Method and apparatus for pilot pattern configuration in a mobile network

Abstract

Described is a network entity (501) for use in a mobile network (500), the network entity being configured for communication with a user equipment device (350, 502) in the mobile network (500), the network entity being configured to allocate (1201) to the user equipment device a set of location-associated pilot patterns for uplink communication from the user equipment device, wherein each of the set of location-associated pilot patterns comprises a respective pilot pattern corresponding to a respective geographic location of the user equipment device. This may improve the latency issue for radio-map based channel estimation, while reducing uplink signalling overhead.

Description

[0001] METHOD AND APPARATUS FOR PILOT PATTERN CONFIGURATION IN A MOBILE NETWORK

[0002] TECHNICAL FIELD

[0003] Embodiments of the present disclosure generally relate to the field of mobile networks, in particular to the configuration of pilot patterns between a network entity and a user equipment device.

[0004] BACKGROUND

[0005] Sounding reference signals (SRSs) are pilot signals sent in the uplink (UL) signals by the user equipment (UE). They allow a radio access network (RAN) entity, such as a base station (BS), to estimate the channel to perform downlink (DL) precoding and scheduling.

[0006] Figure 1 shows a typical scheme for the transmission of SRS pilots in the uplink in time division duplex (TDD) systems. In this example, a mobile network 100 comprises aBS 101 and aUE 102. TheUE 102 can sendUL reference signals L UL, which may be SRS signals, to the BS 101, as shown at 103. The BS 102 estimates the UL channel based on the UL reference signal. The BS 102 obtains DL channel state information (CSI) / / DI. based on channel reciprocity. The BS 102 completes DL scheduling and transmits data 104 based on the DL CSI.

[0007] One issue with SRS is that a UE has power limitations to transmit SRS across the whole frequency band, in particular for upcoming wideband solutions. The density of frequency sampling can be referred to as the comb. In the sense of SRS, a comb is referring to equally spaced signals in the frequency domain (thus resembling a brushing comb with equally spaced spikes), to allow for uniform sampling of the frequency domain. Higher comb width decreases the density of frequency sampling while lowering it increases the frequency information collected by the SRS signal. Thus, adjusting the frequency sampling affects the accuracy of the SRS measured. It is also important to note that adjusting the comb width can have an impact in the form of the number of available positions for other UEs to transmit their SRS without interfering.

[0008] A radiomap, is a representation of the radio frequency (RF) environment within a specific area. Radiomaps are instrumental in planning and optimizing wireless networks, ensuring reliable communication, and enhancing the efficiency of various RF-dependent applications. Traditionally, radiomaps have been used to keep signal strength, interference, localization and frequency usage information for the locations serviced by that BS. The radiomap is stored at the BS to be useful in the event that it needs to perform various downlink (DL) operations when it has limited information provided from the UE.

[0009] Modem and advanced solutions can enable the storage of CSI with the possibility of using various compression methods. Such CSI information is useful in addressing the absence of SRS. However, radiomaps themselves can suffer from many issues when aiming to substitute SRS and are for this reason not useful in current implementations for DL precoding and scheduling.

[0010] One particular issue is that radiomaps suffer when there is latency between the measurement of the user’s location and the transmitted UL pilots. This is particularly exacerbated in cases where the BS provides a specialized pilot configuration for the UE to utilize based on the user’s location. These issues mostly arise in situations of user mobility, in other words, when the user location has changed thus the utilized pilot pattern is not optimal by the time it is configured, due to the latency. Similarly, when sending pilots to the BS, the UE will need to send its location separately from the pilots, resulting in a mismatch due to the latency.In the signalling diagram of Figure 2, UE 102 sends its UE context, including the UE location, to the BS 101 (which may be a gNB) at 201. The BS 102 defines the optimal comb configuration at 202 and sends the configuration to the UE 102 at 203. At 204, the pilot pattern (PP) resource map is generated by the UE 102 and signals are sent to the BS 101 according to the pilot pattern at 205. Channel estimation is then performed at 206.

[0011] If the UE 101 has moved between sending the UE context and generating the PP resource map (shown at a), the configuration may be outdated. Channel to location association errors may also be introduced (shown at b). Therefore, the configuration may be outdated and the latencies and inaccuracies can affect the performance of the channel estimation.

[0012] It is desirable to develop an approach that may overcome at least some of the above issues.

[0013] SUMMARY

[0014] According to a first aspect, there is provided a network entity for use in a mobile network, the network entity being configured for communication with a user equipment device in the mobile network, the network entity being configured to allocate to the user equipment device a set of location-associated pilot patterns for uplink communication from the user equipment device, wherein each of the set of location-associated pilot patterns comprises a respective pilot pattern corresponding to a respective geographic location of the user equipment device.

[0015] This may improve the latency issue for radio-map based channel estimation, while reducing uplink signalling overhead.

[0016] The network entity may be configured to allocate the set of location-associated pilot patterns to the user equipment device by sending a full set of location-associated pilot patterns (for example, a comb width, offset and cyclic shift to be used for each location) and corresponding geographic locations to the user equipment device, or by sending information to the user equipment device that allows the user equipment device to determine the set of location-associated pilot patterns at the user equipment device, for example according to a pre-defined ruleset.

[0017] The network entity may be configured to indicate the set of location-associated pilot patterns to the user equipment device as a limited subset of a base pilot pattern. This may reduce downlink signalling overhead.

