CN105052244B

CN105052244B - Device anchor base station

Info

Publication number: CN105052244B
Application number: CN201480019603.4A
Authority: CN
Inventors: 杨宇; K.迪谋
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2013-02-04
Filing date: 2014-02-03
Publication date: 2021-04-09
Anticipated expiration: 2034-02-03
Also published as: CN105052244A; BR112015018581A2; WO2014118760A1; MX347933B; MX2015010010A; EP2952058A1

Abstract

Systems and methods for providing efficient and reliable communication for wireless devices (16, 20), such as machine type communication devices (16), in a cellular communication network (10) are disclosed herein. In one embodiment, a network node (12) of a cellular communication network (10) identifies a candidate device-anchor base station (20), wherein the candidate device-anchor base station (20) is a wireless device (20) that satisfies one or more predefined criteria for acting as the candidate device-anchor base station (20). The network node (12) then completes selection of the device anchor base station (20) for the wireless device (16, 20) from the candidate device anchor base stations (20) such that communications between the serving base station (12) of the wireless device (16, 20) and the wireless device (16, 20) pass through the device anchor base station (20). In this way, communication between the wireless device (16, 20) and the serving base station (20) of the wireless device (16, 20) is facilitated by the device anchor base station (20).

Description

Device anchor base station

RELATED APPLICATIONS

This application claims priority to provisional patent application 61/760,454 filed on day 2, 4, 2013 and patent application 61/760,462 filed on day 2, 4, 2013, the disclosures of which are hereby incorporated by reference as if set forth herein in their entirety.

This application relates to U.S. patent application 14/165,961 entitled DEVICE-ANCHOR BASE STATION SELECTION AND DETECTION, filed on 28/1/2014, having common owners AND assignee, AND incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates to cellular communication networks, and more particularly, to systems and methods for utilizing wireless devices as device anchor base stations to maintain efficient and reliable communication within a cellular communication network.

Background

In recent years, the research and use of machine to machine (M2M) and/or the deployment of Machine Type Communication (MTC) devices in cellular communication networks has increased dramatically. As used herein, an MTC device is a wireless device that performs MTC or M2M communications. The use of these MTC devices can become an excellent opportunity for telecommunications operators to extend their networks without significant costs. In M2M communications, MTC devices such as smart meters, signs, cameras, remote sensors, laptops and appliances are connected to a cellular communication network. Many MTC devices sporadically transmit one or several short packets containing measurements, reports and triggers such as temperature, humidity or wind speed. In most cases, MTC devices are expected to have low mobility, e.g. they are static. MTC devices are often low complexity, for low end (e.g., low average profit per user, low data rate, high hysteresis margin) applications. For general applications, the power/energy consumption for such MTC devices is also expected to be low.

One of the obvious characteristics in a cellular communication network with M2M communication is a large increase in the number of wireless devices (i.e., typically a large number of MTC devices). This can cause the cellular communication network to become overloaded, which in turn can cause the cellular communication network to be unable to fully support the requested communication service. In addition, MTC devices can be installed indoors or underground (i.e., some MTC devices may be located in coverage holes) where propagation conditions can be greatly degraded. As a result, MTC devices located in such coverage holes may have difficulty maintaining efficient and reliable communications with the cellular communication network.

Therefore, there is a need for systems and methods that provide efficient and reliable communication for MTC devices located in coverage holes. Additionally, there is a need for systems and methods that address potentially high load conditions when a large number of MTC devices are in a cellular communication network.

Disclosure of Invention

The present disclosure relates to systems and methods for providing efficient and reliable communication for wireless devices, such as Machine Type Communication (MTC) devices, in a cellular communication network. In one embodiment, a network node of a cellular communication network identifies candidate device anchor base stations, wherein the candidate device anchor base stations are wireless devices that satisfy one or more predefined criteria for acting as candidate device anchor base stations. The network node then completes the selection of the device-anchor base station for the wireless device from among the candidate device-anchor base stations such that communications between the serving base station of the wireless device and the wireless device pass through the device-anchor base station. In this way, communication between the wireless device and the serving base station of the wireless device is facilitated by the device anchor base station. This is particularly beneficial in situations where the wireless device needs help due to being located in a coverage hole or high cell load condition, for example.

In one embodiment, identifying the candidate device anchor base station comprises selecting the candidate device anchor base station at the network node. Further, in one embodiment, selecting, at the network node, the candidate device anchor base station comprises obtaining information indicative of capabilities of the second wireless device; determining, based on the information, whether the second wireless device satisfies one or more predefined criteria as a candidate device anchor base station; and selecting the second wireless device as the candidate device anchor base station if it is determined that the second wireless device satisfies one or more predefined criteria as the candidate device anchor base station. Also, in one embodiment, obtaining information includes obtaining information from the second wireless device indicating capabilities of the second wireless device. In one embodiment, the information is obtained from the second wireless device via one or more Information Elements (IEs) received from the second wireless device via Radio Resource Control (RRC) signaling. In another embodiment, obtaining the information includes receiving information indicative of a device type of the second wireless device, wherein the device type of the second wireless device indicates capabilities of the second wireless device.

In one embodiment, identifying the candidate device anchor base station includes receiving information from the second wireless device indicating whether the second wireless device is selected as the candidate device anchor base station.

In one embodiment, the network node is further configured to determine that assistance from a device anchor base station is required in a cell served by the wireless base station of the wireless device, wherein the network node identifies candidate device anchor base stations for the cell served by the serving base station. In one embodiment, the network node identifies a candidate device anchor base station in response to determining that assistance from the device anchor base station is needed in a cell served by the wireless base station of the wireless device. In one implementation, if one or more coverage holes are located in a cell, the network node determines that assistance from the device anchor base station is needed in the cell.

Also, in one embodiment, the network node is further configured to determine that one or more predefined coverage holes are located in the cell, and in response, determine that assistance from the device anchor base station is needed in the cell. In another embodiment, the network node is further configured to receive information from the one or more wireless devices indicating that the one or more wireless devices have detected one or more coverage holes in the cell, and in response, determine that assistance from the device anchor base station is needed in the cell. In another embodiment, the network node is further configured to detect one or more coverage holes in the cell and, in response, determine that assistance from the device anchor base station is needed in the cell.

In one embodiment, at least one of the one or more coverage holes is a partial coverage hole. In one embodiment, the network node is further configured to detect the partial coverage hole in response to a predefined number of consecutive unsuccessful Physical Uplink Shared Channel (PUSCH) transmissions from the second wireless device while the second wireless device is located in the partial coverage hole.

In one embodiment, the network node is further configured to detect the one or more coverage holes based on one or more Radio Link Failure (RLF) reports for radio link failures occurring in the coverage holes. In another embodiment, the network node is further configured to detect the one or more coverage holes based on at least one of the group consisting of: a received power for the second wireless device when the second wireless device is located in the coverage hole, a signal to interference plus noise ratio (SINR) for the second wireless device when the second wireless device is located in the coverage hole, and a hybrid automatic repeat request (HARQ) NACK rate for the second wireless device when the second wireless device is located in the coverage hole.

In another embodiment, the network node is further configured to detect one or more coverage holes in the cell in response to the second wireless device being located in a coverage hole operating in a coverage enhancement mode of operation. In another embodiment, the network node is further configured to detect one or more coverage holes in the cell in response to a failed communication with the second wireless device while the second wireless device is located in a coverage hole.

In another embodiment, the network node is further configured to determine that assistance from the device anchor base station is needed in the cell if the network load for the cell is greater than a predefined threshold representing a high network load.

In another embodiment, the network node is further configured to determine that assistance from the device anchor base station is needed in the cell in response to a predefined number of consecutive random access attempts from the second wireless device.

In one embodiment, the wireless device is an MTC device located in a coverage hole. In another embodiment, the wireless device is an MTC device and the network load of a cell served by a serving base station of the wireless device is greater than a predefined threshold representing a high network load.

In one embodiment, a wireless device in a cellular communication network is configured to select the wireless device as a candidate device anchor base station and, in response, inform the cellular communication network that the wireless device is the candidate device anchor base station.

Those skilled in the art will appreciate the scope of the present disclosure and realize additional aspects thereof after reading the following detailed description of the embodiments in association with the accompanying drawing figures.

Drawings

The accompanying drawings incorporated in and forming a part of this specification illustrate several aspects of the present disclosure and, together with the description, serve to explain the principles of the disclosure.

Fig. 1 illustrates a cellular communication network in which a device anchor base station is utilized to facilitate communication between a Machine Type Communication (MTC) device and a serving base station of the MTC device, according to one embodiment of the present disclosure;

figure 2 illustrates a process for utilizing a device anchor base station to facilitate communication between an MTC device and a serving base station of the MTC device, according to one embodiment of the present disclosure;

fig. 3A and 3B illustrate operation of the cellular communication network of fig. 1 according to the process of fig. 2, according to one embodiment of the present disclosure.

Fig. 4 illustrates a process for determining whether to activate or trigger device anchor base station assistance based on coverage holes, according to one embodiment of the present disclosure;

FIG. 5 illustrates a process for detecting coverage holes, according to one embodiment of the present disclosure;

fig. 6 illustrates a process for determining whether to activate or trigger device anchor base station assistance based on network load, according to another embodiment of the present disclosure;

fig. 7 illustrates a process for determining whether to activate or trigger device anchor base station assistance based on coverage holes and network load, according to one embodiment of the present disclosure;

fig. 8 illustrates a process for determining whether to activate or trigger device anchor base station assistance based on a failed random access attempt in accordance with yet another embodiment of the present disclosure;

fig. 9 illustrates a process for selecting a candidate device anchor base station in accordance with one embodiment of the present disclosure;

fig. 10 shows some examples of Information Elements (IEs) containing capability information for a wireless device, according to one embodiment of the present disclosure;

fig. 11 illustrates a process for selecting a candidate device anchor base station in accordance with another embodiment of the present disclosure;

fig. 12 illustrates a process in which a wireless device selects itself as a candidate device anchor base station according to one embodiment of the disclosure;

fig. 13A to 13C illustrate a procedure by which an MTC device selects a device anchor base station for the MTC device from a plurality of candidate device anchor base stations, according to one embodiment of the present disclosure;

figure 14 illustrates a process by which an MTC device selects a device anchor base station for the MTC device from a plurality of candidate device anchor base stations, according to another embodiment of the present disclosure;

fig. 15 illustrates a process by which a base station selects a device anchor base station for an MTC device from a plurality of candidate device anchor base stations, according to one embodiment of the present disclosure;

fig. 16 shows one example of an IE for providing information about the traffic pattern of a wireless device to a cellular communication network according to one embodiment of the present disclosure;

figure 17 graphically illustrates one example of a traffic pattern for an MTC device and a traffic pattern for two candidate device anchor base stations, where the traffic patterns can coexist such that either or both of the two candidate device anchor base stations can act as device anchor base stations for the MTC device, according to one embodiment of the present disclosure;

fig. 18 illustrates an embodiment in which a plurality of device anchor base stations are selected for MTC devices and used to allow communication between the MTC device and a serving base station of the MTC device by using a multipoint communication scheme;

fig. 19 illustrates one embodiment in which candidate device anchor base stations are grouped, in accordance with the present disclosure;

fig. 20 illustrates one example of providing information to IEs of a cellular communication network that allows grouping of candidate device anchor base stations according to one embodiment of the present disclosure;

fig. 21 illustrates a process employed to store and utilize device anchor base stations and wireless device pairings to select a device anchor base station, according to one embodiment of the present disclosure;

FIG. 22 is a block diagram of one of the wireless devices of FIG. 1 according to one embodiment of the present disclosure;

figure 23 is a block diagram of the MTC device of figure 1 according to one embodiment of the disclosure; and

fig. 24 is a block diagram of the base station of fig. 1 according to one embodiment of the present disclosure.

