JP7142670B2 - Adjacent cell self-configuration and optimization in wireless telecommunication networks - Google Patents

Description

The present invention relates to self-configuration and optimization of neighboring cells in wireless telecommunication networks.

Figure 1 of the accompanying drawings shows a wireless telecommunications network. This wireless telecommunication network now defines a number of communication cells (A, B, C, D), each of which is served by a radio base station 2 . Each communication cell covers a geographical area, and many cells can be combined to cover a large area. The illustrated mobile terminal 4 is communicating in cell A and can move around the system 1 .

A base station 2 comprises a number of receivers and transmitters and provides radio coverage for one or more cells. Each base station 2 is connected to a network "backbone" or core network infrastructure (not shown) that allows communication between the base station and other networks. In the example system of FIG. 1, one base station is shown per cell.

An important concept in such networks is the cell and its neighboring cells. During a call, the mobile terminal 4 typically moves between cells, repeatedly moving from one cell to one of its neighbors. For both the network 1 and the mobile terminal 4 a list of known neighbor cells, the so-called "neighbour cell set", is important for reliable inter-cell handovers. . The network 1 can store information about neighboring cell sets for each mobile terminal. The neighboring cell set is used to evaluate and handover a mobile terminal from one cell to another as the mobile terminal crosses cell boundaries. It will be readily appreciated that the cell boundaries are not sharply defined and in practice are somewhat blurred and the base station ranges will overlap each other.

In existing systems, the mobile terminal 4 detects and measures cell operating parameters for neighboring cells by receiving signals from its surroundings. The measured operating parameters are typically physical layer identifiers, eg scrambling codes that are not uniquely assigned to a cell, signal strength, signal quality, timing information. The mobile terminal measures the operating parameters of each neighboring cell and reports them to the network 1 . When the quality of a neighbor cell is determined to be better than the current serving cell, the network performs a handover from the serving cell to the selected neighbor cell. The neighboring cell then becomes the serving cell for the mobile terminal.

Typically in a wideband code division multiple access (WCDMA) system, a common pilot channel (CPICH) from neighboring cells is used to determine the id (scrambling code) and timing information. Pilot Channel) transmission is detected by the mobile terminal.

Each cell's identity is important when the mobile reports neighboring cell signal quality measurements to the network. Currently, cell identities (scrambling codes) are reused in multiple cells. Identity reuse means that the cells may be indistinguishable from each other because the serving cell may have the same identity information as the neighboring cells.

Since the physical layer identifier of a cell is not unique, the introduction and maintenance of neighboring cell sets cannot be fully automated. Manual intervention is required to resolve the conflict of neighboring cells using the same non-unique identifier as the serving cell.

The present invention aims to reduce the cost of designing and maintaining neighboring cell sets. It is based on adding the step of requiring the mobile terminal to perform an additional task to uniquely identify neighboring cells in the wireless network and have the identity reported from the mobile terminal to the network. Embodiments of the present invention are intended to reduce manual intervention. The method can be implemented as part of the operations support system and base station, or it can be implemented only at the RBS. This method is valid for wireless telecommunication technologies like GSM, WCDMA, LTE.

A cellular wireless telecommunications network is shown. A mobile terminal and a base station are shown. 1 illustrates steps of a method for implementing an aspect of the invention; 1 illustrates steps of a method for implementing an aspect of the invention; 1 illustrates steps of a method for implementing an aspect of the invention; 1 illustrates steps of a method for implementing an aspect of the invention;

SUMMARY OF THE INVENTION In response to the shortcomings of previous solutions, the present invention provides a method and architecture for maintaining neighbor cell aggregation within a mobile cellular network.

FIG. 2 is a schematic diagram showing a mobile terminal 4 and a base station 2 communicating via an air interface 6. As shown in FIG. The base station 2 comprises a controller 22 , an input/output (I/O) interface 24 , a radio transceiver 26 and an antenna 28 . The controller communicates with the mobile terminal through the air interface 6, the transmitter/receiver 26 and the antenna 28. FIG. Control unit 22 also communicates with other telecommunications networks via I/O interface 24 .

The mobile terminal 4 includes a control unit 42 , a man machine interface (MMI) 44 , a radio transmission/reception unit 46 and an antenna 48 . The controller of the mobile terminal 4 serves to control communication with the base station 2 via the transceiver 46 and the antenna 48 leading to the air interface 6 . Interaction with the user of the device is accomplished using a man-machine interface 44 . The man-machine interface 44 may include a keypad, microphone, loudspeaker, display device, and the like. The mobile terminal may be a communication device with only a machine-to-machine interface. Such aspects of base stations and mobile terminals are designed to operate according to conventional practice.

However, the base stations 2 and mobile terminals 4 operating according to the invention are adapted to implement the method of the invention, which is described below with reference to FIGS. It will be appreciated that the various functional units may be provided by the control unit or other specific units in the device or network 1 .

A method of implementing the present invention will now be described with reference to the flow charts of FIGS. 3-6 and FIG. FIG. 3 shows the steps performed by the mobile terminal 4 . The first step of the method is step 101, in which the mobile terminal 4 determines parameter measurements for neighboring cells. The mobile terminal then reports measurement information to the base station (step 103).