[0018] The base pilot pattern may be specific to the user equipment device. This may eliminate interference between pilots of two different user equipment devices.

[0019] The network entity may be configured to indicate the base pilot pattern to the user equipment device in the form of a mask for masking a portion of frequency resources to be used by the user equipment to form its pilot pattern. This may reduce downlink signalling overhead.

[0020] The network entity may be configured to indicate a default offset and default cyclic shift of the base pilot pattern to the user equipment device. This may reduce downlink signalling overhead.

[0021] The base pilot pattern may be a regular comb pilot pattern having a comb width X, where X is equal to the width of the base pilot pattern multiplied by an expansion factor. This may enable full resolution of frequency sampling, which is extremely beneficial in wide spectrum implementations. This may allow for allocating the optimal pilot signal structure, which may reduce interference.The network entity may be configured to indicate a base pilot pattern to the user equipment device to allow the user equipment device to select a pilot pattern according to a pre-defined ruleset defining an offset and a cyclic shift of the base pilot pattern (in dependence on the geographical location of the user equipment device) such that each geographical segment of the user equipment device has a unique configuration. When each geographical segment has a unique pilot pattern configuration, this may allow a network entity, such as a base station, receiving pilot signals according to the pilot pattern to determine the location of the UE.

[0022] The expansion factor may be included in a downlink signal from the network entity to the user equipment device. This may allow the set of location-associated pilot patterns to be indicated to the UE using minimal additional signalling.

[0023] The network entity may be configured to determine a respective pilot pattern for each of multiple geographical segments for the user equipment device. This may allow the UE to use a particular pilot pattern in dependence on its location.

[0024] The network entity may be configured to determine the respective pilot pattern for each of the multiple geographical segments in dependence on a map of historical channel state information for geographical locations of the user equipment device. This may allow appropriate pilot patterns for each geographical segment to be formed.

[0025] The network entity may be configured to assign each geographical segment with a corresponding expansion factor. This may allow a unique pilot pattern to be used for each location.

[0026] The network entity may be configured to manage pilot patterns for multiple user equipment devices and / or multiple base stations. This may allow pilot pattern configuration to be handled by a common entity.

[0027] The set of location-associated pilot patterns may be indicated to the user equipment device as a list of pilot patterns covering all possible locations of the user equipment device, wherein the set of location-associated pilot patterns comprises, for each pilot pattern in the set, a respective comb width, offset and cyclic shift. This may allow a full set of pilot patterns to be allocated.

[0028] The network entity may be configured to receive one or more uplink messages from the user equipment device according to one of the set of location-associated pilot patterns. This may allow the UE to send pilot signals to a base station.

[0029] The one or more uplink messages may comprise one or more pilot measurements. The network entity may be configured to determine the location of the user equipment device from the one or more pilot measurements sent according to one of the set of location-associated pilot patterns. The detection of pilot patterns at the network entity can allow for the discovery of UE location, which may reduce signalling overhead.

[0030] Each pilot pattern in the set of location-associated pilot patterns may have a respective comb width. The network entity may be configured to detect the comb width, the offset and the cyclic shift of the received one or more pilot measurements and determine the location of the user equipment device in dependence on the comb width, the offset and the cyclic shift. This may allow the location of the UE to be determined at the network entity with the location having to be explicitly signalled.

[0031] The network entity may be configured to inform the determined location and / or the one or more pilot measurements to a channel estimator. This may allow the network entity to perform downlink precoding and scheduling.

[0032] The set of location-associated pilot patterns may be pilot patterns for sounding reference signals. This may allow the network entity to know the channel conditions in frequency bands outside of the current uplink bands for the UE.The network entity may be a radio access network entity. For example, the network entity may be a base station. This may allow the network entity to be incorporated into existing network infrastructure in mobile communication networks.

[0033] According to a second aspect, there is provided a method for implementation at a network entity in a mobile network, the network entity being configured for communication with a user equipment device in the mobile network, the method comprising allocating to the user equipment device a set of location-associated pilot patterns for uplink communication from the user equipment device, wherein each of the set of location-associated pilot patterns comprises a respective pilot pattern corresponding to a respective geographic location of the user equipment device.

[0034] This may improve the latency issue for radio-map based channel estimation, while reducing uplink signalling overhead.

[0035] According to a third aspect, there is provided a user equipment device for use in a mobile network, the user equipment device configured for communication with a network entity in the mobile network, the user equipment device being configured to: receive an indication of a set of location-associated pilot patterns for uplink communication; and select a location-associated pilot pattern from the set to use for uplink communication with the network entity in dependence on the geographic location of the user equipment device.

[0036] The user equipment device may be allocated the set of location-associated pilot patterns by the network entity. The user equipment device may be configured to receive the indication of the set of location-associated pilot patterns to the user equipment device by receiving a set of location-associated pilot patterns (for example, a comb width, offset and cyclic shift to be used for each location) corresponding to respective geographic locations, or by receiving information that allows the user equipment device to determine the set of location-associated pilot patterns at the user equipment device, for example according to a pre-defmed ruleset.

[0037] This may improve the latency issue for radio-map based channel estimation, while reducing uplink signalling overhead.

[0038] The user equipment device may be configured to receive the set of location-associated pilot patterns from the network entity as a limited subset of a base pilot pattern. This may reduce downlink signalling overhead.

[0039] The base pilot pattern may be specific to the user equipment device. This may eliminate interference between pilots of two different user equipment devices.

