CN101150828B

CN101150828B - Quick paging channel detection with signal to noise ratio dependent thresholds

Info

Publication number: CN101150828B
Application number: CN2007101373907A
Authority: CN
Inventors: 姜仁成; 杨鸿魁; 苏瑾
Original assignee: Via Technologies Inc
Current assignee: Via Technologies Inc
Priority date: 2006-07-25
Filing date: 2007-07-25
Publication date: 2011-09-14
Anticipated expiration: 2027-07-25
Also published as: CN101150828A

Abstract

A method and system is disclosed for detecting paging indicators using a multi-stage and multi-threshold detection mechanism so that a mobile terminal can be removed from an idle mode appropriately. After receiving a first paging indicator, it is determined whether a first indicator measurement corresponding to the first paging indicator is between a first and a second predetermined thresholds. After receiving a second paging indicator which may be a temporal diversity counterpart of the first paging indicator, a second indicator measurement derived based on both the first and second paging indicators is compared against a third predetermined threshold, wherein the mobile terminal is removed from the idle mode when both comparisons are appropriately conducted.

Description

Method and system for detecting quick paging channel by using signal-to-noise ratio related threshold

Technical Field

The present invention relates generally to wireless communication systems, and more particularly to a method and system for detecting the presence of switching signaling in a wireless communication network.

Background

The Quick Paging Channel (QPCH) is an uncoded channel used in CDMA (code division multiple access) based telecommunication systems for carrying switch signaling. This channel carries a variety of indicators such as paging indicator, broadcast indicator, and configuration change indicator. The following discussion will use a specific indicator, such as a paging indicator, as an example, but it should be understood that anything that can be applied to a paging indicator can also be applied to other indicators of QPCH transmissions.

In a wireless communication network, a mobile terminal remains in an idle state to conserve battery power when there is neither a voice nor a data call. In the idle state, the mobile terminal is awakened periodically at intervals, typically on the order of milliseconds, and monitors the paging indicator to detect if there is a page made to the mobile terminal. A relatively simple predetermined algorithm is typically used to determine whether the paging indicator indicates that there is an ongoing or imminent voice or data call. If the result of the predetermined algorithm is positive, the mobile terminal is switched on to decode the information transmitted over the common channel, which may contain dedicated or broadcast messages for up to 100ms intervals. If the final determination according to the simple algorithm is negative, the mobile terminal returns to a "sleep mode" during which most mobile terminal components are turned off to conserve battery power while keeping a few critical components on the basic timing requirements. As known to those of ordinary skill in the art, the more frequently a mobile terminal decodes information in a common channel, the more power the mobile terminal must consume. Therefore, there is a need to increase the latency, or amount of time the mobile terminal is in "sleep mode".

To increase latency, a wireless communication system that periodically communicates with a mobile terminal transmits the same paging indicator several times over time to indicate whether there is a page for the mobile terminal. For example, 3rd Generation Partnership Project 2(3rd Generation Partnership Project 2) describes a quick paging channel designed for this purpose in the CDMA2000 environment. For a reference, see Physical Layer Standard for CDMA2000Spread Spectrum Systems ("Physical Layer Standard for CDMA2000Spread Spectrum Systems", 3gpp2c.s0002, March, 2000). See also "Upper Layer (Layer3) Signaling Standard for CDMA2000Spread Spectrum Systems (2000)", 3gpp2c.s0005, March, 2000 for CDMA2000 Signaling Standard (Layer 3). QPCH indicators are typically on/off keyed to reduce transmission power. The paging indicator is used to signal to the mobile terminal the presence of a paging message within a predetermined paging slot in the QPCH. If the paging indicator indicates on, the mobile terminal should be awake and able to receive a page. If the paging indicator indicates off, the mobile terminal may continue in the idle state to conserve power. The indicator is repeatedly transmitted once to acquire time fading diversity information.

