KR20080075357A - A method and apparatus for measurement using communication gap in a wireless communications system - Google Patents

Abstract

A measurement method using communication gaps in a mobile communication system and an apparatus thereof are provided to implement efficient communication by minimizing the signaling overhead to inform an ENB(Evolved Node B) that measurement for neighbor cells has been completed before an actual gap period expires. A UE(User Equipment) carries out measurement for not a serving frequency bandwidth but other frequency bandwidths during an allocated gap period. If the measurement is completed before the gap period expires(401), the UE calculates an effective remaining gap period which remains until the gap period expires(403,405). Based on the calculated effective remaining gap period, the UE judges whether to perform signaling to inform an ENB that the measurement has been completed before the gap period expires(407). The UE performs or doesn't perform signaling according to a judgement result(411,413). In this case, if the effective remaining gap period is larger than or equal to a preset comparative threshold period, the UE transmits a signaling message to the ENB.

Description

METHOD AND APPARATUS FOR MEASUREMENT USING COMMUNICATION GAP IN A WIRELESS COMMUNICATIONS SYSTEM}

1 is a diagram illustrating an example of a 3GPP LTE system structure.

2 is a view showing an example of a measurement operation using a gap of communication according to the prior art.

3 is a diagram illustrating a measurement operation using a gap of communication according to a preferred embodiment of the present invention.

4 is a flowchart illustrating the operation of a terminal according to an exemplary embodiment of the present invention.

5 is a flowchart illustrating operation of a network ENB according to a preferred embodiment of the present invention.

6 is a block diagram showing an apparatus of a terminal according to a preferred embodiment of the present invention.

7 is a block diagram illustrating an apparatus of a network ENB according to a preferred embodiment of the present invention.

The present invention relates to a mobile communication system, and more particularly, to an efficient method and apparatus for utilizing communication gaps.

The Universal Mobile Telecommunication Service (UMTS) system is based on the European mobile system Global System for Mobile Communications (GSM) and General Packet Radio Services (GPRS), and uses Wideband Code Division Multiple Access (CDMA). Third generation asynchronous mobile communication system). The 3rd Generation Partnership Project (3GPP), which is in charge of UMTS standardization, is discussing the Long Term Evolution (LTE) system, the next generation mobile communication system of the UMTS system. LTE is a technology that implements high-speed packet-based communication with a transmission speed of up to 100Mbps with a goal of commercialization in 2010. To this end, various methods are discussed. For example, a method of simplifying a network structure to reduce the number of nodes located on a communication path or a method of bringing wireless protocols as close as possible to a wireless channel is under discussion.

1 illustrates an example of a structure of a next generation (Evolved) 3GPP LTE system.

Referring to FIG. 1, an Evolved UMTS Radio Access Network (E-UTRAN) 110 may include two nodes of an Evolved Node B (ENB) 120, 122, 124, 126, and 128 and an anchor node 130, 132. Simplified to structure. The upper nodes 130 and 132 may include a mobility management entity (MME) that is in charge of a control plane such as managing mobility and context of a user equipment (hereinafter referred to as UE) 101. It is divided into a user plane entity (UPE) that is in charge of a user data plane such as data transmission and routing. The user terminal (UE) 101 connects to the Internet Protocol (IP) network 114 by the E-UTRAN 110. The ENBs 120 to 128 correspond to existing Node Bs of the UMTS system and are connected to the UE 101 by a radio channel.

Unlike the existing node ratio, the ENBs 120 to 128 play a more complex role. In LTE, all user traffic, including real-time services such as Voice over IP (VoIP) over the Internet protocol, is serviced through a shared channel, which requires a device that collects and schedules context information of UEs. 128). One ENB typically controls a number of cells.

In addition, ENBs 120 to 128 perform adaptive modulation and coding (AMC) to determine a modulation scheme and a channel coding rate according to a channel state of a terminal. Like LTE High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA), also known as Enhanced Dedicated Channel (E-DCH) in LTE, HARQ (Hybrid ARQ) between ENB 120-128 and UE 101 in LTE. , Outer ARQ may be performed. Also, in ENB 120 to 128, measurement control, system information setting and transmission, terminal context and state, which were performed by RNC (Radio Network Controller) of UMTS system It also performs a number of Radio Resource Control (RRC) functions, such as management and control, handover, and the like. Orthogonal Frequency Division Multiplexing (OFDM) is expected to be used as the radio access technology in the 20 MHz bandwidth to achieve a maximum transmission speed of 100 Mbps in 3GPP LTE.

