Patent Application
20180139675
The present invention relates to network nodes. Furthermore, the present invention also relates to corresponding methods, system, a computer program, and a computer program product.
In order to create wireless communication systems that are scalable and possible to manage, mobile communication radio networks covering large areas are often divided into smaller coverage areas. In order to manage the mobility of users in this system, the user must be allowed to move between these smaller areas. This can be achieved by assigning a specific downlink identity broadcasted in a certain area and a certain frequency. This is often called a cell. A multitude of cells are used to provide coverage over a larger area. A Base Station (BS) may be configured to handle one or more cells in such systems.
The mobility in these systems, such as Long Term Evolution (LTE), is achieved by configuring Mobile Station (MS) to measure and report detected cells, i.e. cell identities, and a metric identifying the quality of the connection, e.g. signal strength or signal quality. This is achieved by measuring a downlink reference signal.
The decisions for mobility are made by the radio network and communicated by the BS to the MS. It should however be noted that depending on the system architecture, the decision can be made in the BS (also referred to as access node) like e.g. in LTE, or the decision can be made in a Base Station Controller (BSC) which is a node handling multiple BSs, like e.g. the Radio Network Controller (RNC) in Universal Terrestrial Radio Access Network (UTRAN), handling multiple NodeB.
When moving between different Radio Access Technologies (RAT), one way to achieve this is to let the MS measure the target RAT according to the principles used in the target RAT. This requires that the MS is capable of measuring the target RAT, which is of course anyway needed in order to manage the connection established in the target RAT after a handover.
Hard handover, where the MS is only connected to one BS at a time, is used in 2G cellular wireless system Global System for Mobile Communications (GSM) and 4G cellular wireless system Long-Term Evolution (LTE) and between different RATs.
There are however different schemes for connection management between one or more BSs and a MS. Systems like 3G cellular wireless system UTRAN use a soft handover (also called macro diversity) where the MS is connected to more than one BS and where the same information is sent to/from all participating BSs. In LTE, there is a scheme called dual connectivity (DC) or Multi Stream Aggregation (MSA) where the MS is connected to more than one BS and where different information is sent to/from the different BSs. The common denominator for all these is that there is a need to handle the connection, i.e. to decide when to add/remove/modify a connection between an MS and a BS.
An objective of the present invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions.
Another objective of the present invention is to provide an improved solution for inter-RAT connection handling for user devices.
An “or” in this description and the corresponding claims is to be understood as a mathematical OR which covers “and” and “or”, and is not to be understood as an XOR (exclusive OR).
The above objectives and further objectives are solved by the subject matter of the independent claims. Further advantageous implementation forms of the present invention can be found in the dependent claims.
According to a first aspect of the invention, the above mentioned and other objectives are achieved with a first network node for a wireless communication system, the first network node being configured to operate in a first Radio Access Technique, RAT, and the first network node comprising:
a processor configured to
The radio resource request may be transmitted by a second network node or by the user device, e.g. in the uplink in a cellular system.
The first network node of the first aspect provides a number of advantages over conventional solutions. An advantage of allocating the radio resource for the reference signal in the first RAT (target RAT) is that the first RAT can allocate the radio resource in a unique way to allow the first network node, when receiving a reference signal also determining which user device that transmitted the reference signal. Otherwise, it will be impossible for the first RAT to understand which user device each measured reference signals belongs to. Thereby, inter-RAT connection handling for the user device is possible.
Another advantage is that the first network node of the first aspect makes possible to achieve inter-RAT connection handling for user devices served by a legacy system (such as LTE) where connection handling is based on measurement with DL channels, to another system, where connection handling is based on measurements on UL channels. One advantage of basing the connection handling on (UL) reference signals from the user device to the first network node and thereby reducing the frequency of the downlink reference signal is that it may be possible to achieve reductions in energy consumption both in the network nodes of the wireless communication system, since they do not have to actively transmit regularly; and in the user device, since the user device can transmit a short burst instead of continuously listening and trying to detect transmissions from neighbour network nodes.