To conserve battery power, it is critical to reliably and efficiently detect the presence of a paging indicator. Due to the presence of noise and fading of over-the-air communications, the signal-to-noise ratio (SNR) can become very low, which makes any detection mechanism challenging. There are generally two types of paging related errors. Type I errors, i.e., false alarm errors that may cause false alarms, in turn causing incorrect page detection where more battery power is consumed. Type II errors, i.e. loss errors that miss an incorrect detection of a voice/data call. In wireless communication systems, the detection mechanism has to be designed to minimize false alarms without exponentially increasing the loss rate.

Single-stage detection mechanisms are disclosed in prior art references, in which a threshold is set for a given false alarm and the detection probability is maximized. For more, see "statistical signal processing base: detection Theory ("Fundamentals of Statistical Signal Processing: Detection Theory", PrenticeHall PTR, 1^stEdtion, March1993) ". However, since only a single threshold is used while the channel gain ratio is changing, this mechanism cannot practically minimize false alarms and loss rates simultaneously for multi-level page indicator detection. Other existing methods, while solving some of the problems described above, do not effectively detect paging indicators in multiple stages.

Existing page detection methods cannot take advantage of the known signal-to-noise ratio (SNR) channel to improve detection performance. In fact, most designs are usually proposed to cope with the worst case. If a design keeps the false alarm probability constant over the entire operating range, the loss detection probability will be almost zero at high SNR. Even if the false alarm probability can be reduced to a value lower than the design target with little sacrifice of the probability of lost detection at high SNR, the existing methods cannot change the detection performance using different thresholds since they use fixed thresholds independent of SNR.

Without an effective detection mechanism, battery power would be consumed more and a high loss rate is inevitable, resulting in poor communication performance. Accordingly, there is a need to improve existing methods of detecting paging indicators.

Disclosure of Invention

In view of the foregoing, the present invention provides a method of detecting a paging indicator in a wireless communication system.

Methods and systems for detecting paging indicators using multi-level and multi-threshold detection mechanisms so that mobile terminals can be properly taken out of idle mode are disclosed. After receiving the first paging indicator, it is determined whether a first indicator metric corresponding to the first paging indicator is between first and second predetermined thresholds. If so, a second indicator metric is derived from the second paging indicator, and again a non-decreasing function of the first and second paging indicator metrics is compared to a third predetermined threshold, wherein the first and second predetermined thresholds are based on a square root of a signal-to-noise ratio of the first paging indicator, and the third predetermined threshold is based on a square root of a signal-to-noise ratio corresponding to the second paging indicator.

A method for detecting a paging indicator through a paging channel in order to bring a mobile terminal out of an idle mode in a wireless communication system is disclosed. The method includes receiving a first paging indicator I1; determining first and second thresholds T based on signal-to-noise ratio of first paging indicator₁And T₂The first and second thresholds are different if the signal-to-noise ratio of the first paging indicator is below a predetermined initial signal-to-noise ratio threshold, otherwise the first and second thresholds are the same; deriving a first paging indicator metric x corresponding to the first paging indicator₁(ii) a In the first stage according to x₁Respectively with T₁And T₂The comparison between determines whether the mobile terminal will leave the idle mode, if x₁Less than T₁Then the mobile terminal remains in the idle mode; if x₁Greater than or equal to T₂The mobile terminal is separated from the idle mode; if x₁At T₁And T₂In between, indicating that it cannot be determined in the first stage whether the mobile terminal has left the idle mode, a second paging indicator metric x is derived from the received second paging indicator I2₂And in the second stage according to a third threshold value T₃And x₁And x₂Determines whether the mobile terminal will leave the idle mode if x is₁And x₂Is less than T₃If not, the mobile terminal is separated from the idle mode; wherein, T₁Indicating a margin and T for tolerating a lost call₂Indicating a margin for tolerance of false alarms, T₁And T₂Is based on the signal-to-noise ratio corresponding to the first paging indicatorThe square root of the ratio, and T3 is derived from the square root of the signal-to-noise ratio corresponding to the second paging indicator.