Referring to Figure 4, the base station 2 receives measurement information from the mobile terminal 4 (step 107). Here, the measurement information is each associated with a cell identity (which is not unique) detected by the mobile terminal 4 . The mobile terminal 4 may also be required to retrieve a unique cell identity if the information from the mobile terminal 4 includes measurements from cell identities that were not previously members of the neighboring cell set (step 113). Unique cell identities are transmitted from the base station with a much less frequent periodicity than physical layer identities. In order to receive and decode this information, the mobile terminal 4 may have to briefly interrupt communication with the serving cell. Once the unique cell identity is retrieved (step 115), this information is sent to the serving cell (step 117). If the serving cell receives a unique cell identity (step 119), it may now add the newly discovered neighbor cell to the neighbor cell set (step 121) and establish a transmission connection to that neighbor cell. good. In cellular networks where some mobile terminals identify new neighboring cells, some filtering is applied to the measurement data so that it can be detected under exceptional propagation conditions, e.g. the mobile terminal 4 is in an airplane. It is clear that it may be desirable to prevent adding distant cells that have been overridden.

In another example, mobile terminal 4 can provide unique identity information to base station 2 without having to receive instructions to that effect from base station 2 .

Referring to Figure 6, base station 2 receives the unique identity information (step 119) and then updates the neighbor cell set. Thus, the neighbor cell set contains unique identity information for the cell, and such cell will be determined as a neighbor cell that is a candidate cell for handover of the mobile terminal 4 .

The use of unique cell identifiers (UCIDs) means that there is unambiguous information about the identities of neighboring cells, thereby eliminating confusion about neighboring cells. The non-unique cell identity, which is fast and resource-requiring for most measurements, facilitates efficient resource utilization within the mobile terminal 4 and rapid handover to neighboring cells. Only when a new neighboring cell is detected, or when auditing the relationship between non-unique and unique cell identities is deemed appropriate, does the mobile terminal 4 replace the less cumbersome unique cell identifiers. requested to search.

All cell relationships can be evaluated continuously. Inputs to this evaluation are mobile terminal reports, mobile terminal events, network events, and operator inputs. The result of the evaluation is that cells (or relationships of cells) will hold various properties. This can also be viewed as the cells (relationships) being in various states.

A key advantage of embodiments of the present invention is that it eliminates the need for human involvement in the process of maintaining neighbor cell sets. The operator may choose to leave the neighboring cells completely alone and let the system determine the neighboring cells.

A cell lookup maps a unique cell identity (UCID) to the address of the node that implements that cell. For example, in LTE, this usually corresponds to DNS, which associates cell identities with IP addresses. The IP address then points to the RBS that implements the cell.

Claims (14)

A method of operating a mobile terminal in a wireless communication network comprising a plurality of communication cells, wherein within each communication cell a non-unique cell identity and a unique cell identity are transmitted,
The method includes
communicating with a radio base station serving a first communication cell;
determining the non-unique cell identity of a second communication cell based on information detected from physical layer signals;
reporting the non-unique cell identity of the second communication cell to a radio base station serving the first communication cell;
If the second communication cell is not included in a neighboring cell set that includes known neighboring cells of the first communication cell, then from the radio base station a second one of the plurality of communication cells. receiving instructions to obtain the unique cell identity of a communication cell;
obtaining the unique cell identity of the second communication cell;
and reporting said unique cell identity of said second communication cell to said radio base station of said first communication cell. The reported non-unique cell identity of the second communication cell is related to at least one operating parameter of the second communication cell, the at least one operating parameter being signal strength, signal quality, and timing. 2. The method of claim 1, comprising at least one of information. 2. The method of claim 1, wherein the steps of obtaining and reporting the unique cell identity are performed in response to receiving the instruction from the radio base station of the first communication cell. 2. The method of claim 1, wherein said second communication cell is adjacent to said first communication cell. 2. The method of claim 1, wherein the unique cell identity is a network layer identity. 2. The method of claim 1, wherein the unique cell identity is transmitted on a broadcast channel. 7. The method of claim 6 , wherein the unique cell identities are transmitted less frequently than the non-unique cell identities. A mobile terminal for use in a wireless communication network comprising a plurality of communication cells, wherein within each communication cell a non-unique cell identity and a unique cell identity are transmitted,
The mobile terminal is
a radio transceiver;
and a control unit, wherein the control unit
communicating via the radio transceiver with a radio base station serving a first communication cell;
determining the non-unique cell identity of a second communication cell based on information detected from physical layer signals;
reporting the non-unique cell identity of the second communication cell to a radio base station serving the first communication cell via the radio transceiver;
If the second communication cell is not included in a neighboring cell set that includes known neighboring cells of the first communication cell, then from the radio base station a second one of the plurality of communication cells. receiving instructions to obtain the unique cell identity of a communication cell;
obtaining the unique cell identity of the second communication cell on a second channel;
A mobile terminal for reporting, via said radio transceiver, said unique cell identity of said second communication cell to said radio base station of said first communication cell. The reported non-unique cell identity of the second communication cell is related to at least one operating parameter of the second communication cell, the at least one operating parameter being signal strength, signal quality, and timing. 9. A mobile terminal according to claim 8 , comprising at least one of information. 9. A mobile terminal according to claim 8 , wherein obtaining and reporting said unique cell identity is performed in response to receiving said instruction from said radio base station of said first communication cell. 9. A mobile terminal according to claim 8 , wherein said second communication cell is adjacent to said first communication cell. The mobile terminal of claim 8 , wherein the unique cell identity is a network layer identity. A mobile terminal according to claim 8 , wherein said unique cell identity is transmitted on a broadcast channel. A mobile terminal according to claim 13 , wherein said unique cell identity is transmitted less frequently than said non-unique cell identity.

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