CN1756403A - Intercell measuring method in OFDM system - Google Patents
Intercell measuring method in OFDM system Download PDFInfo
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- CN1756403A CN1756403A CN 200410079351 CN200410079351A CN1756403A CN 1756403 A CN1756403 A CN 1756403A CN 200410079351 CN200410079351 CN 200410079351 CN 200410079351 A CN200410079351 A CN 200410079351A CN 1756403 A CN1756403 A CN 1756403A
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Abstract
The invention discloses a cross-subzone measure method in OFDM, which comprises: system classifies OFDM symbol when mobile platform needs to enter cross-subzone measurement; selecting OFDM symbol satisfied first predetermined condition to transmit business information of said platform; if there is no such symbol, selecting OFDM symbol satisfied second predetermined condition to transmit business information of said platform; using idle time in satisfied OFDM symbol to measure adjacent subzone information; if no such symbol, measuring information by decreasing platform business speed. This method can decrease signaling spending and save cost.
Description
Technical field
The present invention relates to communication technical field, be specifically related to stride in a kind of ofdm system the method for cell measurement.
Background technology
At present, the multimedization of radio communication is one of developing direction of radio communication, professional multimedization inevitable requirement has high-speed data transmission to support, because the inherent characteristics of wireless channel, realize that high-speed transfer must overcome the influence of channel delay expansion, and the OFDM technology has greater advantage in this respect, makes it obtain using widely in the High Bit-rate Wireless Data Communication system.
OFDM (OFDM) is the high speed transmission technology under a kind of wireless environment, is adapted at transmitting high speed data in the wireless mobile channel of multipath transmisstion and Doppler frequency shift.It can effectively resist multipath effect, eliminates intersymbol interference, the decline of contrary frequency selectivity, and channel utilization height.The main thought of OFDM is with the data flow string of serial and converts the lower N of a bit rate parallel branch to that each branch road is modulated on the subcarrier again, synthetic at last output.These subcarriers are mutually orthogonal, make that the frequency spectrum of each subcarrier can be overlapping, improved spectrum efficiency greatly.
Information flow is mapped on the different frequency channels and transmits in the system that adopts the OFDM technology, as shown in Figure 1:
Wherein, P is a pilot signal; D1 is user 1 data; D2 is user 2 data; D3 is user 3 data.
The variation of t in time, data be in continuous transmission, is similar to the subcarrier set is divided into several channels, uses for respectively different users.
When subscriber access system, the bandwidth that its transport service is required is known according to the business information of different user in system, the subcarrier that distributes respective numbers and position then according to this bandwidth for the user, be used to carry user's business information, like this, form a channel by a plurality of subcarriers of different user, each subcarrier data carried by data is transmitted in same time slot (Ts).Obviously, this technology causes that the information transmission between sub-district and travelling carriage generally is continuous in the ofdm system, when travelling carriage enters cell edge, and need be to the signal of other sub-districts, when measuring as pilot frequency intensity and cell broadcast information, transmission and receiving course that can interrupting information.This interruption gently then causes information dropout and high-rise re-transmission the, waste channel width; Heavy then cause losing being connected of travelling carriage and original sub-district, and system produced disturb.
Prior OFDM system, in WLAN (WLAN (wireless local area network)) system, travelling carriage is the measurement of not carrying out striding cell signal in communication process, have only when travelling carriage loses with current sub-district and be connected, UE just begins to measure the signal of other sub-districts, such result is that travelling carriage can lose the contact with system in the long time, cause professional interruption, even because system may not know that travelling carriage has lost the contact with system, proceed the transmission of invalid business, to system resource by causing waste.Be fine in this mode and the system more weak to the mobility support of travelling carriage like this based on transfer of data for WLAN, but when OFDM is applied to 3G and this requirement of 4G big capacity traditional business is being provided, support the multimedia service of high-quality and many speed, and can operate in mobile communication system in multiple communication environment and the multiple communication network time, can influence the quality of service of system greatly, the particularly important real time business and the quality of streaming media service.
The interruption of business when preventing that travelling carriage from striding the sub-district, adopt following dual mode usually:
(1) utilize the scheduling feature of layer two, in network or mobile station equipment, making data send and receive can be discontinuous, thereby obtains the transmission space with the transmission metadata cache of travelling carriage, and the time of vacating just can be used for the measurement of travelling carriage to other sub-districts.Such result must be that the data transmission is discontinuous, and the delay increasing of data transmission, and then can cause data to send failure, a little less than real time business support.Usually because measuring process is longer, during frequent schedule information strengthened following signaling load, reduced network efficiency.And, because scheduling is generally finished at layer two, therefore also need layer two that bigger data buffering is arranged.
