication device activates radio reception circuitry only during short cyclic intervals that may have various cycle lengths.
A drawback of the energy saving scheme specified by DRX becomes noticeable in a scenario where a wireless communication device is located on a high speed train and as a consequence of this experiences an outage situation. Specifically, the wireless
communication device, while in inactivity, may lose coverage of the serving cell without being aware of it. For example, when a wireless communication device is operating according to a scheme with a DRX cycle that is on the same order as a spatial extension of a cell divided by the speed with which the wireless communication device is moving, a so-called outage situation may occur. In some detail, when the wireless communication device wakes up for an ON duration it does not manage to receive anything on the physical downlink control channel (PDCCH) and hence it estimates a low signal to interference and noise ratio (SINR) for the serving cell. After having estimated a low SINR for some time (described in some detail below), RLF is triggered, by which the UE tries to re-establish the connection to the network.
During the work at 3GPP (at RAN4#77) a candidate solution (solution 7 in R4-157272) for reducing outage of wireless communication devices operating in radio resource control (RRC) connected mode with a long DRX cycle (larger than 160ms) in a high-speed train scenario was approved. The solution has been included in the study item report "Study on performance enhancements for high-speed scenario in LTE (Release 13)" 3GPP TR 36.878. The candidate solution, captured in clause 6.3.4 of V2.0.0, is based on reducing the radio link monitoring (RLM) window and the time to trigger a radio link failure (RLF). By reducing the window and/or the time to trigger, the wireless communication device will react sooner on the fact that it has lost coverage of the serving cell, and hence will initiate RRC connection re-establishment earlier than it would with legacy RLM configuration (i.e., up to and including Release 12 of the 3GPP specifications).
Radio link monitoring and associated core network requirements are described in 3GPP TS 36.213 V12.7.0 clause 4.2.1 and 3GPP TS 36.133 V12.9.0 clause 7.6, respectively. The serving cell shall be monitored over TEvaiuate as shown in table 1 below. For example, if the DRX cycle is 640ms or larger, the physical layer in the wireless communication device shall evaluate the serving cell radio link quality over 5 DRX cycles (3.2sec) before indicating to higher layers whether the wireless communication device is in-sync or out-of- sync with the serving cell. In practice the evaluation period is a sliding time window and in- sync and out-of-sync status is reported to higher layers every DRX cycle based on the conditions over the five most recent DRX cycles. Hence it may take several DRX cycles before bad conditions are resulting in an out-of-sync indication to higher layers.
Table 1 :
and Qin Evaluation Period in DRX (3GPP TS 36.133 V12.9.0 Table 7.6.2.2-1 )
Higher layers receive the out-of-sync and in-sync indications from the physical layer and handle them as described in 3GPP TS 36.331 V12.7.0 clause 5.3.1 1. Particularly the UE shall:
1> upon receiving N310 consecutive "out-of-sync" indications for the PCell from lower layers while neither T300, T301, T304 nor T311 is running:
2> start timer T310;
Upon expiry of the T310 timer, a RLF is triggered and a RRC connection re-establishment is initiated. Typical values for N310 and T310 are 1 and 1000ms, respectively.
In worst case for the example of a 640ms DRX cycle it will take 3 to 4 seconds after the wireless communication device has lost serving cell coverage before RLF is triggered. For even longer DRX cycle the time increases and may be as much as 10-12 seconds.
The approved candidate solution above aims at reducing the evaluation period from five to for instance one or a few DRX cycles and/or reducing T310 in order for the UE to detect RLF and initiate RRC connection re-establishment earlier.
However, such a proposal on reducing the RLF detection time does not change the fact that the long DRX cycle in DRX connected mode leads to that the wireless communication device is unaware of when it is losing serving cell coverage. The issue could have been addressed by configuring only shorter DRX cycles (e.g. up to 320ms) thereby allowing the wireless communication device to identify a candidate target cell before losing serving cell coverage, but there is a strong push from, e.g., network operators to support any DRX cycle length.
Allowing the UE by configuration or design to lose coverage means that there will be an impact on the system performance (e.g. in terms of wasting radio resources in turn decreasing the system throughput). The reason is that the network node may try to schedule the wireless communication device at an ON duration when the wireless communication device is not able to receive PDCCH and a physical downlink shared channel (PDSCH). The allocations used when transmitting to the wireless communication device on the downlink could instead have been used for another wireless communication device capable of receiving PDCCH and PDSCH.
SUMMARY In view of the above, an object of the present disclosure is to overcome or at least mitigate at least some of the drawbacks related to DRX in a HST scenario.
