CN101132638A

CN101132638A - Method for acquiring propagation delay from physical random access signal channel

Info

Publication number: CN101132638A
Application number: CNA2007101453390A
Authority: CN
Inventors: 沈伟; 丁杰伟
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2007-09-10
Filing date: 2007-09-10
Publication date: 2008-02-27
Anticipated expiration: 2027-09-10
Also published as: CN100574131C

Abstract

This invention puts forward a method for getting time delay from a physical random access channel, which judges effective autograph from a precursor test and selects the message part of N multi-path demodulated random access information with greatest energy, then accumulates energies of pilot symbols of the demodulated message part and takes unilateral time delay of multi-path air interfaces with the greatest energy as the time delay, which not only increases related integral length greatly but also prevents interference of noise path.

Description

A kind of method that obtains propagation delay from Physical Random Access Channel

Technical field

The present invention relates to the WCDMA system, relate in particular to a kind of method that obtains propagation delay from Physical Random Access Channel in the broadband CDMA system.

Background technology

At WCDMA (Wideband Code-Division Multiple-Access, Wideband Code Division Multiple Access (WCDMA)) in the mobile communication system, when mobile phone initiates to insert at random, NODEB (base station) can be from PRACH (PacketRandem Access Channel, Physical Random Access Channel) obtains the unidirectional PropagationDelay (propagation delay) of air interface in, and this propagation delay reported RNC (radio network controller), when setting up dedicated channel subsequently, RNC can be handed down to NODEB with the propagation delay value that reports as required.

If the dedicated channel that RNC issues is set up and is not with Propagation Delay parameter in the signaling, NODEB need dispose a big multipath search window in RAKE receiver when this dedicated channel of demodulation, carry out Multipath searching in whole cell range; Otherwise dedicated channel is set up when having the one way propagation delay parameter in the signaling, and NODEB can be with this propagation delay as benchmark, and configuration multipath search window original position is carried out Multipath searching with a less multipath search window, thereby saves searching resource.Therefore, obtain propagation delay and become an essential condition of saving searching resource.

In the prior art, when NODEB carries out detection of preamble to random access information, leading part is carried out descrambling, carry out the processing that grades of the descrambling of leading part signature and correlation product, obtain the correlation energy value of the different delay positions of each signature, relatively carry out the access lead judgement with wherein maximum correlation energy value and detection of preamble thresholding then, obtain effectively signature of judgement, utilize the correlation energy value of different delay positions to carry out Multipath searching, and the air interface one way propagation time delay of choosing the multipath correspondence of correlation energy value maximum report RNC as propagation delay.

Be the frame structure of Physical Random Access Channel as Figure 1-1, Physical Random Access Channel is divided into leading part and message part, and leading part length is 4096chips, and message part length is a frame or two frames.

Be depicted as the structure of data division in the physical random cut-in channel frame as Fig. 1-2, the message part of physical random cut-in channel frame comprises, data and two parts of control, and the wireless frame length of each message is 10ms or 20ms, each frame comprises 15 time slots, each time slot 2560chips.

Because leading part length is 4096chips, correlation intergal length is the longest to be 4096chips, the Ec/Io (signal quality) of the mobile phone accidental access signal that receives as NODEB is lower, and in the time of near the detection of preamble thresholding, the multipath of the correlation energy value maximum of choosing very likely is a noise path, the propagation delay of Huo Deing is just inaccurate like this, if the propagation delay error is bigger than normal, when dedicated channel is set up, utilize the search window of this propagation delay setting just can't search true footpath, cause the dedicated channel can't be synchronous, the mobile phone access failure.

Summary of the invention

The present invention proposes a kind ofly to obtain the method for propagation delay from Physical Random Access Channel, can't accurately obtain and causes dedicated channel asynchronous, the problem of mobile phone access failure in order to overcome the propagation delay that exists in the prior art.

The present invention specifically is achieved in that

A kind of method from Physical Random Access Channel acquisition propagation delay comprises,

Step 1, detection of preamble is carried out to random access information in the base station, obtains effectively signature of judgement;

Step 2 is chosen the message part of the N bar multi-path demodulation random access information of correlation energy value maximum;

Step 3, the energy of all frequency pilot signs in the message part behind every the multi-path demodulation that adds up, the air interface One Way Delay of multipath correspondence of getting demodulation energy value maximum is as propagation delay.

