Background
In UMTS radio communication systems, in order for a mobile station to obtain services of the communication network, such as making a call or transferring data, it is necessary to establish an RRC connection from the mobile station to the base station controller, and the establishment of the RRC connection is performed by a random access mechanism, so that the random access procedure is very important and is a bridge for the mobile station to enter a connected state from an idle state. In other cases, the mobile station performs CELL reselection in IDLE state and connected state of CELL _ PCH and URA _ PCH, and also performs CELL update through a random access procedure, so the random access procedure is also frequent for the mobile station.
The random access process is mainly realized by two functional entities, one is a functional entity for receiving cell broadcast information; one is the functional entity that initiates random access. This is mainly determined by the characteristics of the random access channel itself, since the random access channel is a common channel for all mobile stations in the current cell, and the load of this channel is limited, the mobile stations must contend with each other to use this channel. If many mobile stations in the same cell transmit preambles using the random access channel at the same time for contention inquiry, this will inevitably result in increased interference and some mobile stations failing to contend without an access control mechanism. The base station controls the energy level and dynamic duration of the random access preamble pulse by parameters in the system information it broadcasts to achieve interference reduction and congestion control due to the simultaneous contention for the use of the random access channel by a number of mobile stations. The control parameters for the random access procedure in the system information have to be read each time before the mobile station is to initiate the random access procedure.
For the UMTS system, the operation principle of the cell broadcast information receiving entity is as follows: UE firstly obtains time slot synchronization in PSCH channel by cell search, then carries out frame synchronization by SCCH, and finally obtains frame bit information of PCPICH by using time information of previous frame synchronization, the physical channel P-CCPCH receiving cell broadcast information is synchronized, and cell system information is broadcast on this channel, the control of the mobile station by the base station in the idle state and in the CELL _ PCH, URA _ PCH, FACH state is generally achieved by broadcasting system information, which consists of a series of system information blocks, the information includes control information of the current cell to the mobile station and information required for mobile station access, such as current channel configuration and access standard, and neighbor cell information, etc., currently UMTS supports up to 18 system information blocks, in addition to one primary system information block and two scheduling information blocks. The system information is sent through BCCH logical channel, and is mapped to BCH transmission channel and P-CCPCH physical channel, the sending time of main system information block on BCCH logical channel is fixed and known, and the main information block is received on fixed frame position, then the frame position scheduling information of scheduling information block and other information block is obtained from the main information block, and then the scheduling information is used to receive other needed system information block and scheduling information block. Since the frame bit information of a specific system information block is scheduled by the master information block or the scheduling information block, the system information structure always takes the shape of a tree, and the tree root always is the main system information block. The system information is what the UE must receive at the time of cell selection and cell reselection. However, the base station may update the contents of some system information blocks according to different situations according to the current load or the configuration. The system information is updated in two modes, namely a value tag mode and a timing clock overflow reading mode.
As for the way of updating the system information by the value tag, after the mobile station has finished camping, if it does not transmit or receive any user data for a long time, it enters a state intended to extend the battery operating time. In this state, the base station can keep communicating with the mobile station by sending paging messages to the mobile station at a preset time, the interval between two transmissions of paging messages is called DRX cycle, and when the paging time arrives, the mobile station needs to turn on the receiver to receive possible paging messages on the paging channel, and the paging time is usually short. Therefore, the base station can realize system information updating by adding a system information block value label change notification mode in paging information, for example, some relatively static system information changes, the base station sends a paging message in each DRX period to require the mobile station to read, the mobile station judges whether the base station requires system information updating or not from the read paging information, and if so, the mobile station needs to perform system information updating once.
For dynamic information, due to its relatively high frequency of change, updating of system information is performed by a timer clock overflow reading method, such as some information about the open loop power control and access control in the random access procedure, and for system information 7, which mainly includes parameters for calculating the initial transmission power and load control information, which are determined by the base station based on measurements of the uplink burst level and load control information for the random access channel in a certain time, so that there is an effective period, which is included in system information 7, when this effective period overflows, the mobile station generally does not use the outdated information, but reads new system information 7 from the BCCH channel, so that these information are transmitted periodically on the BCCH channel according to the clock set by the base station, and when the mobile station wants to randomly access, the latest contents in the system information 7 must be obtained.