(2) in travelling carriage, increase a transceiver in addition, utilize this transceiver to measure, to guarantee the professional integrality and the continuity of system.Obviously, the shortcoming of this mode is to have increased travelling carriage cost and power loss.
Summary of the invention
The purpose of this invention is to provide the method for striding cell measurement in a kind of ofdm system, stride the shortcoming that can not keep business continuance when cell signal is measured to overcome in the existing ofdm system travelling carriage at cell edge, make travelling carriage under the continual situation of business, finish the measurement of striding cell signal.
For this reason, the invention provides following technical scheme:
Stride the method for cell measurement in a kind of ofdm system, described method comprises:
A, when travelling carriage need enter when striding cell measurement, described system classifies to OFDM symbol;
B, the selected OFDM symbol class that meets first predetermined condition are transmitted the business information of described travelling carriage and are utilized the free time on the described OFDM symbol to measure adjacent cell information;
C, when not meeting the OFDM symbol of described first predetermined condition, the then selected OFDM symbol class that meets second predetermined condition is transmitted the business information of described travelling carriage and is utilized the free time on the described OFDM symbol to measure adjacent cell information;
D, when not meeting the OFDM symbol of described second predetermined condition, measure adjacent cell information by the service rate that reduces described travelling carriage.
Described steps A comprises:
A1, judge whether described travelling carriage is in described current area edge;
A2, described system classifies to OFDM symbol when described travelling carriage is in the current area edge.
Described steps A 2 is specially: described system classifies to described OFDM symbol according to the different user in the described current area.
Described step B comprises:
Whether exist enough idle sub-carrier to be used for transmitting the information of the remaining OFDM symbol class of described travelling carriage on B1, the every class OFDM symbol of inspection;
B2, when existing enough idle sub-carrier to be used on the described OFDM symbol to transmit the information of the remaining OFDM symbol class of described travelling carriage, with it as the OFDM symbol that meets first predetermined condition;
B3, described system send signaling to described travelling carriage, notify described travelling carriage to enter and stride the cell measurement pattern;
B4, described travelling carriage are measured neighbor cell according to described signaling.
Described step B1 comprises:
B11, described system obtain described mobile station service information and measure the required total number of sub-carriers of adjacent cell information;
B12, check sub-carrier number on every class OFDM symbol successively;
B13, when the sub-carrier number on the described OFDM symbol during more than or equal to described total number of sub-carriers, have enough idle sub-carrier to be used for transmitting the information of the remaining OFDM symbol class of described travelling carriage on the described OFDM symbol.
Described step C comprises:
C1, when also existing other need enter the user who strides the cell measurement state in the described system, need enter from described other and to select the described OFDM symbol that meets second predetermined condition user's who strides the cell measurement state the OFDM symbol classification;
C2, need enter when not meeting the described OFDM symbol that meets second predetermined condition in user's OFDM symbol classification of striding the cell measurement state when other of user who does not have other to enter in the described system to stride the cell measurement state or existence, from other users' of described system OFDM symbol classification, select the described OFDM symbol that meets second predetermined condition;
C3, transmit the business information of described travelling carriage and utilize the free time on the described OFDM symbol to measure adjacent cell information by the selected OFDM symbol class that meets second predetermined condition.
Described step C1 is specially: enough transmit information on the remaining OFDM symbol class of described travelling carriage if described other need enter subcarrier on the user's who strides the cell measurement state the OFDM symbol and idle sub-carrier sum, simultaneously subcarrier and the idle sub-carrier of described travelling carriage on residual quadrature frequency division multiplexing symbol class enough transmitted described other and need be entered the user's who strides the cell measurement state information, then with such OFDM symbol as the OFDM symbol class that meets second predetermined condition.
Described step C2 is specially: if subcarrier on described other users' the OFDM symbol and idle sub-carrier sum are enough transmitted the information on the remaining OFDM symbol class of described travelling carriage, simultaneously subcarrier and the idle sub-carrier of described travelling carriage on residual quadrature frequency division multiplexing symbol class enough transmitted described other users' information, then with such OFDM symbol as the OFDM symbol class that meets second predetermined condition.
Described step C3 comprises:
C31, described system send signaling to described travelling carriage and other relevant users respectively, notify described travelling carriage and described other relevant users to enter the cell measurement pattern of striding, and described other relevant user's subcarriers and other idle sub-carrier are distributed to described travelling carriage, and give described other relevant users with the subcarrier allocation of described travelling carriage on all the other class OFDM symbols; Described relevant other users need enter the user that strides the cell measurement state or other users in the described system for described other;
C32, described travelling carriage and described other need enter the user who strides the cell measurement state and according to the signaling that it is received neighbor cell be measured respectively, and other users in the described system enter the cell measurement pattern of striding.
