Device to device interference triggered handover

Various communication systems may benefit from properly triggered handovers. For example, certain communication systems may benefit from device-to-device interference triggered handovers. A method may include identifying, at a device, at least one strong device to device communication. The method may also include reporting, or initiating the reporting, the at least one strong device to device communication to a controlling node, wherein the controlling node is configured to control the device.

BACKGROUND

Various communication systems may benefit from properly triggered handovers. For example, certain communication systems may benefit from device-to-device interference triggered handovers.

2. Description of the Related Art

Proximity services (ProSe) for device-to-device (D2D) communications includes a number of different aspects to be addressed. Amongst those aspects are the co-existence of cellular D2D communications and how to handle the interference among D2D pairs. Hence, D2D radio resource and mobility management may be of value.

Mobility and interference management for D2D communications may help to permit efficient operation of simultaneously communicating D2D pairs or clusters in the same area. To optimize resource re-use and to avoid intolerable interference, D2D pairs or clusters may measure D2D beacons and report to the coordinating base station/network, or alternatively report to a master UE, such as in an out-of-coverage scenario.

SUMMARY

According to certain embodiments, a method includes identifying, at a device, at least one strong device to device communication. The method also includes reporting, or initiating the reporting, the at least one strong device to device communication to a controlling node, wherein the controlling node is configured to control the device.

In certain embodiments, a method includes identifying a strong device to device communication based on a report received from a device. The method also includes determining whether to hand over at least one device based on whether the at least one device is part of strong device to device communication.

An apparatus, according to certain embodiments, may include at least one processor and at least one memory including computer program code. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to identify, at a device, at least one strong device to device communication. The at least one memory and the computer program code may also be configured to, with the at least one processor, cause the apparatus at least to report, or initiate the report of, the at least one strong device to device communication to a controlling node, wherein the controlling node is configured to control the device.

An apparatus, in certain embodiments, may include at least one processor and at least one memory including computer program code. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to identify a strong device to device communication based on a report received from a device. The at least one memory and the computer program code may also be configured to, with the at least one processor, cause the apparatus at least to determine whether to hand over at least one device based on whether the at least one device is part of strong device to device communication.

According to certain embodiments, an apparatus may include means for identifying, at a device, at least one strong device to device communication. The apparatus may also include means for reporting, or initiating the reporting, the at least one strong device to device communication to a controlling node, wherein the controlling node is configured to control the device.

In certain embodiments, an apparatus may include means for identifying a strong device to device communication based on a report received from a device. The apparatus may also include means for determining whether to hand over at least one device based on whether the at least one device is part of strong device to device communication.

A non-transitory computer-readable medium may, according to certain embodiments, be encoded with instructions that, when executed in hardware, perform a process. The process may include identifying, at a device, at least one strong device to device communication. The process may also include reporting, or initiating the reporting, the at least one strong device to device communication to a controlling node, wherein the controlling node is configured to control the device.

A non-transitory computer-readable medium may, in certain embodiments, be encoded with instructions that, when executed in hardware, perform a process. The process may include identifying a strong device to device communication based on a report received from a device. The process may also include determining whether to hand over at least one device based on whether the at least one device is part of strong device to device communication.

According to certain embodiments, a computer program product may encode instructions for performing a process. The process may include identifying, at a device, at least one strong device to device communication. The process may also include reporting, or initiating the reporting, the at least one strong device to device communication to a controlling node, wherein the controlling node is configured to control the device.

In certain embodiments, a computer program product may encode instructions for performing a process. The process may include identifying a strong device to device communication based on a report received from a device. The process may also include determining whether to hand over at least one device based on whether the at least one device is part of strong device to device communication.

DETAILED DESCRIPTION

D2D user equipment devices (UEs) may sometimes be controlled by a network. However, at the cell-edge or handover region, the D2D pairs/clusters may be controlled by different base stations/nodes. This may cause interference between D2D pairs/clusters. One option is for the controlling nodes to coordinate resource re-use of D2D pairs/clusters. This may rely on fast information exchange between the controlling nodes, which may be challenging due to backhaul limitations and may cause additional signaling overhead.