This is achieved in a first aspect by a method performed by a network node. The network node is connected to at least one antenna node that is maintaining a serving radio cell such that a plurality wireless communication devices can communicate with the network node in the serving cell. The method comprises detecting a radio frequency, RF, signal followed by a determination that the detected RF signal originates from a wireless communication device of a group of wireless communication devices. This group of wireless communication devices comprises wireless communication devices that are associated with a common motion characteristic. From at least a subset of the wireless communication devices in the group, a determination is made of respective radio reception status value, and a representative radio reception status value is determined based on the obtained radio reception status values. A calculation then follows, based on
the representative radio reception status value, of a prediction of a point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell. A determination is made that the predicted point in time is imminent and as a consequence of this determination, a control procedure associated with the wireless communication device is performed. This control procedure comprises a prohibitive scheduling action applicable at the point in time when the wireless
communication device will be in an area of non-acceptable radio reception conditions in the serving cell.
In other words, a wireless communication device is assigned to a group comprising at least one other wireless communication device with similar movement or travel pattern. Serving cell reception status is obtained from wireless communication devices in this group and, based on the obtained serving cell reception status, a prediction is made of when the first wireless communication device will not be able to receive the serving cell anymore. The wireless communication device is then subjected to prohibitive scheduling when determined that it is out of sufficient serving cell coverage.
This is advantageous in that it minimizes or even avoids wasting of radio resources (and hence avoids decreasing the system throughput) by only scheduling the wireless communication device when it can receive the serving cell.
In some embodiments, the determination that the detected at least one RF signal originates from a wireless communication device of a group of wireless communication devices having a common motion characteristic may comprise a determination of a RF offset of the detected at least one RF signal relative to a nominal uplink carrier frequency. A determination is then made that the RF offset is equal to a previously determined RF offset associated with a wireless communication device. In some embodiments, the determination that the detected at least one RF signal originates from a wireless communication device of a group of wireless communication devices having a common motion characteristic may comprise a determination of a velocity of the wireless communication device. A determination is then made that the velocity is equal to a previously determined velocity associated with a wireless communication device. For example, the determination of a velocity may comprise obtaining predetermined information available to the network node, where the
predetermined information comprises information associated with geographic locations of the at least one antenna node.
In some embodiments, the determination of a radio reception status value may comprise receiving any of a reference signal received power (RSRP) measurement report, a reference signal received quality (RSRQ) measurement report, a reference signal signal to interference and noise ratio (RS-SINR) measurement report and a channel quality indication (CQI) report. In some embodiments, the determination of a radio reception status value may comprises a determination that no acknowledge (ACK) or negative ACK (NACK) response has been received to a transmitted request.
In some embodiments, the determination of a representative radio reception status value may comprise a statistical calculation. In some embodiments, the calculation of a prediction of a point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell may comprise using the determined velocity and/or a report received from the wireless communication device in relation to the determined representative radio reception status. In some embodiments, the prohibitive scheduling action may comprise preventing use of any of a downlink communication resource and an uplink communication resource.
In some embodiments, the prevention of use of any of a downlink communication resource and an uplink communication resource may comprise discontinuing transmission of scheduling information in a PDCCH. For example, it may comprise a determination of a level of tightness of interaction between the wireless communication device and the serving cell. The discontinuing of transmission of scheduling information may then be conditioned on whether the level of tightness of interaction is below an interaction tightness threshold.
In other embodiments, the control procedure associated with the wireless communication device may comprise transmitting a command to order a handover to a neighbour cell. For example, it may comprise a determination of at least one point in time when the wireless communication device is to be active subsequent to a DRX period. The transmission of the command to order a handover may then be conditioned on whether the determined at least one point in time when the wireless communication device is to be active
subsequent to a DRX period is the last active period prior to the point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell.
In another aspect there is provided a network node configured to be connected to at least one antenna node that is maintaining a serving radio cell such that a plurality wireless communication devices can communicate with the network node in the serving cell. The network node comprises input/output circuitry, a processor and a memory. The memory contains instructions executable by the processor whereby the network node is operative to:
- detect a radio frequency, RF, signal,
- determine that the detected RF signal originates from a wireless communication device of a group of wireless communication devices, said group comprising wireless communication devices that are associated with a common motion characteristic, and
- determine, from at least a subset of the wireless communication devices in the group, a respective radio reception status value,
- determine a representative radio reception status value based on the obtained radio reception status values,
- calculate, based on the representative radio reception status value, a prediction of a point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell,
- determine that the predicted point in time is imminent and as a consequence:
- perform a control procedure associated with the wireless communication device, said control procedure comprising a prohibitive scheduling action applicable at the point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell.
In another aspect there is provided a computer program, comprising instructions which, when executed on at least one processor in a network node, cause the network node to carry out the method as summarized above in connection with the first aspect and the various embodiments of this aspect.
In another aspect there is provided a carrier comprising a computer program according to the summarized aspect above, wherein the carrier is one of an electronic signal, an optical signal, a radio signal and a computer readable storage medium. These other aspects provide the same effects and advantages as summarized above in connection with the method of the first aspect.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 schematically illustrates signal measurements in a HST scenario,
figure 2 schematically illustrates a network node, antenna nodes and a wireless communication device,
figures 3a, 3b and 3c are flowcharts of methods,
figure 4 schematically illustrates a wireless communication system,
figure 5 schematically illustrates functional blocks in a network node and in antenna nodes,
figure 6 schematically illustrates a network node, and
figure 7 schematically illustrates a network node.