For the reception of the cell system information of the pre-flow in the random access process, firstly, the channel configuration information of the random access channel is obtained in the system information 5 or the system information 6 when the cell is selected, the cell is reselected, and the value tag updates the system information; secondly, the content of the dynamic system information 7 is acquired before the preamble is transmitted.
After the system information is received in the processes of cell selection and cell reselection, the UE configures a random access channel according to the configuration parameters of the random access channel in the system information, then data transmission is carried out, the data transmission is composed of two parts, one part is the transmission of a preamble, the other part is the transmission of a data message, the transmission time of the data message is only two frames at most, which means that only a small amount of data can be transmitted, the mobile station needs to transmit an access preamble inquiry before wanting to transmit data by using the random access channel every time, and can transmit data after obtaining a positive response of allowing to use the channel from an AICH channel, the transmission of the access preamble is realized by using pulses, if the mobile station receives a negative response replied by a network side on the AICH due to contention failure after the transmission of the access preamble, the mobile station can initiate an attempt again at a later time, if the mobile station does not get any response on the AICH channel, the mobile station will gradually increase the energy of the transmitted preamble pulse to continue transmitting access preamble inquiries in order to ensure that the access preamble can be received by the base station on which the mobile station is camped to reply. But since the radiation of the pulse is divergent, the rise in the energy of the pulse causes increased interference to all surrounding mobile stations and base stations. Since CDMA systems are very sensitive to interference, if the mobile station transmits a burst that is radiated to a nearby base station that is not the base station on which it is camped and the burst energy is large, it will cause temporary congestion to the base station, and to avoid this, UMTS systems require that the burst transmitted by the mobile station during random access be small enough to be received by the base station on which it is camped. After the data transmission is completed, one random access process is finished, and when the next random access is to be performed, the above processes are repeated.
One of the main drawbacks of the current random access procedure is the delay, an example of which is shown in fig. 1. When the mobile station initiates a random access procedure due to receiving a paging message or when the mobile station initiates a call actively, the system information 7 must be received first, but in the current UMTS system, the scheduling clock period of the system information 7 has a minimum time of 32 frames, which can reach several seconds at most, and the longer the repetition period of the system information 7, the longer the time consumed for the mobile station to initiate the random access procedure. This can cause a poor experience for a timely service, such as telephony.
The system information 7 mainly includes three parameters: uplink interference (UL interference), dynamic persistence level (dynamic persistence level), and timeout factor (expiration time factor). The uplink interference is used for calculating the power of initial transmission, the UE uses the parameter to implement open loop power control, the magnitude of the initial transmission power is related to whether the base station can receive the access preamble sent by the UE, the value range of the parameter is-110 to-70 dbm, if the initial transmission power is too small, the base station may not receive the access preamble sent by the UE and cannot reply, then the UE will continuously increase the transmission power until receiving the response replied by the base station, if the initial transmission power is set to be too large, interference will be caused to other surrounding UEs and base stations, resulting in blocking or communication quality reduction, therefore the base station will dynamically adjust the value of the uplink interference according to the measurement of the current uplink load condition of the cell, if the user accesses too much interference, the base station will increase the corresponding uplink interference value, then the mobile station will increase the pulse power of the initial transmission according to the value, the success rate of receiving the access preamble of the cell in which the cell is camped is improved. The dynamic persistence value is a parameter value ranging from 1 to 8 for calculating the mandatory retransmission delay after the collision of the transmission preamble, the MAC layer uses the parameter to calculate a random backoff value before transmitting data, the backoff value is a range, the mobile station generates a random value by a random number generation algorithm, if the random value is within the range, the mobile station is allowed to transmit the access preamble by using random access, if the random value is not within the range, the mobile station needs to wait for a certain time for backoff, then generates a new random value, repeats the above process until transmission is allowed, reduces the probability that a plurality of mobile stations use the same random access code at the same time by increasing the dynamic persistence value, improves the success probability of the transmission by using random access by the mobile station, and the base station controller count the success and error rates of the received transmission blocks, the dynamic persistence value is determined to achieve the purpose of controlling the user access, and the success and error rate of the transmission block mainly reflect the uplink load condition of the current cell, namely the user quantity. If the number of users is large, the probability of collision may be high and vice versa. The time-out factor is used to tell the mobile station the validity period of the received system information 7, which if exceeded must be re-read by the mobile station for new system information 7, which validity period can be relatively long if the uplink interference and dynamic persistence values do not change. In summary, the parameters of the system information 7 reflect the uplink load degree and interference.