[0040] The user equipment device may be configured to receive the base pilot pattern from the network entity in the form of a mask for masking a portion of frequency resources to be used by the user equipment to form its pilot pattern. This may reduce downlink signalling overhead.

[0041] The user equipment device may be configured to receive an indication of a default offset and default cyclic shift of the base pilot pattern. This may allow the user equipment device to determine a specific offset and specific cyclic shift to use for pilot patterns in dependence on its location.

[0042] The base pilot pattern may be a regular comb pilot pattern having a comb width X, where X is equal to the width of the base pilot pattern multiplied by an expansion factor. This may enable full resolution of frequency sampling, which is extremely beneficial in wide spectrum implementations. This may allow for allocating the optimal pilot signal structure, which may reduce interference.The expansion factor may be included in a downlink signal from the network entity to the user equipment device. This may allow the set of location-associated pilot patterns to be indicated to the UE using minimal additional signalling.

[0043] The user equipment device may be configured to select a pilot pattern according to a pre-defined ruleset defining an offset and a cyclic shift of the base pilot pattern (in dependence on the geographical location of the user equipment device) such that each geographical segment of the user equipment device has a unique configuration. When each geographical segment has a unique pilot pattern configuration, this may allow a network entity, such as a base station, receiving pilot signals according to the pilot pattern to determine the location of the UE.

[0044] The user equipment device may be configured to send one or more uplink messages to the network entity according to the selected location-associated pilot pattern. This may enable full extraction of UE locations only from the pilot pattern, saving 24+ bits of control information. This can omit the need for location updates.

[0045] The set of location-associated pilot patterns may comprise a respective pilot pattern for each of multiple geographical segments for the user equipment device. This may allow the UE to use a particular pilot pattern in dependence on its location.

[0046] The user equipment device may be configurated to select a pilot pattern from the set of location-associated pilot patterns by calculating respective distances from the location of the user equipment device to each geographical segment and selecting the location-associated pilot pattern corresponding to the closest geographical segment. This may allow the UE to determine which geographical segment it is located in and allow it to select an appropriate pilot pattern from the set of location-associated pilot patterns.

[0047] Each geographical segment may have a corresponding expansion factor. This may allow the UE to form a pilot pattern to use for uplink communication in dependence on its location.

[0048] The user equipment device may be configured to receive the set of location-associated pilot patterns as a list of pilot patterns covering all possible location of the user equipment device, wherein the set comprises, for each pilot pattern in the set, a respective comb width, offset and cyclic shift. This may allow a full set of pilot patterns to be allocated.

[0049] The set of location-associated pilot patterns may be pilot patterns for sounding reference signals. This may allow the network entity to know the channel conditions in frequency bands outside of the current uplink bands for the UE.

[0050] According to a fourth aspect, there is provided a method for implementation at a user equipment device in a mobile network, the user equipment device configured for communication with a network entity in the mobile network, the method comprising: receiving an indication of set of location-associated pilot patterns for uplink communication; and selecting a location-associated pilot pattern from the set to use for uplink communication with the network entity in dependence on the geographic location of the user equipment device.

[0051] This may improve the latency issue for radio-map based channel estimation, while reducing uplink signalling overhead.

[0052] According to a further aspect, there is provided a mobile network comprising a network entity having any of the features described above and a user equipment device having any of the features described above.

[0053] The network entity may be a radio access network entity such as a base station. This may allow the network entity to be incorporated into existing network infrastructure in mobile communication networks.The network entity may be an entity separate to the radio access network entity and is configured to directly communicate with multiple radio access network entities in the mobile network that have overlapping coverage. This may be a convenient implementation in some network configurations.

[0054] According to another aspect, there may be provided a mobile network comprising the computing entity having any of the features described herein and the radio access network entity having any of the features described herein.

[0055] According to a further aspect, there is provided one or more computer programs for instructing a computer comprising one or more processors to implement the methods above.

[0056] According to a further aspect there is provided a data carrier storing in non-transitory form the one or more computer programs above.

[0057] BRIEF DESCRIPTION OF THE FIGURES

[0058] Figure 1 schematically illustrates a general implementation for the transmission of SRS pilots in the uplink in time division duplex systems.

[0059] Figure 2 schematically illustrates a signalling block diagram for uplink location and uplink pilot measurement for channel estimation;

[0060] Figure 3 schematically illustrates a network where a UE is configured to use different pilot patterns depending on its location;

[0061] Figure 4 schematically illustrates an example of a set of location-associated pilot patterns allocated to a UE;

[0062] Figure 5 schematically illustrates a signalling block diagram for the allocation of a set of location-associated pilot patterns to a UE and the detection of the location of the UE through the pilot pattern;

[0063] Figure 6 shows an example of a table for mask Co=2 and expansion factors iv(of 1 (for locations 1 , 2), 2 (for locations 3, 4, 5) and 4 (for locations 6, 7).

[0064] Figure 7 shows an example of a table for mask Co=2 and default offset O0=l and the location based expansion factors from Figure 6.

[0065] Figure 8 shows an example of a full table as sent from the BS to the UE if no prior ruleset is established.

[0066] Figure 9 shows an example of a table for full set configuration.

[0067] Figure 10 shows an example of a partial set configuration.

[0068] Figure 11 shows an exemplary implementation where the pilot measurements and location of the UE are sent to a channel estimator;

[0069] Figure 12 schematically illustrates the steps of an exemplary method for implementation at a network entity;Figure 13 schematically illustrates the steps of an exemplary method for implementation at a user equipment device.