DETAILED DESCRIPTION
A high speed scenario as discussed above is illustrated in figure 1 , where wireless communication devices 101 , e.g. one or more UE, are onboard west moving and east moving high speed trains 102,104 on railway tracks 151 . A first network node 1 10, which may be in the form of a radio base station, NodeB, enhanced NodeB (eNodeB), remote radio head (RRH) or any other similar radio network node, maintains a serving cell 1 1 1 , which, as the skilled person will realize, includes downlink (DL) and uplink (UL) radio lobes via which the UEs 101 can communicate with the network node 1 10 and other (not illustrated in figure 1 ) nodes in a communication network. Similarly, a second and a third node 120, 130 maintain respective neighbor cells 121 , 131.
Figure 1 also illustrates theoretical (i.e. simulated) average, and individual reference signal received power (RSRP) measurement result as function of distance from the antenna node 1 10 that maintains the serving cell 1 1 1 (centered at a distance mark of 3000m). Non-DRX and periodic reporting every 200ms by wireless communication devices has been assumed. The average is based on 50 wireless communication devices with randomized positions in a 100m long train travelling in the eastward direction at 350km/h. The dashed curve indicated for the neighbor cells 121 , 131 illustrates theoretical RSRP values for the neighbor cells 121 , 131 had they been measured instantaneously in the middle of the train 102,104. Referring now to figure 2, a network node 200 is connected to a plurality of antenna nodes 210, 220 and maintains cells where a plurality of wireless communication devices, including a wireless communication device 201 , are located. The wireless communication
device 201 may be in motion as indicated by a velocity vector 202, for example as a consequence of being on-board a high speed train such as any of the trains 102, 104 illustrated in figure 1 . Figure 2 further illustrates a plurality of wireless communication devices in the form of a group or subset 261 of wireless communication devices that are moving together with the wireless communication device 201.
The antenna nodes 210, 220 are controlled to maintain respective reception and transmission radio lobes that realize the cells 21 1 , 221 . As the skilled person will realize, reception and transmission radio lobes may have various and differing extent. However, such details are omitted from figure 2 for the sake of avoiding unnecessary detail when illustrating the embodiments of the present disclosure. For the sake of explaining the embodiments in the present disclosure, it is enough to illustrate that cell 21 1 is considered as a serving cell and that cell 221 is considered a neighbor cell.
Moreover, as indicated in figure 2, it is to be noted that the network node 200 may be considered as a single entity as well as a combination of a plurality of entities 240. For example, the network node 200 may be distributed, in terms of functionality as well as in terms of physical hardware, over one or more processing units that are residing in a logical entity 250 that may be defined as a "cloud". Nevertheless, as will be exemplified below, the network node 200 may also be in the form of a node in a 3GPP long term evolution (LTE) system. In the embodiments to be described below, the network node 200 is connected to at least the antenna node 210 that is maintaining the serving cell 21 1 such that a plurality wireless communication devices can communicate with the network node 200 in the serving cell 21 1 .
Turning now to figure 3a, and with continued reference to figure 2, a method will be described with reference to a number of actions that are performed by a network node, such as the network node 200.
Action 302
A detection is made of a radio frequency, RF, signal. Action 304
A determination is made that the detected RF signal originates from a wireless communication device 201 of a group 261 of wireless communication devices. The group
261 comprises wireless communication devices that are associated with a common motion characteristic.
For example, in some embodiments, this determination that said detected at least one RF signal originates from a wireless communication device of a group of wireless
communication devices having a common motion characteristic may comprise a determination of an RF offset of the detected at least one RF signal relative to a nominal uplink carrier frequency. A determination may then be made that the RF offset is equal to a previously determined RF offset associated with a wireless communication device. In these embodiments, the nominal uplink carrier frequency may be associated with at least one of a physical random access channel, PRACH, a physical uplink shared channel, PUSCH, a physical uplink control channel, PUCCH, an uplink, UL, reference signal, and a Sounding Reference Signal, SRS.
In other embodiments, this determination that the detected at least one RF signal originates from a wireless communication device of a group of wireless communication devices having a common motion characteristic may comprise a determination of a velocity of the wireless communication device. A determination may then be made that the velocity is equal to a previously determined velocity associated with a wireless communication device. In these embodiments, the determination of a velocity may comprise obtaining predetermined information available to the network node. This predetermined information may comprise information associated with geographic locations of the at least one antenna node.
Action 306
A determination is made, from at least a subset of the wireless communication devices in the group 261 , of a respective radio reception status value. For example, in some embodiments the determination of a radio reception status value may comprise receiving any of an RSRP measurement report, an RSRQ, measurement report, an RS-SINR, measurement report, and a CQI report.