Detailed Description

The following embodiments set forth information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

Systems and methods for providing efficient and reliable communication for wireless devices, such as Machine Type Communication (MTC) devices, in a cellular communication network are disclosed herein. In this regard, fig. 1 illustrates a cellular communication network 10 according to one embodiment of the present disclosure. Cellular communication network 10 may be any type of cellular communication network such as, but not limited to, a third generation partnership project (3GPP) Long Term Evolution (LTE) or LTE-advanced cellular communication network. Furthermore, while LTE or LTE-advanced terminology is sometimes used throughout this disclosure, the concepts described herein are not limited to LTE or LTE-advanced. Rather, the concepts disclosed herein are applicable to any suitable type of cellular communication network, and more generally to any suitable type of wireless network.

As shown, the base station 12 serves a corresponding cell 14 of the cellular communication network 10. It is noted that although only one base station 12 and one cell 14 are shown for clarity and ease of discussion, cellular communication network 10 generally includes many base stations 12, each serving one or more cells or sectors. The MTC device 16 is located in the cell 14. In this particular example, the MTC device 16 is more specifically located in a coverage hole 18 within the cell 14. For example, the MTC device 16 may be located indoors or in the basement of a building where radio propagation parameters make it difficult, if not impossible, to maintain reliable and efficient communication with the base station 12. However, the MTC device 16 is not necessarily located in a coverage hole. It is noted that although only one MTC device 16 is shown for clarity and convenience of discussion, there may be any number of MTC devices 16 and possibly a large number of MTC devices 16 located in a cell 14. It should also be noted that while many of the embodiments herein focus on MTC devices 16, the embodiments disclosed herein are also applicable to other types of wireless devices.

In addition to the MTC device 16, a plurality of wireless devices 20-1 to 20-5 are located in the cell 14. Wireless devices 20-1 through 20-5 are generally referred to herein collectively or individually as wireless devices 20. The wireless device 20 may comprise another MTC device sometimes referred to as a user equipment device (UE) or terminal and/or a conventional wireless device, such as a smartphone, a tablet equipped with a cellular communication interface, or the like.

As described below, some wireless devices 20 are identified as candidate device anchor base stations. In this particular example, wireless devices 20-1, 20-2, and 20-3 are identified as candidate device anchor base stations, and are therefore also referred to herein as candidate device anchor base stations 20-1, 20-2, and 20-3. One or more candidate device anchor base stations 20-1, 20-2, and 20-3 are selected to act as device anchor base stations for the MTC device 16 to provide communication assistance to the MTC device 16 when, for example, the MTC device 16 is located in a coverage hole 18. The candidate device anchor base stations 20-1, 20-2, and 20-3 may additionally or alternatively be used to provide assistance to the MTC device 16 or other wireless devices 20 when the network load for the cell 14 is greater than a predefined threshold. In this example, the wireless device 20-1 is selected as the device anchor base station for the MTC device 16, and thus, the MTC device 16-1 is also referred to herein as the device anchor base station 20-1 of the MTC device 16. Thereafter, communications (uplink and/or downlink) between the base station 12 and the MTC device 16 pass partially or completely through the device anchor base station 20-1 of the MTC device 16.

As described below, communications to and/or from the MTC device 16 are relayed or repeated by the device anchor base station 20-1 while the MTC device 16 is located in the coverage hole 18. By appropriate selection of the device anchor base station 20-1, reliable and efficient communication can be maintained between the MTC device 16 and the base station 12 even if the MTC device 16 is located in a coverage hole 18. Similarly, when a high network load condition exists in the cell 15, the device anchor base station 20-1 may help mitigate or avoid the high load condition (whether or not the MTC device 16 is located in a coverage hole 18). For example, communication of the MTC device 16 may be received by the device anchor base station 20-1 from the MTC device 16, maintaining the transmission, and transmitting the transmission to the base station 12 at another time slot when the network load falls to an acceptable level. For most applications, the MTC device 16 has low latency requirements (i.e., traffic from the MTC device 16 is delay insensitive), so this scheme is acceptable for the MTC device 16. As another example, in the case of a device-less anchor base station 20-1, the link between the MTC device 16 and the base station 12 can be poor and therefore require a low modulation and coding scheme. A low modulation and coding scheme will require more radio resources for transmission. However, by means of the device anchor base station 20-1, the link quality can become good, so that high modulation and coding schemes can be used, which in turn reduces the amount of radio resources needed for transmission and thus relieves high load conditions in the cell 14.

Before continuing, it should be noted that, as used herein, a "node" of the cellular communication network 10 is a wireless device or network node of the cellular communication network 10. As used herein, a network node is a radio access network node or a core network node. Further, as used herein, a radio access network node is a node (e.g. a base station, a relay or the like) in a radio access network of the cellular communication network, and a core network node is a node (e.g. a serving gateway, a mobility management entity or the like) in a core network (not shown) of the cellular communication network 10.

Further, MTC devices such as MTC device 16 are wireless devices that perform MTC or machine-to-machine (M2M) communications. Some examples of MTC devices are smart meters, signs, cameras, remote sensors, laptops, and appliances connected to a cellular communication network. It is noted that MTC devices are sometimes also referred to as sensors (e.g., temperature sensors). MTC devices typically have reduced latency requirements and low mobility (e.g., are static) compared to other types of wireless devices. Finally, a device anchor base station is a wireless device (e.g., an MTC device or a wireless device) that operates as a relay or repeater for data transfer between another wireless device (e.g., an MTC device) and the base station of the cellular communication network. As described below, the device-anchor base station may additionally include limited base station functionality such as decoding/encoding, demodulation/modulation, and/or signal amplification and other limited base station functionality.

Before continuing, it should be noted that many of the embodiments described herein use the MTC device 16 as an example (i.e., selecting a device anchor base station for the MTC device 16). However, embodiments disclosed herein are not limited to MTC devices 16. Rather, the embodiments described herein may be used to select and use a device anchor base station for any wireless device that needs assistance due to, for example, being located in a coverage hole or high cell load condition.

Fig. 2 illustrates operation of the cellular communication network 10 of fig. 1 according to one embodiment of the present disclosure. This process may be performed by a network node, such as base station 12, or by a combination of the network node and a wireless device for which a selected device anchor base station, such as MTC device 16, is used. It is noted that the steps in the various processes described in this disclosure can be performed in any desired order, unless explicitly or implicitly required. First, it is determined that the cell 14 requires the assistance of a device anchor base station (step 100). As described below, in one embodiment, if one or more coverage holes, such as coverage hole 18, are detected in cell 14, it is determined that assistance from the device anchor base station is required. In another embodiment, if the network load for the cell 14 is greater than a predefined threshold indicative of a high network load condition, it is determined that assistance from the device anchor base station is required. In yet another embodiment, it is determined that assistance from the device anchor base station is required if one or more coverage holes are detected in the cell 14 and/or a high network load condition exists for the cell 14. It is noted that step 100 is optional. For example, in another embodiment, the device anchor base station assistance is always active.

Additionally, and in some embodiments, in response to determining that assistance is needed, a plurality of candidate device anchor base stations are identified (step 102). Likewise, continuing with the example shown in FIG. 1, wireless devices 20-1, 20-2, and 20-3 are identified as candidate device anchor base stations. As described in detail below, candidate device anchor base stations may be selected from a larger group of wireless devices 20 (and possibly all wireless devices) based on one or more predefined criteria. The predefined criteria may include, for example, one or more of the following: the wireless device 20 must be able to transmit in both the uplink and downlink directions in order to be selected as a criterion of a candidate device anchor base station, one or more energy profile-based criteria, one or more traffic profile-based criteria, one or more mobility-based criteria, etc.

Once the candidate device anchor base station has been identified and it is known that the wireless device, which in this example is an MTC device 16, needs assistance, the candidate device anchor base station is selected as the device anchor base station 20-1 for the MTC device 16 (step 104). The device anchor base station 20-1 may be selected from among the candidate device anchor base stations 20-1, 20-2, and 20-3 using any suitable criteria. Once the device anchor base station 20-1 for the MTC device 16 is selected, a connection is established between the MTC device 16 and the device anchor base station 20-1, enabling communication between the MTC device 16 and the base station 12 via the device anchor base station 20-1 (step 106). The connection may be established using, for example, techniques similar to those used for Radio Resource Control (RRC) connections. In some embodiments, the connection may be established such that the MTC device 16 does not know whether the connection to the base station 12 includes 0, 1 or N hops. As described below, in some embodiments,

steps

100 and 102 may be performed by the cellular communication network 10 (e.g., by a network node such as the base station 12), while

steps

104 and 106 may be performed by the cellular communication network 10 (e.g., by a network node such as the base station 12) or by the MTC device 16.