A system for detecting a paging indicator through a paging channel in order to bring a mobile terminal out of an idle mode in a wireless communication system is disclosed. The system includes a receiver for receiving first and second paging indicators I1 and I2; a threshold generator for determining the first and second thresholds T based on the signal-to-noise ratio of the first paging indicator₁And T₂The first and second thresholds are different if the signal-to-noise ratio of the first paging indicator is below a predetermined initial signal-to-noise ratio threshold, otherwise the first and second thresholds are the same; a processor for deriving a first paging indicator metric (x) corresponding to a first paging indicator₁) Or derive a second paging indicator metric x from the received second paging indicator I2₂(ii) a A comparator for in a first stage according to x₁Respectively with T₁And T₂The comparison between determines whether the mobile terminal will leave the idle mode, if x₁Less than T₁Then the mobile terminal remains in the idle mode; if x₁Greater than or equal to T₂The mobile terminal is separated from the idle mode; if x₁At T₁And T₂In the first stage, it is not determined whether the mobile terminal is out of the idle mode, and in the second stage, it is determined according to a third threshold value T₃And x₁And x₂Determines whether the mobile terminal will leave the idle mode if x is₁And x₂Is less than T₃If not, the mobile terminal is separated from the idle mode; wherein, T₁Indicating a margin and T for tolerating a lost call₂Indicating a margin for tolerance of false alarms, T₁And T₂Is derived from the square root of the signal-to-noise ratio corresponding to the first paging indicator, and T3 is derived from the square root of the signal-to-noise ratio corresponding to the second paging indicator.

The construction and method of operation of the invention, together with further objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

Drawings

FIG. 1 is a graph illustrating the difference in signal-to-noise ratio of a paging indicator based on two target thresholds corresponding to a probability of false alarm and a probability of dropped call in accordance with one embodiment of the present invention;

FIG. 2 is a flow diagram illustrating decisions made for multi-level paging indicator detection in accordance with one embodiment of the present invention; and

fig. 3 is a hardware diagram for implementing multiple stages of page indicator detection in accordance with one embodiment of the present invention.

Detailed Description

A detailed description of a method and system for determining the presence of an indicator transmitted on a quick paging channel in a wireless communication network will be provided below. The subject matter set forth herein is applicable to wireless communication systems that utilize multiplexed signals of Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), and Frequency Division Multiplexing (FDM) techniques. For purposes of illustration, a CDMA2000 system is used as an example. In wireless communication systems, such as CDMA2000 systems, several paging indicators are implemented. A paging indicator may be understood by one of ordinary skill in the art as a signal that detects the presence of a paging signal and is broadly defined to include, but is not limited to, the following examples of paging indicators. For example, a quick paging channel paging indicator is designed for the Quick Paging Channel (QPCH). Another quick paging channel configuration change indicator is designed for the Common Control Channel (CCCH). Yet another quick paging channel broadcast indicator is designed for the broadcast control channel (BCCCH).

The present invention estimates the SNR of the QPCH and calculates a detection threshold based on the estimated SNR. The operating range of SNR is divided into two ranges: a high SNR range and a low SNR range. For each range, the SNR related threshold is used for a different decision mechanism. For example, in the high SNR range, both the target loss detection probability and the target false alarm probability may be satisfied with a single threshold value due to good signal quality. In fact, the high SNR range enables the detector to satisfy detection performance between the probability of missed detection and the probability of false alarm with a single SNR correlation threshold. More specifically, a double decision mechanism is used in the high SNR range. In the low SNR range, it is not possible to satisfy both the target loss detection probability and the target false alarm probability with a single threshold. Therefore, it is necessary to use two thresholds, which introduces a suspect or indeterminate state. When the first paging indicator enters this suspect state, subsequent paging indicators are tested for detection and possibly combined with the first page loss indicator. Therefore, the triple decision mechanism is used in the low SNR range.

