CN101296473A - Community boundary solution method based on TDD uplink - Google Patents

Abstract

Disclosed is a solving method for cell boundary based on a TDD uplink. The solving method of the invention comprises the following steps: a system reasonably allocates the time resource of a TDD system according to the capacity requirements of the uplink and downlink; RAC groups the users at boundary; RAC allocates the same time and frequency unit for all users in each group; RAC allocates resource for other users. After the process of the invention, the same frequency transmission of the uplink can be solved, and the resource of the downlink in TDD can be improved.

Description

Community boundary solution method based on the TDD up link

Technical field

The present invention relates to cordless communication network, particularly based on the community boundary solution method of TDD up link based on cellular cell.

Background technology

As everyone knows, in cell system, be that each sub-district particularly border district of each sub-district will be subjected to the co-channel interference of adjacent cells inevitably under 1 the precondition in frequency reuse based on OFDMA.Thereby the transmission rate of being not only the user who is in cell edge is subjected to great restriction, and the throughput of system will significantly reduce.Therefore says, face area interference and be one of main factor that influences based on the cell system performance of OFDM/OFDMA technology.

As shown in Figure 1, the cell splitting that base station is administered is 3 sectors, makes it be respectively Serving cell (Serving Cell), neighbor cell 1 (Adjacent Cell 1) and neighbor cell 2 (AdjacentCell 2); The sector relative with Serving cell then is defined as interfered cell 1 (Interfering Cell 1) and interfered cell 2 (Interfering Cell 2) in other adjacent cells.Terminal UE 1 is the user at Serving cell edge, and UE2 and UE3 are respectively and use and the user UE1 same sub-channel, in interfered cell 1 and the interfered cell 2, and then this user (UE1) will be subjected to the co-channel interference of neighbor cell and interfered cell.That is to say, generally can be expressed as at receiving terminal user's baseband receiving signals r (t)

$r\left(t\right)=s\left(t\right)+\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{I}_m\left(t\right)---\left(1\right)$

Wherein s (t) sends the signal of user UE1 to for Serving cell, and I _m(t) for coming from the co-channel interference signal of neighbor cell and interfered cell, the number of M for disturbing.Be not difficult to find out that thus the area interference of facing that is positioned at that the user of cell edge is subjected to is great (under the condition that each cell transmit power equates, the signal of user's receiving terminal and interference-to-noise ratio (SINR) is very low, about the poorest situation even have only-3dB).And then having caused user's receptivity rapid deterioration, the throughput of system is descended the degradation negative results rapidly.Given this, cell-edge performance enhancing (CEPE) problem is based on the problem that very is worth research and solves in the system of OFDM/OFDMA.

At present, the CEPE problem of OFDM/OFDMA system is the research focus such as standardization bodies such as 3GPP LTE, WiMAX and WiBro.In current agreement or standard, also there is not clear and definite, final solution.

At present, main several Typical solutions are

◆ with Qualcomm company is 2/3 principle that representative proposes; That is, for any one T/F unit, can have two sub-districts to use simultaneously at most, like this, the repeat factor of frequency is probably about 2/3.The subject matter of this method is that the frequency reuse coefficient is low excessively.

◆ adjudicate principle with the soft mark that Huawei, Beijing University of Post ﹠ Telecommunication propose; By the use of soft mark, can be under the situation of system's intermediate part load, the repeat factor of frequency is about 0.7.The subject matter of this method is that the frequency reuse coefficient is low excessively.

◆ the scrambler principle; Utilize scrambler to distinguish different sub-districts and the user in the sub-district.The subject matter of this method is to realize complexity, too relies on the performance of scrambler in addition.

◆ " Virtual-MIMO " strategy that ETRI and Philips etc. propose; On descending the associating, three sub-districts send information, and each user carries out the reception of the spatial multiplexing mode among the MIMO then, and this strategy frequency reuse coefficient in theory is 1.The subject matter of this method is

Antenna number for base station and terminal use (MT) in this method of √ has requirement.If up link requires the antenna number in the base station to be greater than the antenna summation that equals all MT.On down link, the antenna number of MT is greater than the antenna number summation that equals all base stations

√ is on down link, and a MT will know the channel information of every other MT, and this is a very difficult thing implementing, so practicality will be subjected to bigger restriction.

Summary of the invention

The purpose of this invention is to provide a kind of community boundary solution method based on the TDD up link.

For achieving the above object, a kind of community boundary solution method based on the TDD up link comprises step:

A. system reasonably distributes according to the capacity requirement of the uplink downlink time resource to the TDD system;

B.RAC is that the user who is in the border divides into groups;

C.RAC distributes same T/F unit for all users in each group;

D. then, RAC carries out the distribution of resource for other users.

Through after the processing of the present invention, the same frequency sending that can solve up link; Improved the down-chain resource among the TDD simultaneously.

Description of drawings

Fig. 1 is the explanation of district's border issue;

Fig. 2 is the relations of distribution of time resource between up link and the down link in the DD system;

Fig. 3 is that the resource at BS of the present invention place is handled block diagram;

Fig. 4 is that block diagram is handled in the emission at MT of the present invention place;

Fig. 5 is that block diagram is handled in the reception of BS end of the present invention;

Fig. 6 is embodiments of the invention.

Embodiment

In general, solve the solution of considering down link in the method for cell boarder problem at present and account for the overwhelming majority, and consider the less of this problem from up link.And the main advantage in the up link is, as receiving terminal, the processing capacity that it is powerful and the availability of various information are undoubtedly useful for dealing with problems base station (BS).