Described from the method for Physical Random Access Channel acquisition propagation delay, before choosing described N bar multipath, effectively sign for judgement, utilize the correlation energy value of different delay positions to carry out Multipath searching.

Describedly obtain the method for propagation delay from Physical Random Access Channel, N is for greater than 1 and less than the natural number of the quantity of the multipath that searches.

Described from the method for Physical Random Access Channel acquisition propagation delay, the length of described message part is a frame or two frames.

Described from the method for Physical Random Access Channel acquisition propagation delay, when the length of described message part was two frames, N got 8.

Adopt the method for the invention, the multi-path demodulation message part that utilization obtains from detection of preamble, the air interface One Way Delay of multipath correspondence of getting the demodulation energy maximum is as propagation delay, not only increased correlation intergal length greatly, can also effectively prevent the interference of noise path, avoid the noise path demodulation energy to surpass the situation in true footpath, accurately obtain propagation delay, thereby guarantee the successful access of mobile phone.

Description of drawings

Fig. 1-1 is the physical random cut-in channel frame structure;

Fig. 1-2 is the structure of message part in the physical random cut-in channel frame;

Fig. 2 is the Ec/Io of leading part in the prior art and the corresponding relation figure of propagation delay error probability;

Fig. 3 is the main flow chart of the method for the invention.

Embodiment

The major technique thought of invention is, judgement in the detection of preamble is effectively signed, choose the message part of the N bar multi-path demodulation random access information of energy maximum, to the add up energy of message part frequency pilot sign after the demodulation of every multipath, the air interface One Way Delay of multipath correspondence of getting the demodulation energy maximum is as propagation delay.

Below in conjunction with accompanying drawing the specific embodiment of the present invention is described in further detail.

Be illustrated in figure 2 as the Ec/Io of leading part in the prior art and the corresponding relation figure of propagation delay error probability, owing to be to calculate propagation delay in the prior art from the multipath that leading part is sought correlation energy value maximum, as can be seen from the figure, adopting this method can produce noise path causes the acquisition of propagation delay error to occur.

Be illustrated in figure 3 as the main flow chart of the method for the invention, here suppose message part length two frames, choose 8 multi-path demodulation random accessing messages of energy maximum during Multipath searching, and the demodulation energy of choosing all frequency pilot signs in the message part of two frames is accumulated as example, and concrete implementation step is as follows:

Step 1 is carried out descrambling to accidental access signal among the NODEB, and the processing that grades of sign descrambling and correlation product obtains the correlation energy value of the different delay positions of each signature;

Step 2, carrying out access lead detects, relatively carry out the access lead judgement with wherein maximum correlation energy value and detection of preamble thresholding, obtain effectively signature of judgement, utilize the correlation energy value of different delay positions to carry out Multipath searching, choose the message part of 8 multi-path demodulation random access informations of correlation energy value maximum;

Step 3, to 8 multipaths, the energy of all frequency pilot signs in the message part after the two frame message demodulation that add up respectively;

Step 4, the air interface One Way Delay of choosing the multipath correspondence of demodulation energy value maximum in 8 multipaths reports RNC as propagation delay.

Claims

1. the method from Physical Random Access Channel acquisition propagation delay is characterized in that, comprise the steps,

2. the method from Physical Random Access Channel acquisition propagation delay as claimed in claim 1 is characterized in that:

Before choosing described N bar multipath, effectively sign for judgement, utilize the correlation energy value of different delay positions to carry out Multipath searching.

3. the method from Physical Random Access Channel acquisition propagation delay as claimed in claim 2 is characterized in that:

N is for greater than 1 and less than the natural number of the quantity of the multipath that searches.

4. the method from Physical Random Access Channel acquisition propagation delay as claimed in claim 1 or 2 is characterized in that:

The length of described message part is a frame or two frames.

5. want 4 described methods as right, it is characterized in that from Physical Random Access Channel acquisition propagation delay:

When the length of described message part was two frames, N got 8.