In accordance with one embodiment of the present invention, two paging indicators, I1 and I2, are transmitted in each paging slot cycle in a CDMA2000 system, where I2 is the time diversity counterpart of I1. These two indicators span the channel coherence length (approximately 20ms) to achieve time diversity. Suppose that the received symbol signal is expressed as r_i，k，lWhere I is the paging indicator index (1 or 2 for I1 or I2, respectively), k is the index of the multipath including the diversity branches, and 1 is the Quadrature Phase Shift Keying (QPSK) symbol index, where QPSK is understood to be a digital frequency modulation technique that transmits digital data over a communication channel, whose corresponding estimated radio channel information is a_i，k，l，a_i，k，lRepresenting the channel conditions. Then, a measurement metric corresponding to the paging indicator bar display section can be obtained by a predetermined combination method. For example, three normalized measurement metrics (or paging indicator metrics) x are combined by a simple pilot weighted combining method₁、x₂And x₃Expressed as:

(equation 1)

(equation 2)

(equation 3)

Where K1 and K2 are the number of multipaths (including diversity branches) of I1 and I2, respectively, L is the number of QPSK symbols per paging indicator, QPR is the ratio between the power of the quick paging indicator and the pilot signal, and the channel gain, also referred to as base station announcement. In a CDMA2000 system, QPR has a QPR of 10^{(QPCH_POWER_LEVEL_PAGE+3)/20}And QPCH _ POWER _ LEVEL _ PAGE is the PAGE indicator modulation symbol POWER LEVEL relative to the forward pilot channel also defined in the CDMA2000 standard.

It will be appreciated that the measurement metric is derived from the channel gain as signalled by the base station, and that the estimated radio channel information is significantly better than the prior art. The above method may be referred to as a pilot weight combining method. With this approach, no noise reduction weights are explicitly specified to solve the noise problem, since the weighting effect has already been achieved. As shown, since x₁、x₂And x₃Are both functions of and normalized to QPR, so there is a built-in inherent adaptation mechanism that can work with any communication system. The summation corresponding to the radio channel information represented by the above equation provides a normalization process so that the analysis can be simplified. It should also be appreciated that the measurement metric is not necessarily normalized, and indeed, QPR may be considered while determining the threshold to which the measurement metric is to be compared (as will be further explained below). By taking both QPR and signal-to-noise ratio (SNR) into account in deriving and analyzing these measurement metrics and their respective thresholds, both channel conditions and channel configuration can be factored in order to make page detection fully adaptable to a wide variety of channel environments.

In another embodiment using the maximal ratio combining method, three similar normalized indicator metrics x are given as follows₁、x₂And x₃：

(equation 1')

(equation 2')

(equation 3')

Wherein,

Figure DEST_PATH_DEST_PATH_S071D7390720070806D000064

is the noise variance of the ith paging indicator, the kth multipath, and the 1 st symbol. In this derivation x₁、x₂And x₃In the method of (1), the noise is expressed by a factor, and the application weight is also appropriately considered. In general, if the noise is high, the application weight should be lower. As can be seen from the above metrics, the noise variance is placed in the denominator part to represent the "inverse ratio" relationship. In this maximum ratio combining method, specific weights are applied as described above to reduce noise interference, thereby improving the performance of the system.

The effective signal-to-noise ratios (SNRs) of the paging indicators I1 and I2 are referred to as SNR1 and SNR2, respectively. SNR3 is defined as the combined SNR of I1 and I2. In a communication system, it will be appreciated by those skilled in the art that the SNR tends to depend on the characteristics of the mobile terminal demodulator, the channel conditions, and the inherent noise. For the present application, since the QPCH power can be known in advance from the pilot channel power, the SNR can be traded for Eb/Nt, which is the ratio of energy per bit to the effective noise spectral density.