Given this, purpose of the present invention just is, for the cell boarder problem proposes a kind of effective solution, this scheme is in the TDD system, for providing a kind of a plurality of user's (these user distributions are at cell edge) distributed associating, up link sends, utilize several BS of neighbor cell to carry out the reception of uniting then, thereby can promote the service efficiency of Radio Resource on the up link such as spatial reuse, array received etc.And then, on the basis of the uplink capacity that designs in advance, the line of demarcation of uplink and downlink can be shifted to ascender, thereby enlarge the time resource quantity on the down link, so just promote the capacity of down link, perhaps reduced the influence of cell boarder problem on the down link.This explanation as shown in Figure 2.

The present invention mainly is made of structures such as the resource allocation unit of the grouped element of user in TDD system resource allocation unit, data processing unit, Radio Access Controller (Radio Access Controller), the cell boarder, up link, radio frequency units.Main processing procedure of the present invention as shown in Figure 3.

301: system reasonably distributes according to the capacity requirement of the uplink downlink time resource to the TDD system.System can change over time to this distribution.

302:RAC is that the user who is in the border divides into groups according to certain strategy.Here said " being in the user on border " is meant that these users can adhere to different BS separately and manage.One of strategy of grouping carries out different groupings for the Processing Algorithm according to receiving terminal; The strategy of grouping two for the number of antennas sum according to the BS of all neighbor cells be greater than equal to divide into groups in all users' number of antennas sum.This grouping can be divided into a plurality of groups according to all number of users that are in cell boarder.

303:RAC is all these set of dispense resources.RAC need distribute same T/F unit for all users in each group.

304: then, RAC carries out the distribution of resource for other users.This distribution is as good as with traditional method of salary distribution.

Among the present invention, MT in the transmitting terminal processing procedure of up link as shown in Figure 4.

401:MT is to the pre-treatment of data; Processing such as this processing comprises the obtaining of information bit, encodes, interweaves, modulation

402:MT carries out the lift-launch of information, the orthogonal transform on the frequency spectrum, the lift-launch of OFDM symbol on time quantum according to the distribution of system (RAC) to the symbol after the modulation.

403:MT is to the reprocessing of data; This processing comprises loading, Waveform shaping processing of channel estimation symbol etc.;

404:RF handles; This processing comprises that mainly D/A handles and other radio frequency processing processes.

Among the present invention, the receiving terminal processing procedure of BS end as shown in Figure 5.

501: each BS carries out RF to be handled, and comprises the radio frequency processing of A/D etc.

502: the pre-treatment that each BS carries out data comprises that low frequency filtering, time synchronized, Frequency Synchronization, T/F processing such as cut apart.

The OFDM symbol that mixes on the same group that 503:BS will be in cell boundary users sends to RAC.

504:RAC selects suitable associating receiving algorithm according to grouping strategy, and the user profile of these mixing is separated.

Each user's that 505:RAC will separate information sends to the corresponding BS with this user.

506:BS comprises the acquisition of orthogonal transform, demodulation, deinterleaving, decoding and information bit to the reprocessing of data.

Fig. 6 has provided embodiments of the invention.

Three access points are arranged in the system, and AP1, AP2 and AP3 have 6 terminal uses at cell boarder, each user theaomni-directional transmission on up link.MT can be single antenna, can also be many antennas.We suppose that MT and BS are single antenna.In addition, MT1 and MT4 are managed by AP1, and MT2 and MT5 are managed by AP2, and MT3 and MT6 are managed by AP3.

System at first carries out the distribution of time resource for the uplink and downlink link of TDD.

RAC is that the user of cell boarder divides into groups in the system.MT1, MT2 and MT3 are divided into group 1, and MT4, MT5 and MT6 are divided into group 2, and the strategy of grouping is: one, the number of users of each group is adjacent number of cells; Two, the communication quality of each user uplink link is close.

RAC is group 1 and group 2 Resources allocation, the time-frequency resources that each set of dispense is same.Each MT carries out the message transmission of up link according to the resource allocation conditions of RAC then.

At receiving terminal, RAC can adopt V-BLAST and ARRAY PROCESSING algorithm.

It is pointed out that AP both can be traditional BS, also can be RS (Relay Station) just under study for action.

Claims (7)

1. community boundary solution method based on the TDD up link comprises step:

A. system reasonably distributes according to the capacity requirement of the uplink downlink time resource to the TDD system;

B.RAC is that the user who is in the border divides into groups;

C.RAC distributes same T/F unit for all users in each group;

D. then, RAC carries out the distribution of resource for other users.

2. method according to claim 1 is characterized in that the distribution among the described step a is to change over time.

3. method according to claim 1 is characterized in that carrying out different groupings according to the Processing Algorithm of receiving terminal in step b.

4. method according to claim 1 is characterized in that in step b, according to the number of antennas sum of the BS of all neighbor cells be greater than/equal divide into groups in all users' number of antennas sum divide into groups.

5. method according to claim 1 is characterized in that among the described step b, and " being in the user on border " is that these users can adhere to different BS separately and manage.

6. method according to claim 1 is characterized in that described user's transmitting terminal comprises:

MT carries out the lift-launch of information, the orthogonal transform on the frequency spectrum, the lift-launch of OFDM symbol on time quantum according to the distribution of RAC to the symbol after the modulation.

7. method according to claim 1 is characterized in that also comprising step:

The OFDM symbol that mixes on the same group that BS will be in cell boundary users sends to RAC;

RAC selects suitable associating receiving algorithm according to grouping strategy, and the user profile of these mixing is separated;

Each user's that RAC will separate information sends to the corresponding BS with this user.

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