CN101998555A - Method and system for cell reselection - Google Patents

Abstract

The invention discloses a cell reselection method, comprising: a base station (NodeB) measures and obtains the moving speed of a user terminal (UE) in the cell covered by the base station (NodeB) and reports it to a radio network controller (RNC); Set the parameters for the UE to perform cell reselection according to the moving speed, and send the set parameters to all UEs in the cell through the NodeB; the UE measures the cell according to the received parameters, and performs cell reselection according to the measurement results. The invention also discloses a cell reselection system, which solves the problem that the existing cell reselection method cannot be better applied to specific scenarios such as along high-speed railways.

Description

Method and system for cell reselection

technical field

The invention relates to cell reselection technology in mobile communication, in particular to a cell reselection method and system.

Background technique

Modern mobile communication systems are usually built on the basis of cellular networking. The so-called cellular networking means that many regular hexagonal cells are used as the basic unit to combine and cover the entire service area, thereby forming a mobile communication network similar in shape to a cell. A user terminal (UE, User Equipment) is connected to a network device through a wireless channel in a cell, and as the UE moves, it realizes the functions of handover between adjacent cells and automatic roaming across local networks.

Taking the third-generation mobile communication system as an example, its radio access network is composed of multiple radio network subsystems, and each radio network subsystem includes a radio network controller (RNC, Radio Network Controller), multiple base stations (NodeB) And a lot of UE. Cell reselection or handover is triggered when a UE moves from one cell to another. The difference between cell reselection and cell handover is that when the dedicated channel is not established (also called UE in idle mode), when the UE moves from one cell to another, cell reselection is triggered; There is a dedicated channel (also called UE in connected mode), and when the UE moves from one cell to another, a handover (Handover) is triggered.

The process for the UE to implement cell reselection is as follows: when accessing the current serving cell (or simply called the serving cell), the UE receives the system information (SIB, System Information Block) from the broadcast channel (BCH, Broadcast Channel) of this cell, and Obtain the list of cells adjacent to the serving cell (called adjacent cells) from the SIB and the threshold parameters and timer parameters required for cell reselection; UE periodically measures the received signal strength of the current serving cell, and When the measurement result is found to be lower than the determined threshold value, the UE starts to measure the received signal strength of the adjacent cell; if the received signal strength of a certain adjacent cell is found If the grade value is higher than the serving cell, then this cell becomes a cell that satisfies the reselection condition; select the cell with the highest grade value from all the cells that meet the reselection condition as the most suitable target reselection cell, if the cell can be reselected within the timer time If T _reselect is always kept as the most suitable cell, then the UE reselects to this cell.

In the prior art, the parameters required for cell reselection, such as threshold parameters, parameters for calculating cell level values, neighbor cell lists, etc., are all set by the RNC and sent to the UE, and the values of these parameters are all based on engineering The experience of the personnel takes a fixed value.

_The process of cell reselection can be divided into two situations when UE is in low-speed and high-speed motion state. The difference between the two lies in the value of the timer time T _reselect : for UE in low-speed motion state, T A large constant value means that the target reselection cell needs to remain the most suitable for a long time before it can be reselected; when the UE is in a high-speed motion state, T _reselect takes a smaller constant value, that is to say, the target reselection cell The most suitable one that needs to be kept for a shorter time can be re-selected. The basis for judging whether the UE is in the low-speed or high-speed motion state is: judging whether the number of cell reselections of the UE within the timer T _{CR max} before the current moment exceeds the set threshold number N _CR , and if so, the UE is considered is in a high-speed motion state; otherwise, the UE is considered to be in a low-speed motion state.

However, in some realistic scenarios along the high-speed railway line as shown in Figure 1, using the existing technology to achieve cell reselection will have the problem of inaccurate judgment of the UE's motion state: the basis for judging the UE's motion state in the prior art It is the number of cell reselections occurred by the UE in a long period of time before the current moment, that is to say, this judgment is lagging, rather than a real-time value, especially when the high-speed train is accelerating or braking, such judgments often have Large error; further, using T _reselect with errors to affect cell reselection may cause the UE to miss the best opportunity for cell reselection, or the UE may reselect between cells (called ping-pong effect) Condition.

Moreover, when the RNC sets the above-mentioned parameters required for the UE to perform cell reselection (such as the received signal threshold value and several parameters for calculating the cell level value), the RNC in the prior art sets these parameters to fixed values. This makes the setting inflexible and lacks support for high-speed scenes.

To sum up, the method of setting cell reselection parameters and subsequent cell reselection using the existing technology cannot be well applied to specific scenarios such as along high-speed railways, which brings great challenges to actual network deployment applications. inconvenient.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for setting cell reselection parameters and a radio network controller (RNC), so as to solve the problem in the prior art that the setting of cell reselection parameters lacks support for high-speed scenarios.

Correspondingly, another object of the present invention is to provide a method and system for cell reselection to solve the problem that existing cell reselection methods are not well applicable to specific scenarios such as along high-speed railways.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

The present invention provides a method for cell reselection, the method comprising:

The base station (NodeB) measures and obtains the moving speed of the user terminal (UE) in the cell covered by it and reports it to the radio network controller (RNC);

The RNC sets parameters for the UE to perform cell reselection according to the moving speed of the UE reported by the NodeB, and sends the set parameters to all UEs in the cell through the NodeB;

The UE measures the cell according to the received parameters, and performs cell reselection according to the measurement result.

The RNC sets at least one of the following cell reselection parameters as a function of the moving speed of the UE: a first timer time T ₁ and a second timer time T _reselect .

The RNC sets the second timer time T _reselect to decrease as the moving speed of the UE increases.

The RNC sets T _reselect through a linear function, or a piecewise function, or multiplied by a reduction factor.

The RNC sets at least one of the following cell reselection parameters as a function of the moving speed of the UE: a hysteresis parameter Q _hyst used to calculate the level value of the current serving cell and an offset parameter used to calculate the level value of the adjacent cell Q _offsets .

The method further includes: the RNC sets Q _hyst to decrease as the UE's moving speed increases, and sets Q _offsets to decrease as the UE's moving speed increases.

The RNC sets at least one of Q _hyst and Q _offsets through a linear function or a piecewise function.