Any decision rule to determine the paging indicator requires some form of SNR estimation. For example, the SNR can be estimated from the pilot signal. Total received power to interference ratio Ec_pIo is in decibel (dB), where Ec_pAnd Io is the pilot chip energy and the total received input power spectral density containing both signal and interference, respectively. This ratio can be easily obtained from the mobile terminal searcher. Then, the noise factor expressed by SNR is given by:

SNR＝QPCH_Ec/Ioc＝(QPR)²*Ee_pio (equation 4)

Wherein Ec_pAnd Ioc is the chip energy of the pilot signal and the power spectral density of the band-limited white noise and interference from other cells including multipath interference. QPCH _ Ec is the total chip energy of the paging indicator. Due to I_o＝I_or+I_ocFor I_or≌I_ocCan obtain an approximate formula I_oc≌I_o/2, wherein the term I_orIs the post-channel transmit power spectral density. In the forward link, I_orIs the total transmit power spectral density of the base station under soft handoff. In CDMA2000 system, I_or/I_ocCalled the geometry factor.

Therefore, the SNR approximation formulas for I1 and I2 are as follows:

SNR1＝2R*(QPR)²*Ec_p1/I_o1(equation 5)

SNR2＝2R*(QPR)²*Ec_p2/I_o2(equation 6)

The SNR approximation formula for the combination of I1 and I2 is as follows:

SNR3＝2R*(QPR)²*[Ec_p1/I_o1+Ec_p2/I_o2](equation 7)

Where for a CDMA2000 system, R is 256 or 512 for a quick paging channel data rate of 4,800bps or 2,400 bps. When the signal is equal to noise plus interference, the approximation error is approximately zero. When the geometric factor (I)_or/I_oc) Low (e.g., from-5 dB to 5dB), which corresponds to a low SNR region and is primarily important for detection and decoding, the estimate is relatively accurate. In the decision rule discussed below, the decision threshold is constant in the high SNR region corresponding to the high geometry factor.

The estimated indicator SNR is compared to an SNR threshold that determines the boundary between the high SNR range and the low SNR range. The SNR threshold is the SNR that can be met by both the target false alarm probability and the target lost detection probability in the first indicator detection. Giving false alarm probability (P)_F) And loss detection probability (P)_MD) The SNR threshold that divides the SNR range into high SNR or low SNR is obtained by solving the following joint equation:

<math><mrow> <msub> <mi>P</mi> <mi>F</mi> </msub> <mo>=</mo> <mfrac> <mn>1</mn> <msqrt> <mn>2</mn> <mi>π</mi> </msqrt> </mfrac> <msubsup> <mo>&Integral;</mo> <mi>T</mi> <mo>∞</mo> </msubsup> <mi>exp</mi> <mrow> <mo>(</mo> <mo>-</mo> <mfrac> <msup> <mi>x</mi> <mn>2</mn> </msup> <mn>2</mn> </mfrac> <mo>)</mo> </mrow> <mi>dx</mi> </mrow></math>

<math><mrow> <msub> <mi>P</mi> <mi>MD</mi> </msub> <mo>=</mo> <mfrac> <mn>1</mn> <msqrt> <mn>2</mn> <mi>π</mi> </msqrt> </mfrac> <msubsup> <mo>&Integral;</mo> <mrow> <mo>-</mo> <mo>∞</mo> </mrow> <mrow> <mi>T</mi> <mo>-</mo> <msqrt> <mi>SNR</mi> </msqrt> <mo></mo> </mrow> </msubsup> <mi>exp</mi> <mrow> <mo>(</mo> <mo>-</mo> <mfrac> <msup> <mi>x</mi> <mn>2</mn> </msup> <mn>2</mn> </mfrac> <mo>)</mo> </mrow> <mi>dx</mi> </mrow></math>

(equation 8)

Where "T" is a threshold and x is an indicator. In general, T may be derived from a predetermined false alarm probability, and the SNR in the above equation may be derived from T and a predetermined loss detection probability. Thus, the threshold is SNR dependent.

