KR100265421B1 - Apparatus for preventing a hard handoff between frequencies of cdma communication system - Google Patents

Abstract

PURPOSE: A device of preventing hard handoff between frequencies on a digital CDMA wireless communications system is provided to allow frequencies of multiple base stations to share channel elements. CONSTITUTION: In the device of preventing hard handoff, each channel element(1-5,11-13,16-18,21) is able to distribute frequencies and process digital signals. Synthesizers(6,14,19) synthesize output signals from the channel elements(1-5,11-13,16-18,21) which passed a path set by a transmission path setter(22). Transmitters(8,15,20) converts the synthesized signals into high frequency signals. A linear amplifier(10) amplifies the converted high frequency signals and sends the signals out through the antenna. Receivers(9,27,28) separate input signals corresponding to their frequencies. Distributors(7,25,26) distribute the separated signals. A receiving path setter(23) supplies the distributed signals to each channel element. Each channel element(17,21,18) then processes the received signal in digital.

Description

Prevention of hard handoff between frequencies in digital code division multiple access mobile communication system {APPARATUS FOR PREVENTING A HARD HANDOFF BETWEEN FREQUENCIES OF CDMA COMMUNICATION SYSTEM}

The present invention is to provide a method of efficiently using the hardware resources of the base station when the need for the call channel is different between base stations when providing a mobile communication service employing a digital code division multiple access (CDMA) scheme, in particular, different frequencies installed in the base station An apparatus for preventing inter-frequency hard handoff in a digital code division multiple access mobile communication system for jointly using one base station and thus preventing occurrence of inter-frequency hard handoff.

In the code division multiple access system, a plurality of channels distinguished by codes within one frequency are used. In a base station, a forward link toward a mobile station includes one pilot channel, a sink channel, a plurality of paging channels, and a call channel. Where the pilot channel transmits information identifying the location of the terminal at the mobile station and identifying the base station that the terminal is included in, wherein coverage of the base station is determined by the ratio of chip energy to interference density of the pilot channel.

On the other hand, one base station is provided with one or more frequencies by predicting the call demand of the users in advance in the expected coverage of the base station. Usually one frequency can accommodate 20 call requests at the same time. Therefore, the call capacity of the base station system is determined by the installed frequency, and if the expected call demand difference between the base stations is significantly different, the frequency configuration installed between the base stations is changed to reduce the base station equipment cost.

At this time, in a mobile communication system such as cellular, personal mobile communication, mobile satellite communication, or future land mobile communication, handoff is performed to maintain a call when the mobile station crosses a boundary between base stations. On the other hand, in the case of a mobile communication system using digital code division multiple access, if the number and frequency of the use frequency between the two base stations are the same, the call can be continued without a separate process by the function of soft handoff, In the case where the frequency of use between base stations is different, frequency switching is required when the mobile station, which has been talking on a specific frequency, moves to an area of another base station where the frequency is not installed, and this is called hard handoff between frequencies.

In the conventional digital code division multiple access system, the base station to which the handoff target is handed off is installed in the current base station to which the mobile station belongs but is not installed in the base station to which the handoff target is applied. By configuring a pseudo frequency or pilot beacon consisting of a channel, part or all of the paging channel, and configuring the frequency in the same manner as the current base station, the mobile station is configured to acquire information of the base station to be handed off.

Hereinafter, the term "pseudo frequency" will be used in the sense of including a pilot beacon or a dummy pilot transmitting only a pilot channel, and a pseudo frequency including some or all of a pilot channel, a sink channel, and a paging channel.

1 is a block diagram of a system for realizing the generation of a pseudo frequency that supports hard handoff between frequencies resulting from differences in frequency configurations between conventional base stations.

In general, the frequency configuration of the forward link includes a talk frequency having a talk channel and a pseudo frequency without a channel. In the case of a talk frequency, a pilot signal A ₁ , a sync signal B ₁ , and a paging signal C _{1 are used.} ) And the call channel signal (D ₁ -D _N ) are combined in the synthesizer (6) after all digital signal processing including frequency spreading in the channel elements (1-5), respectively, and then high frequency in the transmitter (8). The signal is converted into a signal F ₁ and then amplified in the linear amplifier 10 and supplied to an antenna (not shown).

