CN101835254B - Orthogonal frequency division multiplexing access system and power control method thereof - Google Patents

Abstract

The invention relates to a power control method of an orthogonal frequency division multiplexing access system, comprising the following steps of: acquiring cell interference parameters, a maximum path loss difference threshold value and a minimum path loss difference threshold value sent by a service base station by a mobile terminal; determining a target signal interference noise ratio value of the mobile terminal according to the acquired cell interference parameters, the maximum path loss difference threshold value, the minimum path loss difference threshold value and base station signal path loss acquired by measurement by the mobile terminal; and selecting a modulation encoding manner by the mobile terminal according to the confirmed target signal interference noise ratio value and regulating the transmitting power thereof so as to carry out signal transmission. By applying the power control method, the problem that the current power control method can not cover all selective modulation encoding manners is solved, the power control efficiency can be improved under the condition of lesser expenses and the performance and the frequency spectrum utilization ratio of the system are further enhanced.

Description

OFDM access system and Poewr control method thereof

Technical field

The present invention relates to the communications field, relate in particular to a kind of OFDM access (OFDMA, Orthogonal Frequency Division Multiplexing Access) system and Poewr control method thereof.

Background technology

In wireless communication system, power control is a kind of important transmission quality control device, its objective is the problem that overcomes the wireless channel decline and disturb the communication performance decline that causes.Along with the variation of wireless channel decline or shade, base station or portable terminal are adjusted transmitting power, and compensate for channel changes the to received signal impact of quality, so power control also is a kind of link adaptation techniques.With OFDM (Orthogonal Frequency Division Multiplexing, OFDM) be in the B3G/4G system of core technology, such as LTE (Long term evolution, Long Term Evolution) and WiMAX (WorldInteroperability for Microwave Access, World Interoperability for Microwave Access, WiMax) in the system, OFDMA (Orthogonal Frequency Division Multiplexing Access, OFDM access) has been adopted as important access way.In the OFDMA technology, because the strict orthogonal property between subcarrier has overcome in the residential quarter problem of co-channel interference between the user.Yet under the identical networking mode, namely frequency duplex factor as one is 1 o'clock, and the interference of minizone remains the factor that suppresses power system capacity.Interference between different districts or the sector is called co-channel interference or common-channel interference (co-channelinterference).In a residential quarter, when certain portable terminal uses larger transmitting power transmitted signal, can produce interference effect to adjacent residential quarter, particularly the communication of neighbor cell edge customer be produced stronger interference, cause the covering at neighbor cell edge to reduce and volume lowering.

In the prior art, a kind of power control algorithm is to determine user's target SINR (Signal interference and noiseratio by the pilot power ratio of the signal of measuring serving BS signal and interference base station, Signal Interference and Noise Ratio), and then carry out power control, be called again difference path loss power back-off algorithm.As shown in Figure 1, the serving BS of portable terminal (MS, Mobile Station) is BS1, and disturbing (adjacent cell) base station is BS2.The arrival difference power that difference path loss power back-off algorithm is based on serving BS and interference base station carries out power control.

In difference path loss power back-off algorithm, be according to the poor Δ PL of the strongest adjacent base station interference signal path loss and serving BS signal path loss, determine target SINR value.PL is less when Δ, namely the path loss difference of high reject signal and serving BS is less, it is suitable to illustrate that interference base station and serving BS arrive the path loss of signal of portable terminal, the intensity of portable terminal transmit uplink signal arrival interference base station and serving BS also can be suitable, the degree that is the interference effect that produces of portable terminal is just larger, at this moment target setting SINR just should be less, selects the modulation coding mode of low order, is conducive to reduce disturb; Otherwise Δ PL is larger, and target setting SINR is just larger, is conducive to improve the throughput of system.

