WO2018078216A1

WO2018078216A1 - Mitigating backhaul interference

Info

Publication number: WO2018078216A1
Application number: PCT/FI2017/050737
Authority: WO
Inventors: Seungmo Kim; Eugene Visotsky; Mark Cudak; Ravindra MOORUT
Original assignee: Nokia Technologies Oy
Priority date: 2016-10-25
Filing date: 2017-10-24
Publication date: 2018-05-03

Abstract

An apparatus caused to perform: detecting uplink transmissions from a plurality of user equipments (UEs); determining that at least one of the detected uplink transmissions exceeds a pre-determined interference threshold; identifying a cell from the at least one detected uplink transmission; and sending an interference notice to an access point associated with the identified cell.

Description

MITIGATING BACKHAUL INTERFERENCE

TECHNOLOGICAL FIELD:

The described invention relates to mitigating interference in wireless networks by user equipments (UEs), and more particularly relates to mitigating UE interference to backhaul links such as may be deployed for 5G and/or other new radio systems.

BACKGROUND:

Many of the cellular radio access technologies in use today arose from basic research and/or early planning of the International Telecommunication Union (ITU). During the ITU's World Radiocommunication Conference (WRC-15; Geneva, Switzerland; 2-27 November 2015) a Resolution 238 was adopted to explore the possible addition of frequencies between 24.25 and 86 GHz for primary mobile services. Resolution 238 is entitled "STUDIES ON FREQUENCY-RELATED

MATTERS FOR INTERNATIONAL MOBILE TELECOMMUNICATIONS IDENTIFICATION INCLUDING POSSIBLE ADDITIONAL ALLOCATIONS TO THE MOBILE SERVICES ON A PRIMARY BASIS IN PORTION(S) OF THE FREQUENCY RANGE BETWEEN 24.25 AND 86 GHZ FOR THE FUTURE DEVELOPMENT OF

INTERNATIONAL MOBILE TELECOMMUNICATION FOR 2020 AND BEYOND." Its purpose is to study, in time for the WRC conference in 2019, sharing and compatibility studies for certain bands within that range. Many of these bands will require sharing solutions to unlock their potential for flexible use services. Some of these bands like the 70GHz (71-76GHz) and 80GHz (81-86GHz) have backhaul as incumbent that needs to be protected.

In July 2016 the Federal Communications Commission (FCC) of the US released a FURTHER NOTICE OF PROPOSED RULEMAKING to adopt rules allowing flexible fixed and mobile uses in mmWave bands such as 71-76GHz (70GHz band) and 81-86GHz (80GHz band). At that time there were approximately 22,600 registered fixed links in the 71-76 GHz and 81-86 GHz bands. Previously the FCC's position was that it may not be possible to allow mobile access in these bands without causing interference to the fixed point-to-point links, but more thorough study shows these bands have relatively few registered users concentrated at relatively specific locales; see FIG. 1 for a map of the United States showing locations for those registered sites. Even beyond that map, it is notable that as of June 2016 only 16 counties in the entire US had an average site density of more than one transmission or reception site per square mile, and those 16 counties together contain more than 73 percent of all registered transmitters and receivers in the 71-76 and 81-86 GHz bands. Given the narrow beamwidths and limited path lengths involved (mm Wave systems are generally line-of-sight/LOS due to inherent propagation characteristics at GHz bands), it is reasonable to treat the remaining 3,125 counties and county-equivalents as the functional equivalent of a 'green field'.

The 3 GPP organization is developing 5^th Generation (5G) wireless networks [formally known as New Radio (NR) but often referred to as 5G] that is to utilize radio spectrum on the order of GHz or more in the millimeter-wave (mm Wave) band; generally at 6 GHz and below. Due to these frequencies being largely line-of-sight, 5G is expected to use large numbers of antennas and aggressive beamforming, and it is assumed that many of the access points/transmission points would be best connected to the network backbone only wirelessly. FIG. 1 shows the 70/80 GHz bands are relatively available and can be used for backhaul links carrying data and control signaling from the network access points to the core network and other networks (Internet). By the time it is deployed it may be that the frequency bands for 5G mobile communications are similar to the frequency bands used for backhaul, in which case there would be a risk of interference between the mobile communications with the UEs and wireless backhaul links. These teachings address how to mitigate that risk, whether the operative frequencies are sub-6 GHz, 70/80 GHz or otherwise. BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. 1 is a prior art map of the United States showing locations for sites registered with the FCC to operate in the 71-76 GHz and 81-86 GHz bands as of June 2016.