Measurement refers to a series of processes for measuring the strength of pilots of neighbor cells in order to support mobility of a terminal, and there is a method that uses a gap and a method that does not use a gap of communication. . Measurement using a gap refers to measuring the strength of a pilot of adjacent cells during a gap that temporarily stops communication with a serving cell. The terminal uses the gap for 'neighbor cells that cannot perform the measurement at the same time while communicating with the serving cell'. As an example of a 'neighborhood cell that does not perform a measurement at the same time while communicating with a serving cell', the frequency band of a neighbor cell is different from the frequency band of a serving cell, so that a terminal cannot receive two frequency bands at the same time or a radio adjacent to another cell. Scenarios belonging to the Radio Access Technology (RAT) system.

A gap pattern indicating time intervals at which the terminal temporarily stops communicating with the serving cell is generally assigned from a network node (ie ENB) but may be automatically generated by the terminal. If a gap is allocated, the ENB, which controls the serving cell and is responsible for scheduling for data / signaling transmission of the terminal, excludes the terminal from scheduling during the gap period, thereby causing the terminal to measure adjacent cells during the gap period. To avoid possible packet loss. If the terminal is excluded from the scheduling of the ENB, the terminal does not transmit or receive any data between the serving cells. In this case, the gap pattern to be used by the terminal must be promised to each other through explicit signaling between the terminal and the ENB or by an implicit rule.

2 illustrates an example of a measurement operation using a gap of communication according to the prior art.

Referring to FIG. 2, reference numeral 211 denotes a gap period allocated by a terminal, and the terminal performs measurement on neighbor cells during a gap period 211. If the measurement for neighbor cells is completed before the gap section 211 ends (213), the terminal notifies the ENB through signaling that the measurement is completed before the gap section 211 ends. The ENB then allocates resources through scheduling for the terminal as soon as it receives the signaling without having to wait for the gap section 211 to end, thereby reducing the delay of data / signaling transmission.

However, the conventional method has a problem of having additional signaling overhead by performing signaling informing the ENB whenever the terminal completes the measurement before the gap section ends. This additional overhead is not desirable if you actually get very limited scheduling delay gains. For example, if the signaling that the terminal completes the measurement and transmits is received at the ENB at the end of the actual gap period, substantially no delay gain in scheduling but only incurs overhead according to additional signaling.

Therefore, the present invention provides a method and apparatus for performing an efficient measurement while minimizing the overhead of additional signaling in a mobile communication system.

According to a preferred embodiment of the present invention, in a method using a gap of communication in a mobile communication system,

Performing a measurement for frequencies other than the serving frequency band during the assigned gap period;

If the measurement is completed before the gap section ends, calculating a valid gap remaining section until the gap section ends;

Determining whether to transmit signaling indicating that the measurement is completed before the gap section ends, according to the valid gap remaining section;

And selectively transmitting the signaling according to the determination result.

According to a preferred embodiment of the present invention, in a method using a gap of communication in a mobile communication system,

Determining that the terminal needs to allocate a gap pattern for the measurement, and setting a comparison threshold interval value to be compared with the estimated effective gap residual interval at the terminal;

And transmitting the comparison critical section value to the terminal.

Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention. In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

In the following description of the present invention, a 3GPP LTE system evolved from a 3GPP UMTS (Universal Mobile Telecommunication Service) system will be described as an example. However, the present invention can be applied to other mobile communication systems without any difference.

The main subject of the present invention is to minimize the signaling overhead in the measurement using the gap of communication. In particular, when there is little delay gain in scheduling, the overhead of signaling is avoided. Or, the ENB gives a control function to adjust the signaling overhead by RRM (Radio Resource Management).

To this end, if the terminal completes the corresponding measurement before the end of the gap interval allocated from the system, the UE estimates a reception time for the ENB to receive a signaling indicating the completion of the measurement before the end of the gap period, and the estimated reception time and the The effective gap remaining section is calculated using the end point of the gap section. If the valid gap remaining interval is (or equal to) greater than or equal to a predetermined comparison threshold interval X value, the terminal sends a signaling to the ENB indicating the completion of the measurement before ending the gap interval. On the other hand, if the valid gap remaining interval is less than (or equal to) the comparison threshold interval X value, the terminal does not send a signaling to the ENB indicating the completion of the measurement before the end of the gap interval.