Here, for smooth inter-frequency hard handoff, the base station should have N-1 pseudo frequencies in addition to one talk frequency when it is assumed that the neighboring base stations maintain the talk frequency up to N. The pseudo frequency has channel elements 11-13 for processing the pilot signal A ₂ , the sync signal B ₂ , and the paging signal C ₂ , and these channel elements 11-13 are channels of the talk frequency. In the same manner as in the synthesizer 14 and then converted into a high frequency signal F ₂ at the transmitter 15, and then amplified together with the high frequency signal F ₁ at the talk frequency to the antenna at the line amplifier amplifier 10. Supplied. In addition, the channel elements 16-18 correspond to the N−1 th pseudo frequencies, which are also summed in the synthesizer 19 and then converted to a high frequency signal F ₁ in the transmitter 20, and then a linear amplifier ( 10) amplified together with the high frequency signal F ₁ and the pseudo frequency F ₂ of the call frequency.

On the other hand, the frequency of the reverse link from the mobile station to the base station is composed of only the frequency (F ₁ ') corresponding to the talk frequency (F ₁ ) of the forward link, the signal sent from the mobile station is a receiver (9) in the antenna not shown Is sent to the channel elements 4-5 for the corresponding communication channels D ₁ -D _N via the distributor 7.

Such a conventional system installs a pseudo frequency (F ₂ ,..., F _N ) at a base station to be handoff that can satisfy call requirements by installing only one talk frequency (F ₁ ), Although the frequency is incompletely installed, the hard handoff between the frequencies is smoothly performed due to the difference in the frequency configuration between the base stations.However, due to the nature of the code division multiple access system that dynamically controls the transmission output of the talk frequency (F ₁ ), the talk frequency (F) _There is a problem of how to match the coverage of ₁ ) with the coverage of pseudo frequencies (F ₂ , ...., F _N ) and handoff because it is fundamentally impossible to predict the call demand for the used communication frequencies. There are problems such as reassigning the assigned mobile station to which communication frequency, and it only increases the probability of the call being disconnected when performing frequency hard handoff. But there was a problem that reduces the call quality and transmission delays.

Accordingly, the present invention is to solve such a conventional problem, an object of the present invention is to install the same number of talk frequencies in all base stations, all call frequencies installed in the base station with a low call demand by using a common channel element In addition, the present invention provides a device for preventing hard handoff between frequencies in a digital code division multiple access mobile communication system capable of preventing hard handoff between frequencies.

In order to achieve the above object, the present invention provides a device for preventing hard handoff between frequencies in a mobile communication system of a digital division multiple access method including a plurality of channel elements for processing digital signals of a call channel using a plurality of talk frequencies. A transmission path setting is connected between a plurality of channel elements and a synthesizer for synthesizing output information of the plurality of channel elements, and switching to supply output information of each channel element to a transmitter having a pre-allocated call frequency. And a divider for distributing the received signal of the receiver to channel elements of the corresponding communication frequency and a receiving path setter for switching to supply the received signal to the corresponding channel element.

Fig. 1 shows a configuration of a base station for executing a conventional hard handoff.

Figure 2 shows the configuration of a base station to which the present invention is applied.

* Explanation of symbols for main parts of the drawings

1-5, 11-13, 16-18, 21: Channel elements 6,14,19: Synthesizer

7,25,26: Splitter 8,15,20: Transmitter

9,27,28: receiver 10: linear amplifier

22: transmission path setter 23: reception path setter

24: Channel element pool (P00L)

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a system in which all frequencies installed in a base station to which the present invention is applied commonly use channel elements. That is, the present invention excludes the use of pseudo frequencies and is configured to jointly use the talk frequency using channel elements provided with the same talk frequency between neighboring base stations. By setting up the same talk frequency, it is possible to prevent hard handoff between frequencies.

In Fig. 2, a plurality of channel elements 1-5, 11-13, 16-18, 21 corresponding to all talk frequencies, a transmission path setter 22, a synthesizer 6, 14, 19, a transmitter 8 15, 20, and a forward link consisting of a linear amplifier 10, a receiver 9, 27, 28, a divider 7, 25, 28, a receive path setter 23, and a channel element 17, 21,18).