FIG. 2A is a data plot of interference versus distance for the inventors' simulations of interference from transmitting 5G UEs into a backhaul receiver.

FIG. 2B is similar to FIG. 2A but illustrating interference from a backhaul transmitter to the receiving 5G UEs.

FIG. 3 is a plan view of a radio environment that illustrates UE interference to the backhaul receiver that FIG. 2A quantifies. FIG. 4 is a plan view of a radio environment similar to FIG. 3 but illustrating an example embodiment of these teachings.

FIGs. 5A-B are process flow diagrams summarizing certain aspects of the invention from the perspective of a radio network access node and of an interference probe device, respectively.

FIG. 6 is a diagram illustrating some components of a radio network access node/base station and an interference probe device, each of which are suitable for practicing various aspects of the invention.

DETAILED DESCRIPTION:

The description below assumes the radio network and backhaul receivers and transmitters are operating at mmWave frequencies. While this is the region for which the invention was originally developed it is not in itself a limiting factor to these teachings which are not frequency dependent. Further, while the examples below are in the context of a 5G radio access technology, the 5G system is merely a context for the examples and not limiting in itself to the broader teachings herein.

The inventors have conducted some simulations to estimate interference into 5G backhaul links as discussed in the background section above. Specifically, FIG. 2A plots interference from 5G UEs into a backhaul receiver at varying distances, while FIG. 2B plots similarly for interference from a backhaul transmitter into 5G UEs. As can be seen by comparing these two data plots the interference from the 5G UEs to the wireless backhaul receivers is far worse than interference to the UEs from the companion backhaul transmitters. Even the more generous interference threshold for the backhaul receivers is not sufficient for the interference from the UEs to exceed the threshold (-10 dB at Fig. 2A). This potential for high interference into the incumbent backhaul systems can be avoided by mandating some minimum separation distance on between the two systems. Note the steep drop in interference as the plot at FIG. 2A moves from 500m to 2000m; due to the line-of-sight propagation characteristics at mm Wave-level frequencies and so a few kilometers separation between the backhaul receivers and transmitting UEs is all that would be needed. But reviewing the map at FIG. 1 shows that such a minimum separation requirement around all the backhaul nodes would severely limit the applicability of 5G access systems; in certain areas of the most populated regions in the US even that small separation distance would preclude 5G mobile communications with UEs unless some alternative was found for those limited regions.

One reason why the UE-to-backhaul receiver interference is significantly higher than in the reverse direction is that the UE-to-backhaul interference is aggregated over all of the simultaneously transmitting UEs in the entire 5G access system whom are deployed in the vicinity of the backhaul nodes. It can be reasonably assumed that the backhaul receiver's antenna beam would be very narrow. In the simulations that resulted in FIGs. 2A-B the UEs were modelled as being randomly oriented in azimuth. Regardless of the narrow backhaul receiver beam there is a high probability that some number of these randomly-aligned UE transmitters will align with the backhaul node's receiver beam. This is the primary cause of the high levels of interference shown at FIG. 2A.

FIG. 3 is a plan view of a radio environment that illustrates the UE interference to the backhaul receiver. The 5G UE 10 is transmitting uplink (UL) to a 5G access point (AP) 20. Nearby there are two backhaul (BH) nodes; assume the one at the upper right is a BH receiver and the other is a BH transmitter. While 5G is to be very directional in its transmissions, there will be multiple UEs in a given cell under that same AP 20 and so one or more of them may be aligned as shown in FIG. 3 such that its UL beam interferes with the BH receiver that is getting BH data from the other BH transmitter. This is the radio environment that embodiments of these teachings particularly address.