Nokia corporation proposed a method for setting the system information 7 to permanent contents in order to improve the delay caused by the random access procedure by setting the effective clock period value of the system information 7 to a permanently effective value, so that the SIB7 is always used after the mobile station reads such an SIB7 at the time of cell selection or reselection. The disadvantage of this method is that it cannot be changed with the change of the load level of the network and the channel interference level, for example, in order to avoid setting the initial transmission power too high to cause co-channel interference, a relatively low initial transmission power calculation parameter is set in the system information 7, the UE uses this parameter to calculate the initial transmission power, if the UE is far away from the base station at this time, the UE uses this initial transmission power to transmit the preamble will cause its base station not to receive this pulse and cannot reply, immediately the UE will continuously increase the initial transmission power until it succeeds in transmitting the preamble, and this initial transmission power ramp-up process will cause interference to its neighboring mobile stations and base stations.
In actual life and work, human activities are regular, and most people stay in a work and study area or a living area for most of time due to the limitation of the activity range. The number of mobile users within a certain time range in the coverage area of this type of wireless communication will not vary much, i.e. the load level of a particular cell is in a steady state for a certain period of time, as shown in fig. 2. In a cell C covering a working area, time t1To t2Belonging to working hours, the load degree is large but stable; time t3To t4The users leave the cell in the off-duty time, the load degree is low but stable, and the same condition is repeated every day.
Disclosure of Invention
The present invention aims to overcome the defects in the prior art, and provides a method for realizing a fast random access process in a wireless cellular network, which can effectively reduce the access delay of a mobile station, realize fast network access, greatly improve user experience, and has the advantages of simple and convenient operation process, stable and reliable working performance and wider application range.
In order to achieve the above object, the method for implementing a fast random access procedure in a wireless cellular network of the present invention is as follows:
the method for realizing the fast random access process in the wireless cellular network is mainly characterized in that the method comprises the operation of statistical storage and analysis processing of system information 7 parameters and the operation of fast random access process processing, wherein the operation of statistical storage and analysis processing of the system information 7 parameters comprises the following steps:
(A1) the mobile station reads the system information 7 according to the statistic strategy preset by the system and stores the corresponding parameter information;
(A2) the mobile station analyzes the parameter information and acquires the stable time period part;
the fast random access procedure processing operation comprises the following steps:
(B1) when the mobile station carries out the random access process, judging whether the current random access time is in a certain stable time period part;
(B2) if yes, extracting the current random access process parameter from the parameter information corresponding to the stable time period part;
(B3) if not, establishing a BCCH channel and receiving system information 7, and extracting current random access process parameters from the received system information 7;
(B4) the mobile station carries out random access process operation according to the current random access process parameters;
(B5) if the random access process operation fails and the current random access process parameter is extracted from the parameter information corresponding to the stable time period part, returning to the step (B3);
(B6) otherwise, the statistic updating processing operation of the stable time section and the corresponding parameter information is carried out, and the random access process is completed.
The parameter information in the method for realizing the rapid random access process in the wireless cellular network comprises cell identification, statistical time, uplink interference and dynamic continuous values.
The statistical strategy preset by the system in the method for realizing the rapid random access process in the wireless cellular network comprises the following steps:
(A11) counting parameters of system information 7 used for establishing RRC connection in the registration process and the cell updating process of the mobile station;
(A12) the statistical time is uniformly distributed in a time period preset by the system;
(A13) the dynamic update of the statistical information is performed using a first-in-first-out rule.