For a cell with a layered network structure, the RNC sets the inter-layer offset parameter TO _n to have a functional relationship with the moving speed of the UE, and sets TO _n to decrease as the moving speed of the UE increases.

The RNC sets TO _n through a linear function, or a piecewise function, or multiplied by a reduction factor.

For high-speed railways or communities along the expressway that adopt a hierarchical network structure, the RNC sets the level priority (HCS_PRIO ₁ ) of the private network cells along the line to a low value, and sets the level priority (HCS_PRIO 1 ) of the public network cells to a low value. ₂ ) Set to a high value, that is, HCS_PRIO ₂ >HCS_PRIO ₁ .

The measurement of the cell by the UE according to _T1 is specifically: when the timing time of _T1 is up, the UE measures the received signal strength S _x of the current serving cell, and compares the S _x with the preset measurement trigger threshold S Comparing, and when S _x ≤ S, according to the neighbor cell list sent by the RNC, measuring the received signal strength of the neighbor cells in the neighbor cell list;

Alternatively, the UE measures the received signal strength S _x of the current serving cell with a longer time period before the _T1 timing expires; when the _T1 timing expires, measures the received signal strength Sx of the current serving cell with a shorter time period The received signal strength S _x is measured; the S _x is compared with the preset measurement trigger threshold S, and when S _x ≤ S, according to the neighbor cell list sent by the RNC, the neighbor cell list The received signal strength of neighboring cells is measured.

The method further includes:

The RNC sends the set _T1 to the UE, and the UE performs the measurement of the cell according to the received _T1 ;

Alternatively, the RNC does not send the set T ₁ to the UE, the RNC performs timing according to T ₁ , and triggers the UE to perform cell measurement.

The RNC sets the parameters required for the UE to perform cell reselection according to the moving speed of the UE, further comprising: after the RNC receives the moving speeds of multiple UEs reported by the NodeB, taking the statistical average of the multiple reported moving speeds value, and set parameters required by the UE for cell reselection according to the statistical average value.

The present invention also provides a cell reselection system, the system includes: NodeB, RNC and UE, wherein,

The NodeB is used to measure and obtain the moving speed of the UE in the cell covered by it and report it to the RNC;

The RNC is configured to set parameters for the UE to perform cell reselection according to the moving speed of the UE reported by the NodeB, and send the set parameters to all UEs in the cell through the NodeB;

The UE is configured to measure the cell according to the received parameters, and perform cell reselection according to the measurement result.

The RNC is further configured to set at least one of the following cell reselection parameters to have a functional relationship with the moving speed of the UE: the first timer time T ₁ and the second timer time T _reselect , to calculate the current serving cell The hysteresis parameter Q _hyst of the level value and the offset parameter Q _offsets used to calculate the level value of the adjacent cell.

The RNC is further configured to set the inter-layer offset parameter TO _n to have a functional relationship with the moving speed of the UE, and set TO _n to decrease as the moving speed of the UE increases.

For a network that adopts a layered network structure network layout along the high-speed railway or expressway, the RNC is further used to set the HCS_PRIO ₁ of the private network cell along the line to a low value, and set the HCS_PRIO ₂ of the public network cell to a high value , that is, HCS_PRIO ₂ >HCS_PRIO ₁ .

The UE is further configured to, in the case of not receiving the level priority (HCS_PRIO) of the current serving cell or the level priority of the neighboring cell, the UE sets the level priority of the neighboring cell to be the same as that of the serving area by default .

The present invention also provides a method for setting cell reselection parameters, the method comprising:

The RNC receives the moving speed of the UE reported by the NodeB;

The RNC sets at least one of the following parameters to have a functional relationship with the moving speed of the UE according to the received moving speed of the UE: the first timer time T ₁ , the second timer time T _reselect , used to calculate the current serving cell The hysteresis parameter Q _hyst of the level value, and the offset parameter Q _offsets used to calculate the level value of the adjacent cell.

The method further includes: the RNC setting Q _hyst decreases as the moving speed of the UE increases.

The method further includes: the RNC sets Q _offsets to decrease as the moving speed of the UE increases.

The method further includes: the RNC setting T _reselect decreases as the moving speed of the UE increases.

The RNC sets at least one of T ₁ , T _reselect , Q _hyst , and Q _offsets through a linear function or a piecewise function.

For a network with a hierarchical network structure, the method further includes: the RNC sets the inter-level offset parameter T0 _n to a functional relationship with the moving speed of the UE according to the received moving speed of the UE, and sets T0 _n with the moving speed of the UE increase and decrease.

For a network that adopts a layered network structure network layout along the high-speed railway or expressway, the method further includes: the RNC sets the HCS_PRIO ₁ of the private network cell along the line to a low value, and sets the HCS_PRIO ₂ of the public network cell to a high value value, that is, HCS_PRIO ₂ >HCS_PRIO ₁ .

The present invention also provides an RNC, comprising:

A receiving module, configured to receive the moving speed of the UE reported by the NodeB;

A parameter setting module, configured to set at least one of the following parameters to have a functional relationship with the moving speed of the UE according to the received moving speed of the UE: the first timer time T ₁ , the second timer time T _reselect , used to calculate The hysteresis parameter Q _hyst of the level value of the current serving cell, and the offset parameter Q _offsets used to calculate the level value of the adjacent cell.

The parameter setting module is further used to set Q _hyst to decrease as the UE's moving speed increases, and/or set Q _offsets to decrease as the UE's moving speed increases, and/or set T _reselect to decrease as the UE's moving speed increases. Decreases with increasing movement speed.

The parameter setting module is further configured to set the inter-layer offset parameter _T0n to have a functional relationship with the UE's moving speed according to the received UE's moving speed, and set _TOn to decrease as the UE's moving speed increases .

For a network that adopts a layered network structure network layout along the high-speed railway or expressway, the parameter setting module is further used to set the HCS_PRIO ₁ of the private network community along the line to a low value, and set the HCS_PRIO ₂ of the public network community to High values, ie HCS_PRIO ₂ >HCS_PRIO ₁ .

A method and RNC for setting cell reselection parameters provided by the present invention use the moving speed of the UE to accurately reflect the moving state of the UE, and have the effect of dynamically adjusting with the real-time change of the moving speed of the UE, which solves the problem In existing technologies, such as scenarios along high-speed railways (highways), the setting of cell reselection parameters is fixed, and the flexibility is poor, and it cannot adapt to the movement state of the UE in real time.

