KR100742784B1 - Mobile communication terminal and method for handling pilot search window size according to radio environment - Google Patents

Abstract

A mobile terminal for setting a pilot search window size according to a radio environment and its method are provided to smoothly perform a handoff operation in an area where several pilot PNs are received. A manipulation unit(34) receives a user manipulation command. A wireless communication unit(31) transmits/receives a radio signal to/from a mobile communication network through an antenna. When a call connection command is inputted from the manipulation unit, a call processing unit(361) processes a call connection to the mobile communication network through the wireless communication unit according to a call processing protocol. When a call connection signal is inputted from the call processing unit, a pilot monitoring unit(362) monitors whether there is a pilot PN that can become an active set among multiple base station pilot PNs inputted from the wireless communication unit. When a pilot PN that can become an active set is inputted from the pilot monitoring unit(362), a PSMM(Pilot Strength Measurement Message) processing unit(363) generates a PSMM including the information on the pilot PN that can become the active set, and transmits it to the mobile communication network. A search window size setting unit(364) sets a pilot search window size based on pilot PN information to be added to the active set inputted from the mobile communication network through the wireless communicating unit and a pilot search window size.

Description

MOBILE COMMUNICATION TERMINAL AND METHOD FOR HANDLING PILOT SEARCH WINDOW SIZE ACCORDING TO RADIO ENVIRONMENT}

1 is an exemplary view for explaining a conventional handoff concept.

2 is an exemplary diagram for explaining a conventional handoff concept in association with handoff threshold variables.

3 is a block diagram schematically illustrating a configuration of a mobile communication terminal according to an embodiment of the present invention.

4 illustrates a handoff procedure between a mobile communication terminal and a mobile communication system according to the present invention.

5 is a method for setting a pilot search window size executed during a call in a mobile communication terminal according to an embodiment of the present invention.

<Brief Description of Drawings>

361: call processing unit

362: pilot monitoring unit

364: PSMM processing unit

365: search window size setting unit

366: handoff completion message (HCM) processing unit

The present invention relates to handoff in a mobile communication terminal, and more particularly, to a technique for dynamically setting a pilot search window size according to a wireless environment in a mobile communication terminal.

In general, handoff, or handover, means that the terminal continues to be weak when the current communication channel is weakened due to various situations, such as when the user moves or changes in the channel. It refers to a procedure for changing a call channel with a new strong signal in order to maintain a service.

FIG. 1 is an exemplary diagram for describing a conventional handoff concept, and FIG. 2 is an exemplary diagram for explaining a conventional handoff concept in association with handoff threshold variables.

First, in FIG. 1, Pilot Ec / Io is the ratio of the pilot energy Ec accumulated over one pseudo-noise (PN) chip period to the total power spectral density (Io) in the reception bandwidth. T_ADD is a base station pilot strength value that a base station belonging to a neighbor set must satisfy in order to enter a Candidate Set. That is, when the base station pilot strength belonging to the neighbor set exceeds T_ADD, it transitions to the Candidate Set. T-TDROP is a channel drop timer required for the base station pilot belonging to the active set to be deleted from the active set. T-DROP is a value of the reference pilot strength at which T-TDROP operates. The hatched portion is a handoff section.

In some cases, a mobile communication terminal receives a large number of signals. Accordingly, the mobile communication terminal classifies and manages Active Set, Candidate Set, Neighbor Set, and Remaining Set based on threshold variables including T_ADD, T-DROP, and T-TDROP. Referring to FIG. 2, the mobile communication terminal transitions to the Candidate Set when the base station pilot strength belonging to the neighbor set exceeds T_ADD. After that, when the base station pilot strength belonging to the Candidate Set is maintained for some time, the mobile communication terminal informs the mobile communication system of the base station pilot PN belonging to the Candidate Set through a pilot strength measurement message (PSMM). At this time, the mobile communication system transmits a handoff-direction message to the mobile communication terminal to include the pilot PN in the active set. The mobile communication terminal receiving the handoff-direction message updates the pilot set and transmits a handoff complete message (HCM) to the mobile communication system. Thereafter, the mobile communication terminal transitions to the neighbor set when the strength of the base station pilot signal belonging to the active set falls below T_DROP and is maintained for the T-TDROP time.