In a first possible implementation form of a first network node according to the first aspect, the processor is further configured to
In a second possible implementation form of a first network node according to the first possible implementation form of the first aspect, the transceiver is further configured to
An advantage with the second possible implementation form is that the connection handling decision made in the first network node is sent to the second network node which can execute the decision or be informed about the decision in order to support a coherent handling of the user device between the network nodes. Further, it is preferred that the second network node informs the user device about the connection handling decision made by the first network node since the second network node serves the user device.
In a third possible implementation form of a first network node according to any of the preceding possible implementation forms of the first aspect or to the first aspect as such, the transceiver is further configured to
An advantage with the third possible implementation form is that the third possible implementation form supports decisions in the second network node (source network node). The benefit of making the decision in the second network node is that the second network node has most information available regarding the user device. When combined with the second possible implementation form the second network node may also make a decision, and the benefit of making the decisions in both the first and the second network nodes is to combine the knowledge in both network nodes, and possibly making decisions in different domains. For example, let the second network node decide when to add a connection, but let the first network node decide the detailed connection parameters. It is also possible that the initial decision may trigger a decision for another connection, e.g. one network node decides to add one connection may trigger a decision in the other network node to release or modify an existing connection.
In a fourth possible implementation form of a first network node according to the third possible implementation form of the first aspect, the transceiver is further configured to
An advantage with the fourth possible implementation form by making the decision in the second network node is that the second network node serving the user device has most information available regarding the user device. Thereby, improved connection handling decisions can be made for the user device.
In a fifth possible implementation form of a first network node according to the second or fourth possible implementation forms of the first aspect, the processor is further configured to
An advantage with the fifth possible implementation form is that the first network node can execute the connection handling decision in order to provide a coherent handling of the connections between the user device and the involved network nodes.
In a sixth possible implementation form of a first network node according to the second, fourth, or fifth possible implementation forms of the first aspect, the processor is further configured to
An advantage with the sixth possible implementation form is that the first network node can inform the user device in order to provide a coherent handling of the connections between the user device and involved network nodes.
According to a second aspect of the invention, the above mentioned and other objectives are achieved with a second network node for a wireless communication system, wherein the second network node is configured to operate in a second RAT and serve a user device, and wherein the second network node comprises:
a transceiver configured to
The first network node of the first aspect provides a number of advantages over conventional solutions. An advantage is that by making the decision in the second network node is that the second network node serving the user device has best information available regarding the user device. Thereby, improved connection handling decisions can be made for the user device.
In a first possible implementation form of a second network node according to the second aspect, the processor is further configured to
An advantage with the first possible implementation form is that the second network node can execute the second connection handling decision in order to provide a coherent handling of the connections between the user device and involved network nodes.
In a second possible implementation form of a second network node according to the first possible implementation form of the second aspect or to the second aspect as such, the transceiver is further configured to
An advantage with the second possible implementation form is to enable a coherent handling of the connections between the user device and involved network nodes.
In a third possible implementation form of a second network node according to any of the preceding possible implementation forms of the second aspect or to the second aspect as such, the transceiver is further configured to
An advantage with the third possible implementation form is that the third possible implementation form supports decisions in the second network node (source network node). The benefit of making the decision in the second network node is that the second network node has most information available regarding the user device. When combined with the second possible implementation form the second network node may also make a decision, and the benefit of making the decisions in both the first and the second network nodes is to combine the knowledge in both network nodes, and making decisions in different domains. For example, let the second network node decide when to add a connection, but let the first network node decide the detailed connection parameters. It is also possible that the initial decision may trigger a decision for another connection, e.g. one network node decides to add one connection may trigger a decision in the other network node to release or modify an existing connection.
According to a third aspect of the invention, the above mentioned and other objectives are achieved with a wireless communication system comprising at least one first network node according to the first aspect and at least one second network node according to the second aspect.
In a first possible implementation form of the wireless communication system according to the third aspect per se, the wireless communication system further comprises a user device, which is configured to receive the first control signal from the first network node, wherein the first control signal indicating the allocated radio resource; to transmit the reference signal via (or on) the allocated radio resource to the first network node.
In a second possible implementation form of the wireless communication system according to the third aspect per se or according to the first possible implement form of the third aspect, one of the user device and the second network node is further configured to transmit the radio resource request for the reference signal.