Certain embodiments instead transfer D2D-interference vulnerable D2D pairs to the optimal D2D-controlling node based on the received energy from the neighboring D2D pairs.FIG. 1illustrates a method according to certain embodiments. The method ofFIG. 1may provide for such transfer of D2D-interference vulnerable D2D pairs.

As shown inFIG. 1, the method may include, at110, a D2D pair reporting nearby strong D2D pair(s) to the controlling node. Here, a D2D pair may be classified as a strong D2D pair if the resource-reuse with this pair would not be beneficial for the reporting D2D pair due to inter-D2D pair interference. A threshold level of potential interference may be used to determine whether the D2D pair is a strong D2D pair. A strong D2D pair may be a D2D pair that has over −90 dBm reference signal received power (RSRP). In another example, a strong D2D pair may be relatively stronger than the D2D pair that identified the strong D2D pair by, for example, 6 dB. The controlling node may be a base station, such as an evolved Node B (eNB) or other controlling network element.

At120, at least one controlling node of the reporting D2D pair may identify the controlling node(s) of strong D2D pair(s). There are a variety of ways that this identification may be made. For example, the information about the controlling node(s) of strong D2D pair(s) may be based on, for example, controlling node specific identification embedded/coded in the strong D2D pair's signal/beacon. This information may be decoded by either the reporting D2D pair or by the controlling node.

At130, the cluster of strong D2D pairs together may be kept together. This may be accomplished in a variety of ways, such as by issuing or delaying the D2D-control handover of the reporting D2D to another node, if feasible. This keeping together of the strong D2D pairs may be contingent on the reporting D2D pair itself not being reported as a strong D2D pair by another D2D pair under the same controlling node.

Thus, in certain embodiments the control of a D2D pair may not always be handed over based on the handover (HO) hysteresis and offset conditions, for example in terms of the node specific downlink reference symbol. Instead, the D2D pair may also be handed over to a node based on where the received D2D interference may be intolerable. This may benefit the interference management between D2D pairs under the control of different nodes.

To decode the controlling cell information of a strong D2D pair, the D2D pair beacon or signal could be designed to include the controlling node information, such as the information of the D2D-controlling cell. The information could, for example, be provided as a part of the D2D pair identifier.

This discussion has explained embodiments in terms of a “D2D pair,” but the same may be applied to a unidirectional D2D link or a D2D multicast in, for example, different D2D contexts. Thus, various embodiments are possible.

In certain embodiments, D2D resource allocation and interference management may be managed by a controlling node. The controlling node may be, for example, at least one of a base station or a master user equipment (UE) or a controlling agent.

FIG. 2illustrates a signaling flow according to certain embodiments.FIG. 2more particularly illustrates an exemplary signaling flow for base station controlled mobility and interference/resource management. Interference conditions may change due to the mobility of the D2D pair(s).

At1, D2D pair 1 may send a D2D measurement report (DMR) to the controlling base station. The DMR may include measurements for received or scattered energy from other D2D pairs, such as D2D pair 2. The DMR may also include identification information of D2D pair and/or the controlling cell ID.

At2, if the controlling base station information is not decodable by D2D pair 1 or BS1, BS1 may identify the controlling cell of D2D pair 2 by, for example, inquiring of the network with the available identification information related to D2D pair 2 and/or the controlling cell of D2D pair 2.

At3, depending on the DMRs sent by D2D pair 1 and other D2D pairs under the control of BS1, the controlling base station (BS1) may trigger a D2D-control handover for D2D pair 1.

At4, the D2D-control handover decision for D2D pair 1 may also depend on the other DMRs reported by the neighboring D2D pairs under the control of BS1. Thus, the decision may avoid causing a similar problem to the neighboring D2D pairs in the source cell after issuing the D2D-control handover of D2D pair 1.