Each channel element 1-5, 11-13, 16 receiving the pilot signal A ₁ , the sync signal B ₁ , the paging signal C ₁ and the call channel signal D ₁ , D ₂ , D _N. 18 and 21 are provided to perform frequency spreading and digital signal processing, and channel elements 1-5, 11-13, 16-18, 21 passed through a path established through the transmission path setter 22. A synthesizer (6, 14, 19) receiving the output signal of < RTI ID = 0.0 >

Transmitters 8, 15, and 20 receiving the synthesized signal are provided to convert the synthesized signal into a high frequency signal, and the linear amplifier 10 receiving the converted high frequency signal amplifies the high frequency signal and outputs an amplified signal. And to output this amplified signal through the antenna.

On the other hand, the receivers 9, 27 and 28 which have received the received signal through the antenna are provided to separate the received signal into the corresponding frequency signal, and the distributors 7, 25 and 26 which have received this frequency signal have received this frequency signal. Distribution is performed so that a distribution signal is output. The distribution path setting unit 23 receiving the distribution signal is provided so that the distribution signal is supplied to a predetermined channel element, and the channel elements 17, 21, and 18 receiving the distribution signal are configured to digitally process the distribution signal. It is provided.

Referring to the operation of the present invention configured as described above is as follows. That is, in the case of the forward link, the pilot signal Al, the sync signal Bl, the paging signal C1, and the call channel signals D ₁ , D ₂ , and D _N are each channel elements of the channel element pool 24. 1-5, 11-13, 16-18, and 21 after the digital signal processing including the frequency spread is supplied to the transmission path setter 22.

Through this channel element, the digital processing signal is supplied to each synthesizer 6, 14, 19 assigned to the corresponding frequency according to the path set by the transmission path setter 22, and then combined, and then the transmitter 8, ₁₅ and ₂₀ are converted into the corresponding high frequency signals F ₁ , F ₂ , and F _N , and then amplified by the linear amplifier 10 and supplied to an antenna (not shown).

On the other hand, in the reverse link, the signal transmitted from the mobile station is sent from the antenna (not shown) to the receivers 9, 27, 28, and corresponding to the frequencies F ₁ ′, F ₂ ′, F _N ′ corresponding to the communication frequencies of the forward link. After splitting into the corresponding frequency signal, it is distributed through the divider (7, 25, 26) and through the receive path setter (23) to the corresponding call channel (D ₁ , D ₂ , D _N ) of the channel element pool (24). Is sent to the channel elements 17, 21 and 18.

Here, the transmission path setter 22 supplies the output information of the channel elements 17, 21, and 18 to the transmitters 8, 15, and 20 of the talk frequencies F ₁ , F ₂ , and F _N , which are pre-assigned. The reception path setter 23 switches so that the signal transmitted from the receivers 9, 27, 28 is supplied to the corresponding channel elements 17, 21, 18. Therefore, the base station efficiently uses hardware resources.

As described above, according to the present invention, a transmission path setter and a reception path setter serving as a switching function between a channel element and a transmitter and a receiver are installed to selectively use all channel frequencies installed in each base station as necessary. Therefore, even when call demands between neighboring base stations are different, the same frequency configuration can be maintained between neighboring base stations, thereby obtaining an effect of preventing hard handoff.

While the invention has been shown and described with respect to certain preferred embodiments thereof, the invention is not limited to the embodiments described above, but in the field to which the invention pertains without departing from the spirit of the invention as claimed in the claims. Any person with ordinary knowledge will be able to make various changes.

Claims (1)

(Correction) A digital division multiple access mobile communication system including a plurality of channel elements for processing digital signals of a talk channel using a plurality of talk frequencies, the output of the plurality of channel elements and the plurality of channel elements. A transmission path setter connected between the synthesizers for synthesizing the information, and switching the output information of each channel element to be supplied to a transmitter of a pre-allocated call frequency; And a divider for distributing a received signal of a receiver to channel elements of a corresponding communication frequency and a receiving path setter for switching the received signal to be supplied to the corresponding channel element. A device for preventing hard handoff between frequencies in a multiple access mobile communication system.

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