In actual applications, the access door limit value by target SINR value and various modulation coding modes compares, and determines that the user sends the modulation coding mode of data.It should be noted, (α is the path loss modifying factor to α, and value 0＜α＜1) and Δ PL are the key factors that affects each user's target SINR value, and the value of α to be system determine according to the compromise of network interferences level and cell throughout performance, in a residential quarter, fix.When α one timing, Δ PL and target SINR value consist of simple linear relationship.The selection of the influence of fluctuations user modulation coding mode of Δ PL, the dynamic range of Δ PL must have influence on the scope that modulation coding mode is selected.Parameter alpha be the dynamic range of Δ PL and modulation coding mode range of choice between the factor that zooms in or out of corresponding relation.Therefore the value of α is determining whether Δ PL is corresponding with modulation coding mode reasonable.Suppose Γ _(dB)(Γ _(dB)The target SINR value of cell edge, i.e. target SINR value when Δ PL=0) the access door limit value of corresponding lowest-order modulation coding mode, SINR _(dB) ^Max(SINR _(dB) ^MaxTarget SINR value for the maximum of appointment) the access door limit value of the modulation coding mode of corresponding high-order, the relation of target SINR value and path loss difference Δ PL as shown in Figures 2 and 3.The slope of Fig. 2 and Fig. 3 cathetus M1 is 1-α.In Fig. 2, the slope of straight line M1 is less, be that the α value is larger, the degree that is the path loss compensation is low, even thereby Δ PL is when reaching maximum, target SINR value does not reach the required SINR value of MCS (modulation coding mode) of high-order, causes community user just can not be selected one section modulation coding mode of high-order.Although M1 can cover target SINR value corresponding to all MCS among Fig. 3, yet its slope is unreasonable.In Fig. 3, the M1 slope is larger, and namely the α value is less, and the path loss degree of compensation is high, has just traveled through target SINR value corresponding to all MCS when Δ PL is low, so that community user uses the probability of high-order MCS to increase, produces the level rise that disturbs.Therefore, can find out, when the α value is unreasonable, can cause the cell edge annoyance level of cell spectrum efficient and generation unbalance, limit the excavation of the latent capacity of system, thereby limited the overall performance of system.

In sum, how to solve in the current power control method because the restriction of α value can not cover all optional modulation coding modes, thereby cause the unbalance problem of cell edge annoyance level of cell spectrum efficient and generation, become problem demanding prompt solution.

Summary of the invention

Technical problem to be solved by this invention provides a kind of Poewr control method and device of OFDM access system, has solved the problem that can not cover all optional modulation coding modes in the current power control method.

In order to address the above problem, the invention provides a kind of Poewr control method of OFDM access system, comprise,

Portable terminal obtains area interference parameter, maximum path loss difference threshold value and the minimum path loss difference threshold value that serving BS sends;

Described portable terminal is according to the described area interference parameter, maximum path loss difference threshold value and the minimum path loss difference threshold value that obtain and measure the base station signal path loss that obtains, and determines the echo signal interference noise ratio of this portable terminal;

Described portable terminal is selected modulation coding mode according to the described echo signal interference noise ratio of determining, and adjusts the emission that its transmitting power is carried out signal.

The present invention also provides a kind of OFDM access system, comprises base station and portable terminal,

Described base station is the serving BS of described portable terminal, comprises the parameter notification module, is used for area interference parameter, maximum path loss difference threshold value and minimum path loss difference threshold value are sent to described portable terminal;

Described portable terminal comprises computing module and signal emission module, wherein,

Described computing module, be used for receiving described area interference parameter, maximum path loss difference threshold value and the minimum path loss difference threshold value of described base station transmission and measure the base station signal path loss that obtains, determine the echo signal interference noise ratio of described portable terminal, and send to signal emission module;

Described signal emission module is used for selecting modulation coding mode according to the described echo signal interference noise ratio that the described computing module that receives sends, and adjusts transmitting power and carry out the emission of signal.

Compared with prior art, use the present invention, can solve the problem that can not cover all optional modulation coding modes that exists in the current power control method, under less expense condition, can improve the efficient of power control, further performance and the availability of frequency spectrum of height system.

