CN101192860A - Update method for reference transmission power of relay station based on effective CINR - Google Patents

Abstract

The invention relates to a method for updating transmitting power of a relay station reference based on the active CINR feedback. The method comprises the following steps: a user station estimates the CINR (carrier to interference and noise ratio) and the channel gain through measuring the Preamble of the downlink to implement the calculation of the active CINR target value; the user station feeds back the ''active CINR'' target value to the base station, and the base station completes the update of the reference transmitting power. The invention has the advantage that the method can use the active CINR feedback mechanism provided by IEEE 802. 16e to achieve the renewal of reference transmitting power, ensure the compatibility with prior systems, and implement the compromise of improving the spectrum efficiency of the system and reducing the interference among the relay stations.

Description

Relay station reference transmit power update method based on effective CINR feedback

Technical field

The present invention relates to the multi-carrier communications systems of OFDMA, particularly the relay station reference transmit power update method of feeding back based on effective CINR.

Background technology

(for example: IEEE802.16e), the transmitting power that lacks down link is adjusted mechanism in traditional OFDM/OFDMA system.

For relay system, each relay station (RS) under same base station (BS) can send the subscriber board in its overlay area (MS) simultaneously.In order to improve the availability of frequency spectrum, each RS adopts identical running time-frequency resource to send usually, that is to say that the multiplexing factor between each RS is 1.Because the multiplexing factor is 1, when having improved the availability of frequency spectrum, also can improve the interference level of system, the particularly interference level of the forntier region between the RS, need adjust for the down-link transmitting power of relay station, reduce the interference level of relay station covering overlapping area.

Summary of the invention

The purpose of this invention is to provide a kind of relay station reference transmit power update method based on effective CINR feedback.

For achieving the above object, a kind of relay station reference transmit power update method based on effective CINR feedback comprises step:

Subscriber board is by the measurement for downlink preamble symbol Preamble, and the estimation and the channel gain that obtain Signal Interference and Noise Ratio CINR are estimated, finish the calculating of " effectively CINR " desired value;

Subscriber board feeds back to the base station with " effectively CINR " desired value, and the renewal of reference transmit power is finished in the base station.

Effective CINR feedback mechanism that the present invention can utilize IEEE 802.16e to provide is realized the renewal of reference transmit power, keeps the compatibility with existing system.And realized improving the availability of frequency spectrum of system and reduce and disturb compromise between the two between relay station.

Description of drawings

Fig. 1 is based on the relay station reference transmit power of effective CINR feedback and upgrades block diagram;

Fig. 2 is based on the relay station reference transmit power of effective CINR feedback and upgrades flow chart;

Fig. 3 is based on the relay station reference transmit power of effective CINR feedback and upgrades flow chart.

Embodiment

The reference transmit power brief introduction:

P _r，n(T)＝P _r，n(T)_REF+ΔP _r，n(T)

P _{R, n}(T) _ REF is called reference transmit power, is the current transmit power reference value corresponding to target sir SIR/ carrier-in-interference noise ratio CINR.This value can satisfy active user's modulating-coding level (MCS) and BLER (block error rate) (BLER) requirement.At definite P _{R, n}(T) _ REF need consider path loss and shadow fading.P _{R, n}(T) _ REF is corresponding to the target regulated quantity of slow power control.

Δ P _{R, n}(T) be adjustment amount (increasing/subtract) amount information for k subscriber board (using n the subchannel at present) current transmit power in r the relay station.At definite Δ P _{R, n}(T) needs are considered the fluctuation of channel.Δ P _{R, n}(T) the target regulated quantity of controlling corresponding to fast power.

In the present invention, we have proposed a kind of reference transmit power (P that takes all factors into consideration system spectral efficiency and neighboring relay stations interference _{R, n}(T) _ REF) update method.Effective CINR (Effective CINR) feedback mechanism that this method can utilize IEEE802.16e to provide is realized the renewal of reference transmit power, keeps the compatibility with existing system.

The present invention includes following part, see Fig. 1 for details.