Given the simulated interference data at FIGs. 2A-B the main interference concern is obviously in the UE-to-backhaul direction and that is the focus of these teachings. While FIG. 2B shows that the interference in the other direction, from backhaul transmitter into the 5G UEs, is well below the interference criteria for 5G systems, it may be that in a deployed system the backhaul-to-UE interference may be higher than FIG. 2B illustrates, or it may be that even the modest interference shown at FIG. 2B needs to be mitigated. Other techniques can be utilized to deal with that reverse interference, and such other techniques may be deployed alongside these teachings which are directed more towards the UE-to-backhaul interference proposition.

FIG. 4 is similar to FIG. 3 but with a probe device 30 added in accordance with an embodiment of these teachings. The probe device 30 is disposed physically near the BH receiver and preferably co-located with the BH receiver and with the probe device's directional receive beam aligned with the receive beam of the BH receiver so the probe 30 can sense signals from UEs that would tend to interfere with signals from the BH transmitter intended for the BH receiver. In that regard the structure of the probe device 30 is not unlike a conventional wireless radio receiver, and it is referred to herein as a probe device 30 merely to signify its purpose.

The probe device 30 need not be analogous to the access point AP 20 that the UEs are in communication with; for certain embodiments herein it is not necessary for the probe device 30 to identify individual UEs or know their subscriber status or billing information. As will be evident from the examples below in some embodiments the probe device need not even be in communication with the cellular network infrastructure, apart from signaling to the APs in its vicinity that it senses uplink interference.

One feature in mitigating UE-to-backhaul interference is to identify the UE or UEs that cause high interference at the backhaul receiver. The serving AP 20 is able to identify the UEs under its control from their uplink signaling because the AP 20 is the entity that allocated radio resources for those UEs, so the AP knows which UE is transmitting from its own scheduling decisions and resource grants. In an embodiment the probe device 30 does not have this information and so cannot distinguish one UE from another under the AP's control by only listening to uplink signaling. By listening to uplink signaling the probe device 30 may know there is interference to mitigate when uplink signaling exceeds a certain pre-defined threshold as FIGs. 2A-B illustrate, but lacking more the probe device 30 is unable to identify which UE or UEs are responsible for the interference that needs to be mitigated.

Thus there are two steps to solve the UE-to-backhaul interference problem: i) identify the UEs that cause high interference into the backhaul receivers and ii) suppress or mitigate that interference. To address step i), an embodiment of these teachings has each UE transmit in their uplink signaling an identifier of their serving cell. As one example, the AP 20 can configure the UEs in its cell to embed a special cell-specific pseudo-random signal (a PN sequence) into the UE's uplink demodulation reference signal (DMRS) pilot sequences. While FIG. 4 shows only one AP 20 and one UE 10, in a practical system there will typically be multiple APs 20 within range of the probe device 30 and multiple UEs 10 served by each of those multiple APs 20. The embedded PN sequence uniquely identifies each of these different APs, and therefore enables the probe device to learn which is the serving cell of each interfering UE. The probe device 30 has stored in its own memory a table associating the different PN sequences with the different APs around it. As a table, the different PN sequences may be identified by an index rather than the entire sequence, to reduce any signaling overhead should the probe device 30 need to signal the PN sequence. In this regard the probe device 30 may have a communications link with the core network to get updates to this association table as the list of its AP neighbors changes and/or as the PN sequences in use by those neighboring APs changes from time to time.

Alternatively the probe device can listen for uplink signals and build its association table by directly querying any AP for which it does not yet have an associated PN sequence in its association table. In this regard anytime the probe device 30 detects an uplink signal for which the embedded PN sequence is not already in its stored table, the probe device 30 can query all of its known AP neighbors with the unknown PN sequence. Any AP associated with that PN sequence can respond to the query indicated it is theirs. In a specific embodiment any other AP not associated with that PN sequence will respond to the query with a listing of all its known neighbor APs. The probe device can then send a query to any new APs that are not yet in the probe device's stored list to learn the PN sequence it will be using. In this manner the probe device 30 can learn of any newly established APs from its known AP neighbors without having access to the core network, and learn the PN sequence to be used by such newly established APs.