At5, D2D pair 1 UE(s) may perform measurements for BS2 if needed. Then, at6, the triggered handover may be executed to BS2, if allowed and feasible.

Cellular communication may be minimally impacted by certain embodiments, since the decisions may be made at the cell-edge where the UE is not necessarily connected to the best cell. In addition, the handover triggering/delaying decision may be taken only if the UE does not have an ongoing cellular service; or if the D2D control and cellular control may stay in different cells, for example, in a form of dual connectivity; or if the impact of the handover is negligible to the on-going cellular service(s) or a high-priority service.

InFIG. 2, dashed lines denote optional signaling. However, the steps may also be performed in different orders and even those portions with solid lines may be substituted or omitted, in certain embodiments.

If the intention is to manage the handover of D2D UEs only if there is the actual presence of interference, not only when strong D2D pairs are around, the D2D UE may identify the strong interference in the data or control channel. If D2D communications has certain dedicated resources, then the problem may plainly be due to a neighboring D2D pair. If there is no dedicated resource for D2D, the controlling cell of the interfered D2D pair could identify the root-source of the interference by exchanging information with the controlling cell of the potential D2D interferer.

On the other hand, certain embodiments address the interference problem by solving it before it occurs. Hence, certain embodiments identify the strong D2D pairs in advance and put them under the same controlling cell. Then, even if there is a strong interference presence, it is not because of a strongly interfering D2D pair, for example, due to an uplink transmission).

Certain embodiments may have various benefits or advantages. For example, certain embodiments may provide less D2D interference, more efficient utilization of resources, and less coordination overhead between D2D-controlling nodes. Certain embodiments may be particularly beneficial in systems where nodes tightly control D2D operation. However, certain embodiments may also be of use in systems were D2D operations are more autonomous, with relatively minimal control provided by the base station or master user equipment.

FIG. 3illustrates a method according to certain embodiments. The method ofFIG. 3may be performed by, for example, a user equipment device, such as a device configured for device to device communication.

As shown inFIG. 3, the method may include, at310, identifying, at a device, at least one strong device to device communication. The identification may be based on, for example, measuring at305. The method may also include, at320, reporting, or initiating the reporting, the at least one strong device to device communication to a controlling node, wherein the controlling node is configured to control the device.

The at least one strong device to device communication may be the communication associated with at least one device to device pair, at least one device to device unicast, or at least one device to device multicast. Thus, for example, identifying the at least one strong device to device communication may involve identifying at least one strong device to device pair in either direction or both directions of the communication link between the devices.

The method may further include, at330, reporting, to the controlling node, an identification of at least one controlling node corresponding to the at least one strong device to device communication. The identification may be or include at least one of identification information of a device to device pair or a controlling cell identifier.

FIG. 4illustrates another method according to certain embodiments. The method ofFIG. 4may be performed by a controlling node such as, for example, a base station or master user equipment or a controlling agent.

As shown inFIG. 4, a method may include, at410, identifying a strong device to device communication based on a report received from a device at405. The method may also include, at420, determining whether to hand over at least one device based on whether the at least one device is part of strong device to device communication.

For example, the handover determination may be regarding at least one of the D2D devices with the strong D2D communication being handed over to the controlling node of the device that identified the strong D2D communication. Alternatively, or in addition, the handover determination may be regarding handover of the device (and paired devices) that identified the strong D2D pair to the controlling node of the strong D2D pair. In other words, both cases of handover are broadly included within the determining whether to hand over at least one device based on whether the at least one device is part of strong device to device communication.

The determining may be configured to keep strong device to device communicators under control of a same controlling node. For example, the determination may take into account the number of strong device-to-device pairs under control of the controlling node compared to the number under control of a neighboring controlling node.

The method may further include, at430, identifying a controlling node associated with the strong device to device communication. The identifying the controlling node may include, at435, inquiring of a network based on information included in the report.