The effective gap remaining period is calculated as (Gap end time)-(time of reception of signaling estimated by the terminal) as an example, or is calculated as (Gap end time)-(time when the terminal transmits signaling) as another example. , Or (gap end point)-(measurement completion point).

3 illustrates a measurement operation using a gap of communication according to a preferred embodiment of the present invention.

Referring to FIG. 3, reference numeral 311 denotes a gap section allocated to a terminal, and the terminal performs measurement on neighbor cells during the gap section 311. If the completion of the measurement for the adjacent cells before the gap section 311 is finished (313), the terminal informs the ENB of the reception point that the ENB will receive signaling indicating that the measurement is completed before the end of the gap section 311. Estimate.

The reception time may be different depending on how the signaling is transmitted. For example, if the terminal requests scheduling for the signaling on the uplink, receives the corresponding uplink resource as the downlink, and transmits the uplink resource using the uplink resource in an RRC message including the signaling, scheduling (uplink) The sum of time taken for resource allocation (downlink), RRC message transmission (uplink), etc., and additional time for HARQ retransmission is estimated to estimate the reception time when the ENB receives the signaling.

As another example, if the terminal transmits the signaling using an L1 / L2 dedicated channel, such as a previously allocated channel quality information (CQI) channel, which is periodically available, from (measurement completion time 313 to next) The time until the allocation time of the dedicated channel) and the (L1 / L2 transmission time) are summed to estimate the reception time when the ENB receives the signaling. As another example, if the terminal transmits the signaling using a random access channel, (time from completion of measurement 313 to allocation time of the next random access channel), and (random access procedure) According to the sum of the time it takes for the signaling to be sent to the ENB, and estimates the reception point at which the ENB will receive the signaling. The signal reception time estimated by the terminal is indicated by reference numeral 321. The measurement completion time 313 and the estimated signaling reception time 321 may have a form such as a frame number indicating a system time.

The terminal calculates an effective gap remaining section by using the estimated signaling reception time 321 and the gap end time 323. The effective gap remaining interval is calculated as, for example, (gap end time point 323)-(estimated signaling reception time point 321).

The terminal compares the valid gap remaining interval with a comparison critical interval X signaled or hardcoded from an ENB, and if the valid gap residual interval is greater than or equal to the comparison critical interval X, a measurement before ending the gap interval. The signaling to the ENB is transmitted in a predetermined manner (RRC message, L1 / L2 dedicated channel, or RACH). On the other hand, if the effective gap remaining section is (or less than or equal to) the comparison threshold section X, the terminal determines that it is not necessary to transmit the signaling indicating that the measurement is completed before the gap section ends.

4 is a flowchart illustrating the operation of a terminal according to an exemplary embodiment of the present invention.

Referring to FIG. 4, in step 401, measurement for neighbor cells is completed before the allocated gap section ends. In step 403, the terminal estimates a reception time for receiving a signaling indicating that the measurement is completed before ending the gap section at the ENB. Estimating the signaling reception time depends on how the signaling is transmitted.

In step 405, the terminal calculates the effective gap remaining interval using the estimated signaling reception time and the known gap end time. As an example, the effective gap remaining interval is calculated as (gap end time point)-(estimated signaling reception time point). As another example, the effective gap remaining period is calculated as (gap end point)-(signaling transmission point) or (gap end point)-(measurement completion point). If the signaling transmission time is used, the signaling transmission time is estimated in step 403. When using the completion point of the measurement, step 403 is omitted.

In step 407, the terminal compares the valid gap remaining interval with a comparison threshold interval X that is previously signaled or hardcoded. If the valid gap remaining section is greater than (or equal to) the comparison threshold section X, go to step 411 and the terminal sends a signaling to the ENB informing the ENB of "measurement completion before ending the gap section" in a predetermined manner. Here, the comparison critical section X may be signaled through a terminal dedicated channel or through system information broadcast in a cell. On the other hand, if the valid gap remaining interval is less than (or equal to) the comparison threshold interval X, go to step 413 and the terminal determines that it will not send signaling indicating the completion of the measurement before ending the gap interval to the ENB.

5 is a flowchart illustrating the operation of an ENB according to a preferred embodiment of the present invention. Here, a case where the comparison threshold section X is signaled through a dedicated channel allocated to the terminal is shown.