Described step D comprises:
Other users' that can distribute and divert in D1, the described system of inspection number of sub carrier wave;
D2, when data rate that described subcarrier data carried by data speed needs less than described travelling carriage, reduce the service rate of described travelling carriage;
D3, transmit the information of described travelling carriage on residual quadrature frequency division multiplexing symbol class by the subcarrier on such OFDM symbol of vacating.
Described method also comprises: remaining idle sub-carrier on the every class OFDM symbol of described system log (SYSLOG).
Described method also comprises: when enough idle sub-carrier, recover need not stride cell measurement in the described system but be in the regular traffic pattern of striding the cell measurement mode user.
Described adjacent cell information comprises: the signal strength signal intensity of described neighbor cell and broadcast message.
By above technical scheme provided by the invention as can be seen, the present invention classifies by the symbol to OFDM, when travelling carriage begins to stride cell measurement, this user's information concentrated on a certain class OFDM symbol transmit, thereby vacate the OFDM symbol of other classes, the time of the OFDM symbol class that the travelling carriage utilization is vacated is measured the signal of neighbor cell.Need not increase any other transceiver and can guarantee that the user is striding continuity professional under the cell measurement state, the measurement pattern that only needs designated user to use on the simultaneity factor signaling consumption, be subcarrier and symbol class positional information thereof that the user distributes, reduced signaling consumption.Can support real-time and Streaming Media class business, and keep the connection of system, help of the switching of follow-up travelling carriage in the minizone.
Description of drawings
Fig. 1 is an ofdm system frame signal schematic diagram;
Fig. 2 is the flow chart of the inventive method;
Fig. 3 is the selected flow chart that meets the OFDM symbol class of first predetermined condition;
Fig. 4 is the situation schematic diagram that enough idle sub-carrier are arranged on the OFDM symbol;
Fig. 5 is the selected flow chart that meets the OFDM symbol class of second predetermined condition;
Fig. 6 is the situation schematic diagram that OFDM symbol that can the commutator carrier wave is arranged in the system;
Fig. 7 is the OFDM class symbol situation schematic diagram that travelling carriage receives current area and neighbor cell;
The current area that travelling carriage received when Fig. 8, Fig. 9 were the different measuring interval and the OFDM class symbol situation schematic diagram of neighbor cell;
Figure 10 is OFDM class symbol situation schematic diagram when idle sub-carrier and other user's subcarriers in the OFDM symbol;
Figure 11 strides the schematic diagram of cell measurement by reducing the travelling carriage transmission rate.
Embodiment
Core of the present invention is when travelling carriage begins to stride cell measurement, current area by the travelling carriage place is classified to the symbol of OFDM, the information transmission of travelling carriage and reception be placed on a certain class OFDM symbol transmit, simultaneously, other one or more users are moved on another kind of or a few class OFDM symbols transmit, make travelling carriage can utilize the time of vacating on certain class OFDM symbol to stride cell measurement.
The present technique field personnel know, the principle of ofdm signal transmitter is: subscriber signal is imported transmitter in the mode of serial, and speed is R code word/second.These code words are admitted to earlier in the serial-to parallel converter, and the signal of serial input is outputed on the M bar circuit in parallel mode.Message transmission rate on any one on this M bar circuit then is R/M code word/second, and this speed is the character rate of OFDM just.This OFDM sign indicating number is admitted to a module of carrying out invert fast fourier transformation subsequently, carries out invert fast fourier transformation.Invert fast fourier transformation can be the discrete data conversion of frequency domain the data of time domain discrete.Thus, user's original input data is just handled according to frequency domain data by OFDM.Calculate after the invert fast fourier transformation sample value, before a Cyclic Prefix has been added to sample value, form the OFDM information code word that a circulation is expanded.Cyclic Prefix shows periodically the ofdm signal that is transmitted, and the information in the Cyclic Prefix is redundant, is not need this Cyclic Prefix in some ofdm system.
Receiver is finished the operation opposite with transmitter.The signal that receiver is received is a time-domain signal.Because certain variation has taken place for the influence of wireless channel, the signal that receives is through the transducer of a serial-to-parallel, and the Cyclic Prefix (if there is) is disposed.After having removed Cyclic Prefix, signal will transform back into frequency domain to signal from time domain through a fast fourier transform module.Signal carries out parallel serial conversion through a parallel-to-serial modular converter, has just finished the reception to original ofdm signal.