The probe device 30 listens for interference exceeding a pre-determined threshold interference level, and when that occurs the probe device 30 can log the time at which interference exceeded the threshold and identify the cell/AP 20 that serves the interfering UE (which the probe device 30 is not yet able to identify in this embodiment). Since the probe device 30 can easily synchronize with the various APs in its vicinity in one embodiment it may log the time of interference in radio timing terms, such as a radio frame, sub-frame and time-slot; or a specific symbol position at which the interference first exceeded the threshold, or the like. If the probe device is not synchronized with its neighbor APs the time of interference in its message can be conventional clock time (for example, Universal time UT or Coordinated Universal Time UTC or Universal Metric Time UMT or Greenwich Mean Time GMT).

The probe device 30 has no operational control over any of the UEs and so it cannot mitigate the interference by its own actions. Instead, in this embodiment the probe device 30 sends a message to the AP 20 that it identified from the PN sequence embedded within the interfering uplink transmission. This message indicates to the AP 20 that the probe device 30 sensed UE-to-backhaul interference from one of this AP's UEs and also indicates the time of that interference. From this information the AP 20 can check its radio resource allocation logs to determine which UE or UEs were transmitting at a time corresponding to the time in the probe device's message. This completes step i) of uniquely identifying the UE or UEs that are causing unacceptable UE-to- backhaul interference. Step ii) of mitigating that interference is also performed by the AP 20 itself, which initiates a handover of the interfering UE or UEs to another cell or sector. Because of the highly directional nature of 5G communications, simply handing over will very likely change the direction of the UE's transmit beam or beams even if the UE remains stationary near a cell edge. This change in the transmit beam direction should mitigate or even fully eliminate the interference at the backhaul receiver from that handed-over UE.

If there are multiple UEs all served by the same AP 20 that are causing interference, that one AP 20 will identify them all from comparing the time in the probe device's message 30 against the AP's own resource allocation logs. If there are multiple UEs served by multiple APs that are causing interference, the probe device 30 will be able to identify all of the relevant APs from the different uplink signaling and will send a message to each of them with the time the interference commenced in each message; these times in the different messages may differ somewhat. In that case each AP receiving a message from the probe device 30 will operate as described above, identifying only the UE or UEs it serves as the interfering UEs and handing over only that UE (or those UEs if a given AP is serving multiple interfering UEs).

Rather than send its interference message directly to the relevant serving AP 20, the probe device 30 can in another embodiment send its interference message to a network controller that controls multiple APs. In this case the interference message would include the time and an indication of the relevant PN sequence, such as the index from its table of PN sequences (this assumes the network controller uses the same PN sequence indexing). In this embodiment the probe device 30 does not need to have the different PN sequences associated with specific APs; the probe device 30 only needs to recognize the PN sequence in the interfering transmission and report to the network controller an indication of that sequence. The network controller will have the association table described above and will be able to identify the relevant AP, to whom it will then either forward the original interference message or send a revised message that has the timing but not necessarily the PN sequence. FIG. 6 illustrates such a network controller as the MME/uGW 40, though this is only an example and in a 5G or other new radio system the entity in the position of network controller over multiple APs may be known by a different name. Compare the above embodiments with some other interference suppression techniques. Cooperative Multipoint (CoMP) typically imposes an almost-blank subframe (ABS) on a macro cell or a pico cell so that only the one cell is allowed to transmit data during the subframe that the other cell regards as almost-blank. This is not a suitable solution when one of the entities getting interference is a backhaul server since data on the backhaul backbone is not easily subject to the same scheduling as wireless uplink and downlink user data.

Similar coexistence issues have arisen with other spectrum bands (for example, 3.5 GHz, 28 GHz) where there are different wireless systems that need to co-exist on the same band. One example is Fixed Satellite Service Earth Stations which communicate on the 3.5 GHz band with space- based satellites for geo-positioning purposes. The safest way for suppressing interference, and the technique used to protect the earth stations of such satellite navigation systems, is to geographically separate the different band-sharing wireless systems so that the transmitted power of one system attenuates sufficiently to satisfy the interference criterion of the other system. This protected area of attenuation is generally referred to as an exclusion zone, and in the United States the Federal communications commission (FCC) protects such earth stations from interference by mobile systems so long as the earth stations are registered annually providing (at least) each earth station's geographic location, antenna gain, horizontal and vertical antenna gain pattern, antenna azimuth relative to true north, and antenna elevation angle. This registration information is made available to all approved Spectrum Access Systems (SASs) which dynamically manage frequency assignments and protect such earth stations. But the map at FIG. 1 shows that similar exclusion zones around all the 70/80 GHz registered sites would not be an optimal solution if the 5G new radio system is to be widely adopted and relied upon by the general public.