With respect to the operation of the wireless device 20-1 as a device anchor base station, the device anchor base station 20-1 may not support some of the operations typically provided by the base station, for example, as these operations may not be required. For example, if both the device anchor base station 20-1 and the MTC device 16 are static, the device anchor base station 20-1 may not support mobility functions such as handover. Additionally, these devices may operate in a new air interface that may be similar to the radio interface used within cellular networks (e.g., a "degraded fifth generation (5G) radio interface"). For example, this particular customized version of the 5G radio interface may support only a given amount of modulation and coding schemes, or only a given number of cyclic prefix sizes, etc. It is mentioned here that if the device-anchor base station 20-1 is a static device, the direct communication between the device-anchor base station 20-1 and the base station 12 is between the static devices. If the MTC device 16 is also static, the MTC device 16 may be requested to transmit mobility measurements less frequently, or even not perform measurements. Channel Quality Indication (CQI) reporting can also be minimized if the device anchor base station 20-1 communicates with other wireless devices (e.g., MTC devices 16) that only support one type of modulation, e.g., Quadrature Phase Shift Keying (QPSK) and coding, e.g., turbo 1/3. In some embodiments, link adaptation may not be performed. For example, link adaptation may not be required where the device anchor base station 20-1 and the MTC device 16 are always transmitting at the maximum possible power level. All this information is to go to the normal base station controlling the connection. The same applies to power control. Relaxed hybrid automatic repeat request (HARQ) operation can also be utilized.

In yet another embodiment, the selected device anchor base station is a base station that can be selected to broadcast or push data to multiple sensors. The device anchor base station may also be selected to push data related to updating the sensor or to communicate information to be used/read by the sensor. This is often a problem in networks supporting MTC communications. The access network node can delegate device-anchor base station dissemination information.

Fig. 3A and 3B illustrate operation of the cellular communication network of fig. 1 according to the process of fig. 2, according to two different embodiments of the present disclosure. Likewise, in these embodiments, the wireless device for which the device anchor base station is selected is the MTC device 16. However, the MTC device 16 is only one example. Likewise, a device anchor base station may be selected for other wireless devices. In fig. 3A, selection of the device anchor base station 20-1 is performed at the base station 12, while in fig. 3B, selection of the device anchor base station 20-1 is performed at the MTC device 16.

More specifically, in the embodiment of fig. 3A, base station 12 determines that assistance from device anchor base station 20-1 is needed in cell 14 (step 200). As discussed above with respect to step 100 of fig. 2, step 200 may not be performed in some embodiments. The base station 12 also identifies candidate device anchor base stations (step 202). At some point, when the MTC device 16 needs assistance, the base station 12 selects candidate device anchor base stations from those identified in step 202 as device anchor base stations for the MTC device 16 (step 204).

In this embodiment, the base station 12 triggers the establishment of a connection between the device anchor base station 20-1 and the MTC device 16 (step 206). In one embodiment, the base station 12 instructs or otherwise allows the device anchor base station 20-1 to establish a connection with the MTC device 16. In another embodiment, the base station 12 instructs or otherwise allows the MTC device 16 to establish a connection with the device anchor base station 20-1. The MTC device 16 and the device anchor base station 20-1 then communicate to establish a connection (step 208). It is noted that in another embodiment, the base station 12 establishes the connection such that the device anchor base station 20-1 is transparent to the MTC device 16 (i.e., the device anchor base station 20-1 is unknown to the MTC device 16 such that it appears to the MTC device 16 as if communications were sent/received directly to/from the base station 12). At that time, communication between the base station 12 and the MTC device 16 is provided at least in part via the device anchor base station 20-1. For example, downlink transmissions from the base station 12 are relayed or forwarded from the device anchor base station 20-1 to the MTC device 16 (steps 210 and 212). Likewise, uplink transmissions from the MTC device 16 are relayed or forwarded from the device anchor base station 20-1 to the base station 12 (steps 214 and 216). The transmission of the uplink transmission from the device-anchor base station 20-1 to the base station 12 can use the same or different radio (i.e., time and/or frequency) resources as the uplink transmission from the MTC device 16.

The embodiment of fig. 3B is substantially the same as the embodiment of fig. 3A, but wherein the selection of the device anchor base station 20-1 is performed by the MTC device 16. More specifically, in the embodiment of fig. 3B, the base station 12 determines that assistance from a device anchor base station is needed in the cell 14 (step 300). As discussed above with respect to step 100 of fig. 2, step 300 may not be performed in some embodiments. The base station 12 also identifies candidate device anchor base stations (step 302). At some point, when the MTC device 16 needs assistance, the MTC device 16 selects a candidate device anchor base station 20-1 from those identified in step 302 as the device anchor base station for the MTC device 16 (step 304).

In this embodiment, the MTC device 16 and the device anchor base station 20-1 then communicate to establish a connection (step 306). At that time, communication between the base station 12 and the MTC device 16 is provided at least in part via the device anchor base station 20-1. For example, downlink transmissions from the base station 12 are relayed or forwarded from the device anchor base station 20-1 to the MTC device 16 (steps 308 and 310). Likewise, uplink transmissions from the MTC device 16 are relayed or forwarded from the device anchor base station 20-1 to the base station 12 (steps 312 and 314).

The discussion now turns to various embodiments of the various steps described above with respect to fig. 2 and fig. 3A and 3B. In this regard, fig. 4 illustrates a process for determining whether assistance from a device anchor base station is needed for a cell 14, according to one embodiment. This process may be used in step 100 of fig. 2 or similarly in step 200 or step 300 of fig. 3A or 3B, respectively. As shown, the cell 14 is monitored for coverage holes, such as coverage hole 18 (step 400). A coverage hole is an area within the cell 14 where the signal to interference noise ratio (SINR) or Radio Frequency (RF) signal level falls below a predetermined threshold. For example, in one embodiment, a coverage hole is when the received signal level (power or quality level) at both the receiver of the base station 12 and the receiver of the wireless device 20 (or MTC device 16) falls below the noise sensitivity level for all or at least some of the channels. Coverage holes are typically caused by physical obstacles such as buildings, vegetation, hills, tunnels, parking lots in doors, or the like. Such physical barriers are very common for MTC devices for M2M communication and in non-ideal network deployments.

The monitoring of whether the cell 14 has a coverage hole may be performed by a network node (e.g., base station 12), the wireless device 20 (and/or the MTC device 16), or a combination thereof. It is noted, however, that in some embodiments, step 400 may not be performed. For example, in one embodiment, one or more coverage holes in the cell 14 are predetermined and known to the cellular communication network 10, e.g., via drive testing. However, the coverage hole may be detected in any suitable manner. Some non-limiting examples will now be provided. In one embodiment, the coverage hole may be detected by the wireless device 20 located in the coverage hole. For example, wireless device 20 may detect a coverage hole when the coverage hole is only a partial coverage hole (i.e., a coverage hole for some, but not all, channels). As an example, consider a typical scenario with a robust random access procedure implementation and a less robust Physical Uplink Shared Channel (PUSCH) implementation. In this case, wireless device 20 may successfully perform random access to connect to base station 12, but wireless device 20 cannot successfully transmit PUSCH. In this case, after a predefined number of consecutive failed PUSCH transmissions, it can be determined that the wireless device 20 is located in a coverage hole, or more specifically, a partial coverage hole. The location of the wireless device 20 can then be recorded as a coverage hole. It will be apparent that the location of the wireless device 20 can be estimated or otherwise obtained using any suitable technique, such as by combining previous location information and signal strength information of the wireless device 20. The location of the wireless device 20 can also be obtained by means of other static wireless devices that are not located in the coverage hole.

In another embodiment, coverage holes are detected at the network level (e.g., by the base station 12) based on reports from wireless devices (e.g., the wireless device 20 and the MTC device 16) performing Radio Link Failure (RLF) recovery. During RLF recovery, the wireless device transmits an rcconnectionrequest message containing a logMeasAvailable-rel10 Information Element (IE) containing the last measurements taken by the wireless device before RLF. This message also contains the cell identity of the last serving cell of the wireless device reporting the RLF and positioning information, which identifies the location of the wireless device at the time the RLF occurred. This information can be used by the network (e.g., base station 12) to detect coverage holes, including the location of the coverage holes.

In another embodiment, the base station 12 (i.e., the serving base station) and/or the

wireless devices

16, 20 served by the base station 12 can detect coverage holes (e.g., the coverage hole 18) in real-time, e.g., based on received power, SINR, HARQ NACK rate, or the like, or any combination thereof. For example, a coverage hole 18 may be detected by the base station 12 when the received SINR from the MTC device 16 falls below a predetermined level, e.g., 0 decibel (dB). The location information for the MTC device 16 when the coverage hole 18 is detected can be used to define the location of the coverage hole 18. The location information (i.e., information indicative of location) of the MTC device 16 (or other wireless device 20) may be obtained using any suitable technique. For example, if the MTC device 16 is a mobile device, the location information may be location information obtained from or reported by the MTC device 16 entering the coverage hole 18. The location information alternative may be an estimate of the location of the MTC device 16 obtained using signal strength and direction of arrival (DOA) techniques. As another example, the location of the MTC device 16 can be determined by means of other static wireless devices 20 that are not located in a coverage hole.

In another embodiment, again using MTC devices 16 and coverage holes 18 as an example, a coverage hole 18 may be detected based on the operating mode of the MTC device 16. More specifically, a coverage hole 18 may be detected while the MTC device 16 is operating in a coverage enhanced mode of operation. As used herein, a coverage enhancement mode of operation is a mode of operation in which one or more coverage enhancement techniques are used to allow communication between the MTC device 16 and the base station 12. Examples of such coverage enhancement techniques include, but are not limited to, extended Transmission Time Interval (TTI) bundling, transmission repetition, use of higher pilot density, use of specific radio (i.e., time and/or frequency) resources reserved for coverage enhancement mode, and the like. More specifically, when the base station 12 notices that the MTC device 16 is operating in the coverage enhancement mode, the base station 12 may determine that the MTC device 16 is in a coverage hole (i.e., coverage hole 18). The base station 12 may note that the MTC device 16 is operating in the coverage enhancement mode using any suitable technique, for example, by reporting by the MTC device 16, by detection by the base station 12, or the like.

In monitoring the cells 14 for coverage holes, the base station 12 determines whether any coverage holes have been detected (step 402). If so, the base station 12 triggers or activates device anchor base station assistance (step 404). For example, the base station 12 may then detect or otherwise determine candidate device anchor base stations, determine when the wireless device (e.g., MTC device 16) needs assistance, and then complete the selection of the device anchor base station from the candidates for any wireless device that needs assistance. In other words, the base station 12 then continues the process of fig. 2 or fig. 3A and 3B. If no coverage hole is detected, in some embodiments, base station 12 may disable device anchor base station assistance (step 406). For example, base station 12 may no longer look for wireless devices that need assistance. The process then returns to step 400 and repeats.