FIG. 1 is a graphical representation of a selected region showing a high SNR range in accordance with one example of the present invention. As shown in fig. 1, the SNR related threshold may be represented by a function of the square root (horizontal axis) of the indicator SNR. If the threshold is represented by a linear function, the selected detection performance can be obtained by adjusting the slope and intercept of the threshold. In the high SNR range, only one detection threshold is needed. Satisfying a threshold (T) for a given false alarm probability_f) Is a constant independent of SNR (as shown by the dashed line) while satisfying a threshold (T) for a given probability of missed detection_d) Is a linear function of the square root of the SNR (as shown by the solid line). The detection threshold in the high SNR range can be considered to exceed T to the right_fAnd T_dAt T of the intersection point of_fAnd T_dA non-decreasing function of the square root of the SNR in the region in between. For illustration, this particular region, to which any detection threshold of high SNR can be matched, is shown shaded.

When in the low SNR range, the detection is a multi-level detection mechanism that detects at least two quick paging indicators in a combined manner. To detect the paging indicator according to the SNR, two thresholds T are required₁And T₂However, for combined paging indicator based detection, a third threshold T is required₃。T₁Indicating a margin of tolerance to lost calls, and T₂Indicating the limits of tolerance for false alarms. According to an example of the present invention, detection threshold in low SNR rangeThe determination may be selected as:

T₁＝T_d

T₂＝T_f(equation 9)

T_{3} = f (T_{1}, T_{2}, \sqrt{{(E_{s} / N_{t})}_{1}} \sqrt{{(E_{s} / N_{t})}_{2}})

Where f is a non-decreasing function.

If the threshold value T is set₃Expressed as a linear function, T can be expressed as₃Shown as follows:

T_{3} = a_{3} (T_{1}, T_{2}, \sqrt{{(E_{s} / N_{t})}_{1}}) \sqrt{{(E_{s} / N_{t})}_{2}} + b_{3} (T_{1}, T_{2}, \sqrt{{(E_{s} / N_{t})}_{1}})

(equation 10)

Wherein, with a₃And b₃Precalculated and saved in memory for a given area (E)_s/N_t) The SNR range of 1 is divided into several regions.

FIG. 2 provides a flow diagram 100 illustrating an improved detection process according to one embodiment of the invention. In FIG. 2, x₁And x₂Is a first and second indicator detection metric, and x₁₂Is a combined indicator metric (x)₁₂＝w1*x₁+w2*x₂Where w1 and w2 are optional weights). (E)_s/N_t)₁Is the first indicator symbol energy to noise ratio, and (E)_s/N_t)₂Is the energy to noise ratio of the second indicator symbol. SNR _ threshold is the total SNR threshold, and T₁、T₂And T₃Are the three thresholds discussed above. a is₁、a₂And a₃Is a constant representing the slope of a linear function, and b₁、b₂And b₃Represents T_fAnd T_dThe intercept therebetween.

The flowchart 100 begins with the first stage of entering decision step 102. If the total SNR of the QPCH (i.e., QPCH (E)_s/N_t)₁) Not less than a predetermined threshold SNR threshold, T, based on total SNR, T is calculated₁And T₂Is set to the same value and, in step 104, is mathematically determined as:

T_{1} = T_{2} = a_{12} \sqrt{{(E_{s} / N_{t})}_{1}} + b_{12}

(equation 11)

On the other hand, if the total SNR of the QPCH (i.e., QPCH (E)_s/N_t)₁) Less than a predetermined total SNR-based threshold SNR threshold, T is measured in step 106₁And T₂Is set to different values, and is mathematically determined as:

T_{1} = a_{1} \sqrt{{(E_{s} / N_{t})}_{1}} + b_{1}

and

T_{2} = a_{2} \sqrt{{(E_{s} / N_{t})}_{1}} + b_{2}

(equation 12)

It can be seen that T is still based on the first indicator only₁And T₂Are set to different values based on different weight constants a and b. With T₁And T₂An initial setting is obtained and the process passes to step 108 where, in step 108, a first indicator detection metric x is measured₁And T of setting₁By comparison, if it is less than T₁The mobile terminal should stay in the idle state (step 110). If the first indicator detection metric x is determined in step 108₁Greater than T₁Then the first indicator detection metric x is further determined in step 112₁Whether or not T is greater than or equal to₂. If so, there is a strong indication that the mobile terminal should be turned on in step 114. This means that if the first indicator detects the metric x₁Greater than T₁And T₂Both, false alarms are not possible.