Moreover, in some embodiments, the determination of a radio reception status value may comprise a determination that no ACK or NACK response has been received to a transmitted request.
Action 308
A determination is made of a representative radio reception status value based on the obtained radio reception status values.
In various embodiments, such a determination may comprise a statistical calculation. For example statistical mean, median, percentile values etc. may be calculated.
Action 310
A calculation is made, based on the representative radio reception status value, of a prediction of a point in time when the wireless communication device 201 will be in an area of non-acceptable radio reception conditions in the serving cell 21 1. For example, in some embodiments, the calculation of a prediction of a point in time when the wireless communication device 201 will be in an area of non-acceptable radio reception conditions in the serving cell 21 1 may comprise using a determined velocity of the wireless communication device 201 as well as any of the reports received (in various embodiments of action 306) from the wireless communication device 201 in relation to the determined (in action 308) representative radio reception status.
Action 312
A determination is made that the predicted point in time is imminent. It is to be understood that a definition of "imminent" is a measure of time that is to be seen in relation to a sum of one or more time periods, known to the network node 200, that are required for operations that are to be performed before the wireless communication device 201 will be in an area of non-acceptable radio reception conditions in the serving cell 21 1 . For example, a sum of times needed for operations that are part of an implementation of action 314 may be used in the determination of this action 312.
Action 313
As a consequence of determination in action 312 that the predicted point in time is not imminent, the network node may continue normal operation including continued scheduling of wireless communication devices in any appropriate manner, as the skilled person will realize.
Action 314
As a consequence of the determination in action 312 that the predicted point in time is imminent, a control procedure associated with the wireless communication device 201 is
performed. The control procedure comprises a prohibitive scheduling action applicable at the point in time when the wireless communication device 201 will be in an area of non- acceptable radio reception conditions in the serving cell 21 1 .
For example, in some embodiments the prohibitive scheduling action may comprise preventing use of any of a downlink communication resource and an uplink
communication resource such as discontinuing transmission of scheduling information in a PDCCH. Such embodiments may comprise, as illustrated in figure 3b, a determination 320 of a level of tightness of interaction between the wireless communication device 201 and the serving cell 21 1. The discontinuing 324 transmission of scheduling information may then be conditioned, in action 322, on whether the level of tightness of interaction is below an interaction tightness threshold. In case the level of tightness of interaction is not below the interaction tightness threshold, the method returns to action 313.
In other embodiments, the control procedure 314 may comprise transmitting a command to order a handover to a neighbour cell 221 . Such embodiments may comprise, as illustrated in figure 3c, a determination 330 of at least one point in time when the wireless communication device 201 is to be active subsequent to a DRX period. The transmission 334 of the command to order a handover may then be conditioned, in action 332, on whether the determined at least one point in time when the wireless communication device 201 is to be active subsequent to a DRX period is the last active period prior to the point in time when the wireless communication device 201 will be in an area of non- acceptable radio reception conditions in the serving cell 21 1 . In case it is not the last active period prior to the point in time when the wireless communication device 201 will be in an area of non-acceptable radio reception conditions in the serving cell 21 1 , the method returns to action 313. What these various combinations of actions illustrate are embodiments wherein the network node 200 keeps track of the link status for the active wireless communication devices in the group 261 and based on received link status forms a representative radio link status for the entire group 261 (actions 306, 308). Using this determined link status, in the prediction action 310, for the group 261 the network node 200 may for instance, in action 314, stop scheduling a wireless communication device belonging to the concerned group 261 when some fraction or number of wireless communication devices in the group 261 have been unresponsive (not sent ACK/NACK upon having been scheduled, not
reported CQI or signal strength and quality measurements when expected to, etc.) or have reported a stronger neighbor cell to which they have or are about to be handed over.
Once such instance has been detected, in some embodiments and as discussed above in connection with figure 3b, the network node 200 only schedules a wireless communication 5 device that is interacting tightly enough with the network node (tightness being defined, e.g., by having a short DRX cycle, or being in non-DRX, hence the network node 200 having good knowledge of the exact link status compared to wireless communication devices in long DRX cycles having not exact knowledge) for being able to detect when a more suitable cell than the serving cell is found. In some embodiments the network node 10 200 may even try to reconfigure shorter DRX cycle for wireless communication devices having longer DRX cycles, that in order to get better knowledge of actual radio link performance.
The network node 200 may in some embodiments build up statistics (using reports such as those that may form part of action 306) on where a de facto cell border is between the 15 serving cell 21 1 and the neighbor cell 221 . The velocity estimates (e.g. obtained in action 304) may then be used to determine (in action 310) when the wireless communication device 201 , in case it has a long DRX cycle included in the group 261 (where at least one interact tightly with the network node 200) will pass the cell border.