[0070] DETAILED DESCRIPTION

[0071] The present disclosure relates to mobile networks. The approaches described herein may be implemented in such mobile networks as 3GPP 5G networks and other mobile communication networks that are currently available or developed in the future. The network may comprise a plurality of network entities (NEs). The NEs may be network function (NFs), which may be software-based. The NEs may alternatively be network apparatus (hardware-based).

[0072] A mobile network generally comprises a Radio Access Network (RAN) and a Core Network (CN). The RAN handles the wireless aspects, while the CN handles the management and control aspects. Both the RAN and CN have a User Plane (UP) to transmit traffic. A Control Plane (CP) can carry signalling traffic.

[0073] A BS in a mobile network provides communication services to one or more wireless UEs on downlink (BS to UE information flow), uplink (UE to BS information flow) and sidelink (UE to UE information flow) communications. Examples of BSs include, but are not limited to, a 3GPP 5G next-generation evolved node B (gNB) and an IEEE 802.11 access point (AP).

[0074] In 3GPP 5G networks, a gNB is a RAN node providing new radio (NR) user plane and control plane protocol terminations towards the UE. A gNB is connected via the NG interface to the 5GC. The gNB may in some implementations operate as defined in 3GPP TS 38.300. Other implementations are possible, for example according to future specifications.

[0075] Pilot signals are known signals both to transmitter and receiver used in modem communication systems to perform procedures such as channel estimation, Multiple-Input Multiple-Output (MIMO) precoding, Adaptive Modulation and Coding (AMC), scheduling, beam-management, and other procedures related to adapting the transmission to the current channel conditions. These signals may be scrambled with data signals in time and frequency domains so that the channel conditions experienced by pilots and data are as identical as possible.

[0076] SRS are pilot signals used in TDD and sent by the UE to the BS. SRS are typically allocated in frequency regions not currently used for UL data transmission between a particular UE and BS. This information, together with the assumption of channel reciprocity in TDD systems, allows the BS to know the channel conditions in frequency bands outside of the current UL channel conditions for one UE. With this information, the BS can perform DL precoding, scheduling, etc., without the need of explicit CSI feedback from the UE.

[0077] A radiomap is a memory component that contains CSI data for a specified and limited region covered by one or multiple BSs. Each point in the memory of CSI data is associated with a geographical location. Radiomaps can contain CSI information related to the frequency characteristics of the channel throughout its bandwidth, and considering multiple antenna elements of the host network entity, the spatial characteristics of the channel. The temporal effects can be also included. With this information, BSs can reduce or remove the need for SRS in applications such as DL precoding and scheduling.

[0078] A location (area) is a geographical segment of a geographical area. The UE may be located in one of multiple possible geographical segments. In the context of a radiomap, a respective location contains similar channel conditions for users that are within the borders of that location. The location can be identified by its borders or its centre, and centres of neighbouring locations. A neighbourhood of locations comprises all locations bordering the location (area) that a UE is currently in.In embodiments of the present disclosure, a network entity configured for communication with UE in a mobile network can pre-allocate to the UE a set of location-associated pilot patterns (LAPP) to be used for uplink communication from the UE to send pilot signals, such as SRSs. The set of LAPPs comprises multiple pilot patterns. Each pilot pattern corresponds to a respective location and the UE uses a respective pilot pattern when it is in a respective location. In other words, each of the set of LAPPs comprises a respective pilot pattern and a respective corresponding geographical location segment of the UE. The network entity may form the set of LAPPs, or the set may be formed at another entity and passed to the network entity for allocating the set of LAPPs to the UE.

[0079] The corresponding UE receives the set of LAPPs for uplink communication (or an indication thereof if the full set of LAPPs is not sent to the UE) and can select a pilot pattern from the set of LAPPs to use for uplink communication with a BS in dependence on the UE’s location.

[0080] The network entity may be for example, a BS or access point that determines (optionally) and allocates the set of LAPPs, or may receive the indication of the set of LAPPs from another network entity, such as an Access and Mobility Management Function (AMF) and / or entities that orchestrate the pilot patterns for a geographical area, and allocate the set of LAPPs to the UE. The network entity may be configured to manage pilot patterns for multiple UEs and / or multiple BSs.

[0081] The pilot patterns may be pilot patterns in the frequency domain. The set of LAPPs may be pilot patterns for sounding reference signals (SRSs). SRSs can allow a RAN entity, such as a BS, to estimate the channel to perform DL precoding and scheduling.

[0082] A geographical area is considered that is under the management of a BS, or any entity that manages pilot patterns on behalf of the BS that is associated with a wireless communication system, or co-located with an entity that oversees the operation of one or more BSs, used to transmit and receive information to one or more UEs. The entity is capable of producing geographical segments and deciding the optimal pilot patterns for each of the geographical segments. The entity may manage the pilot patterns for multiple UEs, potentially across multiple BSs. The entity may be responsible for not only allocating the optimal pilot pattern for the UE but also allocating it in a manner in which it does not interfere with patterns allocated for other users.

[0083] Figure 3 schematically illustrates a location (which may also be referred to as a geographical segment) 300 in which UE 350 is currently located. There are other neighbouring locations 301, 302 and 303 which the UE 350 may move into during mobility. Each location 300, 301, 302, 303 has a corresponding pilot pattern to use for uplink communication with a base station (not shown in Figure 3) for the coverage area comprising the locations 300-303.