In ofdm system, information flow is mapped on the different frequency channels and transmits, and the signal of different user is respectively by one or more different carriers carry.According to the situation of change of User Status in the sub-district, system is the quantity and the position of each user's dynamic assignment subcarrier.The present invention is to enter the user who strides the cell measurement state to distribute suitable OFDM class according to the quantity that the subcarrier in the different OFDM symbols takies situation and idle sub-carrier promptly, in the realization system under different user state and the idle sub-carrier quantity situation, make travelling carriage keep finishing under the state of business continuance measurement to neighbor cell.
In order to make those skilled in the art person understand the present invention program better, the present invention is described in further detail below in conjunction with drawings and embodiments.
With reference to Fig. 2, Fig. 2 is the flow chart of the inventive method, may further comprise the steps:
Step 201: travelling carriage obtains the metrical information of current area.In the wireless system, in order to keep the regular traffic of travelling carriage, travelling carriage needs regularly current area to be measured, and metrical information is reported system, with the normally associate of maintenance and system.
Step 202: metrical information is reported system.
Step 203: system judges according to metrical information whether travelling carriage is in the current area edge.
The maximum characteristics of travelling carriage are its mobility, in order to guarantee mobile subscriber's quality of service, have a plurality of different sub-districts in the wireless system, be respectively the user who is in this sub-district service is provided, the variation of user position in the sub-district can reflect by its metrical information.When the user roamed into the edge of current area, this district pilots signal strength signal intensity of its measurement can reduce greatly.System can judge this user according to this information and be in the current area edge, need stride cell measurement.In case shift out this current sub-district, then enter neighbor cell, and provide business service for it by neighbor cell.
Step 204: system classifies to the OFDM symbol when travelling carriage is in the current area edge, concrete mode classification can be determined according to the actual conditions of system, such as, can classify to the OFDM symbol according to the time sequencing cycle of OFDM symbol, as Fig. 4, dividing in chronological order has three classes, is TS1, TS2 and TS3 are to repeat in the cycle then.Also can be other sorting techniques.
Step 205: the OFDM symbol that judges whether to meet first predetermined condition.
If have, then enter step 206: the selected OFDM symbol class that meets first predetermined condition transmits the business information of travelling carriage and utilizes the free time on such OFDM symbol to measure adjacent cell information.Detailed process will describe in detail in the back.
If no, then enter step 207: the OFDM symbol that judges whether to meet second predetermined condition.
If have, then enter step 208: the selected OFDM symbol class that meets second predetermined condition transmits the business information of travelling carriage and utilizes the free time on such OFDM symbol to measure adjacent cell information.Detailed process will describe in detail in the back.
If no, then enter step 209: measure adjacent cell information by the service rate that reduces travelling carriage.
The detailed process that the selected OFDM symbol class that meets first predetermined condition transmits the business information of travelling carriage and strides cell measurement may further comprise the steps as shown in Figure 3:
Step 301: system obtains mobile station service information and measures the required total number of sub-carriers of adjacent cell information;
Step 302: check that successively whether idle sub-carrier number on every class OFDM symbol is more than or equal to described total number of sub-carriers;
When the sub-carrier number on a certain OFDM symbol during more than or equal to described total number of sub-carriers, show the information that has enough idle sub-carrier to be used for transmitting the remaining OFDM symbol class of travelling carriage on the OFDM symbol, at this moment,
Enter step 303: with such OFDM symbol as the OFDM symbol class that meets first predetermined condition.
Then, enter step 304: system sends signaling to travelling carriage, and the notice travelling carriage enters the cell measurement pattern of striding.
Enter step 305: travelling carriage is measured neighbor cell according to the signaling that receives.
For example, OFDM symbol shown in Figure 4 divides in chronological order three classes, is TS1, and TS2 and TS3 are to repeat in the cycle then, and wherein, P represents pilot tone, and D1 represents user 1 data; X represents idle sub-carrier.
On such OFDM symbol, has only user 1, when this user moves to the current area edge, need stride cell measurement, at this moment, subcarrier and the idle subcarrier that this user's transport service information is used known by system, comprise its quantity and position, can judge that therefore the subcarrier whether free time is arranged on such OFDM symbol is used for the transfer of data on its residue OFDM symbol.When enough idle sub-carrier, then such OFDM symbol is measured the OFDM title class (the OFDM symbol class that meets first predetermined condition) of adjacent cell information as user 1, first row as Fig. 4 the latter half, pass through such OFDM symbol transmission with user 1 business information this moment, strides cell measurement in the time of vacating on remaining second and third class OFDM symbol.