As discussed above in connection with figure 3c, in some embodiments the network node 20 200, the control procedure in action 314 involves handing the wireless communication device 201 over to the neighbor cell 221 in the ON duration just before the wireless communication device 201 is predicted to cross the cell border (noting that such handover is typically denoted blind handover). The network node can acquire and use statistics from other wireless communication devices in the group 261 to determine when the target cell 25 is strong enough for the wireless communication device 201 to detect and connect to. The blind handover triggers the wireless communication device 201 to search intensely for the target cell (i.e. neighbor cell 221 ) and hence in this respect looser cell detection requirements where, typically, a wireless communication device has 20 DRX cycles to find, measure and report a cell, are side-stepped and the wireless communication device 30 shall complete the detection within 80 or 800ms depending on side conditions (cf. 3GPP TS 36.133 V12.9.0 clauses 5.1.2.1 and 8.1 .2.2).
More specifically, when the group 261 of wireless communication devices is approaching a cell border (e.g. between serving cell 21 1 and neighbor cell 221 ), the network node 200
may determine for each of the wireless communication devices in the group 261 that is configured with a DRX cycle that is longer than a threshold value, e.g. 320ms
(corresponding to 31 m distance travelled between DRX ON-times when traveling at 350km/h), when the last DRX ON-time occurs before the wireless communication device 5 201 ideally should be handed over to the neighbor cell 221 . For such a wireless
communication device 201 the network node 201 may issue a handover command, which is blind in case the wireless communication device 201 has not reported (periodically or event-triggered) the target cell (here the neighbor cell 221 ). The wireless communication device 201 will search for the target/neighbor cell 221 continuously regardless of the DRX 10 cycle configured in the source cell (i.e. the serving cell 21 1 ), and will perform a random access to the neighbor cell 221 as soon as it finds it.
The network node 200 may further adapt the T304 handover timer (3GPP TS 36.331 V12.7.0 clause 6.3.4) to have suitable length with respect to how long time it takes until the wireless communication device 201 reaches the cell border between the serving cell
15 21 1 and the neighbor cell 221 . The T304 timer value is transmitted to the wireless
communication device 201 in a message that is the same message as the handover command, and the timer T304 may be set to any of the values 50, 100, 200, 500, 1000 and 2000ms. Even though the longest handover timer value is shorter than the maximum DRX cycle length, i.e. 2s vs 2.56s, when the wireless communication device 201 is close
20 to the cell border between the serving cell 21 1 and the neighbor cell 221 it will be able to detect and perform random access towards the neighbor cell 221 as long as the SINR is larger than -3dB. The main problem with long DRX cycles in high-speed scenarios is not the cell detection as such, but the slow round-trip time from detection, via reporting and to receiving a handover command.
25 Turning now to figure 4, which illustrates parts of a 3GPP long term evolution, LTE, wireless network 400 and a compatible core network. Base stations (enhanced NodeB, eNodeB or eNB) 406, 407, 408 are communicating with each other over an X2 interface. The base stations 406, 407 and 408 are connected to a mobility management entity, MME, 410, which keeps information about UEs (i.e. UE contexts) regarding capabilities
30 etc., which the MME 410 shares, e.g., with base stations connected to it. The MME 410 is also managing handover of a UE from one MME to another when a UE leaves the pool of base stations managed by a source MME, or when the X2 connection is missing between the source and target base stations.
The base stations 406, 407 and 408 are further connected to a serving gateway, SGW, 412, which is handing the user data plane transport to and from the base station to which a UE is connected, and to one or more packet data network gateways, PGW, 414, which connect UEs to the internet 416. The MME in whose pool of base stations a UE resides configures which base station the SGW shall connect to for transport of the UE user plane data.
In figure 4, the base station 408 is a network node as defined above and the base station/network node 408 is connected to a number of antenna nodes 420a-f. The base station/network node 408 controls the antenna nodes 420a-f as discussed herein and thereby maintaining respective cells 421 a-f. A UE 430 is illustrated, which may
correspond to any wireless communication device described herein.
Processing actions as exemplified above may be handled by a single network node such as an eNodeB (as indicated in figure 4) using antenna nodes in the form of remote radio heads, RRH, or remote radio units, RRU, for the individual cells 421 a-f. Processing of actions may in other embodiments be handled by a group of eNodeBs with or without RRHs or RRUs operating in a cooperative manner, or such group of eNodeBs under coordination of another network node, either a new entity or an existing one with extended functionality, e.g. an MME.
Turning now to figure 5, an example of arrangements, in the form of functional blocks, in a network node will be described in some more detail. The arrangements in figure 5 may be comprised in any of the network nodes discussed above in connection with figures 2 and 4.
A radio resource management (RRM) circuit 500 comprises an Inter-cell RRM unit 510 for handling information and processing in relation to mobility of wireless communication devices between cells in a wireless communication network, e.g. a single frequency network (SFN), where cells may have one and the same or different physical cell identities.