Correspondingly, the method for cell reselection provided by the present invention improves the accuracy and timeliness of cell reselection performed by the UE in a high-speed scenario.

Description of drawings

Fig. 1 is a schematic diagram of cell coverage along a high-speed railway in the prior art;

Fig. 2 is a flow chart of a method for cell reselection in the present invention;

FIG. 3 is a flowchart of a cell reselection method according to Embodiment 1 of the present invention;

FIG. 4 is a schematic diagram of a layered network structure in Embodiment 2 of the present invention;

FIG. 5 is a flowchart of a cell reselection method according to Embodiment 2 of the present invention;

FIG. 6 is a schematic diagram of realizing the corresponding relationship between Q _hyst and the moving speed of the UE using a segmented function in the present invention;

FIG. 7 is a schematic diagram of the composition and structure of a cell reselection system according to the present invention.

Detailed ways

The technical solutions of the present invention will be further elaborated below in conjunction with the accompanying drawings and specific embodiments.

A kind of cell reselection method provided by the present invention, as shown in Figure 2, mainly comprises the following steps:

In step 201, the NodeB obtains the moving speed of the UE in the cell covered by the NodeB through measurement and reports it to the RNC.

The NodeB can measure the moving speed of the UE in the cell covered by it in the following way: when the UE camps on a certain cell, the cell is the current serving cell of the UE. At this time, a frequency for transmitting signals to each other will be agreed between UE and NodeB. When UE communicates with NodeB, UE sends signals to NodeB at the agreed frequency, but due to the influence of Doppler frequency shift generated when UE moves , resulting in a deviation between the frequency of the signal received by the NodeB from the UE and the agreed frequency. NodeB obtains this deviation through real-time measurement, obtains the Doppler frequency shift of UE according to this deviation, and further calculates the moving speed of UE through the following formula:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; V</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}\mathrm{<span\; class="notranslate">\; COS\&theta;</span>}$

Among them, V represents the moving speed of the UE, f _d represents the Doppler frequency shift of the UE measured by the NodeB, C represents the speed of light, θ represents the angle of arrival of the UE signal to the antenna of the NodeB, and θ is known by the NodeB.

In practical applications, since UEs are usually concentrated on trains along high-speed railways, the NodeB can collect the moving speeds of many UEs in a short time, and report the moving speeds of these UEs to the RNC in a centralized manner.

The NodeB reports the moving speed of the UE to the RNC through a measurement report. The so-called measurement report is a message for the NodeB to report the measurement result to the RNC. The measurement report includes:

(1) An identification number that uniquely identifies the UE, and the identification number may be a radio link number (RL-id, Radio Link id) occupied by the UE.

(2) The NodeB obtains the moving speed of the UE through measurement.

Preferably, the measurement report can also include:

(3) The signal strength index measured by the NodeB reflects the UE's signal strength index, for example: the signal-to-interference ratio (SIR, Signal Interference Ratio) or received signal power (RSCP, Received SignalCode Power) value of the UE signal.

(4) The NodeB measures the Doppler frequency shift of the UE.

Further, the NodeB reports the measured moving speed of the UE to the RNC, and can directly report the actual value of the speed; or can report the level value of the speed, and the level value is pre-agreed by the RNC and the NodeB, for example: 0-30m The speed of /s is predefined as grade A, the speed of 30-50m/s is predefined as grade B, and the speed above 50m/s is predefined as grade C.

In step 202, the RNC sets parameters for the UE to perform cell reselection according to the moving speed of the UE reported by the NodeB, and sends the set parameters to all UEs in the cell through the NodeB.

Preferably, for the case where the NodeB centrally reports the moving speeds of many UEs in the covered cell, the RNC may perform further statistical averaging processing after receiving the moving speeds of these UEs, for example: taking the average of the reported moving speeds Value, median, root mean square, etc., the purpose of using the above processing is to statistically obtain values that reflect the average level of these reported moving speeds, and then use the statistical average value after processing as the basis for RNC to set cell reselection parameters.

The RNC may set at least one of the following cell reselection parameters to have a functional relationship with the UE's moving speed:

The hysteresis parameter Q _hyst used to calculate the level value of the current serving cell;

The offset parameter Q _offsets used to calculate the level value of the adjacent cell;

The second timer time parameter T _reselect ; and

For a cell with a hierarchical network structure, it also includes an inter-level offset parameter TO _n ; and

The RNC may additionally introduce a first timer parameter T ₁ , and set it to have a functional relationship with the moving speed of the UE.

In addition, for the network with hierarchical network structure along the high-speed railway, the RNC also needs to set the priority parameters of the cells along the railway: set the level priority (HCS_PRIO ₁ ) of the adjacent cells of the private network to a low value, and set the public The hierarchical priority (HCS_PRIO ₂ ) of the adjacent cells of the network is set to a high value, ie HCS_PRIO ₂ >HCS_PRIO ₁ .

In step 203, the UE measures the cell according to the received parameters, and performs cell reselection according to the measurement result.

The above method for cell reselection will be further described in detail below in conjunction with specific embodiments. In Embodiment 1 of the present invention, the network structure is a non-hierarchical network, as shown in FIG. 3 , the steps for realizing cell reselection according to the moving speed of the UE are as follows:

In step 301, the UE camps on the current serving cell, and the NodeB of the serving cell measures the moving speed of the UE and reports it to the RNC.

Step 302, the RNC sets the parameters for the UE to perform cell reselection according to the received moving speed of the UE, and sends the set parameters to the UE through the NodeB.

For a cell with a non-hierarchical network structure, the cell reselection parameters set by the RNC according to the reported moving speed of the UE include: the first timer time T ₁ , the second timer time T _reselect , and the parameters used to calculate the level value of the current serving cell The hysteresis parameter Q _hyst and the offset parameter Q _offsets used to calculate the rank value of the neighbor cell. Wherein, the first timer time _T1 is a newly introduced parameter of the present invention. According to actual needs, the RNC can select only one or more parameters to set according to the moving speed of the UE, and the rest of the parameters can still be set according to the existing technology.