Description of drawings

Fig. 1 is the signal that portable terminal receives in the prior art and disturbs schematic diagram;

Fig. 2 is the schematic diagram 1 of the relation of target SINR value and path loss difference in the prior art;

Fig. 3 is the schematic diagram 2 of the relation of target SINR value and path loss difference in the prior art;

Fig. 4 is the flow chart that the power based on the compensation of difference path loss of prior art is controlled;

Fig. 5 is the flow chart of the Poewr control method of OFDM access system of the present invention;

Fig. 6 is the schematic diagram of OFDM access system of the present invention;

Fig. 7 is the residential quarter family schematic diagram of emulation;

Fig. 8 compares schematic diagram according to the system interference level under the different α conditions of the prior art;

Fig. 9 is the interference level schematic diagram of the example according to the present invention.

Embodiment

The invention will be further described below in conjunction with the drawings and specific embodiments.

Current based on difference path loss power back-off algorithm to Poewr control method in, as shown in Figure 4, may further comprise the steps,

Step 401, portable terminal pass through serving BS signal and the strongest continuous measurement of interference signal, and calculate path loss difference by formula (1);

$\mathrm{\Δ}{\mathrm{PL}}_{\left(\mathrm{dB}\right)}=P_{\left(\mathrm{dBm}\right)}^{\mathrm{rx},\mathrm{serving}}-P_{\left(\mathrm{dBm}\right)}^{\mathrm{rx},\mathrm{strongest}\_\mathrm{neighbor}}+P_{\left(\mathrm{dBm}\right)}^{\mathrm{tx},\mathrm{strongest}\_\mathrm{neighbor}}-P_{\left(\mathrm{dBm}\right)}^{\mathrm{tx},\mathrm{serving}}$

Formula (1)

Wherein, P _(dBm) ^{Rx, serving}It is the signal power of the serving BS that receives; P _(dBm) ^{Rx, strongest_neighbor}Signal power for the strongest interference base station that receives; P _(dBm) ^{Tx, strongest_neighbor}Transmit signal power for the strongest interference base station; P _(dBm) ^{Tx, serving}Transmit signal power for serving BS.

The target SINR value of the cell edge that step 402, portable terminal provide according to serving BS, path loss modifying factor, maximum target SINR value utilize formula (2) to calculate target SINR value;

${\mathrm{<figure-callout\; id="0"\; label="SINR"\; filenames="H2009101270064E00012.png,H2009101270064E00021.png"\; state="\{\{state\}\}">SINR</figure-callout>}}_0=\min ({\mathrm{\&Gamma;}}_{\left(\mathrm{dB}\right)}+(1-\mathrm{\&alpha;})\&times;\mathrm{\&Delta;PL},{\mathrm{SINR}}_{\left(\mathrm{dB}\right)}^{\max })$ Formula (2)

Wherein, Γ _(dB)Be the target SINR value of cell edge, i.e. target SINR value when Δ PL=0; Δ PL is signal path loss poor that arrives the signal path loss of maximum adjacent base station of portable terminal and serving BS, and the measurement of the path loss of base station signal is by the preliminary measurement acquisition of the handoff procedure of portable terminal and base station; α is the path loss modifying factor, and 0＜α＜1; SINR _(dB) ^MaxTarget SINR value for the maximum of appointment.

Step 403, portable terminal be according to the suitable modulation coding mode of target SINR value selection that obtains, and calculate the power of emission according to formula (3), carries out the emission of signal.

${\mathrm{TxPSD}}_{\left(\mathrm{dBm}\right)}=\min ({\mathrm{<figure-callout\; id="0"\; label="SINR"\; filenames="H2009101270064E00012.png,H2009101270064E00021.png"\; state="\{\{state\}\}">SINR</figure-callout>}}_0+I+\mathrm{PL},{\mathrm{TxPSD}}_{\left(\mathrm{dBm}\right)}^{\max })$ Formula (3)

Wherein, TxPSD is transmitting power density; SINR ₀Be the target SINR value that obtains; I is the channel disturbance level in residential quarter or the sector; The path loss of PL for measuring; TxPSD _(dBm) ^MaxFor allowing the maximum power density of portable terminal emission in the residential quarter.

Current based on difference path loss power back-off algorithm to Poewr control method, just because of when the α value is unreasonable, can not cover all optional modulation coding modes, cause the cell edge annoyance level of cell spectrum efficient and generation unbalance, limit the excavation of the latent capacity of system, thereby limited the overall performance of system.