An intra-cell RRM unit 520 is comprised in the RRM circuit 500, the intra-cell RRM unit 520 being capable of handling information and processing in relation to mobility within a cell (e.g. part of a SFN cell) managed by this network node, e.g. eNodeB, as exemplified herein.
A scheduling unit 530 is configured, in addition to scheduling operations that are outside of the present disclosure, to handle scheduling of communication as described herein.
The Intra-RRM unit further comprises a velocity and position determination unit 525 that is configured to determine position and velocity of wireless communication devices based on various kinds of measurements (e.g. as discussed herein).
A baseband processing unit 540 comprises one or more baseband processing units 560 connected to a SGW via a user plane packet router 550, and connected to transceiver circuits 580 comprising RF circuitry 590 via a baseband signal router 570. Connection with antenna nodes 595 is realized via the transceiver circuits 580. Turning now to figure 6, a schematically illustrated network node 600 will be described in some more detail. The network node 600 is configured to be connected to at least one antenna node that is maintaining a serving radio cell such that a plurality wireless communication devices can communicate with the network node in the serving cell. The network node comprises input/output circuitry 606, a processor 602 and a memory 604. The memory contains instructions executable by the processor 602 whereby the network node 600 is operative to:
- detect a radio frequency, RF, signal,
- determine that the detected RF signal originates from a wireless communication device 201 of a group 261 of wireless communication devices, said group comprising wireless communication devices that are associated with a common motion characteristic,
- determine, from at least a subset of the wireless communication devices in the group, a respective radio reception status value,
- determine a representative radio reception status value based on the obtained radio reception status values,
- calculate, based on the representative radio reception status value, a prediction of a point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell, and
- determine that the predicted point in time is imminent and as a consequence:
- perform a control procedure associated with the wireless communication device, said control procedure comprising a prohibitive scheduling action applicable at the point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell.
The instructions that are executable by the processor 602 may be software in the form of a computer program 641 . The computer program 641 may be contained in or by a carrier 642, which may provide the computer program 641 to the memory 604 and processor 602. The carrier 642 may be in any suitable form including an electronic signal, an optical signal, a radio signal or a computer readable storage medium.
In some embodiments, the network node 600 is operative such that the determination that the detected at least one RF signal originates from a wireless communication device of a group of wireless communication devices having a common motion characteristic comprises:
- determining a RF offset of the detected at least one RF signal relative to a nominal uplink carrier frequency, and
- determining that the RF offset is equal to a previously determined RF offset associated with a wireless communication device.
In some embodiments, the network node 600 is operative such that the nominal uplink carrier frequency is associated with at least one of:
- a physical random access channel, PRACH,
- a physical uplink shared channel, PUSCH,
- a physical uplink control channel, PUCCH,
- an uplink, UL, reference signal, and
- a Sounding Reference Signal, SRS.
In some embodiments, the network node 600 is operative such that the determination that the detected at least one RF signal originates from a wireless communication device of a group of wireless communication devices having a common motion characteristic comprises:
- determining a velocity of the wireless communication device 201 , and
- determining that the velocity is equal to a previously determined velocity associated with a wireless communication device.
In some embodiments, the network node 600 is operative such that the determination of a velocity comprises:
- obtaining predetermined information available to the network node 600, the predetermined information comprising information associated with geographic locations of the at least one antenna node 210.
In some embodiments, the network node 600 is operative such that the determination of a radio reception status value comprises receiving any of:
- a reference signal received power, RSRP, measurement report,
- a reference signal received quality, RSRQ, measurement report,
- a reference signal signal to interference and noise ratio, RS-SINR, measurement report, and
- a channel quality indication, CQI, report.
In some embodiments, the network node 600 is operative such that the determination of a radio reception status value comprises:
- determining that no acknowledge, ACK, or negative ACK, NACK, response has been received to a transmitted request.
In some embodiments, the network node 600 is operative such that the determination of a representative radio reception status value comprises a statistical calculation.
In some embodiments, the network node 600 is operative such that the calculation of a prediction of a point in time when the wireless communication device 201 will be in an area of non-acceptable radio reception conditions in the serving cell 21 1 comprises using any of:
- the determined velocity, and
- a report received from the wireless communication device 201 in relation to the determined representative radio reception status.
In some embodiments, the network node 600 is operative such that the prohibitive scheduling action comprises preventing use of any of a downlink communication resource and an uplink communication resource.
In some embodiments, the network node 600 is operative such that the prevention of use of any of a downlink communication resource and an uplink communication resource comprises discontinuing transmission of scheduling information in a physical downlink control channel, PDCCH.
In some embodiments, the network node 600 is operative to:
- determine a level of tightness of interaction between the wireless communication device 201 and the serving cell 21 1 , and operative such that the discontinuing
transmission of scheduling information is conditioned on whether the level of tightness of interaction is below an interaction tightness threshold.