The function relationship settings of the parameters are as follows:

1. The first timer time T ₁ : RNC can estimate the time for the UE to run to the border area of the serving cell according to the moving speed of the UE and the known geographical area of the cell, and set the estimated time as the first timer time T ₁ . The effect of setting _T1 is to more accurately trigger the UE to start measuring the received signal strength of the serving cell.

2. The hysteresis parameter Q _hyst used to calculate the level value of the current serving cell and the offset parameter Q _offsets used to calculate the level value of the adjacent cell:

Q _hyst is set to decrease with the increase of the moving speed of the UE, and Q _offsets is also set to decrease with the increase of the moving speed of the UE. Preferably, if the NodeB directly reported the measured actual value to the RNC before, then the RNC can use a linear function to realize the setting of the above parameters, for example: setting the relationship between Q _hyst and the moving speed of the UE is: Q _hyst = Q _hyst0 -q·v, wherein, Q _hyst0 represents the reference value of Q _hyst , which is a constant value, q>0, and v represents the actual value of the moving speed of the UE. If the NodeB previously reported the measured UE moving speed to the RNC in the form of a grade value, then the RNC can use a segmented function to realize the setting of the above parameters, as shown in the segmented function shown in Figure 6. Q _hyst decreases as the moving speed of the UE increases.

The two parameters of Q _hyst and Q _offsets can be set according to the moving speed of the UE, and the other can be set as a fixed value, or both can be set according to the moving speed of the UE.

3. The second timer time T _reselect , set the corresponding relationship between T _reselect and the moving speed of the UE as follows: T _reselect decreases with the increase of the moving speed of the UE, and the setting of T _reselect can also use a linear function or a piecewise function For example: set T _reselect =T _reselect0 -u·v, where T _reselect0 represents the reference value of T _reselect , u>0; the setting of T _reselect can also be realized by multiplying a reduction factor, For example, when the RNC judges that the moving speed of the UE is greater than a certain threshold value, it sets T _reselect =T _reselect0 ·s, 0<s<1, which means the reduction factor.

The function of T _reselect is to measure whether the selected cell most suitable for reselection can be finally reselected, that is, if an adjacent cell can always remain as the most suitable cell for reselection within the T _reselect time, then the UE will reselect to the neighboring cell.

In addition, while setting the above cell reselection parameters according to the moving speed of the UE, the RNC also sets other cell reselection parameters, such as the measurement trigger threshold S and the UE's neighbor cell list, etc. These settings are still based on the existing technology implementation, which will not be repeated in the present invention.

After the RNC sets the parameters for all UEs to perform cell reselection, it sends the set parameters to the NodeB, and then the NodeB forwards them to the UEs through the SIB on the BCH of the cell.

In practical applications, the first timer time T ₁ may or may not be sent to the UE. If T ₁ is sent to the UE, the UE starts timing when T ₁ is received, and when T ₁ timing expires, actively triggers the measurement of the received signal strength of the current serving cell; or before T ₁ timing expires, with The measurement is performed in a longer time period, and when the timing time of _T1 expires, the measurement is performed in a shorter time period. If T ₁ is not sent to UE, then RNC starts timing when T ₁ is estimated internally, and sends a trigger message to UE when T ₁ timing expires, triggering UE to start measuring the received signal strength of the current serving cell.

The embodiment shown in FIG. 3 is described by taking the case that the RNC does not send T ₁ to the UE as an example.

In practical applications, for the case that T _reselect is set by multiplying a reduction factor, RNC may also send T _reselect0 and reduction factor s to UE, and then UE itself sets T _reselect =T _reselect0 ·s.

In step 303, the RNC starts a timer T ₁ , and triggers the UE to measure the received signal strength S _x of the current serving cell when the timer T ₁ expires.

Step 304, judge whether S _x is less than or equal to the measurement trigger threshold S, if yes, execute step 305; otherwise, continue to measure and continue to judge.

Wherein, the measurement trigger threshold S includes: an intra-frequency threshold S _intrasearch , an inter-frequency threshold S _intersearch and an inter-system threshold S _searchratm . The S _x measured by the UE needs to be compared with S _intrasearch , S _intersearch and S _searchratm respectively. According to the comparison result, as long as S _x is less than or equal to any one of them, go to step 305 .

In step 305, the UE measures the received signal strength of the neighboring cells in the neighboring cell list.

The measurement trigger threshold S mentioned above includes: S _intrasearch , S _intersearch and S _searchratm , and the corresponding triggered neighbor cell measurements are intra-frequency neighbor cell measurement, inter-frequency neighbor cell measurement and inter-system neighbor cell measurement respectively. Therefore, UE's measurement of neighboring cells specifically includes the following situations:

If S _x ≤ S _intrasearch , then the UE starts to measure the received signal strength of adjacent co-frequency cells in the list;

If S _x ≤ S _intersearch , the UE starts to measure the received signal strength of adjacent inter-frequency cells in the list;

If S _x ≤ S _searchratm , the UE starts to measure the received signal strength of neighboring cells of different systems in the list.

In practical applications, the priorities of selecting same-frequency cells, selecting inter-frequency cells, and selecting different-system cells for reselection of UE cell reselection are sequentially reduced. Therefore, the values of S _intrasearch , S _intersearch and S _searchratm are sequentially reduced.

In step 306, the UE judges whether there is a neighboring cell satisfying the camping condition according to the measurement result of the received signal strength of the neighboring cell, and if so, proceeds to step 307; otherwise, continues to measure the neighboring cell and continue to judge .

The so-called certain adjacent cell meets the residency condition means:

First, the signal strength of the adjacent cell is greater than a certain value, for example: Qrxlevmeas>Qrxlevmin, wherein, Qrxlevmeas indicates the received signal level value of the adjacent cell measured by the UE, and Qrxlevmin indicates the UE needs to camp on a cell minimum level value.

Second, in addition to meeting the above-mentioned signal strength conditions, the adjacent cell must also be a cell that is allowed to be accessed by the operator.

In step 307, the UE calculates the rank values of all neighboring cells that meet the camping conditions, and selects the neighbor cell with the highest rank value from the neighboring cells whose rank value is greater than the rank value of the current serving cell as the most suitable cell for reselection, and at the same time The timer T _reselect is started for timing.