In order to address this problem, the Poewr control method of the improved OFDM access system of the present invention, comprise, portable terminal determines that according to described area interference parameter, maximum path loss difference threshold value and the minimum path loss difference threshold value of base station notice and the base station signal path loss of measuring acquisition the target SINR value of portable terminal (is SINR in the formula (4) ₀); Target SINR value by definite portable terminal is selected suitable modulation coding mode, and then obtains transmitting power, carries out the emission of signal.

Described portable terminal obtains the area interference parameter that serving BS sends, and comprises cell edge echo signal interference noise ratio and maximum echo signal interference noise ratio.

Described portable terminal is measured the base station signal path loss that obtains and is comprised the signal path loss of serving BS of this portable terminal and the signal path loss of maximum adjacent base station.

${\mathrm{<figure-callout\; id="0"\; label="SINR"\; filenames="H2009101270064E00012.png,H2009101270064E00021.png"\; state="\{\{state\}\}">SINR</figure-callout>}}_0=\left\{\begin{array}{cc}{\mathrm{\&Gamma;}}_{\left(\mathrm{dB}\right)}& \mathrm{\&Delta;PL}<\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="H2009101270064E00051.png"\; state="\{\{state\}\}">C</figure-callout>}1\\ {\mathrm{\&Gamma;}}_{\left(\mathrm{dB}\right)}+\frac{{\mathrm{SINR}}_{\left(\mathrm{dB}\right)}^{\max }-{\mathrm{\&Gamma;}}_{\left(\mathrm{dB}\right)}}{C2-\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="H2009101270064E00051.png"\; state="\{\{state\}\}">C</figure-callout>}1}\&times;(\mathrm{\&Delta;PL}-C1)& \mathrm{<figure-callout\; id="1"\; label="C"\; filenames="H2009101270064E00051.png"\; state="\{\{state\}\}">C</figure-callout>}1\&le;\mathrm{\&Delta;PL}<\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="H2009101270064E00051.png"\; state="\{\{state\}\}">C</figure-callout>}2\\ {\mathrm{SINR}}_{\left(\mathrm{dB}\right)}^{\max }& \mathrm{\&Delta;PL}>\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="H2009101270064E00051.png"\; state="\{\{state\}\}">C</figure-callout>}2\end{array}\right.$ Formula (4)

Wherein, Γ _(dB)Be the target SINR value of cell edge, i.e. target SINR value when Δ PL=0; Δ PL is signal path loss poor that arrives the signal path loss of maximum adjacent base station of portable terminal and serving BS, and wherein the measurement of the signal path loss of maximum adjacent base station is that preliminary measurement by handoff procedure obtains; C1 and C2 are lower limit and the upper limit of path loss difference; SINR _(dB) ^MaxTarget SINR value for the maximum of appointment.

As Δ PL during greater than C2, use the modulation coding mode of high-order; As Δ PL during less than C1, use the modulation coding mode of lowest-order; Thereby the user (user that Δ PL is larger) who guarantees center of housing estate uses the modulation coding mode of high-order, and the user of cell edge (user that Δ PL is less) uses the modulation coding mode of low order; Wherein the modulation coding mode of the modulation coding mode of high-order and lowest-order all is taken from the modulation coding mode option set of system's regulation.

By the target SINR value of the portable terminal determined, so the transmit power spectral density that obtains travelling carriage be target SINR and area interference level and serving BS path loss with, with the minimum value of maximum transmission power thresholding.

${\mathrm{TxPSD}}_{\left(\mathrm{dBm}\right)}=\min ({\mathrm{<figure-callout\; id="0"\; label="SINR"\; filenames="H2009101270064E00012.png,H2009101270064E00021.png"\; state="\{\{state\}\}">SINR</figure-callout>}}_0+I+\mathrm{PL},{\mathrm{TxPSD}}_{\left(\mathrm{dBm}\right)}^{\max })$

Wherein, TxPSD is transmitting power density; SINR ₀Target SINR value for portable terminal; I is the channel disturbance level in residential quarter or the sector; The path loss of PL for measuring; TxPSD _(dBm) ^MaxFor allowing the maximum power density of portable terminal emission in the residential quarter.