The process of analyzing and obtaining the stable time section in the method for implementing the fast random access procedure in the wireless cellular network comprises the following steps:
(A21) the mobile station judges whether the time interval between two statistical times under the same cell identifier in the parameter information is longer than the minimum residence time T preset by the systemc;
(A22) If yes, judging whether the uplink interference and the dynamic continuous value are stable;
(A23) if so, taking the time interval as a stable time interval part, and respectively taking the average value of each uplink interference and dynamic continuous value in the time interval as the parameter information corresponding to the stable time interval part;
(A24) storing said portion of the stable time period and the corresponding parameter information in a results database of the mobile station.
The method for realizing the rapid random access process in the wireless cellular network judges whether the uplink interference and the dynamic continuous value are stable or not, and comprises the following steps:
(A221) respectively obtaining the uplink interference range R and the dynamic continuous value range R according to the following formula, and judging whether the corresponding range R is respectively smaller than an uplink interference range threshold and a dynamic continuous value range threshold delta R preset by the system:
R=Max-Min;
max is the maximum value, and Min is the minimum value;
(A222) if yes, respectively obtaining the standard deviation sigma of the uplink interference and the dynamic continuous value by the following formula, and judging whether the corresponding standard deviation sigma is smaller than an uplink interference standard deviation threshold and a dynamic continuous value standard deviation threshold delta sigma which are preset by a system or not respectively:
<math> <mrow> <mi>σ</mi> <mo>=</mo> <msqrt> <mfrac> <mn>1</mn> <mi>n</mi> </mfrac> <munderover> <mi>Σ</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </munderover> <msup> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mi>i</mi> </msub> <mo>-</mo> <mi>M</mi> <mo>)</mo> </mrow> <mn>2</mn> </msup> </msqrt> <mo>;</mo> </mrow></math>
wherein, <math> <mrow> <mi>M</mi> <mo>=</mo> <mfrac> <mn>1</mn> <mi>n</mi> </mfrac> <munderover> <mi>Σ</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </munderover> <msub> <mi>x</mi> <mi>i</mi> </msub> </mrow></math> ,{x1,x2,…,xnis the set of statistical parameters, and n is the number of parameters.
The method for realizing the fast random access process in the wireless cellular network judges whether the current random access time is in the stable time section or not, and comprises the following steps:
(B11) the mobile station judges whether a stable time period part containing the current random access time exists in the result database according to the current camping cell identification;
(B12) if yes, returning the result that the current random access time is in the stable time section; otherwise, returning the result that the current random access time is not in the stable time section.
The statistical update processing operation of the stable time section and the corresponding parameter information in the method for realizing the fast random access process in the wireless cellular network comprises the following steps:
(B61) judging whether the current random access process parameter in the random access process operation is extracted from the parameter information corresponding to the stable period part;
(B62) if yes, judging whether the current random access process parameter used for the last time is in the range limited by the system; otherwise, ending and returning;
(B63) if the current time is within the range limited by the system, ending and returning; otherwise, deleting the corresponding stable time period part and the corresponding parameter information in the result database, and then returning.
The method for realizing the fast random access process in the wireless cellular network judges whether the current random access process parameter used for the last time is in the range limited by the system, and specifically comprises the following steps:
(B621) judging whether the uplink interference and the dynamic continuous value in the current random access process parameter used for the last time are within the range of +/-delta sigma of the statistical mean value of the uplink interference and the dynamic continuous value in each parameter information corresponding to the stable time period part;
(B622) if so, returning results within a system-defined range; otherwise, a result that is not within the system-defined range is returned.
The method for realizing the fast random access process in the wireless cellular network of the invention is adopted, because the parameters of the system information 7 of the cell where the user stays for a long time are counted in a long distance in a certain period, and the values are evaluated in a time-sharing way, so as to obtain the relative stable value of the parameters in the system information 7 of the cell in a certain time period, and after the statistics is finished, the statistical value is used for directly configuring the parameters of the random access process, so that the parameters in the system information 7 are counted in advance, the distribution condition of the parameters in each time period is obtained, the parameters of the random access at a certain moment after the random access is predicted in advance, the random access transmission can be carried out immediately, the system delay caused by reestablishing a BCCH channel to receive the system information 7 is eliminated, the aim of reducing the delay is achieved, and the user experience is greatly improved, and the operation process is simple and convenient, the working performance is stable and reliable, and the application range is wider.