[0084] Using, for example, a radiomap, the BS can divide its coverage area into smaller geographical segments (such as locations 300, 301, 302, 303 in Figure 3), and can generate or receive from another entity an optimal pilot pattern configuration for uplink pilots in the frequency resources grid in a way that improves the channel estimation performance of the UL pilot transmission for each geographical segment.

[0085] The UE can in some implementations be informed of the full map of optimal LAPPs for each location. In other implementations, the UE can be informed of a partial map of optimal uplink pilot patterns.

[0086] In some implementations, the UE may receive the set of LAPPs by receiving a base pilot pattern mask. Each pilot pattern in the set of LAPPs can be defined as a multiple of the mask. This method can reduce the utilization of uplink signalling resources by masking a portion of the frequency resources to be used by the UE to form its pilot pattern.In some implementations, a pre-defined ruleset may define a comb pattern offset and cyclic shift such that neighbouring locations have unique, orthogonal locations.

[0087] In such implementations, the UE may receive only the expansion factors for each location from the network entity (e.g. BS). The UE can then determine the offset and cyclic shift of the pilot pattern for its current location according to the pre-defined ruleset. This avoids sending a full list of LAPPs to the UE and allows the set of LAPPs to be determined by the UE.

[0088] Using the received full or partial map of LAPPs and optionally a pre-defined ruleset, the UE can configure its pilot pattern based on its current location and transmit pilot signals to the BS according to the selected LAPP in uplink.

[0089] As shown in Figure 4, the set of LAPPs can be provided to the UE in the form of a table. For each location (area) 0, 1,2, 3, etc, parameters of the pilot pattern to be used in each location can be indicated. In the example of Figure 4, each LAPP is a comblike pilot pattern with a comb width X (i.e. combX, where X is a whole number). The comb width may also be referred to as the comb period in the frequency domain. Herein, a comb-like pilot pattern comprises equally spaced signals in the frequency domain. This can allow for uniform sampling of the frequency domain. Increasing the comb width X decreases the density of frequency sampling while lowering it increases the frequency information collected by the signal.

[0090] For each location, an offset, cyclic shift and symbol can also be indicated, as shown in the example of Figure 4. This allows a UE to select a pilot pattern in dependence on its location.

[0091] Figure 5 illustrates an example of a communication flow in a network 500 where a single BS 501 allocates a set of LAPPs to a single UE 502 and subsequently detects the location of the UE through the pilot pattern itself.

[0092] At 503, the BS creates the LAPP set. In other examples, the set creation may be performed at another entity and sent to the BS to perform the allocation of the set to the UE, as described in the subsequent steps of this example.

[0093] At 504, the BS 501 allocates the set of LAPPs to the UE 502. This is sent in a DL message. The set of LAPPs may be in the form of a table.

[0094] At 505, using its location L, the UE 502 searches the set of LAPPs for the configuration it is to use based on its location. At 506, the UE 502 selects the offset and cyclic shift to be used.

[0095] At 507, the UE 502 performs UL communication with the BS 501 using the pilot pattern.

[0096] At 508, the BS 501 detects the pilot pattern used from the pilot signals. Knowing of the pilot pattern, the BS can determine the location of the UE.

[0097] In a typical scenario, the UE can register itself for the wireless communication services along with a report for its capability to support the LAPP system. Given this reported capability of the UE, the entity can decide whether or not to involve the LAPP capabilities. The entity can then send the UE association decision with the UE. If the UE participates in the LAPP system, it can provide its initial location coordinates in a standard manner.

[0098] Regardless of association, the BS can allocate an initial pilot pattern, offset and cyclic shift. After a successful association, the BS can send the LAPPs for each location segment to the UE. Using its own location, the UE associates itself with the appropriate location segment, and extracts the pilot pattern it needs to use for uplink communication with the BS.Generally, there may be a respective pilot pattern corresponding to a respective one of the multiple geographical segments for the UE. The respective pilot pattern for each respective one of the multiple geographical segments may be determined in dependence on a map of historical channel state information for geographical locations of the UE. When sending the set in the form of a mask, each geographical segment has a corresponding expansion factor, w, which will be described in more detail below.

[0099] In one implementation, the UE can follow a pre-defined ruleset to set its offset and cyclic shift based on its current location using the initial offset and cyclic shift. In this case, the BS does not provide the full list of LAPPs and corresponding locations to the UE. This can reduce downlink signalling.

[0100] In other implementations, a full pilot pattern configuration is sent to the UE and declared by the BS. In this case, the set of LAPPs can be indicated to the UE as a list of pilot patterns and corresponding locations covering all possible locations of the UE. When the UE receives the full set of pilot patterns, the set of LAPPs can comprise, for each pilot pattern in the set, a respective comb width, offset and cyclic shift.

[0101] Once the LAPP system starts operating, the BS can notice a switch in locations of the UE. The BS can send an update of the neighbourhood of locations and their pilot patterns. Another option is to send the LAPP information for areas larger than just the neighbourhood of locations, but more sparsely. Alternatively, the BS can also decide to broadcast the LAPP set information to all UEs in its range within one single downlink control message.

[0102] In one exemplary implementation, the network entity can indicate the set of location-associated pilot patterns to the UE as a limited subset of a base pilot pattern. The base pilot pattern may be specific to the UE. The network entity can indicate the base pilot pattern to the UE in the form of a mask for masking a portion of frequency resources to be used by the UE to form its pilot pattern.