As shown in Figure 5, the Poewr control method of OFDM access system of the present invention, concrete steps are as follows:

Step 501, portable terminal pass through serving BS signal and the strongest continuous measurement of interference signal, and obtain circuit loss value by the difference of received signal power and transmit signal power, and then obtain the path loss difference;

$\mathrm{\&Delta;}{\mathrm{PL}}_{\left(\mathrm{dB}\right)}=P_{\left(\mathrm{dBm}\right)}^{\mathrm{rx},\mathrm{serving}}-P_{\left(\mathrm{dBm}\right)}^{\mathrm{rx},\mathrm{strongest}\_\mathrm{neighbor}}+P_{\left(\mathrm{dBm}\right)}^{\mathrm{tx},\mathrm{strongest}\_\mathrm{neighbor}}-P_{\left(\mathrm{dBm}\right)}^{\mathrm{tx},\mathrm{serving}}$

Step 502, portable terminal are according to the target SINR value of the cell edge of serving BS transmission, maximum path loss difference threshold value, minimum path loss difference threshold value and maximum target SINR value, and the path loss difference that obtains, and calculate target SINR value;

${\mathrm{<figure-callout\; id="0"\; label="SINR"\; filenames="H2009101270064E00012.png,H2009101270064E00021.png"\; state="\{\{state\}\}">SINR</figure-callout>}}_0=\left\{\begin{array}{cc}{\mathrm{\&Gamma;}}_{\left(\mathrm{dB}\right)}& \mathrm{\&Delta;PL}<\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="H2009101270064E00051.png"\; state="\{\{state\}\}">C</figure-callout>}1\\ {\mathrm{\&Gamma;}}_{\left(\mathrm{dB}\right)}+\frac{{\mathrm{SINR}}_{\left(\mathrm{dB}\right)}^{\max }-{\mathrm{\&Gamma;}}_{\left(\mathrm{dB}\right)}}{C2-\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="H2009101270064E00051.png"\; state="\{\{state\}\}">C</figure-callout>}1}\&times;(\mathrm{\&Delta;PL}-C1)& \mathrm{<figure-callout\; id="1"\; label="C"\; filenames="H2009101270064E00051.png"\; state="\{\{state\}\}">C</figure-callout>}1\&le;\mathrm{\&Delta;PL}<\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="H2009101270064E00051.png"\; state="\{\{state\}\}">C</figure-callout>}2\\ {\mathrm{SINR}}_{\left(\mathrm{dB}\right)}^{\max }& \mathrm{\&Delta;PL}>\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="H2009101270064E00051.png"\; state="\{\{state\}\}">C</figure-callout>}2\end{array}\right.$

Step 503, portable terminal be according to the suitable modulation coding mode of target SINR value selection that obtains, and calculate the power of emission according to following formula, carries out the emission of signal.

${\mathrm{TxPSD}}_{\left(\mathrm{dBm}\right)}=\min ({\mathrm{<figure-callout\; id="0"\; label="SINR"\; filenames="H2009101270064E00012.png,H2009101270064E00021.png"\; state="\{\{state\}\}">SINR</figure-callout>}}_0+I+\mathrm{PL},{\mathrm{TxPSD}}_{\left(\mathrm{dBm}\right)}^{\max })$

As shown in Figure 6, OFDM access system of the present invention comprises base station and portable terminal, wherein,

Described base station is the serving BS of described portable terminal, comprises the parameter notification module, is used for area interference parameter, maximum path loss difference threshold value and minimum path loss difference threshold value are sent to described portable terminal; Described area interference parameter comprises cell edge target SINR value and maximum target SINR value;

Described portable terminal comprises power measurement module, computing module and signal emission module, wherein,

Described power measurement module is used for measuring the base station signal path loss of described portable terminal, and sends to described computing module; Wherein said base station signal path loss comprises the signal path loss of serving BS of this portable terminal and the signal path loss of maximum adjacent base station;

Described power measurement module is the signal path loss that obtains the adjacent base station of described portable terminal by the preliminary measurement of handoff procedure.