On the other hand, the mobile communication system informs the pilot search window size information through a handoff-direction message so that the mobile communication terminal can quickly search for a base station pilot PN belonging to an active set / candidate set during a call. For example, if the pilot search window size of the active set is 40 PN chips, the most simply considered, the CDMA 1 PN chip is about 244m, so the mobile communication terminal searches for pilot signals of base stations within the range of 4.88 km and classifies it as an active set. do. Here, the Active Set / Candidate Set search window size should be as small as possible for fast retrieval, but large enough to accommodate multipath fading components. The Candidate Set is set only when a traffic channel is assigned and the pilot search window size is typically the same as the Active Set.

The conventional mobile communication system determines the size of the active set search window or sets a specific value uniformly using the base station number information of the region. However, when a mobile communication terminal is located in an area where several pilot PNs having similar electric field strengths are received, such as a metropolitan area where a large base station and a base station are densely received, the terminal has a poor voice quality or a call drop due to frequent handoff operations. There was a problem that occurs.

The present invention has been proposed in the above background, and an object of the present invention is to provide a technique for performing a smooth handoff operation in a region where a plurality of pilot PNs having similar electric field strengths are received in a mobile communication terminal. .

The mobile communication terminal according to an aspect of the present invention for achieving the above object, the operation unit for receiving a user operation command, a wireless communication unit for transmitting and receiving a radio signal with a mobile communication network through an antenna, and a call connection command from the operation unit According to a call processing protocol, a call processing unit which processes a call connection with a mobile communication network through a wireless communication unit, and a pilot PN which can be an active set among a plurality of base station pilot PNs input from the wireless communication unit when a call connection signal is input from the call processing unit. The pilot monitoring unit for monitoring the presence of a pilot and a pilot PN that can be an active set from the pilot monitoring unit, and generates a pilot strength measurement message (PSMM) including the pilot PN information that can be an active set to the mobile communication network. Transmit through a pilot strength measurement message (PSMM) processing unit and a wireless communication unit Search for setting the pilot search window size based on the pilot information and the pilot PN search window size to be added to the Active Set that is input from the Trust window size set is characterized by comprising: a.

According to this aspect, the mobile communication terminal of the present invention is implemented to dynamically set a pilot search window size according to a wireless environment, thereby performing a smooth handoff operation in a region where multiple pilot PNs having similar electric field strengths are received. It can be.

The foregoing and further aspects of the present invention will become apparent from the following examples. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand and reproduce the present invention.

3 is a block diagram schematically illustrating a configuration of a mobile communication terminal according to an embodiment of the present invention.

As shown, the mobile communication terminal according to the present embodiment is a wireless communication unit 31 for transmitting and receiving a wireless signal with the mobile communication network through an antenna, and input and output the voice call signal from the wireless communication unit 31 through a microphone and a speaker And a memory 33 for storing the main program and temporary data in the voice input / output unit 32 and the accessory circuits, an operation unit 34, a display unit 35 for displaying a menu, and an operation state.

The wireless communication unit 31 includes an antenna and an RF circuit for communication with the base station. In the present specification, the wireless communication unit is interpreted to cover not only various versions of CDMA but also existing methods such as cellular, GSM, and W-CDMA, as well as mobile communication. The voice input / output unit 32 is a well-known configuration that processes digital voice data into an analog voice signal or vice versa, and includes an additional circuit such as an audio amplifying circuit or a filter. The memory 33 may be implemented as a single chip including a static random access memory (SRAM) having a capacity of several megabits and a flash memory having a capacity of several tens of megabits. The operation unit 34 is implemented as a means for inputting a user's operation command, and may be a keypad, a side key, a touch panel, a handwriting input unit, a voice recognition unit, and the like composed of numeric keys and function keys. The display unit 35 displays the progress of operation in the device, a menu selection screen of the user, and the like, and may be one of the known display devices such as a liquid crystal display.