The autonomous management of interference between 5G UEs and backhaul nodes presented herein is seen to be far more optimal than an exclusion zone to attenuate otherwise interfering signals. As detailed above, a 5G access system coexisting with a backhaul deployment learns of the UE interference by itself, without the need for a centralized infrastructure (such as SAS) as required for protecting earth stations in the 3.5 GHz band. In general it appears inefficient to apply a database-type solution for a coexistence problem in a mm Wave band, except for the earth station example above where the earth stations can be located in rural or less heavily populated locations where the exclusion zones would have only a very limited effect on cellular service availability. It is likely that 5G systems will be deployed as small cells due to short inter-site distances that are required in microwave propagation conditions, meaning there will be far too many 5G UE devices to be registered and managed by a location database tracking the locations of all UEs that may come within mm Wave radio range of a given BH receiver.

As an overview, it may be considered there are three main aspects to UE-to-backhaul interference suppression according to the examples above. First is modification of the UE's uplink signaling. In the above example this was embedding in the UE's DMRS a PN sequence that uniquely identifies an AP (and thus uniquely identifies a cell or sector) that serves the interfering UE. For reduced signaling overhead each different PN sequence may be associated with a unique index. Second is identification of the interfering UE. If an UL interfering signal (above a certain interference criterion of a backhaul device) is detected by the 5G probe 30, the probe 30 demodulates the UL DMRS and learns the serving cell/sector of the UE "responsible" for the interfering transmission or at least its PN sequence. The probe 30 reports the time-slot in which interference was observed and the identity of the serving cell (which may be simply the index of the PN sequence) to the 5G network controller; or alternatively reports that time-slot directly to the AP 20 associated with the PN sequence embedded within the demodulated UL DMRS. The AP 20 identifies the relevant UE by checking the time-slot from the probe's interference report against the AP's own log of which radio resources it has previously granted to which UEs. Those granted radio resources are defined in terms of time and frequency.

Third, interference is suppressed/mitigated by the AP commanding the identified UE to hand over to another cell or sector. As part of the handover process, the UE will switch to another UL transmit beam, thereby no longer creating interference at the backhaul node even before the handover is completed.

It is possible that the new choice of the serving cell for the handed-over UE will also result in a high level of interference at the backhaul node. In this case the process will repeat again for this newly detected high interference level from this same UE, and this same UE will be commanded again to hand over. To avoid ping-pong handover effects, the network controller can maintain a list of the serving cells/ APs that have resulted in an unacceptable level of interference due to the UE's UL transmissions, and the network controller can avoid handing over UEs to the serving cells on that list. For embodiments that do not include a network controller higher than the level of the AP/network access point, when a handover is commanded the serving AP that commands it can give a code indicating a reason for the handover (known in the art as a HO cause code) to the target AP, either directly or via the UE being handed over. This "HO cause code" will indicate UE-to-BH interference. If the target AP has already handed that UE over to the now-serving AP for the same HO cause code the target AP can refuse the HO to avoid that potential ping pong effect.

FIG. 5A is a flow diagram from the perspective of the radio network that summarizes some of the features that are more particularly detailed above. The network device that implements this portion of the invention may be generically referred to as a radio network access node, and in different radio access technologies may be implemented as an access point AP 20, a base station BS, an eNB, a remote radio head R H, a transmission point TP, or the like. At block 502 the radio network access node configures UEs operating in its cell to transmit an identifier of the cell in their uplink signaling. While in the examples above this was a cell-specific DMRS that the AP 20 assigns to all 5G UEs connected to it, this was only one non-limiting example and various other cell- specific indications can be incorporated into the UEs' uplink signaling to fulfil this purpose of identifying a UE's serving cell/AP from a received uplink message. A conventional DMRS with a cell- specific PN sequence embedded within it would be considered a cell-specific DMRS. Then at block 504, in response to the AP 20 receiving from an other network node an interference notice that a given one of the UEs is interfering, the AP 20 initiates a hand-over of the UE. Sending a handover command to the UE is a particularly tangible way for the AP to confirm it has initiated such a handover. In one embodiment that interference notice only contains the time of the offending interfering uplink transmission and thus does not specifically identify the interfering UE; in this case the AP will additionally identify the UE based on the AP's own log of scheduled UEs.