In another embodiment, the base station 12 (or other radio access network node) may detect a coverage hole (e.g., coverage hole 18) in response to an unsuccessful communication attempt with the wireless device. In this regard, fig. 5 is a flow diagram illustrating the operation of a radio access network node to detect coverage holes in accordance with one embodiment of the present disclosure. Also, in this example, the procedure is described using the base station 12, MTC device 16 and coverage hole 18. However, this process may be used by any radio access network node to detect coverage holes within its corresponding coverage area or cell. First, the base station 12 sends a paging request to the MTC device 16 (step 500). The base station 12 determines whether a response to the paging request has been received within a pre-configured time (step 502). If so, the process ends. If not, the base station 12 determines whether the number of consecutive page attempt failures for the MTC device 16 is greater than a predefined threshold (step 504). If not, the process returns to step 500 and repeats.

Once the number of consecutive paging attempt failures for the MTC device 16 is greater than the predefined threshold, the base station 12 determines that the MTC device 16 is located in a coverage hole (step 506). In other words, in this example, the base station 12 detects the coverage hole 18 in response to the number of consecutive paging attempt failures for the MTC device 16 exceeding a predefined threshold. Furthermore, the location of the MTC device 16, if known, can be used by the base station 12 to define the location of the coverage hole 18 within the cell 14.

The discussion above with respect to fig. 4 and 5 describes embodiments in which assistance of determining that a device anchor base station is needed in response to detecting a coverage hole within the cell 14 is required. In another embodiment, it is determined that assistance from the device anchor base station is required in response to detecting a high load condition in the cell 14. In this regard, fig. 6 is a flow chart illustrating operation of the base station 12 to trigger device anchor base station assistance during high load conditions for a cell 14 in accordance with one embodiment of the present disclosure. This process may be used in step 100 of fig. 2 or similarly in step 200 or step 300 of fig. 3A or 3B, respectively.

As shown, the base station 12 monitors the cell load of the cell 14 (step 600). The cell load may be defined in terms of an amount of resources requested, a number of wireless devices connected to the cell 14, a percentage or amount of unused radio resources of the cell 14 (e.g., a percentage or amount of unused resource blocks), a percentage or amount of used radio resources of the cell 14 (e.g., a percentage or amount of used resource blocks), or the like. In some communication networks, such as LTE or High Speed Packet Access (HSPA) networks, there may be counters implemented (e.g., by the base station 12) on the network side to monitor cell load, e.g., based on a percentage of scheduled resource blocks.

The base station 12 then determines whether the cell load is greater than a predefined threshold indicative of a high load condition (step 602). If so, the base station 12 triggers or activates device anchor base station assistance (step 604). For example, the base station 12 may then detect or otherwise determine candidate device anchor base stations, determine when the wireless device (e.g., MTC device 16) needs assistance, and then complete the selection of the device anchor base station from the candidates for any wireless device that needs assistance. In other words, the base station 12 continues the process of fig. 2 or fig. 3A and 3B. If a high load condition is not detected, in some embodiments, base station 12 may disable device anchor base station assistance (step 606). For example, base station 12 may no longer look for wireless devices that need assistance. The process then returns to step 600 and repeats.

Fig. 7 illustrates another embodiment where detection of both a coverage hole and a high cell load condition triggers device anchor base station assistance in accordance with another embodiment of the present disclosure. This process may be used in step 100 of fig. 2 or similarly in step 200 or step 300 of fig. 3A or 3B, respectively. In this embodiment, the base station 12 monitors the cell for coverage holes and determines whether any coverage holes have been detected (steps 700 and 702), as described above. If any coverage holes are detected, then proceed to step 708, discussed below. If a coverage hole is not detected, the base station 12 monitors the cell load of the cell 14 and determines if the cell load is greater than a predefined threshold, as described above (steps 704 and 706). It is noted that although steps 700-706 are shown as being performed in sequence, some of the steps 700-706 may be performed in parallel (e.g., the base station 12 may monitor the cell for coverage holes while also monitoring the cell load). If the cell load is greater than a predefined threshold, or if there are any coverage holes in the cell 14, the base station 12 triggers or activates device anchor base station assistance (step 708). Otherwise, in some embodiments, base station 12 may disable device anchor base station assistance (step 710). The process then returns to step 700 and repeats.

In another embodiment, in response to a failed Random Access (RA) attempt, it is determined that assistance from a device anchor base station is required. In this regard, fig. 8 is a flow chart illustrating operation of a base station 12 to trigger device anchor base station assistance during high load conditions for a cell 14 in accordance with one embodiment of the present disclosure. Although the base station 12 and MTC device 16 are again used as an example, this process is not so limited and can therefore be performed by other network nodes with respect to RA attempts for other wireless devices. This process may be used in step 100 of fig. 2 or similarly in step 200 or step 300 of fig. 3A or 3B, respectively.

As shown, the base station 12 determines whether the number of consecutive failed RA attempts by the MTC device 16 is greater than a predefined threshold for device anchor base station assistance (step 800). The failed RA attempt may be for the cell 14 and/or for the MTC device 16 regardless of which cell the MTC device 16 is attempting to access. If not, the process returns to step 800. If the number of failed RA attempts exceeds a predefined threshold, the base station 12 triggers or activates device anchor base station assistance as described above (step 802).

While fig. 4-8 focus on embodiments for determining whether device anchor base station assistance is needed, fig. 9-12 relate to embodiments for identifying candidate device anchor base stations as described above with respect to step 102 of fig. 2 and similar steps 202 and 302 of fig. 3A and 3B. More specifically, fig. 9 is a flow chart illustrating a process for identifying candidate device anchor base stations according to one embodiment of the present disclosure. This process may be performed by a network node, a radio access network node (e.g., base station 12), or wireless device 20. As shown, first, information regarding the capability of the wireless device 20 to act as a device anchor base station is obtained (step 900). As discussed below, this information can include any information needed to determine whether the wireless device 20 satisfies one or more predefined criteria as a device anchor base station. Further, the information may be obtained in any suitable manner. For example, if the procedure is performed by a radio access node (e.g., base station 12), the radio access node may obtain some or all of the information from the wireless device 20 via, for example, RRC signaling, one or more information elements included in a new or existing message, or the like. The radio access node may additionally or alternatively obtain some or all of the information from other network nodes.

A determination is then made whether wireless device 20 should be selected to act as a candidate device anchor base station based on one or more predefined criteria for acting as a device anchor base station and information regarding the ability of wireless device 20 to act as a device anchor base station (step 902). If so, the wireless device 20 is selected as the candidate device anchor base station (step 904). Otherwise, in this example, the process returns to step 900 and repeats for another wireless device 20.

In one embodiment, the one or more predefined criteria for acting as a device anchor base station (for selecting candidate device anchor base stations) include one or more of the following criteria. As a first example, the one or more predefined criteria may include a criterion that the wireless device 20 under consideration has the capability to communicate in two aspects, uplink and downlink. More specifically, the criteria may be the ability of the wireless device 20 to transmit its own uplink, receive an uplink from a wireless device (e.g., MTC device 16) attached to the wireless device 20 as a device anchor base station, receive its own downlink, and transmit a downlink to a wireless device (e.g., MTC device 16) attached to the wireless device 20 as a device anchor base station. In a Time Division Duplex (TDD) system, this is straightforward since the uplink and downlink share the same frequency band. However, in Frequency Division Duplex (FDD) systems, this is generally not possible for ordinary wireless devices. In particular, a wireless device may not be able to both transmit and receive on the uplink band, and may not be able to both transmit and receive on the downlink band. For this criterion, the information regarding the capability of wireless device 20 to act as a device anchor base station includes information indicating the capability of wireless device 20 to transmit and receive using downlink resources (e.g., downlink frequency bands in an FDD system) and the capability of wireless device 20 to transmit and receive using uplink resources (e.g., uplink frequency bands in an FDD system). This information may be obtained, for example, from the wireless device 20.

As a second example, the one or more predefined criteria may include a criterion that the wireless device 20 may access an energy or power source. For example, the criteria may be that the wireless device 20 is connected to a permanent power source rather than a temporary power source (i.e., a battery). For this criterion, the information regarding the ability of wireless device 20 to act as a device anchor base station includes an energy profile of wireless device 20. In one embodiment, the energy profile indicates the type of power source available to the wireless device 20, e.g., a permanent power source such as a power supply source or a temporary power supply source such as a battery. Further, if the power source is a battery, the energy profile may indicate a capacity or amount of charge of the battery (e.g., 95% charge or X hours remaining). In this case, the capacity of the battery and/or the charge level of the battery may be used to determine whether wireless device 20 should be selected as a candidate device anchor base station (e.g., if the capacity and/or charge of the battery is greater than a threshold, wireless device 20 is selected as a candidate device anchor base station). The energy profile of the wireless device 20 may be obtained, for example, from the wireless device 20.

As a third example, the one or more predefined criteria may include one or more criteria related to a traffic profile of the wireless device 20. As one particular example, the one or more predefined criteria may include a criterion that wireless device 20 is to be selected as a device anchor base station if the wireless device periodically transmits/receives signals from base station 12 over an explicit period. Instead, wireless devices 20 that are constantly being transmitted to and/or received from cellular communication network 10 and/or wireless devices 20 that are being transmitted to and/or received from cellular communication network 10 in an irregular traffic pattern are selected as device anchor base stations. In addition, devices with a given traffic pattern with a defined packet size and duration are easier to determine the energy available for assistance/relay purposes. For the traffic profile-based criteria, the information regarding the ability of wireless device 20 to act as a device anchor base station includes the traffic profile of wireless device 20. The traffic profile for wireless device 20 may be obtained, for example, by monitoring traffic to and/or from wireless device 20 at the network level (e.g., at base station 12) or at wireless device 20.

As a fourth example, the one or more predefined criteria may include one or more criteria related to a mobility pattern of the wireless device 20. The mobility pattern of the wireless device 20 can indicate, for example, that the wireless device 20 is located in a fixed location (i.e., is static) on a short time scale and larger. In one example, the one or more criteria related to the mobility pattern of wireless device 20 may include a criterion that wireless device 20 is to be selected as a candidate device anchor base station if wireless device 20 is static. Otherwise, if the wireless device is moving, it should not be selected as a candidate device anchor base station. For the mobility pattern based criteria, the information regarding the ability of wireless device 20 to act as a device anchor base station includes the mobility pattern of wireless device 20. The mobility pattern of wireless device 20 may be obtained, for example, by monitoring the movement of wireless device 20 at the network level (e.g., at base station 12) or at wireless device 20.