At x₁At T₁And T₂In between, a second indicator detection metric x is introduced₂And (5) carrying out further detection. Second indicator detection metric x₂Derived from the second paging indicator I2, the second paging indicator I2 may be the time counterpart of the first paging indicator I1. First a combined threshold value T is derived from the square root of the SNR of the second paging indicator₃. That is to say that the position of the first electrode,

T_{3} = a_{3} \sqrt{{(E_{s} / N_{t})}_{2}} + b_{3}

(equation 13)

Wherein, a₃And b₃Are predetermined constants that may be stored in the mobile terminal in advance. Then, x will be followed as its variable in step 116₁And x₂Varying selected non-decreasing functions f and T₃And (6) comparing. If it is determined in step 116 that it is below the threshold T₃Then, the mobile terminal is turned off. Otherwise, the mobile terminal is turned on in step 120. To this end, the two-stage indicator detection process is completed.

It should be noted that SNR threshold is an artificial dividing line that cuts the operating range of SNR into a high SNR range and a low SNR range in step 102. As described above, a single threshold is sufficient to satisfy both the target loss detection probability and the target false alarm probability if in the high SNR range. On the other hand, if it is below the total threshold, it is considered to be in the low SNR range, and a triple decision process needs to be applied. Two different thresholds T₁And T₂Introduce x₁Greater than T₁But less than T₂The suspected state of (c). At this point, it is reasonable to assume that further determinations should be introduced, as seen from step 116 above, and that a second indicator is used to further determine whether or not to further determineThe mobile terminal should be turned on. It should also be noted that T₁、T₂And T₃Some of the values of (c) are based on the square root of the SNR of the respective paging indicator.

Fig. 3 illustrates a hardware diagram 300 containing various components to accomplish paging indicator detection. There is a signal receiver or detector 302 in the mobile terminal that receives the QPCH signal, as well as other signals from other communication channels such as the pilot channel. At least one comparator module 304 is in the mobile terminal that performs multiple rounds of comparison as described above. An SNR calculator 306 provides an SNR value from the received signal, and a threshold generator 308 performs processing for calculating a required threshold. When the SNR and the threshold are fed into the comparator according to the detection signal, the comparator performs comparison in cooperation with a processing unit like the microcontroller 310. Based on the comparison result, the controller 310 provides a decision signal for the mobile terminal to wake up or stay in an idle state. It should also be understood that the various calculators and generators may be implemented in hardware or software means. For example, all processing power may be provided by a microprocessor, such as a controller, in the mobile terminal without being broken down into different units. Alternatively, some of the modules may be implemented by discrete hardware modules operating independently of the controller.

The above illustrations provide many different embodiments or embodiments for implementing different features of the invention. Specific embodiments of these components and processes are described to help clarify the invention. These are, of course, merely embodiments and are not intended to limit the invention from that described in the claims.

Although the invention is illustrated and described herein as embodied in one or more specific examples, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention, as set forth in the following claims.