In one particular embodiment the AP is operating with a 5G radio access technology. Different embodiments were described above for the notice of block 504; in one embodiment that notice is received at the AP directly from a probe device whereas in a different embodiment the AP receives that notice from a network controller. In both embodiments the notice includes a time at which interference was detected. Whomever sends the notice to the AP, the AP can identify the UE for hand-over at block 504 by comparing the time included in the notice against a log stored in a local memory of the AP that lists which of the UEs operating in the cell were scheduled to transmit at different times.

The specific steps of FIG. 5 A, as well as the more detailed non- limiting implementations detailed in the paragraphs immediately above, can be performed by an apparatus comprising at least one processor and at least one memory tangibly storing a computer program. In this case the at least one processor is configured with the at least one memory and the computer program to cause the apparatus to perform these described actions, and such an apparatus may be the radio network access node or components thereof. In another embodiment of these teachings there may be a computer readable memory tangibly storing a program of computer readable instructions that, when executed by a host device such as a radio network access node, cause that host device to perform the steps of Fig. 5 A or the more detailed steps as summarized above.

FIG. 5B is a flow diagram from the perspective of the probe device 30 that summarizes some of the features that are described more particularly above. While the probe device 30 may be co- located with the BH receiver, in other embodiments it may be the BH receiver itself adapted to detect interference above a pre-determined level and signal the APs or network controllers as detailed above. At block 552 the probe device 30 detects uplink transmissions from a plurality of user equipments (UEs) and at block 554 it determines that at least one of the detected uplink transmissions exceeds a pre-determined interference threshold. The dotted lines at FIGs. 2A-B are examples of pre-determined interference thresholds. At block 556 the probe device 30 identifies a cell from the at least one detected uplink transmission (for purposes herein, identifying a specific AP is equivalent to identifying a specific cell); and at block 558 the probe device 30 sends an interference notice to an access point associated with the identified cell.

In one particular embodiment the probe device may be disposed adjacent to or co-located with a backhaul receiver. In one embodiment detailed above the notice at block 558 is sent to an access point operating with a 5G radio access technology, or to a network controller over such an access point. In the specific but non-limiting examples above the cell is identified at block 556 by a cell- specific pseudo-random sequence that is embedded within a demodulation reference signal (DMRS), and that DMRS is included within the at least one detected uplink transmission of block 554. And as further detailed above the notice of block 558 may include a time at which the predetermined interference threshold was exceeded. The specific steps of FIG. 5B, as well as the more detailed non- limiting implementations detailed in the paragraphs immediately above, can be performed by an apparatus comprising at least one processor and at least one memory tangibly storing a computer program. In this case the at least one processor is configured with the at least one memory and the computer program to cause the apparatus to perform these described actions, and such an apparatus may be the probe device 30 or components thereof. In another embodiment of these teachings there may be a computer readable memory tangibly storing a program of computer readable instructions that, when executed by a host device such as a probe device 30, cause that host device to perform the steps of Fig. 5B or the more detailed steps as summarized above. Embodiments of these teachings improve on earlier interference suppression techniques in that they operate without the need for any type of database or service registration, either registration by the backhaul server or by the 5G system. Earlier coexistence solutions relied on location databases to ensure that a sufficient separation distance is maintained between new and incumbent (earth-station) system deployments.