[0103] The LAPP set can be generated in a way that defines a base comb as a mask and limited subset (i.e. base 2 - subset 4,6,8... ). The UE can then use an offset and cyclic shift selection method to have unique combination of combX, offset, cyclic shift for each pilot pattern.

[0104] The UE can be provided with the set of LAPPs in a downlink (DL) message containing the configuration set (for example, as a table). The UE can then select a LAPP from the set in dependence on its current location.

[0105] One method of creating the set of pilot patterns will now be described. In this example, the pilot patterns may be SRS patterns. The allocation entity can define the set of LAPPs in a way that defines a base comb as a mask and limited subset (i.e. base 2 -subset 4,6,8... ). Each location may have a unique combination of combX, offset and cyclic shift.

[0106] The UE can then select a pilot pattern from the set of LAPPs in dependence on its location. The UE can search the set of LAPPs to determine the pilot pattern that should be used based on the location of the UE.

[0107] In one implementation, a base pilot pattern mask is defined. Each pilot pattern for each of the location segments of the maps is defined as a multiple of the mask. This serves as a method that reduces the utilization on uplink signalling resources by masking a portion of the frequency resources to be used by the UE to form its pilot pattern as instructed by the BS. This may also avoid overallocation of subcarriers.The mask may be the most dense comb from the set of LAPPs. The base pilot pattern may be a regular comb pilot pattern having a comb width X, where X is equal to the width of the base pilot pattern multiplied by an expansion factor. The set of pilot patterns can be is created as integer multipliers of the mask comb = mask * w (where w is an expansion factor). The expansion factor w may be included in a downlink signal from the network entity to the UE.

[0108] There may be a pre-defined ruleset defining the comb pattern offset and cyclic shift of the base pilot pattern in a manner which each neighbouring locations of the map have orthogonal (unique) configurations. The UE may be configured to select a pilot pattern according to the pre-defined ruleset.

[0109] Given each area in the map received by the UE, the UE can determine which location it belongs to by calculating the distance from itself to the centre of each location. The location which has the shortest distance from the UE to the centre of the location may be selected as the location of the UE. Once the UE has determined its location, the UE can select the appropriate pilot pattern from the set of LAPPs to use for uplink signalling.

[0110] The UE receives the LAPPs and transmits the pilot patterns in uplink to the BS using the LAPP and the ruleset.

[0111] A BS that allocated the set of LAPPs to the UE can discover the area in which a UE is present through configuration discovery. Upon reception of the pilot pattern from the BS, the BS can read the masked pilot positions for that UE. The BS can, for example, detect the width of the comb-like structure in the pilot pattern, the offset and cyclic shift. The BS can refer to the table with the same ruleset used to generate the set of LAPPs to discover which location the UE is in.

[0112] An embodiment of the present disclosure will now be described where the LAPP set generation is performed at the BS and the generated set of PPs are allocated to the UE.

[0113] The BS may assign the pilot pattern to the UE over the physical downlink control channel (PDCCH), while the UE sets the pattern offset and cyclic shift according to a pre-defined ruleset. The LAPP generation procedure initiates at the BS and defines the pilot pattern mask (from here on referred to as mask Co).

[0114] In this example, each pilot pattern is a regular comb-like structure, where the mask is all resources assigned to a particular UE (i.e. is not shared between different UEs). Through conventional means, the BS informs the UE of the mask as a default pilot pattern, in addition to the default offset and cyclic shift for the Zadoff-Chu sequence transmitted within the pilot pattern.

[0115] The BS (or other entity generating the information indicating the set of LAPPs, where the full set its not sent to the UE directly) then calculates the optimal width of the UE transmission comb as a multiple w of the mask. Therefore each location is assigned the number w (that is the mask expansion factor) as a multiplier to define how much more sparse the actual comb-like structure for a specific location is from the sampling width of the mask w * Co. An example of the process for mask 2, used to transmit the expansion factors for 7 areas, and the default offset O0and cyclic shift is shown in Figure 6. Here, mask Co=2, and expansion factors iv(of 1 (for locations 1,2,) , 2 (for locations 3,4,5) ,4 (for locations 6,7).

[0116] Given the possibility for identical comb expansion factors in locations adjacent to each other, it is not possible to identify the exact area that the UE transmits from using only the updated configuration with only expansion factors. Therefore a ruleset can be pre-defined for populating the offset and cyclic shift parameters for each location (area). The pre-defined ruleset can be shared prior to the communication to both the participating BS and UE. The pilot pattern for each location is unique. With initial offset O0and mask width Co, the offset O(for location I can be calculated as:

[0117]

[0118] where KCi.c , is used to count the repetitions of a comb, in the neighborhood of locations as:

[0119] f C,. Ct) = {1, C, = Ci, 0. Ct* Ct},

[0120] where C(is the assigned comb for location I in the form of L(= uq * Co.

[0121] In some embodiments, the offsets may be changing with a step equal to the width of the comb-like structure of the mask Cofor each repetition of a pattern. As such, changing Coto a value that is multiple of Coin the equation above is also possible under this embodiment. Any offset non divisible by Comay result in violating the base mask offset and potentially interfering with other UEs.

[0122] As an example, shown in the first row of Figure 6, mask comb-X=2, offset=l, cyclic shift (cf)=l.

[0123] Figure 7 shows an exemplary table including offsets calculated according to the pre-defined ruleset for mask Co=2 and default offset O0= 1 , and the location-based expansion factors from Figure 6.