In some embodiments, the network node 600 is operative such that the control procedure comprises transmitting a command to order a handover to a neighbour cell 221. In some embodiments, the network node 600 is operative to:
- determine at least one point in time when the wireless communication device 201 is to be active subsequent to a discontinuous reception, DRX, period, and operative such that the transmission of the command to order a handover is conditioned on whether the determined at least one point in time when the wireless communication device 201 is to be active subsequent to a DRX period is the last active period prior to the point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell 21 1.
Figure 7, illustrates schematically a network node 800 that comprises:
- a detecting module 702 configured to detect a radio frequency, RF, signal,
- a determining module 704 configured to determine that the detected RF signal originates from a wireless communication device of a group of wireless communication devices, said group comprising wireless communication devices that are associated with a common motion characteristic,
- a determining module 706 configured to determine, from at least a subset of the wireless communication devices in the group, a respective radio reception status value,
- a determining module 708 configured to determine a representative radio reception status value based on the obtained radio reception status values,
- a calculating module 710 configured to calculate, based on the representative radio reception status value, a prediction of a point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell, and
- a determining module 712 configured to determine that the predicted point in time is imminent, and
- a performing module 714 configured to perform a control procedure associated with the wireless communication device, said control procedure comprising a prohibitive scheduling action applicable at the point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell.
The network node 700 may comprise further modules that are configured to perform in a similar manner as, e.g., the network node 600 described above in connection with figure 6.
Claims
1 . A method performed by a network node (200), where the network node is connected to at least one antenna node (210) that is maintaining a serving radio cell (21 1 ) such that a plurality wireless communication devices can communicate with the network node in the serving cell, the method comprising:
- detecting (302) a radio frequency, RF, signal,
- determining (304) that the detected RF signal originates from a wireless communication device (201 ) of a group (261 ) of wireless communication devices, said group comprising wireless communication devices that are associated with a common motion characteristic,
- determining (306), from at least a subset of the wireless communication devices in the group, a respective radio reception status value,
- determining (308) a representative radio reception status value based on the determined radio reception status values,
- calculating (310), based on the representative radio reception status value, a prediction of a point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell, and
- determining (312) that the predicted point in time is imminent and as a consequence:
- performing (314) a control procedure associated with the wireless communication device, said control procedure comprising a prohibitive scheduling action applicable at the point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell.
2. The method of claim 1 , wherein said determination that said detected at least one RF signal originates from a wireless communication device of a group of wireless
communication devices having a common motion characteristic comprises:
- determining a RF offset of the detected at least one RF signal relative to a nominal uplink carrier frequency, and
- determining that the RF offset is equal to a previously determined RF offset associated with a wireless communication device.
3. The method of claim 2, wherein said nominal uplink carrier frequency is associated with at least one of:
- a physical random access channel, PRACH,
- a physical uplink shared channel, PUSCH,
- a physical uplink control channel, PUCCH,
- an uplink, UL, reference signal, and
- a Sounding Reference Signal, SRS.
4. The method of claim 1 , wherein said determination that said detected at least one RF signal originates from a wireless communication device of a group of wireless
communication devices having a common motion characteristic comprises:
- determining a velocity of the wireless communication device, and
- determining that the velocity is equal to a previously determined velocity associated with a wireless communication device.
5. The method of claim 4, wherein said determination of a velocity comprises:
- obtaining predetermined information available to the network node, said predetermined information comprising information associated with geographic locations of the at least one antenna node.
6. The method of any of claims 1 -5, wherein said determining a radio reception status value comprises receiving any of:
- a reference signal received power, RSRP, measurement report,
- a reference signal received quality, RSRQ, measurement report,
- a reference signal signal to interference and noise ratio, RS-SINR, measurement report, and
- a channel quality indication, CQI, report.
7. The method of any of claims 1 -6, wherein said determining a radio reception status value comprises:
- determining that no acknowledge, ACK, or negative ACK, NACK, response has been received to a transmitted request.
8. The method of any of claims 1 -7, wherein said determining a representative radio reception status value comprises a statistical calculation.
9. The method of any of claims 4-8, wherein said calculation of a prediction of a point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell comprises using any of:
- said determined velocity, and
- a report received from the wireless communication device in relation to said determined representative radio reception status.
10. The method of any of claims 1 -9, wherein said prohibitive scheduling action comprises preventing use of any of a downlink communication resource and an uplink
communication resource.
1 1 . The method of claim 10, wherein said preventing use of any of a downlink
communication resource and an uplink communication resource comprises discontinuing (324) transmission of scheduling information in a physical downlink control channel, PDCCH.
12. The method of claim 1 1 , comprising:
- determining (320) a level of tightness of interaction between the wireless
communication device and the serving cell, and wherein the discontinuing transmission of scheduling information is conditioned (322) on whether the level of tightness of interaction is below an interaction tightness threshold.
13. The method of any of claims 1 -9, wherein said control procedure comprises transmitting (334) a command to order a handover to a neighbour cell (221 ).