While not limiting to the broader teachings herein, embodiments of this invention are particularly advantageous for 5G communication networks, particularly once the 70 GHz band or other mm Wave bands with incumbent backhaul deployments are opened for 5G access systems. Since 5G is not yet deployed in a commercial environment, deployment of these teachings can contribute to establishing a 5G broadband system by greatly reducing interference into coexisting wireless backhaul systems. The interference suppression approach detailed herein is seen to be superior to other spectrum sharing scenarios (such as in the 3.5 GHz and 28 GHz bands) but is seen to be superior in that the techniques shown here do not require existence of a centralized infrastructure or a location database for coexistence interference management. Embodiments of these teachings can effectively suppress 5G-into-backhaul interference while keeping the performance of the 5G access system operational, and can do so simply by establishing a set of probes or 5G nodes in the vicinity of the backhaul receivers and enabling the 5G access system to identify interfering UEs if an unacceptable level of interference is detected. FIG. 6 is a high level diagram illustrating some relevant components of various communication entities that may implement various portions of these teachings, including a base station identified generally as a radio network access node 20, a mobility management entity (MME) which may also be co-located with a user-plane gateway (uGW) 40, and a user equipment (UE) 10. In the wireless system 630 of FIG. 6 a communications network 635 is adapted for communication over a wireless link 632 with an apparatus, such as a mobile communication device which may be referred to as a UE 10, via a radio network access node 20. The network 635 may include a MME/Serving-GW 40 that provides connectivity with other and/or broader networks such as a publicly switched telephone network and/or a data communications network (e.g., the internet 638).

The UE 10 includes a controller, such as a computer or a data processor (DP) 614 (or multiple ones of them), a computer-readable memory medium embodied as a memory (MEM) 616 (or more generally a non-transitory program storage device) that stores a program of computer instructions (PROG) 618, and a suitable wireless interface, such as radio frequency (RF) transceiver or more generically a radio 612, for bidirectional wireless communications with the radio network access node 20 via one or more antennas. The UE may have a dedicated processor 615. In general terms the UE 10 can be considered a machine that reads the MEM/non-transitory program storage device and that executes the computer program code or executable program of instructions stored thereon. While each entity of FIG. 6 is shown as having one MEM, in practice each may have multiple discrete memory devices and the relevant algorithm(s) and executable instructions/program code may be stored on one or across several such memories.

In general, the various embodiments of the UE 10 can include, but are not limited to, mobile user equipments or devices, cellular telephones, smartphones, wireless terminals, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions. The radio network access node 20 also includes a controller, such as a computer or a data processor (DP) 624 (or multiple ones of them), a computer-readable memory medium embodied as a memory (MEM) 626 that stores a program of computer instructions (PROG) 628, and a suitable wireless interface, such as a RF transceiver or radio 622, for communication with the UE 10 via one or more antennas. The radio network access node 20 is coupled via a data/control path 634 to the MME 40. The path 634 may be implemented as an SI interface. The radio network access node 20 may also be coupled to other radio network access nodes via another data/control path (not shown) which may be implemented as an X5 interface. The probe device 30 is similar to the network access node 20 in that it also may include a controller such as a computer or a data processor (DP, or multiple ones of them), a computer-readable memory (MEM) that stores a program of computer instructions (PROG), and a suitable wireless interface, such as a RF transceiver or radio, for receiving at least uplink signals from UEs under control of the access node 20. The probe device 30 may send its interference message to the MME 40 via control path 634, or in other embodiments it may send its interference messages to the AP 20 via control path 636 which may be wired or wireless.

The MME 640 includes a controller, such as a computer or a data processor (DP) 644 (or multiple ones of them), a computer-readable memory medium embodied as a memory (MEM) 646 that stores a program of computer instructions (PROG) 648.

At least one of the PROGs is assumed to include program instructions that, when executed by the associated one or more DPs, enable the host device to operate in accordance with exemplary embodiments of this invention. That is, various exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP of the probe device 30; and/or by the DP 624 of the radio network access node 20; and/or by the DP 644 of the MME 40; and/or by hardware, or by a combination of software and hardware (and firmware).

For various exemplary embodiments, in accordance with this invention the probe device 30 and/or the radio network access node 20 may also include dedicated processors (625 shown for the access node 20). The computer readable MEMs may be of any memory device type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The DPs may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multicore processor architecture, as non-limiting examples. The wireless interfaces (e.g., RF transceivers) may be of any type suitable to the local technical environment and may be implemented using any suitable communication technology such as individual transmitters, receivers, transceivers or a combination of such components.