Detailed Description
In order to clearly understand the technical contents of the present invention, the following examples are given in detail.
First, the concept used in the present invention is briefly introduced:
(1) extremely poor R: the maximum difference in the values in a set of data, R Max-Min, i.e., Max-Min, can be used to evaluate the degree of dispersion in the set of data.
(2) Standard Deviation (Standard development): the mean of the distances of each data from the mean (mean deviation), which is the square of the deviation and the square root after the mean, is expressed as σ. Thus, the standard deviation is also an average, and the formula:
<math> <mrow> <mi>σ</mi> <mo>=</mo> <msqrt> <mfrac> <mn>1</mn> <mi>n</mi> </mfrac> <munderover> <mi>Σ</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </munderover> <msup> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mi>i</mi> </msub> <mo>-</mo> <mi>M</mi> <mo>)</mo> </mrow> <mn>2</mn> </msup> </msqrt> <mo>,</mo> </mrow></math> <math> <mrow> <mi>M</mi> <mo>=</mo> <mfrac> <mn>1</mn> <mi>n</mi> </mfrac> <munderover> <mi>Σ</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </munderover> <msub> <mi>x</mi> <mi>i</mi> </msub> <mo>,</mo> </mrow></math> {x1,x2,…,xn}
where M is the mean of the data set. Standard deviation is one of the most commonly used forms of quantization to reflect the degree of dispersion of a set of data. If the standard deviation value is large, the data set is not compact, namely the numerical value is changed greatly; on the contrary, the numerical value is relatively stable and does not change much.
(3) Cell Residence Time (Cell Residence Time): refers to the length of time a mobile user is camped on a cell. If the residence time of the user in the cell is very longShort, it indicates that the user is not stable in the cell, and the probability of initiating the random access procedure is relatively small, and there is no statistical significance. The method only focuses on that the residence time of the mobile user in the specific cell is more than a certain time TcThe case (1).
Referring to fig. 3 to 5, the method for implementing a fast random access procedure in a wireless cellular network includes a statistical storage and analysis processing operation of system information 7 parameters, and a fast random access procedure processing operation, where the statistical storage and analysis processing operation of the system information 7 parameters includes the following steps:
(A1) the mobile station reads system information 7 according to a statistical strategy preset by the system, and stores corresponding parameter information, wherein the parameter information comprises a cell identifier, statistical time, uplink interference and a dynamic continuous value, and the statistical strategy preset by the system comprises the following steps:
(a) counting parameters of system information 7 used for establishing RRC connection in the registration process and the cell updating process of the mobile station;
(b) the statistical time is uniformly distributed in a time period preset by the system;
(c) dynamically updating the statistical information by using a first-in first-out rule;
(A2) the mobile station analyzes the parameter information and obtains the stable time period part, which comprises the following steps:
(a) the mobile station judges whether the time interval between two statistical times under the same cell identifier in the parameter information is longer than the minimum residence time T preset by the systemc;
(b) If yes, judging whether the uplink interference and the dynamic continuous value are stable, and comprising the following steps:
(i) respectively obtaining the uplink interference range R and the dynamic continuous value range R according to the following formula, and judging whether the corresponding range R is respectively smaller than an uplink interference range threshold and a dynamic continuous value range threshold delta R preset by the system:
R=Max-Min;
max is the maximum value, and Min is the minimum value;
(ii) if yes, respectively obtaining the standard deviation sigma of the uplink interference and the dynamic continuous value by the following formula, and judging whether the corresponding standard deviation sigma is smaller than an uplink interference standard deviation threshold and a dynamic continuous value standard deviation threshold delta sigma which are preset by a system or not respectively:
<math> <mrow> <mi>σ</mi> <mo>=</mo> <msqrt> <mfrac> <mn>1</mn> <mi>n</mi> </mfrac> <munderover> <mi>Σ</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </munderover> <msup> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mi>i</mi> </msub> <mo>-</mo> <mi>M</mi> <mo>)</mo> </mrow> <mn>2</mn> </msup> </msqrt> <mo>;</mo> </mrow></math>
wherein, <math> <mrow> <mi>M</mi> <mo>=</mo> <mfrac> <mn>1</mn> <mi>n</mi> </mfrac> <munderover> <mi>Σ</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </munderover> <msub> <mi>x</mi> <mi>i</mi> </msub> </mrow></math> ,{x1,x2,…,xnthe n is the number of the parameters;
(c) if so, taking the time interval as a stable time interval part, and respectively taking the average value of each uplink interference and dynamic continuous value in the time interval as the parameter information corresponding to the stable time interval part;
(d) storing the stable time period part and the corresponding parameter information into a result database of the mobile station; the fast random access procedure processing operation comprises the following steps:
(B1) when the mobile station carries out the random access process, the mobile station judges whether the current random access time is in a certain stable time interval part, and the method comprises the following steps:
(a) the mobile station judges whether a stable time period part containing the current random access time exists in the result database according to the current camping cell identification;
(b) if yes, returning the result that the current random access time is in the stable time section; otherwise, returning the result that the current random access time is not in the stable time period part;
(B2) if yes, extracting the current random access process parameter from the parameter information corresponding to the stable time period part;
(B3) if not, establishing a BCCH channel and receiving system information 7, and extracting current random access process parameters from the received system information 7;
(B4) the mobile station carries out random access process operation according to the current random access process parameters;
(B5) if the random access process operation fails and the current random access process parameter is extracted from the parameter information corresponding to the stable time period part, returning to the step (B3);
(B6) otherwise, the statistic updating processing operation of the stable time section and the corresponding parameter information is carried out, and the random access process is completed, which comprises the following steps:
(a) judging whether the current random access process parameter in the random access process operation is extracted from the parameter information corresponding to the stable period part;
(b) if yes, judging whether the current random access process parameter used for the last time is in the range limited by the system; otherwise, ending and returning; the method for judging whether the current random access process parameter used for the last time is in the range limited by the system specifically comprises the following steps:
(i) judging whether the uplink interference and the dynamic continuous value in the current random access process parameter used for the last time are within the range of +/-delta sigma of the statistical mean value of the uplink interference and the dynamic continuous value in each parameter information corresponding to the stable time period part;
(ii) if so, returning results within a system-defined range; otherwise, returning the result which is not in the range limited by the system;
(c) if the current time is within the range limited by the system, ending and returning; otherwise, deleting the corresponding stable time period part and the corresponding parameter information in the result database, and then returning;
in practical use, the basic idea of the invention is as follows:
referring to fig. 3, before performing the random access procedure, the BCCH channel is established to receive the system information 7, and the random access configuration parameters are obtained, so as to determine the initial transmission power, the retransmission delay, and the like, which may cause delay. According to the above-described rules of human activities, the parameters in the system information 7 can be counted in advance to obtain the distribution of the parameters in each time period, so that the parameters randomly accessed at a certain moment can be predicted in advance, random access transmission can be performed immediately, and the delay caused by receiving the system information 7 is eliminated.
Therefore, one method for improving the reading of system information 7(SIB7) in the random access procedure of the wireless cellular network of the present invention is as follows:
1. statistical storage of system information 7 parameters, the mobile station reads the system information 7 at intervals in a certain time period and stores the parameter values therein. Firstly, cell identification is carried out, and statistical parameters are only effective in a specific cell; secondly, counting time t, wherein parameter values in the system information 7 are counted at the time t; and finally, system information 7 parameter values, which are mainly uplink interference and dynamic persistence values, are used, and the invention uses statistical values and does not concern timeout factors.
2. Analyzing the statistical value to obtain the stable part, such as t in FIG. 21、t2、t3、t4The time of day value, and the statistical mean of the parameters during the period, which is the key of the present invention. The basic idea of the algorithm for obtaining the stable time period is that the parameter value dispersion degree in the time period uses the extreme difference and the standard deviation, if the two values are large, the parameter value of the system information 7 in the time period is greatly changed, otherwise, the parameter value is relatively stable.
3. In the improved random access process, whether the random access time is in a stable part counted before is judged firstly when the random access process is carried out, if not, BCCH channel receiving system information 7 is established, random access configuration parameters are obtained, and a normal random access process is carried out; if yes, the process of reading the system information 7 from the BCCH channel is skipped, and the parameter statistical mean value at the moment is directly used as a random access configuration parameter to carry out random access transmission, so that the time delay generated by receiving the system information 7 can be eliminated.
