KR100908833B1 - Finger Tracking Method of Rake Receiver - Google Patents

Abstract

The present invention is directed to a moving propagation phenomenon due to deep fading that may occur in a time change channel, and a bus-death propagation phenomenon that may occur during handover or at a downtown roadside. The present invention relates to a finger tracking method of a rake receiver for minimizing a loss of a predetermined path. When deep fading occurs from two path presence states (PES I and II), the path is switched to a path loss state (PFS). A first step of searching for a path by an expanded window size; A second step of switching to a bus-desk provisioning state (BDPS) and searching for a path by an expanded window size when it is difficult to search a path in the first step; When the path search is difficult in the second step, it is achieved by the third step of switching to the pathless state to perform the cell search.

Description

Finger tracking method of rake receiver {FINGER TRACKING METHOD FOR RAKE RECEIVER}

1 is an exemplary diagram for explaining mobile propagation conditions;

2 is an exemplary diagram for explaining a bus-des propagation condition.

Figure 3 is a simplified view showing a rake finger management method under a time change channel according to the present invention.

4 is a state diagram showing the state of FIG. 3 in terms of window size;

5 is a state diagram showing in more detail the simplified state of FIG.

6 is an exemplary view illustrating a search window size according to each propagation state of FIG. 3.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finger tracking method of a rake receiver, and more particularly to moving propagation due to deep fading, which may occur in a time change channel, and a bus that may occur during handover or at a downtown roadside. The present invention relates to a finger tracking method of a rake receiver capable of minimizing a loss of a predetermined path due to a death-depropagation phenomenon.

In general, a W-CDMA system requires a multipath searcher because it requires high resolution for multipaths under a time-changing channel, and the multipath searcher receives a primary-common pilot channel (P-CPICH) to receive a given window. It is determined whether or not there is a valid path in the system.

The signals obtained while repeating the above process are managed by a predetermined finger management algorithm and are assigned to the fingers of the rake receiver, since the strength of the set signal varies according to the state of the channel under the time change channel. Appropriate measures are required.

As a situation to be considered in finger tracking of the rake receiver, there are firstly moving propagation conditions as shown in FIG.

In this case, the dynamic propagation condition for the base band performance test is a non-fading propagation channel having two taps, which is a fixed path (Path0) and a moving path (Path1). The taps used here have the same intensity and the same phase.

The time difference between the two paths is given by Equation 1 below.

Here, the parameter A is 5 ms, B is 1 ms, and Δω is 40 * 10 ⁻³ s ⁻¹ .

Such a propagation state may occur in the case of deep fading in which a signal falls into a goal for several frames or more, and in this case, a predetermined path is away from the finger.

Next, the second to be considered in finger tracking of the rake receiver is a bus-death propagation state as shown in FIG.

In this case, the dynamic propagation condition for the base band performance test is a non-fading propagation channel having two taps, which is a bus path Path1 and death. It is composed of a path (Path2), wherein the position of the appearing path is randomly selected with the same probability.

That is, the two paths Path1 and Path2 are randomly selected from the range [-5, -4, -3, -2, -1,0,1,2,3,4,5] ㎲, and after 191 ms, The path path1, which is the bus, disappears, and the path is death within the range [-5, -4, -3, -2, -1,0,1,2,3,4,5] It will be in a new position except the position of (path2), and the tap coefficients of the two paths will maintain the same magnitude and phase.

Next, after 191ms, the path Path2, which is Death, disappears and immediately falls within the range of [-5, -4, -3, -2, -1,0,1,2,3,4,5] ㎲. It exists in a new position except the position of the path Path1, which is the bus, where the tap coefficients of the two paths Path1 and Path2 maintain the same magnitude and phase.

Such a propagation state may occur at the time of handover or at a downtown roadside, which also affects the finger performance of the rake receiver, and if a proper countermeasure for the two states is not considered, the preset path If the loss of the cell searcher operates again, the next multi-path searcher operates to find the path, there is a problem that causes a significant waste of time.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, moving propagation due to deep fading, which may occur in a time change channel, and during handover or in a downtown roadside. It is an object of the present invention to provide a finger tracking method of a rake receiver which can minimize the loss of a predetermined path due to a possible bus-death propagation phenomenon.

According to the present invention for achieving the above object, in the rake finger management according to each state of the time change channel, the second path existence of the two path existence state (PES I, II) of the first window size (Size I) When deep fading occurs from the state PES II, a first step of switching to the lost path state PFS to search for a path by a second window size Size II; A second step of switching to a bus-desk provisioning state (BDPS) and searching for a path by a third window size (Size III) if the path cannot be found in the first step; When the path cannot be searched in the second step, a third step of switching to a no path state (NPS) and performing cell search is performed.
Preferably, the window size according to each state,
With respect to the first window size (Size I) of the path existence state (PES I, II), the second window size (Size II) and the bus-describing state ( And larger in the order of the size (III) of the third window of the BDPS.
Preferably, the two path existence states (PES I, II) are determined as the second path state (PES II) when the strength of the received signal is very large and in the handover area, or the first path state (Path) Characterized in existed state I).
In addition, the present invention for achieving the above object, in the rake finger management according to each state of the time change channel, in the rake finger management according to each state of the time change channel,
Searching for a path in a discovery mode (PFS Mode) or a confirmation mode (PFS Verification Mode) when deep fading of the two path existence states (PES I, II) occurs from the first path existence state (PES I); If the path cannot be searched in the above step, the mobile station enters a no path state (NPS) and performs a cell search.