Described computing module, be used for receiving described area interference parameter, maximum path loss difference threshold value and the minimum path loss difference threshold value of described base station transmission and measure the base station signal path loss that obtains, echo signal interference noise ratio by this portable terminal of calculative determination, obtain transmitting power according to this echo signal interference-to-noise ratio value of determining, echo signal interference noise ratio and the transmitting power of this portable terminal of obtaining sent to signal emission module;

Described signal emission module, be used for receiving described computing module and send to described echo signal interference noise ratio and described transmitting power, select modulation coding mode according to described echo signal interference noise ratio, adjust transmitting power by the described transmitting power that obtains, carry out the emission of signal.

The invention will be further described below in conjunction with instantiation.

Adopt the static system emulation platform that difference path loss backoff algorithm and improved difference path loss backoff algorithm of the present invention are carried out emulation in the example.System forms and comprises 7 cell clusters, and each cell cluster is comprised of 19 orthohexagonal residential quarters, and each microzonation is divided into three sectors.Cell cluster forms as shown in Figure 7.Frequency duplex factor as one is 1, and namely same frequency resource is used in all sectors.Emulation stipulates that each sector is sprinkled into 10 users, and the user evenly is sprinkling upon in the network.Portable terminal is judged to receive the strongest sector of signal as Serving cell by measuring the signal strength signal intensity that receives of 57 sectors.

Behind each portable terminal allocated channel, and calculate signal strength signal intensity and the interference strength that receives, obtain each user's target SINR value, thereby carry out selection and the power control of modulating-coding.The system emulation parameter is as shown in table 1; The OFDMA parameter that emulation is used is as shown in table 2; Mode is as shown in table 3; Threshold value shown in the table 4 is adopted in the selection of modulation coding mode.

Table 1: simulation parameter

Table 2:OFDMA system parameters

Table 3: mode

Table 4: error code is 10 ^-3The time modulation coding mode corresponding enter thresholding

The power control simulation of different α values the results are shown in Table 5 and Fig. 8 in the difference path loss power back-off algorithm.Fig. 8 is the IoT probability distribution curve of system user.In simulation configurations, the maximum of Δ PL is 20dB, when α is 0.575, and SINR ₀With Δ PL be linear relationship completely; When α (for example α=0.6) greater than 0.575 the time, the modulation coding mode of high-order loses the chance that is used; When α less than 0.575 (for example α=0.4), the probability that the modulation coding mode of high-order is used increases.Can see that from simulation result the reduction of α (being the raising of slope) has improved the throughput of system, but the interference level of whole system increases, the covering probability of whole system reduces; The raising of α can reduce the interference level of system, improve to cover probability, but throughput of system reduces.Transverse axis is IoT (interference over thermal) for disturbing the heat ratio of making an uproar among Fig. 8, is the parameter of reflection presence of intercell interference level.

Table 5: the systematic function during different α relatively

Emulation such as the table 6 and shown in Figure 9 of improved difference path loss power back-off algorithm of the present invention.Table 6 is under different C1, the C2 value, the performance simulation of system.In Fig. 9, the position of curve is the closer to the upper left side, and interference level corresponding to illustrative graph is lower, can find out that C1 is different with the C2 value, can bring the different interference level of system.C1 increases, and can reduce the throughput of system, increases the covering of system; C2 increases, and can increase the throughput of system, reduces the covering of system.Choose the optimum state that suitable C1, C2 can obtain systematic function, such as C1=8dB, during C2=15dB, can reach throughput 1.86, cover 98.48%.And in difference path loss power compensating method, use a parameter alpha, and be difficult to coordinate cover the best compromise that reaches of probability and throughput, α=0.4 for example, it is lower to cover when better throughput, and α=cover but when 0.6 throughput is high descends.

Table 6: the systematic function under different C1, the C2 relatively

Power control algorithm in sum, be can be clearly seen that by the result of emulation in the example that the present invention is by the adjustment to parameters C 1 and C2, so that can reach the compromise that best throughput of system and system cover.Simultaneously, the adjustment of C1 and C2 has more simply directly perceived and advantage flexibly with respect to the adjustment of path loss modifying factor α.