The baseband circuit of the wireless communication unit 32 and most of the circuits of the control unit 36 are commercially provided as a single integrated circuit. This integrated circuit, commonly referred to as Qualcomm ^TM 's Mobile Station Modem (MSM) chip, includes dedicated hardware to process communications therein, a digital signal processor and a general purpose microprocessor. In hardware, such an integrated circuit includes a searcher, a finger, and a Rake receiver to synchronize radio signals with a base station.

The searcher calculates the correlation between the PN code of the received signal and the PN code generated by itself and calculates the phase of the PN code of the received signal and the self-generated PN code based on the energy value accumulated by the threshold time. Acquisition of synchronization with a sub-chip error includes a PN code generator, a correlator, and a synchronization acquisition checker (ACQ_CHK). Fingers use the PN code tracking loop for the time-varying received signal based on the approximate PN code phase information of the received signal by the searcher to continuously synchronize and fine-tune the chip boundary. To maintain. In general, the number of fingers may be referred to as the number of pilot PNs in an active set that a mobile communication terminal can process simultaneously. The number of fingers is determined in the mobile communication terminal according to the mobile station modem (MSM) chip. For example, the MSM5000 series has four fingers, and the MSM6000 series has six fingers. The Rake receiver includes a symbol combiner and a frequency error combiner.

The control unit 36 includes a call processing unit 361, a pilot monitoring unit 362, a pilot strength measurement message (PSMM) processing unit 363, a search window size setting unit 364, and a handoff completion message (HCM) processing unit 365. ).

When a call connection command is input from the operation unit 34, the call processing unit 361 processes the call connection with the base station through the wireless communication unit 31 according to a conventional call processing protocol. For example, the call processor 361 transmits an origination message including a MIN, an ESN, and an incoming / outgoing terminal phone number to the base station, and receives a traffic channel assignment message from the base station. . The traffic channel assignment message includes system parameters such as pilot search window size.

When the call connection signal is input from the call processor 361, the pilot monitor 362 monitors whether there is a pilot PN that can be an active set among a plurality of base station pilot PNs input from the wireless communication unit 31. The pilot monitoring unit 362 is a pilot search window size obtained through the traffic channel assignment message (Taffic Channel Assignment Messaage), and T_ADD, T-DROP and T- received through the overhead message in the idle state (typically). Monitor the pilot PN, which may be an active set, for example, through a threshold containing the TDROP.

When the pilot strength measurement message (PSMM) processor 363 receives a pilot PN that can be an active set from the pilot monitoring unit 362, a pilot strength measurement message (PSMM) includes pilot PN information that can be an active set. Create and transmit to mobile communication network.

The search window size setting unit 364 sets the pilot search window size based on the handoff indication message (HDM). Typically, when a call is based on 1FA 3 sectors, three pilot PNs enable smooth handoff. Accordingly, according to a characteristic aspect of the present invention, the search window size setting unit 364 may add pilot PN information and pilot to be added to an active set included in a handoff indication message (HDM) input from the mobile communication network through the wireless communication unit 31. Set the pilot search window size based on the search window size.

In one embodiment, the search window size setting unit 364 is the number of pilot PNs to add to the active set is greater than or equal to the threshold and the pilot search window size included in the handoff indication message (HDM) is larger than the previously set pilot search window size. If it is equal to or greater than the pilot search window size, the pilot search window size may be set to be smaller than the previously set pilot search window size. Here, the threshold is preferably about 3 to 5 in consideration of the number of fingers used in the terminal.

Typically, the pilot search window has 16 steps, and the window size is determined for each step. The search window size setting unit 364 may be implemented to have such a pilot search window size as a look-up table. The pilot monitoring unit 362 can reduce the pilot search time by using the pilot search window size set smaller by the search window size setting unit 364 to prevent frequent handoffs to several pilots.