[0124] Given the aforementioned pre-defmed ruleset for assigning offsets to each location, to achieve a unique pilot pattern configuration for each location, the cyclic shift can be adjusted. The cyclic shift can be modified to maintain the original complex value transmitted per each subcarrier, such that no unintentional cyclic shifting occurs due to the novel self-calculated offsets. Any change in the transmitted complex value might introduce unintentional interference with other UEs.

[0125] In some implementations, the pre-defmed offset and cyclic shift calculation ruleset may not be used. In this case, the BS has the full liberty to assign any pilot pattern, offset, and cyclic shift for all possible location of the UE (for example, for all locations within the coverage area of the BS). The BS can transmit the full table to the UE without the need for any prior agreement on the pre-defmed ruleset. For example, the BS may transmit the entire table shown in Figure 8. The table includes a CombX, offset and cyclic shift for each possible location of the UE.

[0126] An example of a table of locations, corresponding CombX values and corresponding expansion factors w are shown in Figure 9.

[0127] In another example, a partial set configuration may be performed. An exemplary table of locations, corresponding CombX values and expansion factors w for each location are shown in Figure 10.

[0128] The UE may determine its location using self-association. As mentioned above, given each location (area) (which can be referred to as a geographical segment) in the map received by the UE, the UE can determine which location it belongs to by calculating the distance from itself to the centre of each location.The UE can select a pilot pattern from the set of location-associated pilot patterns by calculating respective distances from the location of the user equipment device to each geographical segment and selecting the location-associated pilot pattern corresponding to the closest geographical segment.

[0129] For example, using a Voronoi diagram, the location of the UE may be determined using the distances to each location area centre:

[0130] Location = argmin ( dn(LUE, £n))

[0131] where LUE= UE location, Ln= center of location area n, dn= distance to location area n.

[0132] Upon reception of the pilot signals sent according to the selected pilot pattern, the BS can read the masked pilot positions for that UE. The BS can detect the width of the comb in the pilot pattern, along with the offset and the cyclic shift. The BS can refer to the table with the same ruleset that the UE used to generate its pilot pattern configuration to determine which geographical segment the UE is located in (at the time it sent the pilot signals using the pilot pattern).

[0133] In some implementations, the network entity can extract the location of the UE and one or more pilot measurements from pilot signals sent according to the pilot pattern. The network entity can inform the determined location and / or the one or more pilot measurements to a channel estimator.

[0134] An implementation example of the LAPP detection for channel estimation is schematically illustrated in Figure 11.

[0135] As shown at 1101, the BS receives the pilots signals that are sent according to the LAPP selected by the UE with a mask.

[0136] In this example, the UE is in location 3. Therefore, the UE has determined that it should use comb-4, offset= 1 , cf = 1 , which corresponds to location 3, as its pilot pattern. The UE then uses the determined location-associated pilot pattern to send pilot signals to the network entity (for example, BS). The BS can determine the location of the UE (which in this example is in location 3) using the pilot measurements sent using the selected LAPP.

[0137] As described above, each pilot pattern in the set of LAPPs may have a respective comb width. The network entity can detect the comb width, the offset and the cyclic shift of the received one or more pilot measurements from the UE and, for example by searching the set of LAPPs that was allocated to the UE, determine the location of the UE in dependence on the comb width, the offset and the cyclic shift. The BS can refer to the same table and / or pre-defined ruleset that was used by the UE to select its pilot pattern.

[0138] The network entity can then send the UE location and the pilot measurements to a channel estimator. The channel estimator may be a separate entity to the network entity or a part thereof.

[0139] Figure 12 shows exemplary steps of a method 1200 for implementation at a network entity in a mobile network, the network entity being configured for communication with a user equipment device in the mobile network. The method comprises, at 1201, allocating to the user equipment device a set of location-associated pilot patterns for uplink communication from the user equipment device, wherein each of the set of location-associated pilot patterns comprises a respective pilot pattern corresponding to a respective geographic location of the user equipment device.Figure 13 shows an exemplary method for implementation at a user equipment device in a mobile network, the user equipment device configured for communication with a network entity in the mobile network. At step 1301, the method comprises receiving an indication of a set of location-associated pilot patterns for uplink communication. At step 1302, the method comprises selecting a location-associated pilot pattern from the set to use for uplink communication with the network entity in dependence on the geographic location of the user equipment device.

[0140] The network entity and the UE may each comprise at least one processor and at least one memory. The memory is arranged to communicate with the processor. The memory may store data that is executable by the processor. By executing program code contained in such data, the one or more processors may perform functions as described herein. The memory may store such program code in a non-transitory manner. The processor may be configured to operate in accordance with a computer program stored in non-transitory form on a machine-readable storage medium. The computer program may store instructions for causing the processor to perform its methods in the manner described herein. Each of the network entity and the UE also comprise a transceiver for receiving and / or sending data from and / or to one or more of the other entities.

[0141] The approach described herein may improve the latency issue for radio-map based channel estimation, while reducing uplink signalling overhead.

[0142] The allocation of a set of PPs to a UE to be used in dependence on the UE’s location can enable full extraction of UE locations only from the pilot pattern used, potentially saving 24+ bits of control information. This can omit the need for location updates.

[0143] The detection of pilot patterns at the network entity can allow the discovery of UE location (anonymized to the exact resolution / quantization demanded by radioMAP) on PHY level.