As a fifth example, the one or more predefined criteria may include a criterion that the wireless device 20 is capable of operating as a relay or repeater before being selected as a candidate device anchor base station. Further, this criterion may be combined with a mobility criterion such that if the wireless device 20 has the capability to operate as a relay or repeater, and has a mobility (e.g., static or low mobility) less than a predefined threshold, the wireless device 20 may be selected as a candidate. As is known, repeaters repeat their received signals in the same frequency band. Not all wireless devices 20 are able to retransmit a received signal on the same frequency band of the received signal. Furthermore, for wireless device 20 to operate as a relay, wireless device 20 must be able to process received signals up to the Radio Link Control (RLC) or Packet Data Convergence Protocol (PDCP) level and forward the received information in the same frequency band as the received signal. Not all wireless devices 20 may have this capability. For this criterion, information regarding the ability of the wireless device 20 to operate as a relay or repeater may be obtained from the wireless device 20 and/or the network node.

As a sixth example, the one or more predefined criteria may include one or more hardware-based criteria. For example, the one or more predefined criteria may include a criterion that the wireless device 20 has a certain hardware capacity, e.g., at least a threshold number of transmitter/receiver antennas. For this criterion, information regarding the hardware capability of the wireless device 20 to operate as a relay or repeater may be obtained from the wireless device 20 and/or the network node.

As a seventh example, the one or more predefined criteria may include a criterion that the wireless device 20 is within a threshold proximity to the serving base station 12 of the wireless device 20 in order to be selected as a candidate device anchor base station. In one example, the Reference Signal Received Power (RSRP) reported by wireless device 20 to base station 12 can be used as an indicator of the proximity of wireless device 20 to base station 12, in which case, since RSRP increases with decreasing proximity, it can be determined that wireless device 20 is within threshold proximity if the reported RSRP is greater than a predefined RSRP threshold. Alternatively, the measured SINR and received power at the base station 12 can be used as an indicator of proximity to the base station 12. As another alternative, location techniques may be used to determine the location of wireless device 20 relative to base station 12. Information indicative of the proximity of wireless device 20 to base station 12 may be obtained, for example, from wireless device 20 or a network node.

As an eighth example, the one or more predefined criteria may include a criterion that the wireless device 20 is within a threshold proximity of one or more wireless devices (e.g., MTC devices 16) that need assistance in order to be selected as a candidate device anchor base station. For example, by using the pilot signal, the proximity of the wireless device 20 to one or more wireless devices that need assistance can be estimated. If the Received Signal Strength (RSS) at the wireless device 20 from one or more wireless devices requiring assistance is below a threshold, the wireless device 20 is not selected as a candidate device anchor base station for at least those wireless devices whose RSS is less than the threshold.

As a final example, the one or more predefined criteria may include a criterion related to the number of wireless devices to which wireless device 20 is or is capable of being adapted as a device anchor base station. For example, if the number of wireless devices to be accommodated by the wireless device as the device anchor base station is less than a predefined threshold, the wireless device 20 is not selected as the candidate device anchor base station.

As discussed above, the information regarding the ability of the wireless device 20 to act as a device anchor base station can be or include various types of information and can be obtained in any suitable manner. As one example, fig. 10 illustrates a plurality of IEs that can be used for RRC messages that convey at least some information about the ability of wireless device 20 to act as a device anchor base station from wireless device 20 to base station 12 via RRC signaling. In this example, the IE includes a UE capability information IE that includes several capabilities of the wireless device, including: power supply access (yes/no), maximum output power, packet size, periodicity, start time offset, mobility pattern, ability to operate as receiver and transmitter in uplink and downlink, and ability to operate as relay/repeater. In this example, the UE capability information IE is appended to the RRC connection request message. As an alternative example, the UE capability information IE may additionally or alternatively be appended to the UE informativeresponse message as a response to a UE information request message sent from the network (e.g., from base station 12) to wireless device 20, as defined in 3GPP TS 36.331.

The selection of wireless device 20 as a candidate device anchor base station may be made by an appropriate access network node (e.g., base station 12) at the time of wireless device 20 setup and registration. The wireless device 20 is selected as the candidate device anchor base station if one or more criteria are met for the candidate device anchor base station. In one embodiment, a new wireless device class is defined for the wireless device 20 selected as the device anchor base station, and a list of wireless devices 20 belonging to this class and related information such as energy access, traffic profile, mobility pattern, etc. are stored in the network.

Fig. 11 is a flow diagram illustrating a process for identifying candidate device anchor base stations according to one embodiment of the present disclosure. This process is performed by the base station 12. Moreover, this process is similar to the process of fig. 9, but where a specific example of predefined criteria for acting as a candidate device anchor base station is used. As shown, base station 12 receives capability information from wireless device 20 via RRC signaling (step 1000). In this example, the capability information is the UE capability information shown in fig. 10. Base station 12 determines whether wireless device 20 has the capability to communicate (transmit and receive) in both uplink and downlink (e.g., in uplink and downlink frequency bands in an FDD system) based on capability information for wireless device 12 (step 1002). If not, the process ends. If so, base station 12 determines whether wireless device 20 has an available power supply (step 1004). If not, the process ends. If so, base station 12 determines whether wireless device 20 has a suitable traffic profile for the candidate device anchor base station, e.g., whether wireless device's traffic profile 20 indicates a periodicity greater than a predefined threshold (N) (step 1006). If not, the process ends. If so, base station 12 determines whether wireless device 20 is static (step 1008). If not, the process ends. If so, wireless device 20 is identified or selected as a candidate device anchor base station (step 1010).

In some of the embodiments described above, the selection of the candidate device anchor base station is performed at the network level (e.g., by base station 12). Fig. 12 illustrates another embodiment in which the wireless device 20 selects itself as the candidate device anchor base station. As shown, the wireless device 20 selects itself as a candidate device anchor base station (step 1100). For example, wireless device 20 may use any of the embodiments described above for candidate device anchor base station selection in order to select itself as the candidate device anchor base station. Wireless device 20 then informs base station 12 that it has been selected as a candidate device anchor base station (step 1102). This notification may be accomplished, for example, via an additional field in the RRCConnectionRequest message indicating that wireless device 20 has the added capability of operating as a device anchor base station. In turn, wireless device 20 may inform base station 12 that it belongs to the new wireless device category for the candidate device anchor base station.

Fig. 13A, 13B, and 13C through 18 now turn to an embodiment for selecting a candidate device anchor base station as a device anchor base station according to step 102 of fig. 2. More specifically, fig. 13A-13C illustrate embodiments in which a wireless device in need of assistance, which in these examples is an MTC device 16, selects a device anchor base station for itself from a plurality of candidate device anchor base stations. Although these embodiments are described with respect to the example of fig. 2, these embodiments are not limited thereto. As shown in fig. 13A, the base station 12 assigns time and/or frequency resources (i.e., radio resources) to the MTC device 16 for device anchor base station selection (step 1200). It is to be noted that as used herein, a radio resource is any radio resource, such as a time and/or frequency resource, a code resource (e.g. as in Wideband Code Division Multiple Access (WCDMA)), or the like. Furthermore, although time and/or frequency resources are used in some examples described herein, other types of radio resources may additionally or alternatively be used.

In addition to time and/or frequency resources, MTC devices 16 for device anchor base station selection are assigned a signature signal. At some point, the base station 12 determines that the MTC device 16 needs assistance (step 1202). The base station 12 may determine that the MTC device 16 needs assistance in any suitable manner. For example, the base station 12 may determine that the MTC device 16 needs help when the MTC device 16 is in a coverage hole 18, is about to enter the coverage hole 18, or is expected to enter the coverage hole 18. As another example, when the load of the cell 14 is greater than a threshold and the MTC device 16 is not a candidate device anchor base station, the base station 12 may determine that the MTC device 16 needs assistance. It is noted that these examples are only examples. Any suitable technique or criteria may be used to determine that the MTC device 16 needs assistance.

Upon determining that the MTC device 16 needs assistance, the base station 12 sends time and/or frequency resources, or more specifically, information indicating time and/or frequency resources assigned to the MTC device 16, to the candidate device anchor base station, which in this example is the wireless device 20-1 to 20-3 (steps 1204-1 to 1204-3). In addition to time and/or frequency resources, the base station 12 may send a feature signal or information indicating a feature signal assigned to the MTC device 16 for device anchor base station selection to the candidate device anchor base stations 20-1 to 20-3. Thereafter, to detect one or more candidate device anchor base stations 20-1 through 20-3, the MTC device 16 transmits a characteristic signal assigned to the MTC device 16 on time and/or frequency resources assigned to the MTC device 16 for device anchor base station selection (step 1206). In one embodiment, the signature signal is a predefined sequence, e.g., a sequence similar to that used for RA, which may be referred to herein as an "RA-like sequence," e.g., a Constant Amplitude Zero Autocorrelation (CAZAC) Zadoff-Chu sequence or the like.

The wireless devices 20-1 to 20-3 acting as candidate device anchor base stations listen for transmission of characteristic signals of MTC devices 16 on time and/or frequency resources assigned to the MTC device 16 for device anchor base station selection. Each wireless device 20-1 to 20-3 determines whether the received power for transmission is greater than a predefined threshold (steps 1208-1 to 1208-3). In this example, the received power at wireless devices 20-2 through 20-3 is not greater than the threshold and, therefore, those wireless devices 20-2 and 20-3 do not respond. In contrast, the received power at wireless device 20-1 is greater than a predefined threshold. Accordingly, the wireless device 20-1 transmits a response to the MTC device 16 (step 1210). The response may include the received power level used at the wireless device 20-1 for transmission of the signature.

Upon receiving the response, the MTC device 16 has detected the wireless device 20-1 as a candidate device anchor base station. The MTC device 16 selects the wireless device 20-1 as the device anchor base station for the MTC device 16 (step 1212). In this embodiment, the MTC device 16 then notifies the base station 12 that the MTC device 16 has selected the wireless device 20-1 as its device anchor base station (step 1214). As one alternative, the MTC device 16 may inform the wireless device 20-1 that the MTC device 16 has selected the wireless device 20-1 as its device anchor base station, and then the wireless device 20-1 may inform the base station 12 of the selection. Once the wireless device 20-1 is selected as the device anchor base station, the MTC device 16 and the wireless device 20-1 communicate to establish a connection in this embodiment (step 1216). Thereafter, when the MTC device 16 transmits on the uplink, the wireless device 20-1, acting as a device anchor base station for the MTC device 16, receives the transmission and retransmits the uplink transmission to the base station 12 (steps 1218 and 1220). The transmission of the uplink transmission from the device anchor base station to the base station 12 can use the same or different time and/or frequency resources as the uplink transmission from the MTC device 16.