In order to implement the method of the present invention, two databases, called a statistics database and a results database, respectively, are added to the mobile station to store the statistics data and the analysis results. A statistical database for storing statistical data of the real-time system information 7, including statistical time, uplink interference and dynamic persistence values in the system information 7, and cell identification; a result database for storing the result of the statistical data analysis, i.e. the stable part in the statistical data, including the start-stop time T of the stable partbegin、TendStatistical mean of uplink interference and dynamic persistence value, and cell identification.
When the system information 7 is counted, the following method is adopted:
(1) in order to reduce the power consumption statistics of the mobile station as much as possible, the parameter values in the existing system information 7 are used as much as possible, such as the parameters of the system information 7 used for establishing the RRC connection in the processes of registration, cell update, and the like, and the number of times of additionally establishing the BCCH channel and reading the parameters in the system information 7 is reduced.
(2) The statistical time is spread as evenly as possible over a certain period of time. Due to the regularity of human activities, the present invention assumes that these cells repeat the same situation every day, and then only a small number of statistics are needed every day, repeating the statistics for many days. Assuming that, in a 5-day statistical period, the parameters in the system information 7 are counted at each whole point, such as 8:00, 9:00, etc., on the first day, statistics can be performed at 8:12, 9:12, etc., on the second day, statistics can be performed at 8:24, 9:24, etc., on the third day, and so on, 5 statistical values which are uniformly distributed can be obtained in each hour.
(3) To reduce memory usage space and computational complexity, the statistics database is dynamically updated using a First-In-First-Out (FIFO) strategy.
In the present invention, the algorithm for obtaining the stable time period is as follows: in cell C, if the residence time of the user is more than T per daycIf the user is stable in the cell C, the parameters of the system information 7 in the cell need to be counted, and it is assumed that the time t is the time tiHas a statistical value of viThen during a time period t1To tnObtaining a set of statistical data vl,...,vi,...,vnIf at time tiTo tjStatistical value vi,...,vjBoth the range and the standard deviation of (a) are less than a certain threshold, namely R (i, j)<ΔR,σ(i,j)<Δ σ, and is required to last for a certain time, i.e., tj-ti>At, the parameters of the system information 7 are considered stable during this time period. The statistical result can be directly used later when initiating the random access procedure in this time period, that is, the parameter values of the system information 7 are:
<math> <mrow> <mi>M</mi> <mrow> <mo>(</mo> <mi>i</mi> <mo>,</mo> <mi>j</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <mn>1</mn> <mrow> <mi>j</mi> <mo>-</mo> <mi>i</mi> </mrow> </mfrac> <munderover> <mi>Σ</mi> <mrow> <mi>n</mi> <mo>=</mo> <mi>i</mi> </mrow> <mi>j</mi> </munderover> <msub> <mi>V</mi> <mi>n</mi> </msub> </mrow></math>
wherein, the parameter T involved in the present inventioncAnd the delta R, the delta sigma and the delta t can be designed according to different requirements. The pseudo code of the algorithm of the present invention is given below:
Input Array:Time{t1,...,ti,...,tn},statistic value{v1,...,vi,...,vn}
Initialize the time begin Tb:=t1
Initialize the time end Te:=t1
Initialize the statistic mean value M:=0
Initialize the max difference value R:=0
BEGIN LOOPT=t1
Calculateб,M and R from data array{v(Tb),...,v(Te)}
IFб<△б and R<△R
Te:=T
Continue Loop
ELSE
IF(Te-Tb)>△T
THEN Add Tb,Te,and M into result database
Initialize Tb:=Te:=T and M:=0
END Index>n
the following example illustrates how the above algorithm of the present invention works:
referring to fig. 4, it is assumed that the statistics of the uplink interference parameters in the system information 7 in a certain cell are as follows:
Time |
7:00 |
7:12 |
7:24 |
7:36 |
7:48 |
uplink interference value |
-105dbm |
-108dbm |
-105dbm |
-75dbm |
-89dbm |
Time |
8:00 |
8:12 |
8:24 |
8:36 |
8:48 |
Uplink interference value |
-88dbm |
-90dbm |
-95dbm |
-96dbm |
-90dbm |
Time |
9:00 |
9:12 |
9:24 |
9:36 |
9:48 |
Uplink interference value |
-89dbm |
-88dbm |
-86dbm |
-87dbm |
-87dbm |
Time |
10:00 |
10:12 |
10:24 |
10:36 |
10:48 |
Uplink interference value |
-86dbm |
-88dbm |
-86dbm |
-87dbm |
-86dbm |