If find not meet the OFDM symbol class of first predetermined condition by systems inspection, then need system to detect whether the OFDM symbol class that meets second predetermined condition is arranged, in such is selected, need judge whether the situation that other users can exchange the subcarrier of different OFDM symbol classes with this travelling carriage that need stride cell measurement, the situation of perhaps diverting other user's subcarriers.If also have other need stride the user of cell measurement in the system, then at first from need striding user's the OFDM symbol class of cell measurement, these select whether can exchange subcarrier; If do not have interchangeablely, then in system, select whether can divert subcarrier other users' the OFDM symbol class again.
The detailed process that the selected OFDM symbol class that meets second predetermined condition transmits the business information of travelling carriage and strides cell measurement may further comprise the steps as shown in Figure 5:
Step 501: whether systems inspection also exists other need enter the user who strides the cell measurement state.
If exist, then enter step 502: judge whether subcarrier on other certain class OFDM symbols that need enter the user who strides the cell measurement state and idle sub-carrier sum enough transmit the information on the remaining OFDM symbol class of travelling carriage, whether subcarrier and the idle sub-carrier of travelling carriage on residue OFDM symbol class enough transmits the information that other need enter the user who strides the cell measurement state simultaneously.
If satisfy above-mentioned condition, then enter step 503: with such OFDM symbol as the OFDM symbol class that meets second predetermined condition, then expression can be exchanged the subcarrier of other users on such OFDM symbol with the subcarrier on the residue OFDM symbol class, utilizes other idle sub-carrier simultaneously.
If do not satisfy above-mentioned condition, then enter step 504: from other users' of described system OFDM character class, select the described OFDM symbol that meets second predetermined condition.Concrete selection mode is:
Judge whether subcarrier on other certain class OFDM symbols that does not need to enter the user who strides the cell measurement state and idle sub-carrier sum enough transmit the information on the remaining OFDM symbol class of travelling carriage, whether subcarrier and the idle sub-carrier of travelling carriage on residue OFDM symbol class enough transmits the information that other do not need to enter the user who strides the cell measurement state simultaneously.If meet this condition, then expression can be diverted other users' subcarrier and other idle sub-carrier, promptly can be with other users' OFDM symbol as the OFDM symbol class that meets second predetermined condition.
When not having other need enter the user who strides the cell measurement state in the described system, also need to enter above-mentioned steps 504: the OFDM symbol of from other users' of system OFDM character class, selecting to meet second predetermined condition.
Behind the selected qualified OFDM symbol class, travelling carriage just can utilize the free time on such OFDM symbol to measure adjacent cell information.
At this moment, enter step 505: system sends signaling to travelling carriage and other associated users that need exchange or divert subcarrier respectively, notice travelling carriage and these associated users enter the cell measurement pattern of striding, and these associated users' subcarrier and other idle sub-carrier distributed to travelling carriage, give these associated users with the subcarrier allocation of travelling carriage on all the other class OFDM symbols.
Enter step 506: travelling carriage and other need enter the user who strides the cell measurement state and according to the signaling that it is received neighbor cell be measured respectively.
Do not need to stride cell measurement if it should be noted that these associated users, then only enter the cell measurement pattern of striding, thereby vacate subcarrier for travelling carriage, but it does not do corresponding measurement.And system need recover this user as early as possible and be the regular traffic pattern when idle sub-carrier is arranged.
For example, OFDM symbol shown in Figure 6 divides in chronological order three classes, is TS1, and TS2 and TS3 are to repeat in the cycle then, and wherein, P represents pilot tone, and D1 represents user 1 data; D2 represents user 2 data; D3 represents user 3 data.
On such OFDM symbol, there are 3 users to enter and stride cell measurement, at this moment, subcarrier and the idle subcarrier that each user's transport service information is used known by system, comprise its quantity and position, therefore can judge whether the OFDM symbol class that meets second predetermined condition is arranged on such OFDM symbol.Such as, for user 1, can certain class OFDM symbol subcarrier allocation of checking the user (user 2 and user 3) that other need be entered the measurement state on the OFDM of first line display symbol to user 1, if satisfy condition, the subcarrier that then makes user 1 and other need enter the user of measurement state exchanges and uses.Shown in this figure the latter half:
Give user 1 with the OFDM allocation of symbols of the first kind (first row), at this moment, user 1 has occupied three users simultaneously on the 1st class OFDM symbol subcarrier transmits data, and therefore, user 1 can measure neighbor cell on the 2nd, the 3rd class OFDM symbol.Simultaneously, user 2 has occupied three users simultaneously on the 2nd class OFDM symbol subcarrier transmits data, so user 2 can measure neighbor cell on the 1st, the 3rd class OFDM symbol; User 3 has occupied three users simultaneously on the 3rd class OFDM symbol subcarrier transmits data, so user 3 can measure neighbor cell on the 1st, the 2nd class OFDM symbol.And the distribution situation of pilot tone all is constant to each OFDM symbol.