A computer readable medium may be a computer readable signal medium or a non-transitory computer readable storage medium/memory. A non-transitory computer readable storage medium/memory does not include propagating signals and may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. Computer readable memory is non- transitory because propagating mediums such as carrier waves are memoryless. More specific examples (a non-exhaustive list) of the computer readable storage medium/memory would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. It should be understood that the foregoing description is only illustrative. Various alternatives and modifications can be devised by those skilled in the art. For example, features recited in the various dependent claims could be combined with each other in any suitable combination(s). In addition, features from different embodiments described above could be selectively combined into a new embodiment. Accordingly, the description is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

A communications system and/or a network node/base station may comprise a network node or other network elements implemented as a server, host or node operationally coupled to a remote radio head. At least some core functions may be carried out as software run in a server (which could be in the cloud) and implemented with network node functionalities in a similar fashion as much as possible (taking latency restrictions into consideration). This is called network virtualization. "Distribution of work" may be based on a division of operations to those which can be run in the cloud, and those which have to be run in the proximity for the sake of latency requirements. In macro cell/small cell networks, the "distribution of work" may also differ between a macro cell node and small cell nodes. Network virtualization may comprise the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization may involve platform virtualization, often combined with resource virtualization. Network virtualization may be categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to the software containers on a single system.

Below are some acronyms used herein:

AP Access Point

BH Backhaul

BS Base Station (also eNB for enhanced nodeB)

dB decibel

DL Downlink

DMRS Demodulation Reference Signal

MME Mobility Management Entity

mmWave Millimeter wave

PN Pseudo-Noise (or pseudo-random)

RX Receive or Receiver

TX Transmit or Transmitter

UE User Equipment

uGW user-plane gateway

UL Uplink

Claims

CLAIMS:

1. A method, comprising:

configuring user equipments operating in a cell to transmit an identifier of the cell in their uplink signaling; and

in response to receiving from an other network node a notice that a given one of the UEs is interfering, initiating a hand-over of the UE.

2. The method according to claim 1, wherein the method is performed by an access point operating with a 5G radio access technology.

3. The method according to claim 2, wherein the notice is received directly from a probe device.

4. The method according to claim 2, wherein the notice is received from a network controller.

5. The method according to any of claims 1-4, wherein the identifier is a pseudo-random sequence embedded within a cell-specific demodulation reference signal (DMRS).

6. The method according to any of claims 1-5, wherein the notice includes a time at which interference was detected.

7. The method according to claim 6, further comprising, after receiving the notice:

identifying the UE for hand-over by comparing the time included in the notice against a log stored in a local memory listing which of the UEs operating in the cell were scheduled to transmit at different times.

8. An apparatus comprising at least one processor and at least one memory tangibly storing a computer program; wherein the at least one processor is configured with the at least one memory and the computer program to cause the apparatus to perform the method according to any of claims 1-7.

9. A computer readable memory tangibly storing a program of computer readable instructions that, when executed by a host device, cause the device to perform the method according to any of claims 1-7.

10. A method comprising :

detecting uplink transmissions from a plurality of user equipments (UEs);

determining that at least one of the detected uplink transmissions exceeds a predetermined interference threshold;

identifying a cell from the at least one detected uplink transmission; and

sending an interference notice to an access point associated with the identified cell.

11. The method according to claim 10, wherein the method is performed by a probe device disposed adjacent to or co-located with a backhaul receiver.

12. The method according to claim 11, wherein the notice is sent to an access point operating with a 5G radio access technology, or to a network controller over such an access point.

13. The method according to any of claims 10-12, wherein the cell is identified by a cell- specific pseudo-random sequence embedded within a demodulation reference signal (DMRS) within the at least one detected uplink transmission.

14. The method according to any of claims 10-13, wherein the notice includes a time at which the pre-determined interference threshold was exceeded.

15. An apparatus comprising at least one processor and at least one memory tangibly storing a computer program; wherein the at least one processor is configured with the at least one memory and the computer program to cause the apparatus to perform the method according to any of claims 10-14.

16. A computer readable memory tangibly storing a program of computer readable instructions that, when executed by a host device, cause the device to perform the method according to any of claims 10-14.