Fig. 13B is similar to fig. 13A, but where multiple candidate device anchor base stations respond to the transmission of the feature signal by the MTC device 16. More specifically, as shown, the base station 12 assigns time and/or frequency resources to the MTC device 16 for device anchor base station selection (step 1300). In addition to time and/or frequency resources, MTC devices 16 for device anchor base station selection are assigned a signature signal. As described above, at some point, the base station 12 determines that the MTC device 16 needs assistance (step 1302). Upon determining that the MTC device 16 needs assistance, the base station 12 sends time and/or frequency resources, or more specifically, information indicating time and/or frequency resources assigned to the MTC device 16, to the candidate device anchor base station, which in this example is the wireless device 20-1 to 20-3 (steps 1304-1 to 1304-3). In addition to time and/or frequency resources, the base station 12 may send a feature signal or information indicating a feature signal assigned to the MTC device 16 for device anchor base station selection to the candidate device anchor base stations 20-1 to 20-3. Thereafter, to detect one or more candidate device anchor base stations 20-1 through 20-3, as described above, the MTC device 16 transmits a characteristic signal assigned to the MTC device 16 on time and/or frequency resources assigned to the MTC device 16 for device anchor base station selection (step 1306).

The wireless devices 20-1 to 20-3 acting as candidate device anchor base stations listen for transmission of characteristic signals of MTC devices 16 on time and/or frequency resources assigned to the MTC device 16 for device anchor base station selection. Each wireless device 20-1 to 20-3 determines whether the received power for transmission is greater than a predefined threshold (steps 1308-1 to 1308-3). In this example, the received power at all wireless devices 20-1 to 20-3 is greater than the threshold and therefore all wireless devices 20-1 to 20-3 transmit a response to the MTC device 16 (steps 1310-1 to 1310-3). The response may include the received power level used for transmission of the signature at the corresponding wireless device 20-1 through 20-3. It is noted that although the received power is greater than the threshold at all wireless devices 20-1 through 20-3 in this example, the received power may be greater than the threshold at any number of wireless devices 20-1 through 20-3 (i.e., 0, 1, 2, or 3 at wireless devices 20-1 through 20-3 in this example), as appropriate.

Upon receiving the response, the MTC device 16 detects the wireless devices 20-1 to 20-3 as candidate device anchor base stations. Based on the response, the MTC device 16 selects the wireless device 20-1 as the device anchor base station for the MTC device 16 (step 1312). In one embodiment, the response from the wireless device 20-1 to 20-3 includes the received power level of the wireless device 20-1 to 20-3 at the time for transmission of the characteristic signal by the MTC device 16, and the MTC device 16 selects the wireless device 20-1 to 20-3 with the highest received power as the device anchor base station. However, any suitable selection process may be used. In this example, the wireless device 20-1 is selected as the device anchor base station for the MTC device 16.

In this embodiment, the MTC device 16 then notifies the base station 12 that the MTC device 16 has selected the wireless device 20-1 as its device anchor base station (step 1314). As one alternative, the MTC device 16 may inform the wireless device 20-1 that the MTC device 16 has selected the wireless device 20-1 as its device anchor base station, and then the wireless device 20-1 may inform the base station 12 of the selection. Once the wireless device 20-1 is selected as the device anchor base station, in this embodiment, the MTC device 16 and the wireless device 20-1 communicate to establish a connection (step 1316). Thereafter, when the MTC device 16 transmits on the uplink, the wireless device 20-1, which serves as a device anchor base station for the MTC device 16, receives the transmission and retransmits the uplink transmission to the base station 12 (steps 1318 and 1320). The transmission of the uplink transmission from the device anchor base station to the base station 12 can use the same or different time and/or frequency resources as the uplink transmission from the MTC device 16.

Fig. 13C is similar to fig. 13A and 13B, but where initially no candidate device anchor base station responds to the transmission of the characteristic signal by the MTC device 16. More specifically, as shown, the base station 12 assigns time and/or frequency resources to the MTC device 16 for device anchor base station selection (step 1400). In addition to time and/or frequency resources, MTC devices 16 for device anchor base station selection are assigned a signature signal. As described above, at some point, the base station 12 determines that the MTC device 16 needs assistance (step 1402). Upon determining that the MTC device 16 needs assistance, the base station 12 sends time and/or frequency resources, or more specifically, information indicating time and/or frequency resources assigned to the MTC device 16, to the candidate device anchor base station, which in this example is the wireless device 20-1 to 20-3 (steps 1404-1 to 1404-3). In addition to time and/or frequency resources, the base station 12 may send a feature signal or information indicating a feature signal assigned to the MTC device 16 for device anchor base station selection to the candidate device anchor base stations 20-1 to 20-3. Thereafter, as described above, to detect one or more candidate device anchor base stations 20-1 through 20-3, the MTC device 16 transmits a characteristic signal assigned to the MTC device 16 on time and/or frequency resources assigned to the MTC device 16 for device anchor base station selection (step 1406).

The wireless devices 20-1 to 20-3 acting as candidate device anchor base stations listen for transmission of characteristic signals of MTC devices 16 on time and/or frequency resources assigned to the MTC device 16 for device anchor base station selection. Each wireless device 20-1 to 20-3 determines whether the received power for transmission is greater than a predefined threshold (steps 1408-1 to 1408-3). In this example, the received power at all wireless devices 20-1 through 20-3 is less than the threshold and thus none of the wireless devices 20-1 through 20-3 respond.

The MTC device 16 determines that a response to the transmission of its characteristic signal has not been received, e.g., after a predefined amount of time has elapsed since the transmission of the characteristic signal (step 1410). In other words, the MTC device 16 has not detected any candidate device anchor base stations 20-1 to 20-3. To again attempt to detect one or more candidate device anchor base stations 20-1 through 20-3, the MTC device 16 then retransmits a characteristic signal on the time and/or frequency resources assigned to the MTC device 16 for device anchor base station selection (step 1412). Upon receiving the transmission of the characteristic signal of the MTC device 16 again, the wireless device 20-1 to 20-3 lowers the threshold (steps 1414-1 to 1414-3) and determines whether the received power of the characteristic signal for the MTC device 16 is greater than the lowered threshold (steps 1416-1 to 1416-3). In this example, the received power at wireless device 20-1 is greater than the reduced threshold only. Accordingly, the wireless device 20-1 transmits a response to the MTC device 16 (step 1418). The response may include the received power level used at the wireless device 20-1 for transmission of the signature. It is noted that although only the received power at wireless device 20-1 is greater than the reduced threshold, the received power may be greater than the reduced threshold at any number of wireless devices 20-1 through 20-3 (i.e., 0, 1, 2, or 3 at wireless devices 20-1 through 20-3 in this example), as appropriate.

Upon receiving the response, the MTC device 16 has detected the wireless device 20-1 as a candidate device anchor base station. As described above, the MTC device 16 selects the wireless device 20-1 as the device anchor base station for the MTC device 16 (step 1420). In this embodiment, the MTC device 16 then informs the base station 12 that the MTC device 16 has selected the wireless device 20-1 as its device anchor base station (step 1422). As one alternative, the MTC device 16 may inform the wireless device 20-1 that the MTC device 16 has selected the wireless device 20-1 as its device anchor base station, and then the wireless device 20-1 may inform the base station 12 of the selection. Once the wireless device 20-1 is selected as the device anchor base station, in this embodiment, the MTC device 16 and the wireless device 20-1 communicate to establish a connection (step 1424). Thereafter, when the MTC device 16 transmits on the uplink, the wireless device 20-1, acting as a device anchor base station for the MTC device 16, receives the transmission and retransmits the uplink transmission to the base station 12 (steps 1426 and 1428). The transmission of the uplink transmission from the device anchor base station to the base station 12 can use the same or different time and/or frequency resources as the uplink transmission from the MTC device 16.

Fig. 14 illustrates an embodiment in which a wireless device in need of assistance, which in this example is an MTC device 16, selects a device anchor base station for itself from a plurality of candidate device anchor base stations. This embodiment may be particularly beneficial in the case where the base station 12 transmits downlink traffic of data to the MTC device 16, e.g., known to be in a coverage hole 18 (or the base station 12 knows that the MTC device 16 otherwise needs help). Likewise, in the example of fig. 14, the MTC device 16 needs assistance. However, the present disclosure is not limited thereto.

As shown, the base station 12 determines that the MTC device 16 needs assistance (step 1500). The base station 12 may determine that the MTC device 16 needs assistance in any suitable manner. For example, the base station 12 may determine that the MTC device 16 needs help when the MTC device 16 is in a coverage hole 18, is about to enter the coverage hole 18, or is expected to enter the coverage hole 18. As another example, when the load of the cell 14 is greater than a threshold and the MTC device 16 is not a candidate device anchor base station, the base station 12 may determine that the MTC device 16 needs assistance. It is noted that these examples are only examples. Any suitable technique or criteria may be used to determine that the MTC device 16 needs assistance.

Upon determining that the MTC device 16 needs assistance, the base station 12 sends an instruction to transmit pilot symbols to the MTC device 16 to the wireless devices 20-1 to 20-3 as candidate device anchor base stations (steps 1502-1 to 1502-3). The wireless devices 20-1 to 20-3 then transmit pilot symbols to the MTC device 16 (steps 1504-1 to 1504-3). The MTC device 16 detects the pilot symbols (and thus the candidate device anchor base stations 20-1 to 20-3) and then selects one of the candidate device anchor base stations (i.e., one of the wireless devices 20-1 to 20-3) as the device anchor base station for the MTC device 16 (steps 1506 and 1508). In one example, the MTC device 16 selects a device anchor base station based on the received power levels for the pilot symbols received from the wireless devices 20-1 to 20-3. In this example, the wireless device 20-1 has the highest received power and is therefore selected as the device anchor base station for the MTC device 16. While received power can be used as a selection criterion, one or more additional or alternative criteria can be used for selection.

In this embodiment, the MTC device 16 then notifies the wireless device 20-1 that it has been selected as the device anchor base station for the wireless device 20-1 (step 1510). As shown, the wireless device 20-1 may then inform the base station 12 that the wireless device 20-1 has been selected as the device anchor base station for the MTC device 16. Thereafter, the base station 12 transmits a downlink transmission for the MTC device 16 (step 1512). The wireless device 20-1, operating as a device anchor base station for the MTC device 16, receives the downlink transmission and transmits the downlink transmission to the MTC device 16 (step 1514). The transmission of the downlink transmission from the device anchor base station to the MTC device 16 can use the same or different time and/or frequency resources as the downlink transmission from the base station 12.

