CN101170347B - Method for coordinating inter-cell interference in OFDM access system - Google Patents

Abstract

The invention discloses a method for coordinating disturbance among cells in an orthogonal frequency division multiplexing (OFDM) access system, which includes the following steps: a media access control layer determines the sign region scope of an overlapping and coverage area and an non-overlapping and coverage area distributed to each cell requiring the disturbance coordination among the cells requiring the disturbance coordination, according to the overlapping relationship among the cells requiring the disturbance coordination as well as the carrier wave reflection way and the sub-channels that can be used by access terminals in the cells requiring the disturbance coordination; a cell base station determines whether the access terminal is in the overlapping coverage area according to the feedback information of the access terminal which is accessed therein; if the access terminal is in the overlapping coverage area, the cell base station informs the access terminal of using the usable carrier wave reflection way, and of receiving signals in the sign region scope distributed to the cell in the media access control layer. The invention is applicable to all terminals.

Description

The method that is used for the coordination presence of intercell interference of OFDM access system

Technical field

The present invention relates to the communications field, relate in particular to a kind of method that is used for the coordination presence of intercell interference of OFDM access system.

Background technology

Overlapping covered terminal can receive the downlink frame signal that send each sub-district between the sub-district.When these sub-districts employings were sent with frequency band signals, for the terminal, the signal that the cell base station that is not linked into sends was a kind of interference.As shown in Figure 1, three base station cells that drawn among the figure are respectively A cell base station, B cell base station and C cell base station.Wherein, terminal MS 1 is linked into the B cell base station, and the signal of A cell base station transmission is a kind of interference signal for terminal MS 1 so.

The method of existing head it off is partial frequency multiplexing (FractionalFrequency Reuse is called for short a FFR) method, and promptly the transmit frame of different districts takies different frequency ranges.As shown in Figure 2; A cell base station, B cell base station, C cell base station in order to utilize bandwidth to greatest extent, send the down link frame signal of full frequency band F1+F2+F3 in Non-overlapping Domain, because each sub-district Non-overlapping Domain signal strength signal intensity is different; Even, can not produce interference with frequently yet.For the overlapping region, the A cell base station is given the terminal transmitting section frequency range F1 that is linked into the overlapping region, and the B cell base station is given the terminal transmitting section frequency range F2 that is linked into the overlapping region, and the C cell base station is given the terminal transmitting section F3 that is linked into the overlapping region.Like this, because the descending sub frame of A, B, the transmission in the overlapping region of C cell base station takies different frequency ranges, insert the terminal of A cell base station and can not go demodulation to be in the downlink frame signal of frequency range F2 or F3, each sub-district is sent between downlink frame and can not produced interference like this.

But the prerequisite of this solution is, the downlink frame of receiving unit frequency range is supported at the terminal, and promptly the terminal is supported in and carries out the subcarrier de mapping in the parton channel.In present communication field; The OFDM of a lot of producers inserts (Orthogonal Frequency DivisionMultiple Access; Be called for short OFDMA) system terminal not support sector divide the carrier wave in the subchannel to separate mapping, and can only support the carrier wave in whole subchannels to separate mapping.When these terminals were in the overlapping region, the base station just can't adopt FFR to coordinate to eliminate the interference between the different base station transmit frame.Like this, under fixing frequency range, for only supporting whole subchannel intercarriers to separate the terminal of mapping, the down link signal interference that how to suppress between the sub-district is the problem that the present invention need solve.

Summary of the invention

To be in the down link signal that also can coordinate to eliminate between the sub-district in the terminal of only supporting whole subchannel intercarriers to separate mapping of sub-district in overlapping covered and to disturb in order to make, the present invention proposes a kind of method of the new inhibition presence of intercell interference that is used for OFDM access system.

According to the method that is used for the coordination presence of intercell interference of OFDM access system of the present invention; May further comprise the steps: S302; Media access control layer is the overlapping covering relation between the sub-district of coordinates interference and need the carrier wave that can use that accesses terminal in the sub-district of coordinates interference to separate mapping mode and subchannel as required, and confirming is needing overlapping covered and non-overlapped overlay area between the sub-district of coordinates interference to distribute to the symbol area scope of the sub-district that respectively needs coordinates interference; S304, cell base station be according to the feedback information that accesses terminal that inserts it, confirms to access terminal whether to be in overlapping covered between the sub-district that needs coordinates interference; And S306, be in overlapping coveredly if access terminal, then cell base station notice accesses terminal and uses its carrier wave that can use to separate mapping mode, in media access control layer is distributed to the symbol area scope of this sub-district, receives signal.