The method for the UE to calculate the level value of the current serving cell is: R _s =Qmeas _s +Q _hyst +Q _offmbms ,

Among them, R _s represents the level value of the UE's current serving cell, and Qmeas _s represents the measured received signal strength of the UE's current serving cell, for example: it can be the primary common control physical channel (P-CCPCH, Primary Common Control Physical Channel). Received Signal Code Power (RSCP, Received Signal Code Power) value; Q _offmbms indicates the offset when the UE uses the multimedia broadcast frequency band, and Q _offmbms is also a cell reselection parameter sent by the RNC to the UE in the SIB message in advance. I won't repeat them here.

The method for UE to calculate the level value of neighboring cells is: R _n =Qmeas _n -Q _offsets +Q _offmbms

Among them, R _n represents the level value of the adjacent cell, Qmeas _n represents the level value of the received signal strength of the adjacent cell obtained by measurement, that is, the RSCP value on the P-CCPCH, and Q _offmbms represents the UE using the multimedia broadcast frequency band Offset.

It can be seen that when the UE is in a fast moving state (its moving speed is very high), then either R _s becomes smaller (because Q _hyst becomes smaller), or R _n becomes larger (because Q _offsets becomes smaller), so that the adjacent cells The grade value of is more likely to be higher than the grade value of the current serving cell.

The UE compares the priority R _n of all neighboring cells that meet the camping conditions with the priority R _s of the current serving cell of the UE, selects the maximum value from the R _n that is greater than R _s , and assigns the value corresponding to the maximum R _n The adjacent cell is the most suitable cell for reselection, and a timer T _reselect is started at the same time for timing.

From the above analysis, it can be seen that no matter which parameters Q _hyst and Q _offsets are set to be related to the moving speed of the UE, the effect is that when the UE moves at a high speed (that is, when the moving speed of the UE increases), the neighbor cell The level value of is more likely to be higher than the level value of the current serving cell, so setting any one of the two parameters as a function of the moving speed of the UE has equivalent effects.

Step 308, the UE judges whether the selected cell can remain as the most suitable cell for reselection within the duration of the timer T _reselect , if yes, executes step 309; otherwise, returns to step 307, and continues to search for the most suitable cell for reselection district.

Step 309, the UE reselects to the most suitable cell for reselection, and registers with the network through a registration message; after receiving the UE's registration message, the RNC sends the updated neighbor cell list and related parameters to the UE.

In Embodiment 2 of the present invention, the network structure is a layered network. The so-called layered network, as shown in FIG. 4 , refers to the establishment of macro cells with different coverage areas and more micro cells in the same area. In the actual wireless network deployment along the high-speed railway, a layered network is more common, in which the macro cell constitutes a network dedicated to serving UEs in the train (private network); the micro cell is an ordinary network (public network), To cover other UEs, the cells of the two types of networks belong to different levels.

For a UE in a high-speed train covered by a private network, cell reselection based on the UE's moving speed information can not only improve the accuracy and efficiency of cell reselection, but also achieve the goal of keeping the UE on the train. Beneficial effects in private network communities.

As shown in Figure 5, the steps to implement cell reselection using UE's moving speed in a hierarchical network are as follows:

In step 501, the UE camps on the current serving cell, and the NodeB of the serving cell measures the moving speed of the UE and reports it to the RNC.

In practical applications, the NodeB can often collect the moving speeds of multiple UEs concentrated on a train in a short period of time, and send the measurement results of these UEs to the RNC in a centralized manner.

Step 502, the RNC sets the parameters required for the UE to perform cell reselection according to the reported moving speed of the UE, and sets the UE's neighbor cell list, and sends the set parameters and list to the UE through the NodeB.

Preferably, similar to Embodiment 1, when the NodeB centrally reports the moving speeds of multiple UEs in its covered cell, the RNC can perform further statistical average processing after receiving the moving speeds of multiple UEs, and then use the statistical average result to set parameters.

For hierarchical cells, the cell reselection parameters set by the RNC according to the moving speed of the UE include: the first timer time T ₁ , the second timer time T _reselect , the hysteresis parameter Q _hyst used to calculate the level value of the current serving cell, The offset parameter Q _offsets and the inter-level offset parameter TO _n are used to calculate the level value of the adjacent cell. According to actual needs, the RNC may only select one or more parameters to set according to the moving speed of the UE, and the rest of the parameters are still set according to the prior art.

The setting methods of T ₁ , T _reselect , Q _hyst , and Q _offsets are the same as those in the first embodiment, and their corresponding relationship with the moving speed of the UE is: T _reselect is set to decrease with the increase of the moving speed of the UE, Q _hyst and Q _offsets is set to decrease as the moving speed of the UE increases.

In practical applications, T ₁ may or may not be sent to the UE. When the T _reselect is set by a reduction factor, it may not be sent directly to the UE, but the reduction factor and the reference value of T _reselect are sent to the UE, and then let the UE set it by itself, which will not be repeated here.

The inter-level offset parameter TO _n is set to decrease as the moving speed of the UE increases, and this setting can be realized by using a linear function or a piecewise function, for example: TO _n = TEMP_OFFSET ₀ -v|f _d |, among them, TEMP_OFFSET ₀ represents the reference value of TO _n , v>0. In practical applications, a time limit is often added to the function of TO _n , such as setting a Tn timer, then the expression of TO _n becomes TO _n =(TEMP_OFFSET ₀ -v |f _d |) W(Tn), the meaning of W(Tn) is to make the value of TO _n valid only within Tn time, that is, within Tn time, W(Tn)=1, and when it exceeds Tn time, W(Tn)=0 .

In addition, for the layered network structure along the high-speed railway or highway, the RNC sets the level priority (HCS_PRIO ₁ ) of the private network cells along the railway to a low value, and sets the level priority (HCS_PRIO ₂ ) of the public network cells to A high value, that is, HCS_PRIO ₂ >HCS_PRIO ₁ ; the hierarchical priority (HCS_PRIO) mentioned here is also a parameter set by the RNC, which is an integer in the range of 0 to 7, 7 means the highest priority, and 0 means the lowest priority.