According to a fourth aspect of the invention, the above mentioned and other objectives are achieved with a method in a first network node for a wireless communication system, the first network node being configured to operate in a first Radio Access Technique, RAT, the method comprising:
In a first possible implementation form of a method according to the fourth aspect, the method further comprises
In a second possible implementation form of a method according to the first possible implementation form of the fourth aspect, the method further comprises
In a third possible implementation form of a method according to any of the preceding possible implementation forms of the fourth aspect or to the fourth aspect as such, the method further comprises
In a fourth possible implementation form of a method according to the third possible implementation form of the fourth aspect, the method further comprises
In a fifth possible implementation form of a method according to the second or fourth possible implementation forms of the fourth aspect, the method further comprises
According to a fifth aspect of the invention, the above mentioned and other objectives are achieved with a method in a second network node for a wireless communication system, wherein the second network node is configured to operate in a second RAT and serve a user device, the method comprising:
In a first possible implementation form of a method according to the fifth aspect, the method further comprises
In a second possible implementation form of a method according to the first possible implementation form of the fifth aspect or to the fifth aspect as such, the method further comprises
In a third possible implementation form of a method according to any of the preceding possible implementation forms of the fifth aspect or to the fifth aspect as such, the method further comprises
The advantages of the methods according to the fourth or the fifth aspects are the same as those for the first and second network nodes according to the first and second aspects.
The present invention also relates to a computer program, characterized in code means, which when run by processing means causes said processing means to execute any method according to the present invention. Further, the invention also relates to a computer program product comprising a computer readable medium and said mentioned computer program, wherein said computer program is included in the computer readable medium, and comprises of one or more from the group: ROM (Read-Only Memory), PROM (Programmable ROM), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically EPROM) and hard disk drive.
Further applications and advantages of the present invention will be apparent from the following detailed description.
The appended drawings are intended to clarify and explain different embodiments of the present invention, in which:
According to the present invention, the mobility or connection handling is not based on measurement on downlink (DL) channels, but rather based on measurement on uplink (UL) channels. This however means that the defined methods for mobility or connection handling according to conventional techniques cannot directly be re-used when handing over from a DL based mobility scheme to an UL based scheme. For instance, inter-RAT mobility from 3GPP systems based on DL measurements, and reported by the user device (UD) to the network is not an optimal solution.
Assuming wireless communication systems use a different scheme for reference signals, e.g. where the UL reference signal is transmitted more often and the DL reference signal is transmitted more seldom, the existing methods for mobility between different RATs and connection handling in general would require the use of a more frequent DL reference signal, which may not be needed for other purposes. Instead, it has been realised by the inventor that a method where UL measurements are used for inter-RAT connection handling is beneficial. But this requires new schemes for connection handling.
Therefore, embodiments of the present invention relates to a first network node, a second network node and a wireless communication system. Embodiments of the present invention also relates to corresponding methods thereof.
According to the present solution, the processor 102 is configured to receive a radio resource request for a Reference Signal (RS) to be transmitted by a user device 300 (see
According to the present solution, the transceiver 604 is configured to receive a measurement of a RS from a first network node 100. The RS has been transmitted from the user device 300 to the first network node 100, and the first network node 100 is configured to operate in a first RAT. The processor 602 is configured to make a second connection handling decision for the user device 300 based on the received measurement of the RS.
The first network node 100 and the second network node 600 may be a (radio) network node or an access node or an access point or a base station, e.g. a Radio Base Station (RBS), which in some networks may be referred to as transmitter, “eNB”, “eNodeB”, “NodeB” or “B node”, depending on the technology and terminology used. The radio network nodes may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. The radio network node can be a Station (STA), which is any device that contains an IEEE 802.11-conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM).
The target RAT (RAT1 associated with the first network node 100) determines a resource allocation or configuration (e.g. the time pattern, radio resources, and an identity) of an UL Reference Signal (URS) for the user device 300 and sends this allocation or configuration to the user device 300, either directly or through the source RAT (RAT2 associated with the second network node 600). The radio resource request can be sent from the second network node 600 or the user device 300 to the first network node. The radio resource request is described more in the following disclosure.
Measurements on the URS are performed by the first network node 100. The benefit from using the URS rather than a downlink reference signal is that there is no need for additional DL reference signals to support inter-RAT connection handling. Adding an additional RS for this purpose would reduce the available capacity in the cell served by the first network node 100.