Claims

1. A method for detecting a paging indicator through a paging channel in order to bring a mobile terminal out of an idle mode in a wireless communication system, the method comprising:

receiving a first paging indicator I1;

determining first and second thresholds T based on signal-to-noise ratio of first paging indicator₁And T₂The first and second thresholds are different if the signal-to-noise ratio of the first paging indicator is below a predetermined initial signal-to-noise ratio threshold, otherwise the first and second thresholds are the same;

deriving a first paging indicator metric x corresponding to the first paging indicator₁；

In the first stage according to x₁Respectively with T₁And T₂The comparison between determines whether the mobile terminal will leave the idle mode, if x₁Less than T₁Then the mobile terminal remains in the idle mode; if x₁Greater than or equal to T₂The mobile terminal is separated from the idle mode; if x₁At T₁And T₂In between, indicating that it cannot be determined in the first stage whether the mobile terminal has left the idle mode, a second paging indicator metric x is derived from the received second paging indicator I2₂(ii) a And

in the second stage according to a third threshold value T₃And x₁And x₂Determines whether the mobile terminal will leave the idle mode if x is₁And x₂Is less than T₃If not, the mobile terminal is separated from the idle mode;

wherein, T₁Indicating a margin and T for tolerating a lost call₂Indicating a margin for tolerance of false alarms, T₁And T₂Is derived from the square root of the signal-to-noise ratio corresponding to the first paging indicator, and T3 is derived from the square root of the signal-to-noise ratio corresponding to the second paging indicator.

2. The method of claim 1, wherein the steps of determining the first and second thresholds further comprise thresholding T if the signal-to-noise ratio of the first paging indicator is below a predetermined initial SNR threshold₁And T₂Is defined as

And

wherein,

is the signal-to-noise ratio, a, corresponding to the first paging indicator₁、a₂、b₁、b₂Is a predetermined constant.

3. The method of claim 1, wherein the steps of determining the first and second thresholds further comprises applying T if the signal-to-noise ratio of the first paging indicator is above a predetermined initial signal-to-noise ratio threshold₁And T₂Is defined asWherein,

is the signal-to-noise ratio, a, corresponding to the first paging indicator₁₂And b₁₂Is a predetermined constant.

4. The method of claim 1, wherein a third threshold T₃Is determined as

Wherein,

is the signal-to-noise ratio corresponding to the second paging indicator, and a₃And b₃Is a predetermined constant.

5. The method of claim 1, wherein the second paging indicator I2 is a time diversity counterpart of the first paging indicator I1.

6. A system for detecting a paging indicator through a paging channel in order to bring a mobile terminal out of an idle mode in a wireless communication system, the system comprising:

a receiver for receiving first and second paging indicators I1 and I2;

a threshold generator for determining the first and second thresholds T based on the signal-to-noise ratio of the first paging indicator₁And T₂The first and second thresholds are different if the signal-to-noise ratio of the first paging indicator is below a predetermined initial signal-to-noise ratio threshold, otherwise the first and second thresholds are the same;

a processor for deriving a first paging indicator metric (x) corresponding to a first paging indicator₁) Or derive a second paging indicator metric x from the received second paging indicator I2₂；

A comparator for in a first stage according to x₁Respectively with T₁And T₂The comparison between determines whether the mobile terminal will leave the idle mode, if x₁Less than T₁Then the mobile terminal remains in the idle mode; if x₁Greater than or equal to T₂The mobile terminal is separated from the idle mode; if x₁At T₁And T₂In the first stage, it is not determined whether the mobile terminal is out of the idle mode, and in the second stage, it is determined according to a third threshold value T₃And x₁And x₂Determines whether the mobile terminal will leave the idle mode if x is₁And x₂Is less than T₃If not, the mobile terminal is separated from the idle mode;

7. The system of claim 6, wherein the second paging indicator I2 is a time diversity counterpart of the first paging indicator I1.

8. The system of claim 6, wherein if the first paging indicatorThe signal-to-noise ratio is lower than the predetermined initial signal-to-noise ratio threshold, the first and second threshold values T₁And T₂Is defined as

And

wherein,

9. The system of claim 6, wherein the first and second thresholds T are based on the signal-to-noise ratio of the first paging indicator being above a predetermined initial signal-to-noise ratio threshold₁And T₂Are set to be identical and set to

Wherein,is the signal-to-noise ratio, a, corresponding to the first paging indicator₁₂And b₁₂Is a predetermined constant.

10. The system of claim 6, wherein the third threshold T₃Is determined asWherein,