In the embodiments of fig. 13A-13C and fig. 14, selection of a device anchor base station for the MTC device 16 is performed by the MTC device 16. Fig. 15 shows another embodiment in which the network node performs the selection. In the particular example of fig. 15, the base station 12 selects a device anchor base station for the MTC device 16. However, the process may be performed by other network nodes and for other wireless devices that need assistance. As shown, the base station 12 determines that the MTC device 16 needs assistance as described above (step 1600). Upon determining that the MTC device 16 needs assistance, the base station 12 selects one of the candidate device anchor base stations as the device anchor base station for the MTC device 16 (step 1602). In this example, wireless device 20-1 is selected as the device anchor base station for MTC device-1. Any suitable selection process and criteria may be used. As one example, the base station 12 may know the locations of the MTC device 12 and the candidate device anchor base station, and then select the candidate device anchor base station closest to the MTC device 16 as the device anchor base station for the MTC device 16. In another embodiment, the base station 12 may know that the MTC device 18 is in the coverage hole 18 and know the location of the candidate device anchor base station, where the base station 12 selects the candidate device anchor base station closest to the coverage hole 18 as the device anchor base station for the MTC device 16.

The base station 12 then notifies the wireless device 20-1 that it has been selected as the device anchor base station for the MTC device 16 (step 1604). The base station 12 may provide any information needed for the wireless device 20-1 to act as a device anchor base station for the MTC device 16. In one example, the wireless device 20-1 acts as a device anchor base station for the MTC device 16 in a manner that is transparent to the MTC device 16. Thereafter, the MTC device 16 transmits an uplink transmission (step 1606). The wireless device 20-1, operating as a device anchor base station for the MTC device 16, receives the uplink transmission from the MTC device 16 and transmits the uplink transmission to the base station 12 (step 1608). Likewise, for the downlink, the base station 12 transmits a downlink transmission for the MTC device 16 (step 1610). The wireless device 20-1, operating as a device anchor base station for the MTC device 16, receives the downlink transmission and transmits the downlink transmission to the MTC device 16 (step 1612). In one example, for the uplink and downlink, the wireless device 20-1 operates in such a manner that the wireless device 20-1 is transparent to the MTC device 16 (i.e., to the MTC device 16 as if the MTC device 16 is communicating directly with the base station 12).

As described above, in some embodiments, the device anchor base station 20-1 is transparent to the MTC device 16. In other words, the MTC device 16 is unaware that communication between the MTC device 16 and the base station 12 is by means of the device anchor base station 20-1 of the MTC device 16 or even N device anchor base stations in a multi-hop scenario (i.e. where the device anchor base station is connected to the base station 12 by one or more further hops, e.g. one or more further device anchor base stations). In some embodiments, to achieve this transparency, the cellular communication network 10 obtains knowledge of the traffic patterns of all or at least some of the wireless devices in the cellular communication network 10, e.g., each installed wireless device with a given traffic pattern in the cellular communication network 10 registers with the cellular communication network 10, and the base station 12 knows the traffic pattern of each fixed wireless device (e.g., MTC device 16) located in the cell 14 with an explicit traffic pattern. The information related to the traffic pattern can indicate for the wireless device one or more of periodicity of transmission, average data transmission size, transmission start time offset, mobility pattern, and the like. The information may be provided to the cellular communication network 10 (e.g., to the base station 12) via an IE as shown in fig. 16.

For example, assume that three thermometers (which are MTC devices) periodically transmit temperature measurements on different time slots as shown in fig. 17. Assume that thermometer 1 is located in a coverage hole and therefore needs help, and the other two thermometers 2 and 3 are located nearby and can act as device anchor base stations for thermometer 1 (i.e., are candidate device anchor base stations). In one embodiment, base station 12 assigns thermometer 2 as the device anchor base station for thermometer 1 by considering the traffic patterns of thermometers 1 and 2. In other words, since the traffic patterns of thermometers 1 and 2 can coexist, or in other words do not overlap, base station 12 assigns thermometer 2 as the device anchor base station for thermometer 1. Subsequently, base station 12 can send a request to thermometer 2 (as the device anchor base station for thermometer 1) to obtain a temperature measurement from thermometer 1, for example. Thermometer 2 may then transmit the temperature measurement from thermometer 1 and its own temperature measurement to base station 12 because the traffic patterns for the two thermometers do not overlap. In contrast, the traffic patterns of thermometers 1 and 3 do overlap, so thermometer 3 cannot act as a device anchor base station for thermometer 1 in this embodiment.

The above embodiments have focused on selecting and using a single device anchor base station. However, in other embodiments, more than one device anchor base station can be selected for wireless devices that need assistance (e.g., more than one device anchor base station may be selected for MTC devices 16 in coverage holes 18). This may be desirable to achieve multi-drop operation. One such example is shown in fig. 18, where three wireless devices 20-1, 20-2, and 20-3 are selected and operate as device anchor base stations for the MTC device 16. In this embodiment, for uplink transmissions, the MTC device 16 transmits the uplink transmissions. Each wireless device 20-1, 20-2, and 20-3 operating as a device anchor base station receives the uplink transmission and transmits the uplink transmission to the base station 12. For this uplink scenario, multiple uplink transmissions are received by the base station 12 and can be combined according to a multipoint reception scheme to thereby improve reception robustness. Similarly, for the downlink, the base station 12 transmits downlink transmissions. Each wireless device 20-1, 20-2, and 20-3 operating as a device anchor base station receives the downlink transmission and transmits the downlink transmission to the MTC device 16. The multiple downlink transmissions received by the MTC device 16 can be combined at the MTC device 16 according to a multipoint reception scheme to thereby improve reception robustness.

In some embodiments, the candidate device anchor base station may be a static device. In this case, in one particular embodiment, the static candidate device anchor base stations are divided into groups according to their geographic locations. One such embodiment is shown in fig. 19. As shown, in the embodiment of fig. 19, the cellular communication network 10 includes a base station 12, MTC devices 16 in coverage holes 18, and a plurality of wireless devices 20 having the capability to act as candidate device anchor base stations, and these devices are divided into three groups 22-1, 22-2, and 22-3 based on the geographic location of the candidate device anchor base stations. Specifically, wireless device 20(1) -1 to 20(1) -N1 is a candidate device anchor base station in the first group 22-1, wireless device 20(2) -1 to 20(2) -N2 is a candidate device anchor base station in the second group 22-2, and wireless device 20(3) -1 to 20(3) -N3 is a candidate device anchor base station in the third group 22-3. In one example, wireless devices 20(1) -1 to 20(1) -N1, 20(2) -1 to 20(2) -N2 and 20(3) -1 to 20(3) -N3 are static devices such that grouping occurs only once. However, in another embodiment, the wireless devices 20(1) -1 to 20(1) -N1, 20(2) -1 to 20(2) -N2 and 20(3) -1 to 20(3) -N3 are mobile (e.g., have low mobility), and the groupings can be updated as needed.

When the MTC device 16 needs assistance, the base station 12 selects a group of candidate device anchor base stations according to its geographical location relative to the MTC device 16, or in this example, according to the location of the coverage hole 18. As shown in fig. 20, by adding the location information IE to the RRC connection request message, the location information for the wireless device 20 and the MTC device 16 can be transmitted to the network during device setup via, for example, RRC signaling. Subsequently, one or more device anchor base stations are selected for the MTC device 16 from the selected group of candidate device anchor base stations using, for example, any of the selection schemes described above.

In another embodiment, for a static device registered with the network, once a connection is established between the two devices, the network node (e.g., a radio access node such as base station 12) may store information identifying the two devices as a device anchor base station and a device pair that needs assistance. The list of paired devices may be stored at the network node (e.g., at base station 12) for future decisions. When a particular wireless device needs assistance, pairing can be used to automatically select an appropriate device anchor base station for the wireless device. Fig. 21 is a flow chart illustrating operation of a base station 12 (or other radio access node) operating according to one such embodiment.

As shown in fig. 21, the base station 12 stores a pairing from the connection between the

wireless device

16, 20 and the device anchor base station (step 1700). For example, since wireless device 20-1 has been previously selected as the device anchor base station for MTC device 16, the corresponding pairing is stored by base station 12. Subsequently, in this example, the base station 12 determines that the MTC device 16 needs assistance (step 1702). The base station 12 then determines whether a pairing is stored for the MTC device 16 (step 1704). If so, the base station 12 selects a device anchor base station for the MTC device 16 according to the stored pairing (step 1706). If not, in this example, the base station 12 selects a device anchor base station for the MTC device 16 (step 1708). Alternatively, the device anchor base station can be selected by the MTC device 16 as described with respect to some embodiments above. Finally, in this embodiment, a connection is established between the MTC device 16 and the device anchor base station (step 1710). Thus, by storing the pairing, the selection of the device anchor base station may be performed only once for static or low mobility devices.

Although the embodiments may be implemented in any suitable type of telecommunications system that supports any suitable communication standard and uses any suitable components, particular embodiments of the solution may be implemented in a 3GPP LTE cellular communication network 10 such as that shown in fig. 1. As shown in fig. 1, an example cellular communication network 10 may include wireless communication devices 16, 20 (e.g., conventional wireless devices (UEs) or MTC devices), one or more radio access network nodes (e.g., evolved node bs (enbs) or other base stations, radio network controllers, gateways, or relay nodes) capable of supporting communication for the

wireless devices

16, 20, along with any additional elements suitable to enable communication between the wireless devices or between the wireless devices and another communication device, such as a landline telephone. As noted above, at least some

wireless devices

16, 20 are capable of acting as device anchor base stations.

Although the illustrated wireless device 20 may represent a communication device including any suitable combination of hardware or any suitable combination of hardware and software, the wireless device 20 may represent a device in particular embodiments, such as the example wireless device 20 shown in more detail in fig. 22. As shown in fig. 22, the example wireless device 20 includes a processor 24, a memory 26, a transceiver 28, and one or more antennas 30. In a particular embodiment, some or all of the functionality described above as being provided by the wireless device 20 may be provided by the processor 24 executing instructions stored on a computer-readable medium, such as the memory 26. Alternative embodiments of wireless device 20 may include additional components beyond those shown in fig. 22 that may be responsible for providing certain aspects of the functionality of wireless device 20, including any of the functionality described above and/or any functionality needed to support the above-described embodiments.