Under this metering system, each user data quantity transmitted in the unit interval is constant, and the measurement pattern that only needs designated user to use on the system signaling expense has reduced signaling consumption.And can support real-time and Streaming Media class business, and keep the connection of system, help follow-up minizone and switch.The another one benefit is, if the broadcasting of each sub-district is also carried out repetition according to the OFDM class, the travelling carriage that is in cell edge can also read the broadcast message of neighbor cell.
It is to be noted, system can adopt the OFDM classification of sign mode of arbitrary carry system, for example, if there are five identical users of service rate need enter the cell measurement pattern of striding, can adopt quinary OFDM classification of sign mode this moment, each user occupies the transfer of data that a class OFDM symbol class carries out this sub-district, utilizes other idle time slot to measure.In addition, this moment, system also can still adopt ternary OFDM classification of sign mode, was one group with three users, carried out ternary OFDM allocation of symbols, and two other user cooperates remaining idle OFDM subcarrier to carry out the OFDM allocation of symbols.
Network system (current area) is sent the instruction of measuring peripheral cell to travelling carriage when needing thinking, and the notice travelling carriage enters the pattern of striding cell measurement, the measurement pattern of specifying travelling carriage to use simultaneously, the OFDM symbol class of promptly specifying travelling carriage to adopt, at this moment, system does not also know neighbor cell that travelling carriage receives and the time difference τ of the signal of current area, as shown in Figure 7.Wherein, Ts1, Ts2, Ts3 represent different time slots respectively, and the time slot of band shading is represented the free time of current area in the current area.This What is that time difference no matter, travelling carriage can detect at least one complete OFDM class symbol of other neighbor cells in the free time of current area, as the Ts2 symbol among Fig. 7.Travelling carriage can be on this symbol to neighbor cell carry out synchronously, measurement and information reads work.
The difference of the system of measuring according to the travelling carriage needs, the required measuring intervals of TIME of travelling carriage is different.The current area that travelling carriage received when Fig. 8, Fig. 9 were the different measuring interval respectively and the OFDM class symbol situation schematic diagram of neighbor cell:
Wherein, Ts1, Ts2, Ts3 represent different time slots respectively, and the time slot of band shading is represented the free time of current area in the current area, and the time slot of band background color is represented the Measuring Time of neighbor cell in other neighbor cells.
Shown in Figure 8 is a kind of pattern of continuous measurement, be that travelling carriage is the most intensive to the measuring period of other sub-districts, if travelling carriage does not need the measuring frequency of very dense, system also can measure of the change in the notice measurement pattern at interval, as shown in Figure 9, the measuring frequency of active user in other sub-districts descended half at interval than measurement shown in Figure 1, and at this moment the user has also descended half in the free time of current area.
In system, there are not other need stride the user of cell measurement, need to divert the subcarrier of other users' subcarrier this moment as travelling carriage transmission neighbor cell data, at this moment, the associated user also will enter simultaneously and stride the cell measurement state, but does not do corresponding measurement.
In this case, mode classification and Fig. 6 of OFDM symbol are similar, and just this moment, user 2 and user 3 did not need to stride cell measurement.
If on certain class OFDM symbol idle sub-carrier is arranged, simultaneously other users, this user being arranged also may be the user that need stride cell measurement, also may be the user who does not need to stride cell measurement.At this moment, can consider that the subcarrier part of travelling carriage and the subcarrier of these users in the system exchange, part adopts idle sub-carrier to stride cell measurement.
For example, OFDM symbol shown in Figure 10 divides in chronological order three classes, is TS1, and TS2 and TS3 are to repeat in the cycle then, and wherein, P represents pilot tone, and D1 represents user 1 data; D2 represents user 2 data, and X represents idle sub-carrier.
User 1 parton carrier wave and user's 2 parton carrier wave is exchanged, add idle subcarrier, during the data of enough transmission user 1, transmit user 1 data by the 1st class OFDM symbol; Transmit user 2 data by the 2nd class OFDM symbol.
When the idle sub-carrier on all OFDM character classs and other users' all not enough travelling carriage of the negative carrier sum that can exchange or divert transmits required business datum and measurement data, will consider to reduce the speed of travelling carriage, so that travelling carriage is finished the measurement of neighbor cell under the situation of non-interrupting service.