While setting the above cell reselection parameters according to the UE's moving speed, the RNC also sets other cell reselection parameters and a list of adjacent cells (not based on the UE's moving speed). Afterwards, the RNC sends the set parameters and the neighbor cell list to the NodeB, and then the NodeB forwards it to the UE through the SIB message on the BCH channel of the cell.

In step 503, the UE starts a timer T ₁ , and starts measuring the received signal strength S _x of the current serving cell when the timing of T ₁ expires.

Step 504, judge whether S _x is less than or equal to the measurement trigger threshold S, if yes, execute step 505, otherwise continue to measure and continue to judge.

The measurement trigger threshold S includes: the same-frequency threshold S _intrasearch , the inter-frequency threshold S _intersearch , and the inter-system threshold S _searchratm , the three of which have been described in the embodiment shown in FIG. 3 . In order to simplify the description, S _intersearch is taken as an example in this embodiment to continue the description; in the actual high-speed railway private network scenario, the frequencies of the private network and public network neighbors are often configured with different frequencies. Correspondingly, if S _x ≤ S _intersearch , go to step 505 .

Step 505, when S _x ≤ S _mtersearch , the UE starts to measure the received signal strength of adjacent inter-frequency cells in the list.

In step 506, the UE judges whether there is an adjacent cell satisfying the camping condition according to the measurement result of the received signal strength of the adjacent inter-frequency cell, and if so, executes step 507; otherwise, continues to measure the adjacent cell and Go ahead and judge.

In step 507, the UE calculates the rank values (H values) of all neighboring cells that meet the camping conditions, and finds out all neighboring cells whose H value is greater than 0, if no neighboring cell with an H value greater than 0 is found, then Go to step 506 (not indicated in the figure). The calculation method of H value is as follows:

The UE calculates the H value of the current serving cell: H _s =Qmeas _s -Qhcs _s ,

The UE calculates the H value of the neighboring cell: H _n =Qmeas _n -Qhcs _n -TO _n Ln,

Among them, the subscript s indicates the current serving cell, and the subscript n indicates the adjacent cell; Qmeas indicates the received signal strength obtained by measurement; Qhcs _s and Qhcs _n are other parameters configured in the system information (SIB); TO _n is different levels Inter-offset parameters; Ln is a level flag, that is, when the adjacent cell is not at the same level as the current serving cell, Ln=1; when it is at the same level, Ln=0.

If the UE can find a cell with an H value greater than 0, then the UE sorts these cells according to the priority level (HCS_PRIO); and then looks for:

1. Find the cell with the highest hierarchical priority among the cells with lower hierarchical priority than the current serving cell, and form a cell set.

2. When condition 1 cannot be satisfied, find the cell with the lowest priority among the cells with the same or higher priority than the current serving cell.

It can be seen that because the RNC previously set the level priority of the private network cells along the line to be lower than the level priority of the public network cells, and cooperated with the function of the TO _n Ln item, the UE moving at a high speed can accurately camp on the In private network. The analysis is as follows: when a certain UE is in a state of high-speed movement, TO _n becomes smaller, and the effect of TO _n Ln is weakened, so regardless of the adjacent cells with the same priority level or the adjacent cells with the same level priority, H _n becomes larger, That is to say, the H value of the adjacent cell is more likely to be greater than 0, thereby increasing the possibility of the adjacent cell being reselected. Further, since the hierarchical priority of the private network cell is lower than that of the public network cell, the UE will preferentially select the private network cell. Therefore, regardless of whether the cell where the UE originally resides is a private network or a public network cell, as long as it moves quickly, it will reside in the private network.

Due to the unreliability of transmission in the wireless environment, the hierarchy priority of the service area or neighboring cells may not be sent to the UE. At this time, the UE should set the hierarchy priority of the neighboring cell to be the same as that of the service area by default, that is, HCS_PRIO ₂ = HCS_PRIO ₁ . The advantage of this default setting is that it does not reduce the frequency of UE reselection, that is to say, after the signal quality of the current serving cell drops, it will not affect the normal cell reselection of the UE due to layer priority; at the same time, as much as possible The UE is prevented from camping in cells of different levels, so the UE in the original private network can continue to camp in the private network.

In step 508, after finding these cells, the UE forms a subset of cells, and then calculates its rank value (R value) for each cell in the subset.

The UE calculates the rank value of the current serving cell: R _s =Qmeas _s +Q _hyst +Q _offmbms ,

The UE calculates the rank value of the neighboring cell: R _n =Qmeas _n -Q _offsets +Q _offmbms -TOn·(1-Ln)

Here, the meanings of Qmeas, Q _hyst , Q _offsets and Ln are consistent with the previous description.

The UE calculates the grade value (R value) of the cells in the above-mentioned subset and sorts them according to the grade value; finds out the neighbor cell with the highest grade value as the most suitable cell for reselection, and starts the second timer T _reselect at the same time timing.

It can be seen that when the UE moves rapidly, the R _n value of the adjacent cell becomes larger, thus speeding up the reselection.

Step 509, the UE judges whether the selected cell can remain as the most suitable cell for reselection within the duration of the timer T _reselect , if yes, executes step 510; otherwise, returns to step 507, and continues to search for the most suitable cell for reselection district.

According to step 502, the set T _reselect decreases with the increase of UE's moving speed. Therefore, the greater the UE's moving speed, the shorter the time for the most suitable cell to be reselected.

Step 510, UE reselects to the most suitable cell for reselection.

The above two embodiments use the cell reselection of cells along the high-speed railway to illustrate the implementation of the present invention. However, it must be noted that, besides high-speed railways, the present invention is also applicable to the implementation of cell reselection in high-speed moving scenes of user terminals such as highways and maglevs.

In addition, corresponding to the cell reselection method of the above-mentioned non-hierarchical network structure, the present invention also provides a method for setting cell reselection parameters for cells with a non-hierarchical network structure in the RNC, including:

In step a, the RNC receives the moving speed of the UE reported by the NodeB.

In step b, the RNC sets at least one of the following parameters to have a functional relationship with the UE's moving speed according to the received UE's moving speed: T ₁ , T _reselect , Q _hyst and Q _offsets .

Preferably, the RNC can set Q _hyst to decrease with the increase of UE's moving speed, set Q _offsets to decrease with the increase of multiple UE's moving speed, set T _reselect to decrease with the increase of UE's moving speed Small. And the setting of the above parameters can be realized by linear function or piecewise function.