Wherein, need definite process of the sub-district of coordinates interference may further comprise the steps: cell base station is measured the overlay area of himself, and gives media access control layer with reporting measuring result; Media access control layer is confirmed the overlapping covering relation between each sub-district according to the measurement result that cell base station reports, and confirms the sub-district of needs coordinates interference according to the overlapping covering relation between each sub-district.Wherein, each cell base station takies different symbol area scopes to being in the overlapping covered transmission signal that accesses terminal.

Wherein, Cell base station is through frame control head (frame control header; Being called for short FCH) message informing its carrier wave that can use that accesses terminal separates mapping mode; Insert the symbol area scope at the signal place that needs reception end through downlink map (DownLink Map is called for short DLMAP) message informing.

Wherein, In the OFDMA system; The carrier wave mapping mode mainly contains following several kinds: use parton channel (partial usage of subchannels is called for short PUSC), optional PUSC arrangement mode (optional permutations of PUSC is called for short OptionalPUSC), use whole subchannels (full usage of subchannels; Be called for short FUSC) and self adaptation arrangement mode (adaptive modulation and coding is called for short AMC).

Wherein, Confirm in the overlapping covered symbol area scope of distributing to the sub-district that needs coordinates interference and the symbol area scope of confirming to distribute to the sub-district that needs coordinates interference, can realize through the mode of zone (territory) division in the downlink frame in the OFDMA system in non-overlapped overlay area.

The present invention is different with the FFR method of partial frequency multiplexing; The FFR method of partial frequency multiplexing requires the terminal must support sector to divide the subchannel intercarrier to separate to shine upon to receive the downlink frame signal; Promptly must support the PUSC arrangement mode; And the terminal that proposes to be directed against when of the present invention is not support the PUSC arrangement mode, and only supports Optional PUSC and FUSC and AMC arrangement mode etc.Just only support whole subchannel intercarriers to separate mapping mode, support sector does not divide the subchannel intercarrier to separate mapping mode.But method described in the present invention goes for all terminals, no matter the terminal supports whole subchannel intercarriers to separate mapping, or support sector divides subchannel intercarrier is separated mapping, or the both supports.

Description of drawings

Accompanying drawing described herein is used to provide further understanding of the present invention, constitutes the application's a part, and illustrative examples of the present invention and explanation thereof are used to explain the present invention, do not constitute improper qualification of the present invention.In the accompanying drawings:

Fig. 1 is that cell coverage area disturbs sketch map;

Fig. 2 is a FFR coordinating district interference method sketch map;

Fig. 3 is the flow chart according to the method between the coordination area interference of the embodiment of the invention;

Fig. 4 is the sketch map of the different symbol area (time period) of overlapping covered division in the sub-district how;

Fig. 5 is the sketch map that sub-district A has adopted the embodiment of the transmit frame behind the time-division disturbance coordination method;

Fig. 6 is the sketch map that sub-district B has adopted the transmit frame embodiment behind the time-division disturbance coordination method; And

Fig. 7 is the sketch map that sub-district C has adopted the transmit frame embodiment behind the time-division disturbance coordination method.

Embodiment

With reference to accompanying drawing, specify embodiment of the present invention below.

With reference to figure 3, explain according to the method between the coordination area interference of the embodiment of the invention.As shown in Figure 3, this method may further comprise the steps:

S302, each cell base station is measured the overlay area of this base station, confirms non-overlapped overlay area and overlapping covered, and report measurement information is given media access control layer (MediumAccess Control is called for short MAC).Mac layer is confirmed the overlapping covering relation between each sub-district according to the metrical information that each cell base station reports, thereby need to confirm the base station of coordinates interference.For example, as shown in Figure 1, the base station that needs coordinates interference is A cell base station, B cell base station and C cell base station.Mac layer is confirmed in the overlapping covered symbol area scope of distributing to the sub-district that needs coordinates interference, and is distributed to the symbol area scope of the sub-district that needs coordinates interference in non-overlapped overlay area.Suppose that the symbol lengths of descending sub frame is 31 symbols.The prefix signal (24 symbols) of a descending sub frame symbol is divided into first zone that each coordinates the sub-district.Send FCH and DLMAP information among first zone.Coordinating the sub-district has 3, therefore needs to divide 4 zone zones.Wherein, the data at the terminal, overlapping region of A cell base station are placed among second zone, and the data at the terminal, overlapping region of B cell base station are placed among the 3rd zone, and the data at the terminal, overlapping region of C cell base station are placed among the 4th zone.First zone takies 25 symbols, and promptly symbol 0～24, adopts full subchannel intercarrier arrangement mode or parton channel intercarrier arrangement mode.Second zone takies 2 symbols, and promptly symbol 25～26, adopts full subchannel intercarrier arrangement mode or parton channel intercarrier arrangement mode.The 3rd zone takies 2 symbols, and promptly symbol 27～28, adopts full subchannel arrangement mode of PUSC or parton channel intercarrier arrangement mode.The 4th zone takies 2 symbols, and promptly symbol 29～30, adopts full subchannel arrangement mode of PUSC or parton channel intercarrier arrangement mode (the distinct symbols dividing region in the sub-district is overlapping covered is as shown in Figure 4).The A cell base station can not use the 3rd zone and the 4th zone.The B cell base station can not use second zone and the 4th zone.The C cell base station can not use second zone and the 3rd zone.