Assuming that Δ R is 5, Δ σ is 2, and Δ t is 1hour, the above data is analyzed to be between 7:00 and 7:24, and although the range and standard deviation satisfy the conditions, the duration is less than 1hour, which cannot be regarded as a stable portion; the uplink interference value is greatly changed and unstable between 7:36 and 8: 48; between 9:00 and 10:48, it can be seen from the figure that the uplink interference value changes very little and is relatively smooth, where the range R is 3, σ is 1, M is-87 dbm, and the duration time reaches 2 hours, then the requirement of the algorithm of the present invention is met, the cell is marked, the starting time is 9:00, the ending time is 10:48, and the statistical mean value-87 dbm is stored in the result database.
The RACH parameters have dynamic continuous values besides uplink interference and also need to be counted and analyzed, in the actual use process, only the stable parts of the two parameters are stored, and if the dynamic continuous values are stable in 8:00 to 10:00 and the uplink interference values are stable in 9:00 to 10:48, only the common stable parts, namely 9:00 to 10:00 data can be stored in the result database.
Referring to fig. 5, the random access procedure includes the following steps:
(1) before sending preamble access in each RACH process, the mobile station firstly queries a result database, judges whether parameter statistical mean data of the stable system information 7 in the time period exist in the result database according to the current camping cell and RACH time, and executes the step (2) if the parameter statistical mean data does not exist; if so, then step (3) is performed immediately using these data as RACH procedure parameters.
(2) The BCCH channel is established and the system information 7 is received by the system information receiving entity, followed by step (3).
(3) The RACH procedure is performed according to the parameters of the system information 7, uplink interference and dynamic persistence values (these parameters are from the statistics database or the system information receiving entity).
(4) Judging whether the RACH process is successful or not according to the response of the network, and if the RACH process is failed, executing the step (5); if the RACH procedure is successful, step (6) is performed.
(5) The RACH process fails, whether the previous RACH parameters are acquired from the system information 7 by the system information receiving entity is judged, and if yes, the step (6) is executed; if not, i.e. it is stated that the previous RACH parameters were obtained from the results database, step (2) is re-executed.
(6) And (4) finishing the RACH process, and judging whether the parameters in the result database are used by the previous RACH process or not, wherein the parameters comprise the success and failure conditions of the RACH process. If not, the process ends executing step (9); if the parameters in the results database are used, step (7) is performed.
(7) It is determined whether the last used RACH parameters are within a defined range, such as within ± Δ σ of the statistical mean of the parameters. If yes, the statistical result before is valid, and step (9) is executed; if not, indicating that the statistical data has expired, step (8) is performed.
(8) And (4) deleting the used data of the corresponding time period in the statistical database and the result database when the statistical data is invalid, and executing the step (9).
(9) The random access procedure ends.
The method for realizing the fast random access process in the wireless cellular network is adopted, because the parameters of the system information 7 of the cell where the user is camped for a long time are counted for a long distance in a certain period, and the values are evaluated in different time periods, so that the relative stable values of the parameters in the system information 7 of the cell in a certain time period are obtained, and after the statistics is finished, the statistical values are used for directly configuring the parameters of the random access process, so that the parameters in the system information 7 are counted in advance, the distribution condition of the parameters in each time period is obtained, the parameters of the random access at a certain moment are predicted in advance, the random access transmission can be immediately carried out, the system delay caused by reestablishing a BCCH channel to receive the system information 7 is eliminated, the aim of reducing the delay is achieved, and the user experience is greatly improved, and the operation process is simple and convenient, the working performance is stable and reliable, and the application range is wider.
In this specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.