Detailed process is as follows:
(1) other users' that can distribute and divert in the check system idle sub-carrier number;
(2) when data rate that described subcarrier data carried by data speed needs less than travelling carriage, reduce the service rate of travelling carriage;
(3) transmit the information of described travelling carriage on residue OFDM symbol class by the subcarrier on such OFDM symbol of vacating, make described travelling carriage no information on remaining OFDM symbol class transmit, idle OFDM symbol class is used for measuring.
For example, OFDM symbol shown in Figure 11 divides in chronological order three classes, is TS1, and TS2 and TS3 are to repeat in the cycle then, and wherein, P represents pilot tone, and D1 represents user 1 data; D2 represents user 2 data, and D3 represents user 3 data, and X represents idle sub-carrier.
At this moment the subcarrier that user 2 and user 3 do not exchange or divert for user 1, reduces the transmission rate of travelling carriage, utilizes the X time slot in the latter half among Figure 11 to make user 1 stride cell measurement.At this moment, promptly deteriorate to the transmission rate that reduces travelling carriage in the prior art by the mode that sends metadata cache, make the transmission space that obtains be used for the measurement of travelling carriage other sub-districts.
Need to prove that under the situation of transmission mobile station data on the above-mentioned different OFDM symbols, system all needs to write down remaining idle sub-carrier on every class OFDM symbol.When enough idle sub-carrier, need not stride cell measurement in the recovery system as early as possible but be in the regular traffic pattern of striding the cell measurement mode user.
In addition, travelling carriage has the metrical information of neighbor cell: the signal strength signal intensity of other sub-districts, broadcast message, other customizing messages of sub-district and time synchronization information are as frame number etc.
This shows, the present invention utilizes the OFDM technology, by monitoring the unexpected variation of communication characteristic on the transmission medium continuously, dynamically distribute suitable OFDM symbol class for the user that need stride cell measurement, the ability that makes OFDM and communication path transmit data adapts, guaranteed that the user is striding continuity professional under the cell measurement state, has guaranteed the service transmission rate of user's maximum possible simultaneously.
Though described the present invention by embodiment, those of ordinary skills know, the present invention has many distortion and variation and do not break away from spirit of the present invention, wish that appended claim comprises these distortion and variation and do not break away from spirit of the present invention.
Claims (13)
1, stride the method for cell measurement in a kind of ofdm system, it is characterized in that, comprising:
A, when travelling carriage need enter when striding cell measurement, described system classifies to OFDM symbol;
B, the selected OFDM symbol class that meets first predetermined condition are transmitted the business information of described travelling carriage and are utilized the free time on the described OFDM symbol to measure adjacent cell information;
C, when not meeting the OFDM symbol of described first predetermined condition, the then selected OFDM symbol class that meets second predetermined condition is transmitted the business information of described travelling carriage and is utilized the free time on the described OFDM symbol to measure adjacent cell information;
D, when not meeting the OFDM symbol of described second predetermined condition, measure adjacent cell information by the service rate that reduces described travelling carriage.
2, method according to claim 1 is characterized in that, described steps A comprises:
A1, judge whether described travelling carriage is in described current area edge;
A2, described system classifies to OFDM symbol when described travelling carriage is in the current area edge.
3, method according to claim 2 is characterized in that, described steps A 2 is specially: described system classifies to described OFDM symbol according to the different user in the described current area.
4, method according to claim 1 is characterized in that, described step B comprises:
Whether exist enough idle sub-carrier to be used for transmitting the information of the remaining OFDM symbol class of described travelling carriage on B1, the every class OFDM symbol of inspection;
B2, when existing enough idle sub-carrier to be used on the described OFDM symbol to transmit the information of the remaining OFDM symbol class of described travelling carriage, with it as the OFDM symbol that meets first predetermined condition;
B3, described system send signaling to described travelling carriage, notify described travelling carriage to enter and stride the cell measurement pattern;
B4, described travelling carriage are measured neighbor cell according to described signaling.
5, method according to claim 4 is characterized in that, described step B1 comprises:
B11, described system obtain described mobile station service information and measure the required total number of sub-carriers of adjacent cell information;
B12, check sub-carrier number on every class OFDM symbol successively;
B13, when the sub-carrier number on the described OFDM symbol during more than or equal to described total number of sub-carriers, have enough idle sub-carrier to be used for transmitting the information of the remaining OFDM symbol class of described travelling carriage on the described OFDM symbol.