S304 according to the feedback information that accesses terminal that is linked into cell base station, confirms that each position that accesses terminal is in non-overlapped overlay area or is in overlapping covered.

S306 is in accessing terminal of non-overlapped overlay area, is not coordinating within the control range between the sub-district.For being in overlapping covered accessing terminal, cell base station uses FCH message to inform that it uses its carrier wave that can use to separate mapping mode and receives signal, uses DLMAP message to inform that it receives data in the symbol area of coordinating.For example; The A cell base station is told accessing terminal in the overlapping area of coverage that is linked into the A sub-district in the DLMAP of its transmission message; Its data are placed in the symbol area at second zone place; The B cell base station is told accessing terminal in the overlapping area of coverage that is linked into the B sub-district in the DLMAP of its transmission message; Its data are placed in the symbol area at the 3rd zone place, and the C cell base station is told accessing terminal in the overlapping area of coverage that is linked into the C sub-district in the DLMAP of its transmission message, and its data are placed in the symbol area at the 4th zone place (sub-district A, B, C have adopted the embodiment of the transmit frame behind the time-division disturbance coordination method as shown in Figs. 5 to 7).

Wherein, the transmission signal of different districts has taken different symbol areas.Can use the mode of dividing zone in the OFDMA system to divide different symbol areas.Wherein, zone is a set that takies a plurality of symbols of these all subchannels of sub-district.Like this; The descending transmission signal of different districts arrives with different symbol times overlapping covered; Only need be thereby access terminal through in the transmission signal code time of access base station, resolving; Receive data and get final product, in other symbol time, do not resolve the reception data, the signal of other sub-district transmission just can not produce interference like this.

The above is merely embodiments of the invention, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.All within spirit of the present invention and principle, any modification of being done, be equal to replacement, improvement etc., all should be included within the claim scope of the present invention.

Claims (5)

1. a method that is used for the coordination presence of intercell interference of OFDM access system is characterized in that, may further comprise the steps:

The media access control layer overlapping covering relation between the sub-district of coordinates interference and said as required needs the carrier wave that can use that accesses terminal in the sub-district of coordinates interference to separate mapping mode and subchannel; Confirm that the overlapping covered and non-overlapped overlay area between the said sub-district that needs coordinates interference distributes to each said symbol area scope that needs the sub-district of coordinates interference; Wherein, use the territory in the OFDM access system to divide the said overlapping covered symbol area scope and the symbol area scope of said non-overlapped overlay area;

Cell base station is according to the feedback information that accesses terminal that inserts it, confirm said access terminal whether be in said overlapping covered; And

If said accessing terminal is in said overlapping coveredly, then said cell base station notifies said accessing terminal to use its carrier wave that can use to separate mapping mode, in said media access control layer is distributed to the symbol area scope of this sub-district, receives signal.

2. method according to claim 1 is characterized in that, the said definite process of the sub-district of coordinates interference that needs may further comprise the steps:

Said cell base station is measured the overlay area of himself, and gives said media access control layer with reporting measuring result;

Said media access control layer is confirmed the overlapping covering relation between each sub-district according to the measurement result that said cell base station reports, and confirms the sub-district of said needs coordinates interference according to the overlapping covering relation between said each sub-district.

3. method according to claim 1 is characterized in that, each said cell base station takies different symbol area scopes to being in the said overlapping covered transmission signal that accesses terminal.

4. method according to claim 3 is characterized in that, said cell base station is separated mapping mode through said its carrier wave that can use that accesses terminal of frame control head message informing.

5. method according to claim 4 is characterized in that, said cell base station needs the symbol area scope at the signal of reception place through said the accessing terminal of downlink map message informing.

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