The handoff completion message (HCM) processor 365 transmits a handoff completion message (HCM) including a pilot PN information currently included in the active set to the mobile communication network.

4 illustrates a handoff procedure between a mobile communication terminal and a mobile communication system according to the present invention. Here, it is assumed that the mobile communication system includes a base station, a base station controller, and a mobile telephone exchange.

When the power is turned on (S401), the mobile communication terminal 41 performs a normal authentication procedure with the mobile communication system while performing a terminal initialization process. Thereafter, the mobile communication terminal 41 receives an overhead message including a threshold including T_ADD, T-DROP, and T-TDROP from the handoff processing system of the present invention included in the mobile communication system 42 (S402). ). The mobile communication terminal 41 classifies and manages Active Set, Candidate Set, Neighbor Set, and Remaining Set based on Thresholds including T_ADD, T-DROP, and T-TDROP (S403). When all the procedures from step S401 to step S403 are performed, the mobile communication terminal maintains an idle state.

Subsequently, when a call connection is requested according to a user's operation (S404), the mobile communication terminal 41 includes an origination message including a mobile identification number (MIN), an electronic serial number (ESN), and an incoming / outgoing terminal phone number. Is transmitted to the mobile communication system 42 (S405). The mobile communication system 42 attempts to connect a call according to a conventional call connection protocol. Here, the handoff processing system of the present invention included in the mobile communication system 42 lowers the pilot search window size through a traffic channel assignment message (S406). Thereafter, the mobile communication terminal 41 transmits and receives a voice signal through a communication channel connected to the counterpart terminal (S407).

The mobile terminal 41 uses a pilot discovery window size obtained through a traffic channel assignment message during a call and a threshold including T_ADD, T-DROP, and T-TDROP received through an overhead message. The pilot of the received signals is monitored (S408). When the mobile communication terminal 41 identifies the pilot PN that can be an active set, the mobile terminal 41 uploads a pilot strength measurement message (PSMM) including the pilot PN information that can be the active set to the mobile communication system 42 (S409). ). At this time, the mobile communication system 42 sets the pilot search window size of the mobile communication terminal (S410). Thereafter, the mobile communication system 42 generates a handoff direction message including a pilot search window size of the mobile communication terminal along with the pilot PN information to be added to the active set and transmits it to the mobile communication terminal 41. (S411, S412).

The mobile communication terminal 41 sets the pilot search window size based on the pilot PN information and the pilot search window size to be added to the active set included in the handoff indication message (HDM) (S413). In one embodiment, the mobile communication terminal 41 has the number of pilot PNs to add to the active set equal to or greater than the threshold and the pilot search window size included in the handoff indication message (HDM) is equal to or larger than the previously set pilot search window size. If large, the pilot search window size may be set to be one step smaller than the previously set pilot search window size. In general, the pilot search window has 16 steps, and each step may be implemented to have a look-up table in which the corresponding window size is determined. The mobile communication terminal 41 can reduce the pilot search time by using a pilot search window size set smaller by one level, thereby preventing frequent handoff to several pilots.

Thereafter, the mobile communication terminal 41 uploads a handoff completion message (HCM: Handoff Completion Message) including the pilot PN information included in the active set to the mobile communication system 42 (S414).

5 is a method for setting a pilot search window size executed during a call in a mobile communication terminal according to an embodiment of the present invention.

First, the mobile communication terminal transmits an origination message including the MIN, ESN and the incoming / outgoing terminal Phone No to the mobile communication system according to a user call connection command. The mobile communication terminal receives a traffic channel assignment message including a pilot search window size from the mobile communication system. Thereafter, the mobile communication terminal detects whether there is pilot PN information that can be an active set from the mobile communication terminal when the call connection with the incoming mobile communication terminal (S501).

When the mobile communication terminal detects a pilot PN that can be an active set, the mobile terminal generates a pilot strength measurement message (PSMM) including the pilot PN that can be an active set, and transmits it to the mobile communication system (S502).