-base station transmitter: be used for sending information to relay station and/or subscriber board;

-base station power control module: be used to generate transmitting power control TPC (Transmission PowerCommand: emissive power control command), the transmitting power of control relay station, so that the functional module of disturbing between the minimizing relay station is one of related main functional modules of invention;

-relay station receiver: be used to receive information from base station transmitter;

-relay station transmitter: the subscriber board that is used in the relay station overlay area sends information;

-subscriber board " effectively CINR desired value " information gathering: be used to finish the collection of " effectively CINR desired value " information that subscriber board feeds back to;

-subscriber board receiver: be used to receive information from the relay station transmitter;

-effectively CINR measurements and calculations: being used to finish the measurement and the effectively calculating of CINR value of link-quality between subscriber board and the different relay stations (ownership relay station and neighboring relay stations), is to invent one of related main functional modules;

Workflow of the present invention, as Fig. 2 and/or shown in Figure 3 (be that relay station carries out the information gathering of " effectively CINR " desired value and is transmitted to the base station among Fig. 2; Be the information gathering that " effectively CINR " desired value is directly carried out in the base station among Fig. 3, the difference of the two is function implementor's difference in the 2nd step, and the former realizes that at relay station the latter realizes in the base station.)。

A) step 1: effectively CINR measurements and calculations

B) step 2: subscriber board " effectively CINR desired value " information gathering

C) step 3: reference transmit power P _{R, n}(T) REF upgrades

D) step 4: relay station is based on the P after upgrading _{R, n}(T) _ REF adjustment transmitting power P _{R, n}(T) method of " the relay station reference transmit power based on effective CINR feedback is upgraded " comprises following part:

1) step 1: effectively CINR measurements and calculations

At the subscriber board place, effectively CINR can calculate by the following method:

Wherein:

-CINR _MINAnd CINR _MAXIt is minimum and maximum CINR limit.They can be according to the transmission power limit [P of relay station _{R, kr_MIN}, P _{R, kr_MAX}] and the decision of the MCS level supported;

-CINR _{R, kr_preamble}It is the CINR value that subscriber board that subscriber board records records according to down link Preamble;

-G _{R, kr_preamble}It is the channel yield value that subscriber board that subscriber board records records according to down link Preamble; Can calculate according to following method:

$G_{r,\mathrm{kr}\_\mathrm{preamble}}\≅\frac{{\mathrm{PSSI}}_{r,\mathrm{kr}\_\mathrm{preamble}}}{P_{r,\mathrm{kr}\_\mathrm{preambe}}}$

-G _MAXBe according to CINR _MAXThe maximum channel gain that obtains, therefore:

Can be considered as normalized channel gain;

-0＜γ＜1st, the maximum downstream transmitting power ratio of Traffic Channel and Preamble.It is a system parameters.For example: γ=0.8 shows that the maximum transmission power of Traffic Channel can reach 80% Preamble channel energy.

-0≤α≤1 is used for the spectrum efficiency of balance sysmte and for the interference of adjacent relay station sub-district:

■ works as α=0:

CINR _{R, kr_target}=γ CINR _{R, kr_Preamble}, mean: CINR _{R, kr_target}Can keep and CINR _{R, kr_preamble}Fixed proportion (γ=0.8).

This situation is exactly the transmission means that the downlink traffic channel power of traditional OFDM/OFDMA remains unchanged.

■ works as α=1:

${\mathrm{CINR}}_{r,\mathrm{kr}\_t\arg \mathrm{et}}=\mathrm{\γ}\·{\mathrm{CINR}}_{r,\mathrm{kr}\_\mathrm{Preamble}}\·\frac{G_{r,\mathrm{kr}\_\mathrm{preamble}}}{G_{\mathrm{MAX}}}.$ If will

CINR _{R, kr_Preamble}G _{R, kr_preamble}Be considered as being similar to P _{R, preamble}And remain unchanged, then CINR _{R, kr_target}Can be considered as remaining unchanged, promptly equal:

In this case, the relay station presence of intercell interference has been reduced, but the spectrum utilization efficiency of system has reduced.

The selection of ■ α:

When we choose 0＜α＜1, just can and reduce in the availability of frequency spectrum that improves system disturb between relay station obtain between the two compromise.For example: get α=0.5

2) effectively CINR feedback and information gathering

CINR _{R, kr_target}Can be expressed as: CINR _{R, kr_target}(dB)=10log (CINR _Target)

In the IEEE802.16e standard, CINR _{R, kr_target}(dB) can be by with " report feedback message " (REP_RSP) or in the fast feedback channel (fast_feedback channel (CQICH)):

Effectively CINR territory (" Effective CINR field ") is set at: CINR _TargetCan realize.