Similarly, while the MTC device 16 shown may represent a communication device including any suitable components of hardware and/or software, the MTC device 16 may represent a device in particular embodiments, such as the example MTC device 16 shown in more detail in fig. 23. As shown in fig. 23, the example MTC device 16 includes a processor 32, a memory 34, a transceiver 36, and one or more antennas 38. In particular embodiments, some or all of the functionality described above as being provided by the MTC device 16 may be provided by the processor 32 executing instructions stored on a computer readable medium, such as the memory 34. Alternative embodiments of the MTC device 16 may include additional components beyond those shown in fig. 23, which may be responsible for providing certain aspects of the functionality of the MTC device 16, including any of the functionality described above and/or any functionality required to support the embodiments described above.

Finally, while the illustrated base stations 12 may represent base stations including any suitable combination of hardware or any suitable combination of hardware and software, these base stations may represent apparatus such as the example base station 12 shown in more detail by fig. 24 in particular embodiments. As shown in fig. 24, the example base station 12 includes a baseband unit 40 having a processor 42, a memory 44, and a network interface 46, and a radio unit 48 having one or more antennas 52 connected thereto. This discussion is equally applicable to other types of radio access nodes. In particular embodiments, some or all of the functionality described above as being provided by base station 12 may be provided by processor 42 executing instructions stored on a computer-readable medium, such as memory 44. Alternative embodiments of base station 12 may include additional components responsible for providing additional functionality, such as any of the functionality identified above and/or any functionality needed to support the above-described embodiments.

The following acronyms are used throughout this disclosure.

3GPP third generation partnership project

5G fifth Generation

Constant amplitude zero autocorrelation of CAZAC

CQI channel quality indication

dB decibel

Direction of arrival of DOA

eNB evolved node B

FDD frequency division Duplex

HARQ hybrid automatic repeat request

HSPA high speed packet access

IE information element

LTE Long term evolution

M2M machine-to-machine

MTC machine type communication

PDCP packet data convergence protocol

PUSCH physical uplink shared channel

QPSK quadrature phase shift keying

RA random Access

RF radio frequency

RLC radio link control

RLF radio link failure

RRC radio resource control

RSRP reference signal received power

RSS received signal strength

SINR Signal to interference and noise ratio

TDD time division duplexing

TTI Transmission time Interval

UE user equipment

WCDMA wideband code division multiple access.

Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.

Claims

1. A method of operation of a network node (12) of a cellular communication network (10), comprising:

determining that assistance from a device anchor base station is needed in a cell served by a serving base station of a wireless device if one or more coverage holes are located in the cell;

in response to determining that the assistance is needed, identifying a plurality of candidate device-anchor base stations (20) for the cell served by the serving base station, the plurality of candidate device-anchor base stations (20) being wireless devices (20) that satisfy one or more predefined criteria for acting as candidate device-anchor base stations (20); and

completing selection of a device anchor base station (20) for the wireless device (16, 20) from among the plurality of candidate device anchor base stations (20) based on the traffic pattern of the plurality of candidate device anchor base stations (20) such that communication between the serving base station (12) of the wireless device (16, 20) and the wireless device (16, 20) passes through the device anchor base station (20) and the device anchor base station (20) is transparent to the wireless device (16, 20),

wherein the traffic pattern can indicate periodicity of transmission and/or transmission start time offset.

2. The method of claim 1 wherein identifying the plurality of candidate device-anchor base stations (20) comprises selecting the plurality of candidate device-anchor base stations (20) at the network node (12).

3. The method of claim 2, wherein selecting the plurality of candidate device anchor base stations (20) at the network node (12) comprises:

obtaining information indicative of capabilities of a second wireless device (20);

determining, based on the information, whether the second wireless device (20) satisfies one or more predefined criteria as candidate device anchor base stations (20); and

selecting the second wireless device (20) as a candidate device-anchor base station (20) if it is determined that the second wireless device (20) satisfies the one or more predefined criteria as a candidate device-anchor base station (20).

4. The method of claim 3, wherein obtaining the information comprises obtaining the information from the second wireless device (20) indicating the capabilities of the second wireless device (20).

5. The method of claim 4, wherein obtaining the information from the second wireless device (20) indicating the capabilities of the second wireless device (20) comprises receiving, via radio resource control, RRC, signaling, one or more information elements from the second wireless device (20) that include the information.

6. The method of claim 3, wherein obtaining the information from the second wireless device (20) indicative of the capabilities of the second wireless device (20) comprises receiving information indicative of a device type of the second wireless device (20), wherein the device type of the second wireless device (20) is indicative of the capabilities of the second wireless device (20).

7. The method of claim 3 wherein obtaining the information indicative of the capabilities of the second wireless device (20) comprises obtaining information indicative of at least one capability selected from the group consisting of: a capability of the second wireless device (20) to communicate in both uplink and downlink directions, an energy profile of the second wireless device (20), a traffic profile of the second wireless device (20), and a mobility pattern of the second wireless device (20).

8. The method of claim 3 wherein obtaining the information indicative of the capabilities of the second wireless device (20) comprises obtaining information indicative of at least one capability selected from the group consisting of: the ability of the second wireless device (20) to operate as a relay, the ability of the second wireless device (20) to operate as a repeater, the number of antennas of the second wireless device (20), the proximity of the second wireless device (20) to a serving base station, the proximity of the second wireless device (20) to one or more other wireless devices that need assistance, and the number of wireless devices that the second wireless device (20) can accommodate as a device anchor base station.

9. The method of claim 3, wherein the one or more predefined criteria for being a candidate device-anchor base station (20) include a criterion capable of communicating in both the uplink and downlink directions.

10. The method of claim 3, wherein the one or more predefined criteria for being a candidate device anchor base station (20) include a criterion of being connected to a permanent power source.

11. The method of claim 3, wherein the one or more predefined criteria for being a candidate device anchor base station (20) comprise a criterion having a desired traffic profile.

12. The method of claim 3, wherein the one or more predefined criteria for being a candidate device anchor base station (20) comprises a criterion of having low mobility.

13. The method of claim 1 wherein identifying the plurality of candidate device anchor base stations (20) comprises receiving information from a second wireless device (20) indicating whether the second wireless device (20) is selected as a candidate device anchor base station (20).

14. The method of claim 1 wherein identifying the plurality of candidate device-anchor base stations (20) comprises identifying the plurality of candidate device-anchor base stations (20) in response to determining that assistance from a device-anchor base station (20) is needed in the cell (14) served by the serving base station (12) of the wireless device (16, 20).

15. The method of claim 1, wherein if one or more coverage holes (18) are located in the cell (14), determining that assistance from a device anchor base station (20) is needed in the cell (14) comprises:

determining that one or more predefined coverage holes (18) are located in the cell (14); and

in response, it is determined that assistance from a device anchor base station (20) is required in the cell (14).

16. The method of claim 1, wherein if one or more coverage holes (18) are located in the cell (14), determining that assistance from a device anchor base station (20) is needed in the cell (14) comprises:

receiving information from one or more wireless devices (16, 20) indicating that the one or more wireless devices (16, 20) have detected one or more coverage holes (18) in the cell (14); and

17. The method of claim 1, wherein if one or more coverage holes (18) are located in the cell (14), determining that assistance from a device anchor base station (20) is needed in the cell (14) comprises:

detecting one or more coverage holes (18) in the cell (14); and

18. The method of claim 17, wherein at least one coverage hole (18) is a partial coverage hole (18).

19. The method of claim 18 wherein detecting the one or more coverage holes (18) in the cell (14) comprises detecting the partial coverage hole (18) in response to a predefined number of consecutive unsuccessful physical uplink shared channel, PUSCH, transmissions from a second wireless device (20) while the second wireless device (20) is located in the partial coverage hole (18).

20. The method of claim 17 wherein detecting the one or more coverage holes (18) in the cell (14) comprises detecting the coverage hole (18) based on one or more radio link failure, RLF, reports of radio link failures occurring in coverage holes (18).

21. The method of claim 17, wherein detecting the one or more coverage holes (18) in the cell (14) comprises detecting a coverage hole (18) based on at least one of the group consisting of: a received power for a second wireless device (20) when the second wireless device (20) is located in the coverage hole (18), a signal to interference plus noise ratio, SINR, for the second wireless device (20) when the second wireless device (20) is located in the coverage hole (18), and a hybrid automatic repeat request, HARQ, NACK, rate for the second wireless device (20) when the second wireless device (20) is located in the coverage hole (18).

22. The method of claim 17 wherein detecting the one or more coverage holes (18) in the cell (14) comprises detecting the coverage hole (18) in response to a second wireless device (20) operating in a coverage enhancement mode of operation while located in a coverage hole (18).

23. The method of claim 17 wherein detecting the one or more coverage holes (18) in the cell (14) comprises detecting a coverage hole (18) in response to a failed communication with a second wireless device (20) while the second wireless device (20) is located in the coverage hole (18).

24. The method of claim 1 wherein determining that assistance from a device-anchor base station (20) is needed in the cell (14) comprises determining that assistance from a device-anchor base station (20) is needed in the cell (14) if the network load of the cell (14) is greater than a predefined threshold representing a high network load.

25. The method of claim 1 wherein determining that assistance from a device anchor base station (20) is needed in the cell (14) comprises determining that assistance from a device anchor base station (20) is needed in the cell (14) in response to a predefined number of consecutive random access attempts from a second wireless device (20).

26. The method of claim 1, wherein the wireless device (16, 20) is a machine type communication, MTC, device (16) located in a coverage hole (18).

27. The method of claim 1, wherein the wireless device (16, 20) is a machine type communication, MTC, device (16) and a network load of a cell (14) served by the serving base station (12) of the wireless device (16) is greater than a predefined threshold representing a high network load.

28. A network node (12) of a cellular communication network (10), comprising:

a transceiver (50); and

a processor (42) associated with the transceiver (50) and configured to:

29. The network node (12) of claim 28 wherein, to identify the plurality of candidate device-anchor base stations (20), the processor (42) is further configured to select the plurality of candidate device-anchor base stations (20) at the network node (12).

30. The network node (12) of claim 28 wherein to select the plurality of candidate device anchor base stations (20) at the network node (12), the processor (42) is further configured to:

31. The network node (12) of claim 28 wherein, to identify the plurality of candidate device anchor base stations (20), the processor (42) is further configured to receive information from a second wireless device (20) indicating whether the second wireless device (20) can be selected as a candidate device anchor base station (20).

32. The network node (12) of claim 28, wherein the wireless device (16, 20) is a machine type communication, MTC, device (16) located in a coverage hole (18).

33. The network node (12) of claim 28, wherein the wireless device (16, 20) is a machine type communication, MTC, device (16), and a network load of a cell (14) served by the serving base station (12) of the wireless device (16) is greater than a predefined threshold representing a high network load.