The mobile communication terminal receives a handoff indication message (HDM) including a pilot search window size (PSWS) and information including a pilot PN number (N) to be added to an active set from the mobile communication system. (S503). Thereafter, the mobile communication terminal compares the pilot PN number (N) to be added to the active set with a threshold (S504). Here, the threshold is preferably about 3 to 5 in consideration of the number of fingers used in the terminal.

If the number of pilot PNs (N) to be added to the active set is greater than or equal to the threshold, the mobile communication terminal compares the pilot search window size (PSWS) included in the handoff indication message (HDM) with the previously set pilot search window size (PSWS). (S505). The comparison step S505 is for determining whether the mobile communication system has set a pilot search window size suitable for the wireless environment of the terminal. As a result of the check, the mobile communication terminal determines that the pilot search window size is previously set when the pilot search window size PSWS included in the handoff indication message HDM is equal to or larger than the previously set pilot search window size PSWS. One step smaller than the window size is set (S506). The mobile communication terminal typically has 16 pilot search window sizes, and can be implemented to have a look-up table in which the corresponding window size is determined for each step.

Thereafter, the mobile communication terminal transmits a handoff completion message (HCM: Handoff Completion Message) including pilot PN information currently included in the active set to the mobile communication network (S507). Thereafter, the mobile communication terminal checks whether the call connection is terminated (S508) and repeatedly detects whether there is pilot PN information that can be an active set if the call connection is not terminated. Otherwise, the mobile terminal terminates the system.

As described above, the mobile communication terminal of the present invention can be configured to dynamically set the pilot search window size according to the wireless environment, so that the handoff operation can be performed more smoothly in an area where several pilot PNs having similar electric field strengths are received. That has a useful effect.

Although the present invention has been described with reference to the accompanying drawings, it will be apparent to those skilled in the art that many various obvious modifications are possible without departing from the scope of the invention from this description. Therefore, it should be interpreted by the claims described to include many such variations.

Claims (4)

An operation unit which receives a user operation command; A wireless communication unit transmitting and receiving a wireless signal with a mobile communication network through an antenna; A call processing unit which processes a call connection with a mobile communication network through the wireless communication unit according to a call processing protocol when a call connection command is input from the operation unit; A pilot monitoring unit for monitoring whether a pilot PN that can be an active set among a plurality of base station pilot PNs input from the wireless communication unit when a call connection signal is input from the call processor; When the pilot PN, which can be an active set, is input from the pilot monitoring unit, a pilot strength measurement message (PSMM) including a pilot PN information including the pilot PN information, which can be an active set, is transmitted to a mobile communication network (PSMM). A processing unit; A search window size setting unit for setting a pilot search window size based on pilot PN information and a pilot search window size to be added to an active set inputted from a mobile communication network through the wireless communication unit; Mobile communication terminal comprising a. The apparatus of claim 1, wherein the search window size setting unit comprises: If the number of pilot PNs to add to the active set is greater than or equal to a threshold and the input pilot search window size is equal to or larger than the previously set pilot search window size, the pilot search window size is one step smaller than the previously set pilot search window size. A mobile communication terminal, characterized in that the setting to a predetermined window size. In a method for dynamically setting a pilot search window size according to a wireless environment in a mobile communication terminal, Detecting whether there is a pilot PN that can be an active set among the plurality of base station pilot PNs; Generating a pilot strength measurement message (PSMM) and transmitting it to a mobile communication network when a pilot PN capable of being an active set is detected; Receiving a handoff indication message (HDM) including pilot PN information to be added to the active set and a pilot search window size; Setting a pilot search window size based on pilot PN information to be added to the active set and a pilot search window size; Pilot search window size setting method comprising a. 4. The method of claim 3, wherein setting the pilot search window size comprises: If the number of pilot PNs to add to the active set is greater than or equal to a threshold and the input pilot search window size is equal to or larger than the previously set pilot search window size, the pilot search window size is one step smaller than the previously set pilot search window size. Pilot search window size setting method characterized in that the set to a fixed window size.

Images