The connection handling decision may for example be to add a connection between the user device 300 and the network node when the signal quality exceeds a threshold, or where the signal quality is measured by comparing the received signal power of a reference signal compared to the total received power (interference), or by removing a connection if the signal quality is lower than a threshold. Similarly, the decision can be made based on received signal power. The benefit of using signal quality is that this takes the interference of the uplink into account, whereas the benefit of using received signal power is that reflects the signal propagation in both uplink and downlink.
Therefore, the present solution provides means for performing inter-RAT connection handling. With connection handling we mean actions related to managing the connection(s) between the user device 300 and one or more network nodes, including such functionality as adding, removing or modifying a connection between one user device 300 and one network node. Typical examples of connection handling are:
Connection handling may also be used to modify existing connections to adjust the parameters used for transmission of information, e.g. change radio resource parameters assigned to control channels. One example of this is that different URS may be used by the user device 300 depending on the distance between the user device 300 and the first network node 100. It is also possible to modify the connection in a similar manner such that if the measurement is above or below a threshold, the connection can be modified, e.g. by using a lower power for the URS if the user device 300 is located close to the network node.
The general scheme for connection handling is that that a network node receives measurements, makes a decision, execute the decision, and inform the user device 300 so that the user device 300 can be configured accordingly.
With further reference to
With further reference to
With further reference to
In the following disclosure further exemplary embodiments of the present invention are illustrated and described. In the following embodiments, the following set of building blocks for information exchange to and from the first network node 100 are used. The first network node 100 is in the following a target network node belonging to a target first RAT (RAT1). The second network node 600 is a source network node belonging to a source second RAT (RAT2).
URS resource request (corresponding to the RRR described above): this is a request for URS resources sent to the first network node 100 and may include capabilities of the user device 300, information about currently ongoing services, and information about current radio characteristics (e.g. neighbour ells, velocity, etc.), and transmission configuration (e.g. MIMO, DRX/DTX, etc.). The allocation of radio resource for the URS may be based on this information (e.g. measurements, or service information) provided by the user device 300 or by the source RAT via e.g. the second network node 600. The benefit of including this information is that the first RAT can select an URS that is suitable for the user device 300, e.g. an URS that the user device 300 will be able to use (e.g. matching the user device 300 capabilities, and possible to transmit without impacting the QoS of ongoing services), and that will be frequent enough to accurately allow the first network node 100 to track the mobility and channel characteristics of the user device 300 (e.g. depending on the user device velocity). If the first RAT cannot use this additional information when selecting a suitable URS, the first RAT will have to select one based on the worst case, e.g. assume highest mobility, which will lead to a higher resource usage, both over the air and in the network node receiver. A further benefit of including this information is that the target first RAT can select an URS that is suitable for the user device 300, e.g. an URS that the user device 300 will be able to use (e.g. matching the user device capabilities, and possible to transmit without impacting the Quality of Service (QoS) of ongoing services), and that will be frequent enough to accurately allow the first network node 100 to track the mobility and channel characteristics of the user device 300, e.g. depending on the user device 300 velocity. If the first RAT is not able to select a suitable URS, it will have to select one based on the worst case, e.g. assume highest mobility, which will lead to a higher resource usage, both over the air and in the network node receiver.
URS resource request Acknowledgment (ACK): this is sent from first network node 100 to the second network node 600. This contains the time pattern, radio resources (e.g. time, frequency, code, power) and possibly an identity to be used by the user device 300 for the URS assigned by the first network node 100. This also enables the transmission from the first network node 100 to the user device 300. The benefit of this is similar as stated above. Note that the second network node 600 may take this into account for Radio Resource Management (RRM) purposes, e.g. this pattern indicates when the user device 300 will transmit the URS and may not be available for UL/DL transmission for the second network node 600. The benefit of taking this into account in the second network node 600 is that the user device 300 will be able to transmit the URS as requested by the first network node 100.
URS configuration: this is similar to URS resource request ACK but sent to a user device 300. The URS configuration enables the end to end transmission from the first network node 100 to the user device 300.