The above; only for the better embodiment of the present invention, but protection scope of the present invention is not limited to this, anyly is familiar with the people of this technology in technical scope disclosed in this invention; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claim.

Claims (6)

1. the Poewr control method of an OFDM access system is characterized in that, comprise,

Portable terminal obtains area interference parameter, maximum path loss difference threshold value and the minimum path loss difference threshold value that serving BS sends;

Described portable terminal is according to the described area interference parameter, maximum path loss difference threshold value and the minimum path loss difference threshold value that obtain and measure the base station signal path loss that obtains, and determines the echo signal interference noise ratio of this portable terminal;

Described portable terminal is selected modulation coding mode according to the described echo signal interference noise ratio of determining, and adjusts the emission that its transmitting power is carried out signal,

Wherein, described portable terminal obtains the area interference parameter that serving BS sends, and comprises cell edge echo signal interference noise ratio and maximum echo signal interference noise ratio; Described portable terminal is measured the base station signal path loss that obtains and is comprised the signal path loss of serving BS of this portable terminal and the signal path loss of maximum adjacent base station; Described portable terminal is selected modulation coding mode, also comprises, as Δ PL during greater than described maximum path loss difference threshold value, described portable terminal is selected the modulation coding mode of high-order; As Δ PL during less than described minimum path loss difference threshold value, described portable terminal is selected the modulation coding mode of lowest-order; Wherein, Δ PL is signal path loss poor that arrives the signal path loss of maximum adjacent base station of described portable terminal and serving BS.

2. Poewr control method as claimed in claim 1 is characterized in that,

Described portable terminal carries out the step of the emission of signal, comprises,

Described portable terminal obtains transmitting power according to the described echo signal interference-to-noise ratio value of determining, adjusts its transmitting power by this transmitting power that obtains, and carries out the emission of signal.

3. Poewr control method as claimed in claim 1 is characterized in that,

The measurement of the signal path loss of the adjacent base station of described portable terminal is the preliminary measurement acquisition by handoff procedure.

4. an OFDM access system comprises base station and portable terminal, it is characterized in that,

Described base station is the serving BS of described portable terminal, comprises the parameter notification module, is used for area interference parameter, maximum path loss difference threshold value and minimum path loss difference threshold value are sent to described portable terminal;

Described portable terminal comprises computing module and signal emission module, wherein,

Described computing module, be used for receiving described area interference parameter, maximum path loss difference threshold value and the minimum path loss difference threshold value of described base station transmission and measure the base station signal path loss that obtains, determine the echo signal interference noise ratio of described portable terminal, and send to signal emission module;

Described signal emission module is used for selecting modulation coding mode according to the described echo signal interference noise ratio that the described computing module that receives sends, and adjusts transmitting power and carry out the emission of signal,

Wherein, the described parameter notification module area interference parameter that sends to described portable terminal also comprises cell edge echo signal interference noise ratio and maximum echo signal interference noise ratio; Described portable terminal also comprises power measurement module, is used for measuring the base station signal path loss of described portable terminal, and sends to described computing module; Wherein, described base station signal path loss comprises the signal path loss of serving BS of this portable terminal and the signal path loss of maximum adjacent base station; Described portable terminal is selected modulation coding mode, also comprises, as Δ PL during greater than described maximum path loss difference threshold value, described portable terminal is selected the modulation coding mode of high-order; As Δ PL during less than described minimum path loss difference threshold value, described portable terminal is selected the modulation coding mode of lowest-order; Wherein, Δ PL is signal path loss poor that arrives the signal path loss of maximum adjacent base station of described portable terminal and serving BS.

5. OFDM access system as claimed in claim 4 is characterized in that,

Described computing module also is used for obtaining transmitting power and sending to described signal emission module according to the described echo signal interference-to-noise ratio value of the described portable terminal of determining.

6. OFDM access system as claimed in claim 4 is characterized in that,

Described signal emission module is to select modulation coding mode according to described echo signal interference noise ratio, adjusts transmitting power by the described transmitting power that obtains, and carries out the emission of signal.

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