Effectively CINR feedback and information gathering include participation and two kinds of situations of non-relay station participation of relay station:

-relay station participates in the forwarding of effective CINR information: as shown in Figure 2.At this moment, subscriber board is collected CINR report information ownership relay station " the effectively CINR desired value " of affiliated subscriber board by the ownership relay station, and is transmitted to base station BS.

-relay station does not participate in the forwarding of effective CINR information: as shown in Figure 3.At this moment, subscriber board is directly reported home base station BS with CINR information, under being collected by home base station " the effectively CINR desired value " of subscriber board

3) reference transmit power P _{R, n}(T) _ the REF renewal

The base station is adjusted and is upgraded reference transmit power according to effective CINR information of subscriber board feedback.

4) relay station is based on the P after upgrading _{R, n}(T) _ REF adjustment transmitting power P _{R, n}(T) relay station according to relay station based on the P after upgrading _{R, n}(T) _ REF adjustment transmitting power P _{R, n}(T).Thereby in the availability of frequency spectrum that improves system and reduce disturb between relay station obtain between the two compromise.

Claims (4)

1. relay station reference transmit power update method based on effective CINR feedback comprises step:

Subscriber board is by the measurement for downlink preamble symbol Preamble, and the estimation and the channel gain that obtain Signal Interference and Noise Ratio CINR are estimated, finish the calculating of " effectively CINR " desired value;

Subscriber board feeds back to the base station with " effectively CINR " desired value, and the renewal of reference transmit power is finished in the base station.

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

Relay station is used to collect " effectively CINR " desired value of subscriber board feedback, and is transmitted to the base station.

3. method according to claim 1 is characterized in that described effective CINR desired value calculates by the following method:

$\mathrm{CIN}{R}_{r,\mathrm{kr}\_t\arg \mathrm{et}}=\left\{\begin{array}{cc}{\mathrm{CINR}}_{\mathrm{MAX}}& \mathrm{whenCIN}{R}_{r,\mathrm{kr}\_t\arg \mathrm{et}}>{\mathrm{CINR}}_{\mathrm{MAX}}\\ \mathrm{\&gamma;}\&CenterDot;{\mathrm{CINR}}_{r,\mathrm{kr}\_\mathrm{preamble}}\&CenterDot;{\left(\frac{G_{r,\mathrm{kr}\_\mathrm{preamble}}}{G_{\mathrm{MAX}}}\right)}^{\mathrm{\&alpha;}}& \mathrm{whenCIN}{R}_{\mathrm{MIN}}<{\mathrm{CINR}}_{r,\mathrm{kr}\_t\arg \mathrm{et}}<{\mathrm{CINR}}_{\mathrm{MAX}}\\ {\mathrm{CINR}}_{\mathrm{MIN}}& \mathrm{whenCIN}{R}_{r,\mathrm{kr}\_t\arg \mathrm{et}}>{\mathrm{CINR}}_{\mathrm{MAX}}\end{array}\right.$

Wherein:

-CINR _MINAnd CINR _MAXIt is minimum and maximum CINR limit.They can be according to the transmission power limit [P of relay station _{R, kr_MIN}, P _{R, kr_MAX}] and the decision of the MCS level supported;

-CINR _{R, kr_preamble}It is the CINR value that subscriber board that subscriber board records records according to down link Preamble;

-G _{R, kr_preamble}It is the channel yield value that subscriber board that subscriber board records records according to down link Preamble; Can calculate according to following method:

$G_{r,\mathrm{kr}\_\mathrm{preamble}}\&cong;\frac{{\mathrm{RSSI}}_{r,\mathrm{kr}\_\mathrm{preamble}}}{P_{r,\mathrm{kr}\_\mathrm{preamble}}}$

-G _MAXBe according to CINR _MAXThe maximum channel gain that obtains, therefore:

Can be considered as normalized channel gain;

-0＜γ＜1st, the maximum downstream transmitting power ratio of Traffic Channel and Preamble.It is a system parameters;

-0≤α≤1 is used for the spectrum efficiency of balance sysmte and for the interference of adjacent relay station sub-district.

4. method according to claim 1, it is characterized in that in IEEE 802.16 compatible systems, by the effective CINR territory in " report feedback message " or the fast feedback channel being set at the feedback of " target CINR value " realization " effectively CINR " desired value.

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