6, method according to claim 1 is characterized in that, described step C comprises:
C1, when also existing other need enter the user who strides the cell measurement state in the described system, need enter from described other and to select the described OFDM symbol that meets second predetermined condition user's who strides the cell measurement state the OFDM symbol classification;
C2, need enter when not meeting the described OFDM symbol that meets second predetermined condition in user's OFDM symbol classification of striding the cell measurement state when other of user who does not have other to enter in the described system to stride the cell measurement state or existence, from other users' of described system OFDM symbol classification, select the described OFDM symbol that meets second predetermined condition;
C3, transmit the business information of described travelling carriage and utilize the free time on the described OFDM symbol to measure adjacent cell information by the selected OFDM symbol class that meets second predetermined condition.
7, method according to claim 6, it is characterized in that, described step C1 is specially: enough transmit information on the remaining OFDM symbol class of described travelling carriage if described other need enter subcarrier on the user's who strides the cell measurement state the OFDM symbol and idle sub-carrier sum, simultaneously subcarrier and the idle sub-carrier of described travelling carriage on residual quadrature frequency division multiplexing symbol class enough transmitted described other and need be entered the user's who strides the cell measurement state information, then with such OFDM symbol as the OFDM symbol class that meets second predetermined condition.
8, method according to claim 6, it is characterized in that, described step C2 is specially: if subcarrier on described other users' the OFDM symbol and idle sub-carrier sum are enough transmitted the information on the remaining OFDM symbol class of described travelling carriage, simultaneously subcarrier and the idle sub-carrier of described travelling carriage on residual quadrature frequency division multiplexing symbol class enough transmitted described other users' information, then with such OFDM symbol as the OFDM symbol class that meets second predetermined condition.
9, method according to claim 6 is characterized in that, described step C3 comprises:
C31, described system send signaling to described travelling carriage and other relevant users respectively, notify described travelling carriage and described other relevant users to enter the cell measurement pattern of striding, and described other relevant user's subcarriers and other idle sub-carrier are distributed to described travelling carriage, and give described other relevant users with the subcarrier allocation of described travelling carriage on all the other class OFDM symbols; Described relevant other users need enter the user that strides the cell measurement state or other users in the described system for described other;
C32, described travelling carriage and described other need enter the user who strides the cell measurement state and according to the signaling that it is received neighbor cell be measured respectively, and other users in the described system enter the cell measurement pattern of striding.
10, method according to claim 1 is characterized in that, described step D comprises:
Other users' that can distribute and divert in D1, the described system of inspection number of sub carrier wave;
D2, when data rate that described subcarrier data carried by data speed needs less than described travelling carriage, reduce the service rate of described travelling carriage;
D3, transmit the information of described travelling carriage on residual quadrature frequency division multiplexing symbol class by the subcarrier on such OFDM symbol of vacating.
11, method according to claim 1 is characterized in that, described method also comprises: remaining idle sub-carrier on the every class OFDM symbol of described system log (SYSLOG).
12, method according to claim 1 is characterized in that, described method also comprises: when enough idle sub-carrier, recover need not stride cell measurement in the described system but be in the regular traffic pattern of striding the cell measurement mode user.
13, method according to claim 1 is characterized in that, described adjacent cell information comprises: the signal strength signal intensity of described neighbor cell and broadcast message.
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| CNB2004100793512A CN100372415C (en) | 2004-09-30 | 2004-09-30 | Intercell measuring method in OFDM system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101312575B (en) * | 2007-05-22 | 2011-10-19 | 展讯通信（上海）有限公司 | Method for terminal in TD-SCDMA system to measure GSM neighbor cell |
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| US5912876A (en) * | 1997-01-15 | 1999-06-15 | Ericsson, Inc. | Method and apparatus for channel estimation |
| CN1124714C (en) * | 1998-02-13 | 2003-10-15 | 日本胜利株式会社 | Method and apparatus for receiving orthogonal frequency division multiplexed signal |
| EP1176750A1 (en) * | 2000-07-25 | 2002-01-30 | Telefonaktiebolaget L M Ericsson (Publ) | Link quality determination of a transmission link in an OFDM transmission system |
| US7260054B2 (en) * | 2002-05-30 | 2007-08-21 | Denso Corporation | SINR measurement method for OFDM communications systems |
| CN100486127C (en) * | 2002-08-06 | 2009-05-06 | 中兴通讯股份有限公司 | Channel evaluation method in wide band CDMA communication system |
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| CN101312575B (en) * | 2007-05-22 | 2011-10-19 | 展讯通信（上海）有限公司 | Method for terminal in TD-SCDMA system to measure GSM neighbor cell |
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