[0144] Hybrid channel estimation in a closed-loop implementation can allow for fully time-synchronized location for hybrid channel estimation that has two core benefits: (i) the transmission of always optimal SRS in uplink, (ii) perfect location-measurement association for storing in the RadioMap.

[0145] The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein. The applicant indicates that aspects of the present disclosure may consist of any such individual feature or combination of features. In view of the foregoing description, it will be evident to a person skilled in the art that various modifications may be made within the scope of the disclosure.

Claims

CLAIMS1. A network entity (501) for use in a mobile network (500), the network entity being configured for communication with a user equipment device (502) in the mobile network, the network entity being configured to allocate (1201 ) to the user equipment device a set of location-associated pilot patterns for uplink communication from the user equipment device, wherein each of the set of location-associated pilot patterns comprises a respective pilot pattern corresponding to a respective geographic location of the user equipment device.

2. The network entity as claimed in claim 1, wherein the network entity is configured to indicate the set of location-associated pilot patterns to the user equipment device as a limited subset of a base pilot pattern.

3. The network entity as claimed in claim 2, wherein the network entity is configured to indicate a default offset and default cyclic shift of the base pilot pattern to the user equipment device.

4. The network entity as claimed in claim 2 or claim 3, wherein the base pilot pattern is a regular comb pilot pattern having a comb width X, where X is equal to the width of the base pilot pattern multiplied by an expansion factor.

5. The network entity as claimed in any preceding claim, wherein the network entity is configured to indicate a base pilot pattern to the user equipment device to allow the user equipment device to select a pilot pattern according to a pre-defined ruleset defining an offset and a cyclic shift of the base pilot pattern such that each geographical segment of the user equipment device has a unique configuration.

6. The network entity as claimed in any preceding claim, wherein the network entity is configured to determine a respective pilot pattern for each of multiple geographical segments for the user equipment device.

7. The network entity as claimed in claim 1, wherein the set of location-associated pilot patterns are indicated to the user equipment device as a list of pilot patterns covering all possible locations of the user equipment device, wherein the set of location-associated pilot patterns comprises, for each pilot pattern in the set, a respective comb width, offset and cyclic shift.

8. The network entity as claimed in any preceding claim, wherein the network entity is configured to receive one or more uplink messages from the user equipment device according to one of the set of location-associated pilot patterns.

9. The network entity as claimed in claim 8, wherein the one or more uplink messages comprise one or more pilot measurements, wherein the network entity is configured to determine the location of the user equipment device from the one or more pilot measurements sent according to one of the set of location-associated pilot patterns.

10. The network entity as claimed in claim 9, wherein each pilot pattern in the set of location-associated pilot patterns has a respective comb width and wherein the network entity is configured to detect the comb width, the offset and the cyclic shift of the received one or more pilot measurements and determine the location of the user equipment device in dependence on the comb width, the offset and the cyclic shift.

11. The network entity as claimed in claim 9 or claim 10, wherein the network entity is configured to inform the determined location and / or the one or more pilot measurements to a channel estimator.

12. A method (1200) for implementation at a network entity (501) in a mobile network (500), the network entity being configured for communication with a user equipment device (350, 502) in the mobile network, the method comprising allocating (1201) to the user equipment device a set of location-associated pilot patterns for uplink communication from the user equipment device, wherein each of the set of location-associated pilot patterns comprises a respective pilot pattern corresponding to a respective geographic location of the user equipment device.

13. A user equipment device (350, 502) for use in a mobile network (500), the user equipment device configured for communication with a network entity (501) in the mobile network, the user equipment device being configured to:receive (1301) an indication of a set of location-associated pilot patterns for uplink communication; and select ( 1302) a location-associated pilot pattern from the set to use for uplink communication with the network entity in dependence on the geographic location of the user equipment device.

14. The user equipment device as claimed in claim 13, wherein the user equipment device is configured to receive the set of location-associated pilot patterns from the network entity as a limited subset of a base pilot pattern.

15. The user equipment device as claimed in claim 14, wherein the user equipment device is configured to receive an indication of a default offset and default cyclic shift of the base pilot pattern.

16. The user equipment device as claimed in claim 14 or 15, wherein the base pilot pattern is a regular comb pilot pattern having a comb width X, where X is equal to the width of the base pilot pattern multiplied by an expansion factor.

17. The user equipment device as claimed in any of claims 13 to 16, wherein the user equipment device is configured to select a pilot pattern according to a pre-defined ruleset defining an offset and a cyclic shift of the base pilot pattern such that each geographical segment of the user equipment device has a unique configuration.

18. The user equipment device as claimed in any of claims 13 to 17, wherein the user equipment device is configured to send one or more uplink messages to the network entity according to the selected location-associated pilot pattern.

19. The user equipment device as claimed in any of claims 13 to 18, wherein the set of location-associated pilot patterns comprises a respective pilot pattern for each of multiple geographical segments for the user equipment device.

20. The user equipment device as claimed in claim 13, wherein the user equipment device is configured to receive the set of location-associated pilot patterns as a list of pilot patterns covering all possible location of the user equipment device, wherein the set comprises, for each pilot pattern in the set, a respective comb width, offset and cyclic shift.

21. A method (1300) for implementation at a user equipment device (350, 502) in a mobile network (500), the user equipment device configured for communication with a network entity in the mobile network, the method comprising:receiving (1301) an indication of a set of location-associated pilot patterns for uplink communication; and selecting (1302) a location-associated pilot pattern from the set to use for uplink communication with the network entity in dependence on the geographic location of the user equipment device.

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