The method may additionally include, at440, triggering handover of the at least one device, based on the determining, when handing over the device places more strong device to device communications under a single controlling node.

The method may also include, at450, confirming with a target controlling node that handing over the device places more strong device to device communications under the single controlling node, prior to, at460, commanding the at least one device to hand over.

FIG. 5illustrates a system according to certain embodiments of the invention. In one embodiment, a system may include multiple devices, such as, for example, at least one UE510, at least one eNB520or other base station or access point, and at least one D2D device530. In certain systems, UE510, eNB520, D2D device530, and a plurality of other user equipment and D2D devices may be present. Other configurations are also possible, including those with multiple base stations, such as eNBs. The UE510may be equipped for both cellular and D2D communication. In other word, the UE510may operate in a cellular mode for cellular communication, and in a D2D mode for D2D communication.

Each of these devices may include at least one processor, respectively indicated as514,524, and534. At least one memory may be provided in each device, as indicated at515,525, and535, respectively. The memory may include computer program instructions or computer code contained therein. The processors514,524, and534and memories515,525, and535, or a subset thereof, may be configured to provide means corresponding to the various blocks ofFIGS. 1,3, and4. Although not shown, the devices may also include positioning hardware, such as global positioning system (GPS) or micro electrical mechanical system (MEMS) hardware, which may be used to determine a location of the device. Other sensors are also permitted and may be included to determine location, elevation, orientation, and so forth, such as barometers, compasses, and the like.

As shown inFIG. 5, transceivers516,526, and536may be provided, and each device may also include at least one antenna, respectively illustrated as517,527, and537. The device may have many antennas, such as an array of antennas configured for multiple input multiple output (MIMO) communications, or multiple antennas for multiple radio access technologies. Other configurations of these devices, for example, may be provided. For example, eNB520may additionally be configured for wired communication, and in such a case antenna527would also illustrate any form of communication hardware, without requiring a conventional antenna.

Transceivers516,526, and536may each, independently, be a transmitter, a receiver, or both a transmitter and a receiver, or a unit or device that is configured both for transmission and reception.

Processors514,524, and534may be embodied by any computational or data processing device, such as a central processing unit (CPU), application specific integrated circuit (ASIC), or comparable device. The processors may be implemented as a single controller, or a plurality of controllers or processors.

Memories515,525, and535may independently be any suitable storage device, such as a non-transitory computer-readable medium. A hard disk drive (HDD), random access memory (RAM), flash memory, or other suitable memory may be used. The memories may be combined on a single integrated circuit as the processor, or may be separate from the one or more processors. Furthermore, the computer program instructions stored in the memory and which may be processed by the processors may be any suitable form of computer program code, for example, a compiled or interpreted computer program written in any suitable programming language.

The memory and the computer program instructions may be configured, with the processor for the particular device, to cause a hardware apparatus such as UE510, eNB520, and D2D device530, to perform any of the processes described above (see, for example,FIGS. 1-4). Therefore, in certain embodiments, a non-transitory computer-readable medium may be encoded with computer instructions that, when executed in hardware, perform a process such as one of the processes described herein. Alternatively, certain embodiments may be performed entirely in hardware.

Furthermore, althoughFIG. 5illustrates a system including a UE, eNB, and D2D device, embodiments of the invention may be applicable to other configurations, and configurations involving additional elements.

GLOSSARY

ASIC Application Specific Integrated Circuit

CN Core Network

CPU Central Processing Unit

D2D Device to Device Communications

DMR D2D Measurement Report

eNB Evolved Node B

GPS Global Positioning System

HDD Hard Disk Drive

MEMS Micro Electrical Mechanical System

MIMO Multiple Input Multiple Output

MME Mobility Management Entity

ProSe Proximity Services

RAM Random Access Memory

RAN Radio Access Network

ROM Read Only Memory

RSRP Reference Signal Received Power

UE User Equipment