Corresponding to the cell reselection method of the above layered network structure, the present invention also provides a method for setting cell reselection parameters for cells with a layered network structure, including:

In step A, the RNC receives the moving speed of the UE reported by the NodeB.

In step B, the RNC sets the inter-layer offset parameter TO _n to have a functional relationship with the UE's moving speed according to the received UE's moving speed, and sets TO _n to decrease as the UE's moving speed increases.

Of course, the RNC may also set at least one of T ₁ , T _reselect , Q _hyst , and Q _offsets to have a functional relationship with the moving speed of the UE. For a network that adopts a layered network structure along the high-speed railway or expressway, the RNC sets the HCS_PRIO ₁ of the private network cells along the line to a low value, and sets the HCS_PRIO ₂ of the public network cells to a high value, that is, HCS_PRIO ₂ > HCS_PRIO ₁ .

In order to realize the above cell reselection method, the present invention also provides a cell reselection system, as shown in Figure 7, the system includes: NodeB 10, RNC 20 and UE 30. NodeB 10 is used to measure and obtain the moving speed of UE 30 in the cell covered by it and report it to RNC 20. RNC 20 is used to set parameters for UE 30 to perform cell reselection according to the moving speed of UE 30 reported by NodeB 10, and send the set parameters to all UEs 30 in the cell through NodeB 10. The UE 30 is configured to measure the cell according to the received parameters, and perform cell reselection according to the measurement result.

Wherein, the RNC 20 further includes a receiving module 21 and a parameter setting module 22 . The receiving module 21 is configured to receive the moving speed of the UE 30 reported by the NodeB 10 . The parameter setting module 22 is configured to set at least one of the following cell reselection parameters to have a functional relationship with the moving speed of the UE 30 according to the received moving speed of the UE 30: the first timer time T ₁ , the second timer The time T _reselect , the hysteresis parameter Q _hyst used to calculate the level value of the current serving cell and the offset parameter Q _offsets used to calculate the level value of the neighboring cell. Set Q _hyst to decrease as UE's moving speed increases, and/or set Q _offsets to decrease as UE's moving speed increases, and/or set T _reselect to decrease as UE's moving speed increases .

For a cell with a hierarchical network structure, the parameter setting module 22 is also used to set the inter-level offset parameter T0 _n to have a functional relationship with the moving speed of the UE 30, and T0 _n is set to increase with the increase of the moving speed of the UE 30 decrease.

For the network that adopts the layered network structure network layout mode along the high-speed railway or the expressway, the parameter setting module 22 is further used to set the HCS_PRIO ₁ of the private network community along the line to a low value, and the HCS_PRIO ₂ of the public network community to be set to a high value value, that is, HCS_PRIO ₂ >HCS_PRIO ₁ .

In addition, when the UE 30 does not receive the level priorities of the current service area and neighboring cells, the UE should set the level priorities of the neighboring cells to be the same as those of the service area by default.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (29)

1. a method of cell reselection is characterized in that, this method comprises:

Base station (NodeB) measures the translational speed of user terminal (UE) in its coverage cell and reports radio network controller (RNC);

Described RNC is provided with the parameter that UE carries out the sub-district gravity treatment according to the translational speed of the UE that NodeB reports, and the parameter that is provided with is sent to all UE in the sub-district by NodeB;

UE measures the sub-district according to the parameter that receives, and carries out the sub-district gravity treatment according to measurement result.

2. according to the described method of cell reselection of claim 1, it is characterized in that described RNC is arranged in the following cell reselection parameters at least one to have functional relation with the translational speed of UE: the first timer time T ₁With the second timer time T _Reselect

3. according to the described method of cell reselection of claim 2, it is characterized in that described RNC is provided with the second timer time T _ReselectIncrease with the translational speed of UE reduces.

4. according to the described method of cell reselection of claim 3, it is characterized in that described RNC is by linear function, or piecewise function, or multiply by and dwindle factor pair T _ReselectBe provided with.

5. according to claim 1 or 2 described method of cell reselection, it is characterized in that described RNC is arranged in the following cell reselection parameters at least one to have functional relation with the translational speed of UE: in order to calculate the sluggish parameter Q of current service cell grade point _HystWith offset parameter Q in order to calculating neighbor cell grade point _Offsets

6. according to the described method of cell reselection of claim 5, it is characterized in that this method further comprises: described RNC is provided with Q _HystIncrease with the translational speed of UE reduces, and Q is set _OffsetsIncrease with the translational speed of UE reduces.

7. according to the described method of cell reselection of claim 6, it is characterized in that, described RNC by linear function or piecewise function to Q _HystAnd Q _OffsetsIn at least one be provided with.

8. according to the described method of cell reselection of claim 1, it is characterized in that for the sub-district of hierarchical network architecture, described RNC is with offset parameter TO between level _nBe arranged to have functional relation with the translational speed of UE, and, TO is set _nIncrease with the translational speed of UE reduces.

9. described according to Claim 8 method of cell reselection is characterized in that, described RNC is by linear function, or piecewise function, or multiply by and dwindle factor pair TO _nBe provided with.

10. according to claim 1 or 8 described method of cell reselection, it is characterized in that for the sub-district that high-speed railway or highway adopt hierarchical network architecture cloth net mode along the line, described RNC is with the level priority (HCS_PRIO of private network sub-district along the line ₁) be arranged to low value, with the level priority (HCS_PRIO of public network cell ₂) be arranged to high value, i.e. HCS_PRIO ₂＞HCS_PRIO ₁

11., it is characterized in that UE is according to T according to the described method of cell reselection of claim 2 ₁Execution is specially the measurement of sub-district: described UE is at T ₁Timing then, to the received signal strength S of current service cell _xMeasure, with described S _xCompare with default measurement triggering thresholding S, and at S _xDuring≤S,, the received signal intensity of the neighbor cell in the described neighbor cell list is measured according to the neighbor cell list that RNC sends;

Perhaps, described UE is at T ₁Before timing time arrives, with the received signal strength S of long time cycle to current service cell _xMeasure; At T ₁Timing time then, with the received signal strength S of short time cycle to current service cell _xMeasure; With described S _xCompare with default measurement triggering thresholding S, and at S _xDuring≤S,, the received signal intensity of the neighbor cell in the described neighbor cell list is measured according to the neighbor cell list that RNC sends.