14. The method of claim 13, comprising:
- determining (330) at least one point in time when the wireless communication device is to be active subsequent to a discontinuous reception, DRX, period, and wherein the transmission of the command to order a handover is conditioned (332) on whether the determined at least one point in time when the wireless communication device is to be active subsequent to a DRX period is the last active period prior to the point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell.
15. A network node (200, 600) configured to be connected to at least one antenna node (210) that is maintaining a serving radio cell (21 1 ) such that a plurality wireless
communication devices can communicate with the network node in the serving cell, the network node comprising input/output circuitry (606), a processor (602) and a memory (604), said memory containing instructions executable by said processor whereby said network node is operative to:
- detect a radio frequency, RF, signal,
- determine that the detected RF signal originates from a wireless communication device (201 ) of a group (261 ) of wireless communication devices, said group comprising wireless communication devices that are associated with a common motion characteristic,
- determine, from at least a subset of the wireless communication devices in the group, a respective radio reception status value,
- determine a representative radio reception status value based on the obtained radio reception status values,
- calculate, based on the representative radio reception status value, a prediction of a point in time when the wireless communication device will be in an area of non- acceptable radio reception conditions in the serving cell, and
- determine that the predicted point in time is imminent and as a consequence:
- perform a control procedure associated with the wireless communication device, said control procedure comprising a prohibitive scheduling action applicable at the point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell.
16. The network node of claim 15, operative such that said determination that said detected at least one RF signal originates from a wireless communication device of a group of wireless communication devices having a common motion characteristic comprises:
- determining a RF offset of the detected at least one RF signal relative to a nominal uplink carrier frequency, and
- determining that the RF offset is equal to a previously determined RF offset associated with a wireless communication device.
17. The network node of claim 16, operative such that said nominal uplink carrier frequency is associated with at least one of:
- a physical random access channel, PRACH,
- a physical uplink shared channel, PUSCH,
- a physical uplink control channel, PUCCH,
- an uplink, UL, reference signal, and
- a Sounding Reference Signal, SRS.
18. The network node of claim 15, operative such that said determination that said detected at least one RF signal originates from a wireless communication device of a group of wireless communication devices having a common motion characteristic comprises:
5 - determining a velocity of the wireless communication device, and
- determining that the velocity is equal to a previously determined velocity associated with a wireless communication device.
19. The network node of claim 18, operative such that said determination of a velocity comprises:
10 - obtaining predetermined information available to the network node, said
predetermined information comprising information associated with geographic locations of the at least one antenna node.
20. The network node of any of claims 15-19, operative such that said determining a radio reception status value comprises receiving any of:
15 - a reference signal received power, RSRP, measurement report,
- a reference signal received quality, RSRQ, measurement report,
- a reference signal signal to interference and noise ratio, RS-SINR, measurement report, and
- a channel quality indication, CQI, report.
20 21 . The network node of any of claims 15-20, operative such that said determining a radio reception status value comprises:
- determining that no acknowledge, ACK, or negative ACK, NACK, response has been received to a transmitted request.
22. The network node of any of claims 15-21 , operative such that said determining a 25 representative radio reception status value comprises a statistical calculation.
23. The network node of any of claims 18-22, operative such that said calculation of a prediction of a point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell comprises using any of:
- said determined velocity, and
5 - a report received from the wireless communication device in relation to said determined representative radio reception status.
24. The network node of any of claims 15-23, operative such that said prohibitive scheduling action comprises preventing use of any of a downlink communication resource and an uplink communication resource.
10 25. The network node of claim 24, operative such that said preventing use of any of a downlink communication resource and an uplink communication resource comprises discontinuing transmission of scheduling information in a physical downlink control channel, PDCCH.
26. The network node of claim 25, operative to:
15 - determine a level of tightness of interaction between the wireless communication device and the serving cell, and operative such that the discontinuing transmission of scheduling information is conditioned on whether the level of tightness of interaction is below an interaction tightness threshold.
27. The network node of any of claims 15-23, operative such that said control procedure 20 comprises transmitting a command to order a handover to a neighbour cell (221 ).
28. The network node of claim 27, operative to:
- determine at least one point in time when the wireless communication device is to be active subsequent to a discontinuous reception, DRX, period, and operative such that the transmission of the command to order a handover is conditioned on whether the
determined at least one point in time when the wireless communication device is to be active subsequent to a DRX period is the last active period prior to the point in time when the wireless communication device will be in an area of non-acceptable radio reception conditions in the serving cell.
29. A computer program (641 ) comprising instructions which, when executed on at least one processor (602) in a network node (600), cause the network node to carry out the method according to any one of claims 1 to 14.
30. A carrier (642), comprising the computer program of claim 29, wherein the carrier is one of an electronic signal, an optical signal, a radio signal and a computer readable storage medium.
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| PCT/EP2016/056316 WO2017162276A1 (en) | 2016-03-23 | 2016-03-23 | Mitigating system capacity loss in high speed scenario |
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