URS measurement configuration: this is a measurement configuration to the first network node 100 indicating the identity or network address of the second network node and possibly what parameters (e.g. thresholds, time-to-trigger, etc.) that should be used in the measurement phase in the first network node 100. The benefit of including this information is that the measurement reports that are sent from the first network node 100 may be reduced, since the second network node 600 can indicate when the reports are important to be transmitted since there is no need to send unnecessary reports increasing overhead.
URS decision configuration: this is similar to the URS measurement configuration but this is used when first network node 100 performs a connection decision. This is a configuration to the first network node 100 indicating the identity or network address of the second network node and possibly what parameters (thresholds, time-to-trigger, etc.) that should be used in the decision (when applicable) in the first network node 100. The benefit of including this information is that the first network node 100 can make better decisions since the second network node 600 who has most information available regarding the user device 300 remains in partial control of the decision by deciding the criteria for the decision.
Measurement report: this report is sent from the first network node 100 to the second network node 600. The measurement report includes the result from the measurement, e.g. a user device 300 identity, the signal strength or the radio quality, and the radio entity identity. With radio entity, we mean the entity for which the signals are reported, which can be a cell, antenna or group of antennas, The benefit these measurements is that the URS can be used for measurement decisions, rather than relying on the normal measurement report from the user device 300 to the second network node 600, and therefore, this is needed to achieve the benefits listed for the overall solution. Therefore, there is no need to send a specific DL reference signal. The benefit of sending this information is to enable decisions in a different network node than the one performing the measurements.
Decision indication: this indication is sent to/from the first network node 100. This includes information about a decision that was made in the network node sending this indication. This may include information about connection handling (addition/removal/modification) and associated parameters so that the network node receiving can perform the actions required for this connection handling decision. It may also include the measurement report. The benefit of including the measurement report is that this gives additional information for the receiving network node regarding the conditions at the time the decision was made and can e.g. be used to partly allocate new parameters for the connection(s) in the receiving network node.
A set of exemplary embodiments are described, where in exemplary embodiments 1-3, the first network node 100 (target network node) provides measurement results to the second network node 600 (source network node) which makes a connection handing decision. After this, the first network node 100 is informed and can make additional connection handing decisions. In exemplary embodiments 4-6, the first network node 100 makes the first decision and sends a decision indication to the second network node 600, which may then make additional handling decisions. Hence a decision may be taken in the first network node 100, the second network node 600 or in both first network node 100 and second network node 600. In
In the following embodiments we give examples how the above mentioned information content (such as URS resource request, decision indication, etc.) may be transferred. Note that this is just illustrative examples and that information content may also be split into one or more different messages and sent in a different order.
In this exemplary embodiment shown in
In this embodiment shown in
In this embodiment shown in
In this embodiment shown in
In this embodiment shown in
In this embodiment shown in
The receiver device (UD) 300 discussed in the present disclosure may be a user device, such as a User Equipment (UE), mobile station (MS), wireless terminal or mobile terminal is enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The User Equipment (UE) may further be referred to as mobile telephones, cellular telephones, computer tablets or laptops with wireless capability. The UEs in the present context may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice or data, via the radio access network, with another entity, such as another receiver or a server. The UE can be a Station (STA), which is any device that contains an IEEE 802.11-conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM).
Furthermore, any method according to the present invention may be implemented in a computer program, having code means, which when run by processing means causes the processing means to execute step s of the method. The computer program is included in a computer readable medium of a computer program product. The computer readable medium may comprises of essentially any memory, such as a ROM (Read-Only Memory), a PROM (Programmable Read-Only Memory), an EPROM (Erasable PROM), a Flash memory, an EEPROM (Electrically Erasable PROM), or a hard disk drive.
Moreover, it is realized by a skilled person that the present first network node and second network node comprises the necessary communication capabilities in the form of e.g., functions, means, units, elements, etc., for performing the present solution. Examples of other such means, units, elements and functions are: processors, memory, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selecting units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, MSDs, TCM encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged together for performing the present solution.
Especially, the processors of the present devices may comprise, e.g., one or more instances of a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The expression “processor” may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above. The processing circuitry may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like.
Finally, it should be understood that the present invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.
This application is a continuation of International Application No. PCT/EP2015/065060 filed on Jul. 2, 2015, which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2015/065060 | Jul 2015 | US |
| Child | 15856104 | US |