Referring to FIG. 5, in step 501, the ENB determines that the terminal needs to allocate a gap pattern for the measurement. Then, in step 503, the ENB sets the comparison threshold interval X value in consideration of the load status in the cell, the class or the capability of the terminal, and transmits the comparison threshold interval X to the terminal in step 505. do. In a modified embodiment, in step 503, gap pattern information indicating gap periods, which are points in time at which the terminal temporarily stops communication with the serving cell and performs a measurement for frequency bands other than the serving cell's frequency band, is set. In step 505, the gap pattern information may be transmitted to the terminal.

6 is a block diagram illustrating an apparatus of a terminal according to an exemplary embodiment of the present invention.

Referring to FIG. 6, the transceiver 601 receives gap pattern information indicating a position of gap sections or a comparison critical section X or a pilot channel signal for a measurement from an ENB, and when the measurement is completed before the gap section ends. Send the corresponding signaling to inform the ENB. The gap pattern information and the comparison critical section X are stored in the gap management / control unit 603.

The gap manager / control unit 603 changes the frequency band of the transceiver unit 601 according to the gap pattern information. For example, the transmitter / receiver 601 is controlled to receive the frequency bands of the adjacent cells to perform the measurement, not the frequency band of the serving cell, during the gap period indicated by the gap pattern information. The measurement for adjacent cells using the received signal during the gap section is performed in the measurement unit 605. If the measurement is completed in the adjacent cells in the measurement unit 605 before the gap section ends, the effective gap remaining section calculation / determination unit 611 calculates an effective gap remaining section as described above, and manages gaps. The comparison completion interval X stored in the / control unit 603 is compared with the calculated effective gap remaining period to control the measurement completion signaling generator 613.

The measurement completion signaling generator 613 determines / determinates generation of the “measurement completion before ending the gap section” signaling according to the comparison result of the valid gap remaining section calculation / determination unit 611. Specifically, the measurement completion signaling generator 613 generates the signaling only when the effective gap remaining interval is greater than or equal to the comparison threshold interval X. The signaling is transmitted to the ENB through a transceiver 601 by a predetermined method.

7 is a block diagram showing an apparatus of an ENB according to a preferred embodiment of the present invention.

Referring to FIG. 7, the comparison threshold section setting unit 701 sets a value of the comparison threshold section X to be compared with the effective gap remaining section calculated by the terminal. The X value is set in consideration of the cell load state managed by the RRM 703, the terminal class managed by the terminal context manager 705, the terminal capability information, and the like. The comparison threshold section X is transmitted to the terminal through the transceiver 711.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

According to the present invention, when the measurement for neighbor cells is completed before the actual gap period is terminated, the communication overhead is minimized by minimizing signaling overhead for notifying the ENB.

Claims (7)

In the method using the gap of communication in a mobile communication system, Performing a measurement for frequencies other than the serving frequency band during the assigned gap period; If the measurement is completed before the gap section ends, calculating a valid gap remaining section until the gap section ends; Determining whether to transmit signaling indicating that the measurement is completed before the gap section ends, according to the valid gap remaining section; And transmitting the signaling selectively according to the determination result. The method of claim 1, wherein the determining is performed. And determining that the signaling message is to be transmitted if the valid gap remaining section is greater than or equal to a predetermined comparison threshold section. The method of claim 1, wherein the comparison threshold section, Measurement method characterized in that it is hardcoded to the terminal, or signaled to the terminal from the system. The method of claim 1, wherein the effective gap remaining section, (Gap end point)-(point of reception of the signaling estimated by the terminal), (Gap end point)-(transmission point of the signaling), or (Measurement end point)-(Measurement completion time point) is a measurement method characterized in that. The method of claim 4, wherein the reception time is, Is estimated by summing up scheduling on the uplink, resource allocation on the downlink, transmission of radio resource control (RRC) messages including the signaling, and additional time on HARQ retransmission; The time from the completion of the measurement to the allocation time of the next corresponding dedicated channel and (the estimated time by summing the transmission times of the L1 / L2 messages including the signaling; And a time from the completion of the measurement to the allocation time of the next random access channel and the time taken for the signaling to reach the system according to the random access procedure. In the method using the gap of communication in a mobile communication system, Determining that the terminal needs to allocate a gap pattern for the measurement, and setting a comparison threshold interval value to be compared with the estimated effective gap residual interval at the terminal; And transmitting the comparison critical section value to the terminal. The method of claim 6, wherein the terminal temporarily stops communication with the serving cell and sets gap pattern information indicating gap intervals, which are points of time for performing a measurement for a frequency band other than the serving cell frequency band. The method of claim 1, further comprising the step of transmitting to the terminal.

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