The present invention classifies two situations based on the strength of the terminal received power, performs a signal re-search for each state, and causes a mobile propagation phenomenon due to a deep fading phenomenon, which may occur in a time change channel, Mainly, the performance of the system is maintained stably by minimizing the loss of the preset path caused by the bus-des propagation phenomenon occurring at the time of handover and at the downtown road.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 3 is a state diagram schematically illustrating a method for managing a rake finger under a time change channel according to the present invention, which basically includes two path existed states I and II (PES I and II) and a path lost state (Path). faded state (PFS), bus-desk provisioning state (BDPS) and non-path state (NPS).

The two path existence states (PES I, II) can be divided into the strength of the received signal and the handover area (the criterion of the handover area is the number of active cells). In the case of an over area, it may be determined as a second path existed state II, or may be determined as a first path existed state I.

Next, the path loss state (PFS) is a case where deep fading occurs, wherein the window size is preferably smaller than that of the two path existence states (PES I, II), but the same may be used to reduce implementation complexity.

Next, since the bus-des propagation state (BDPS) is not a state that occurs probabilistically frequently, it is preferable to consider only the area where this phenomenon is likely to occur.

Next, the no path state (NPS) is a state in which no signal is transmitted. In this case, after driving again from the cell searcher, the multi-path searcher must be driven to find a new path.

FIG. 4 is a state diagram showing the state of FIG. 3 in terms of the window size, with respect to the window size (Size I) of the path existence state (PES I, II), the path lost state (PFS) and the bus-des propane. The window size (Size II, Size III) of the gated state (BDPS) is larger.

That is, when the path suddenly disappears, the multi-path searcher searches for the path by covering a predetermined amount of windows from both the existing path disappearing locations to both sides. In the present invention, the search is performed by appropriately adjusting the window size according to each state. Thereby increasing efficiency.

Next, FIG. 5 is a state diagram showing the simplified state of FIG. 3 in more detail. Since the multi-path searcher uses the "Double-dwell serial search" method, a search mode and a verification mode are used. Will be operated.

That is, in FIG. 5, when deep fading occurs from the second path presence state PES II among the two path existence states PES I and II, a PFS search mode or a PFS verification mode step is performed. If the path is not detected at, the switch enters the bus-de-propagation state and searches for the path with the expanded window size.

Similarly, even if the path is not detected in the PFS Search Mode or the PFS Verification Mode step, the bus-desk provisioning state is switched to the No Path State (NPS).

Next, when deep fading occurs from the first path existence state (PES I), if no path is detected in the PFS Search Mode or the PFS Verification Mode step, the system immediately switches to the NPS. do.

As described above, when the non-path state is reached, the cell searcher is driven again, and then a new path must be found by operating the multipath searcher.

Next, FIG. 6 is an exemplary view showing a search window size according to each propagation state of FIG. 3, wherein (a) is a window size in a deep fading state, and (b) is a routine bus-de-specation. As the window size in the state, the first search is performed at the location of the missing path, and then the second search is performed at the location of the other path.

Next, in the case of (c), it is possible to save time in a somewhat special situation. When the two paths are separated by an interval between 2 and 4 chips, the search is not performed from both sides of each path. Only the outer side is searching.                     

This is because the path difference can be recognized as an independent path only when at least two chips are separated, and there is no possibility that the newly moved path will be located until the interval of four chips.

The above method can be applied even when the two paths are farther apart. In this case, it is necessary to set a value through experimentation and some loss may occur.

As described above, the finger tracking method of the rake receiver according to the present invention minimizes the factors caused by the dynamic change of the channel, which affects the performance of the terminal, such as mobile propagation and bus-despropagation due to deep fading. It is effective to keep the performance of the system constant and to smooth the time distribution in the DSP operation.

Claims (4)

In the rake finger management according to each state of the time change channel, When a deep fading occurs from the second path presence state PES II among the two path existence states PES I and II of the first window size Size I, the deep window fades to the path loss state PFS, thereby switching to the second window size. A first step of searching for a route by (Size II); A second step of switching to a bus-desk provisioning state (BDPS) and searching for a path by a third window size (Size III) if the path cannot be found in the first step; 3. The method of claim 2, wherein when the path cannot be searched in the second step, the mobile station switches to a no path state (NPS) and performs a cell search. The method of claim 1, wherein the window size according to each state is With respect to the first window size (Size I) of the path existence state (PES I, II), the second window size (Size II) and the bus-describing state (BDPS) of the path lost state (PFS) And larger in order of the size of the third window (Size III). The method of claim 1, wherein the two path existence states (PES I, II) are determined as a second path state (PES II) when the strength of the received signal is quite large and in the handover area, or the first path state. A finger tracking method of a rake receiver, characterized in that it is determined by (Path existed state I). In the rake finger management according to each state of the time change channel, Searching for a path in a discovery mode (PFS Mode) or a confirmation mode (PFS Verification Mode) when deep fading of the two path existence states (PES I, II) occurs from the first path existence state (PES I); And if the path cannot be found in the step, switching to a no path state (NPS) and performing a cell search.

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