12., it is characterized in that this method further comprises according to the described method of cell reselection of claim 11:

Described RNC is with the T that is provided with ₁Send to UE, described UE is according to the T that receives ₁Execution is to the measurement of sub-district;

Perhaps, described RNC is not with the T that is provided with ₁Send to UE, described RNC is according to T ₁Carry out timing, and trigger the measurement of described UE execution the sub-district.

13. according to the described method of cell reselection of claim 1, it is characterized in that, described RNC is provided with UE according to the translational speed of UE and carries out the required parameter of sub-district gravity treatment, further comprise: receiving the translational speed of a plurality of UE that NodeB reports as described RNC after, get the assembly average of a plurality of translational speeds that report, and UE is set carries out the required parameter of sub-district gravity treatment according to described assembly average.

14. the system of a sub-district gravity treatment is characterized in that, this system comprises: NodeB, RNC and UE, wherein,

Described NodeB is used to measure the translational speed of UE in its coverage cell and report described RNC;

Described RNC, the translational speed that is used for the UE that reports according to NodeB is provided with the parameter that UE carries out the sub-district gravity treatment, and the parameter that is provided with is sent to all UE in the sub-district by NodeB;

Described UE is used for according to the parameter that receives the sub-district being measured, and carries out the sub-district gravity treatment according to measurement result.

15. the system according to claim 14 described sub-district gravity treatment is characterized in that, described RNC is further used for, and in the following cell reselection parameters at least one is arranged to have functional relation with the translational speed of UE: the first timer time T ₁, the second timer time T _Reselect, in order to calculate the sluggish parameter Q of current service cell grade point _HystWith offset parameter Q in order to calculating neighbor cell grade point _Offsets

16. the system according to claim 14 or 15 described sub-district gravity treatments is characterized in that described RNC is further used for, with offset parameter TO between level _nBe arranged to have functional relation with the translational speed of UE, and TO _nBe arranged to reduce with the increase of the translational speed of UE.

17. the system according to claim 14 or 15 described sub-district gravity treatments is characterized in that, adopts the network of hierarchical network architecture cloth net mode along the line for high-speed railway or highway, described RNC is further used for, with the HCS_PRIO of private network sub-district along the line ₁Be arranged to low value, with the HCS_PRIO of public network cell ₂Be arranged to high value, i.e. HCS_PRIO ₂＞HCS_PRIO ₁

18. system according to claim 14 described sub-district gravity treatment, it is characterized in that, described UE is further used for, under the situation of the level priority of level priority (HCS_PRIO) that does not receive current service cell or adjacent area, the level priority with the adjacent area of described UE acquiescence is arranged to identical with service area.

19. the method that cell reselection parameters is set is characterized in that, this method comprises:

The translational speed of the UE that described RNC reception NodeB reports;

Described RNC is arranged in the following parameter at least one to have functional relation with the translational speed of UE according to the translational speed of the UE that receives: the first timer time T ₁, the second timer time T _Reselect, in order to calculate the sluggish parameter Q of current service cell grade point _Hyst, in order to calculate the offset parameter Q of neighbor cell grade point _Offsets

20. according to the described method that cell reselection parameters is set of claim 19, it is characterized in that this method further comprises: described RNC is provided with Q _HystIncrease with the translational speed of UE reduces.

21. according to the described method that cell reselection parameters is set of claim 19, it is characterized in that this method further comprises: described RNC is provided with Q _OffsetsIncrease with the translational speed of UE reduces.

22. according to the described method that cell reselection parameters is set of claim 19, it is characterized in that this method further comprises: described RNC is provided with T _ReselectIncrease with the translational speed of UE reduces.

23. according to the described method that cell reselection parameters is set of claim 19, it is characterized in that, described RNC by linear function or piecewise function to T ₁, T _Reselect, Q _Hyst, Q _OffsetsIn at least one be provided with.

24., it is characterized in that for the hierarchical network architecture network, this method further comprises according to the described method that cell reselection parameters is set of claim 23: described RNC according to the translational speed of the UE that receives with offset parameter TO between level _nBe arranged to have functional relation, and TO is set with the translational speed of UE _nIncrease with the translational speed of UE reduces.

25. according to claim 23 or the 24 described methods that cell reselection parameters is set, it is characterized in that, adopt the network of hierarchical network architecture cloth net mode along the line for high-speed railway or highway, this method further comprises: described RNC is with the HCS_PRIO of private network sub-district along the line ₁Be arranged to low value, with the HCS_PRIO of public network cell ₂Be arranged to high value, i.e. HCS_PRIO ₂＞HCS_PRIO ₁

26. a RNC is characterized in that, comprising:

Receiver module is used to receive the translational speed of the UE that NodeB reports;

Parameter is provided with module, is used for being arranged to have functional relation with the translational speed of UE according at least one with following parameter of the translational speed of the UE that receives: the first timer time T ₁, the second timer time T _Reselect, in order to calculate the sluggish parameter Q of current service cell grade point _Hyst, in order to calculate the offset parameter Q of neighbor cell grade point _Offsets

27., it is characterized in that described parameter is provided with module and is further used for, and Q is set according to the described RNC of claim 26 _HystIncrease with the translational speed of UE reduces, and/or Q is set _OffsetsIncrease with the translational speed of UE reduces, and/or T is set _ReselectIncrease with the translational speed of UE reduces.

28. according to claim 26 or 27 described RNC, it is characterized in that described parameter is provided with module and is further used for, according to the translational speed of the UE that receives with offset parameter TO between level _nBe arranged to have functional relation, and TO is set with the translational speed of UE _nIncrease with the translational speed of UE reduces.

29., it is characterized in that adopt the network of hierarchical network architecture cloth net mode along the line for high-speed railway or highway, described parameter is provided with module and is further used for, with the HCS_PRIO of private network sub-district along the line according to the described RNC of claim 28 ₁Be arranged to low value, with the HCS_RIO of public network cell ₂Be arranged to high value, i.e. HCS_PRIO ₂＞HCS_PRIO ₁

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