WO2005022883A2

WO2005022883A2 - Method of controlling transmission power of retransmission packet and mobile terminal using the same

Info

Publication number: WO2005022883A2
Application number: PCT/KR2004/002188
Authority: WO
Inventors: Ki Jun Kim; Young Woo Yun; Jong Hoe An; Soon Yil Kwon; Jee Woong Seol; Chan Ho Kyung
Original assignee: Lg Electronics Inc.
Priority date: 2003-09-03
Filing date: 2004-08-31
Publication date: 2005-03-10
Also published as: CN1846365B; WO2005022883A3; KR20050024587A; DE602004025829D1; AU2004302746B2; AU2004302746A1; EP1665578A2; CN1846365A; ATE460013T1; US20060252445A1; CA2537508A1; HK1091335A1; EP1665578B1; CA2537508C; US7372834B2; BRPI0413781A; KR100985104B1

Abstract

The transmission power of a retransmission packet is controlled in the event of a packet retransmission request being sent from a receiving side in a wireless mobile communication system supporting hybrid automatic retransmission request (HARQ) transmission. In a method of controlling transmission power of retransmission packets by a mobile terminal in a wireless mobile communication system supporting hybrid automatic retransmission request (HARQ) transmission, the method includes steps of receiving, from a base station, gain information associated with the sequence of the retransmission packets; determining, using the gain information, transmission power of one of the retransmission packets; and transmitting the retransmission packet with the determined transmission power.

Description

METHOD OF CONTROLLING

TRANSMISSION POWER OF RETRANSMISSION PACKET

AND MOBILE TERMINAL USING THE SAME

Technical Field

The present invention relates to a wireless mobile communication system

supporting hybrid automatic retransmission request (HARQ) transmission, and more

particularly, to a method of controlling the transmission power of a retransmission

packet according to sub-packet identifier (SPID) information.

Background Art

HARQ transmission is a link adaptation technique used to provide higher data

rates for emerging services utilizing wireless Internet communication via a mobile

communication system. Other forms of link adaptation, including transmit power

control schemes, are used in conjunction with HARQ transmission to increase receiver

reliability when demodulating and decoding the transmission. In a known power

control scheme for use in a conventional mobile communication system, the power level

of a transmitted signal to be received by a base station is controlled (adjusted) in

response to a specific request from the receiver side, to enable data reception for a

desired quality of service (QoS) level. Specifically, transmit power control is

performed in a mobile communication system to solve the near-far problem occurring in

a reverse link, whereby the transmission power of each terminal of both near and far terminals is individually controlled based on the respective power levels received at a

specific base station, such that each power level is adjusted to a predetermined level.

There are technical difficulties, however, in simultaneously adopting multiple

link-adaptation techniques into an integrated mobile communication system. For

example, there are compatibility obstacles to overcome when simultaneously adopting a

transmit power control scheme, i.e., a feature of the reverse link, in a mobile

communication system together with forward-link features such as adaptive modulation

and coding (AMC).

Meanwhile, once an error is detected in a received data packet, a wireless mobile

communications system supporting HARQ transmission compensates for the error using

the conventional techniques of automatic retransmission request transmission and

forward error correction, by temporarily storing (rather than aborting) transmission-

failed packets in memory so that the previously received and temporarily stored data

may be combined with retransmitted data to secure a higher decoding probability.

HARQ transmission, which is carried out by the physical layer in a wireless mobile

communications system, is classified as type I, II, or III, based on the amount and type

of data included in ensuing retransmissions of a failed data packet. In HARQ type I, if

an error occurs in an initial transmission, the same information is fully retransmitted to

enable the receiving side to use Chase combining. In HARQ types II and III, which

require higher coding gains than in Chase combining, redundancy is incremented in

each retransmission, whereby a receiving side can lower a code rate when performing

code combining. HARQ types II and III are distinguished based on whether each transmission is self-decodable, whereby HARQ type II is self-decodable and HARQ

type III is not.

Meanwhile, the transmission power of a data packet transmitted via a reverse

link in a mobile communication system is based on a traffic-to-pilot ratio or TPR, which

is calculated for each of a known set of data rates as the ratio of the pilot channel's

transmission power to the traffic channel's transmission power and is known to the base

station and the mobile terminal. The TPR is determined based on a nominal gain value

and an adjustment gain value, each of which are values typically expressed in decibels.

The nominal gain value corresponds to a specific or "nominal" situation and serves as a

known reference to the mobile terminal, while the adjustment gain value varies

situationally, i.e., according to the mobile terminal usage, and is transmitted via

signaling from the base station to the mobile terminal.

In performing HARQ transmission in a reverse link of a conventional wireless

mobile communication system, the power level for initial packet transmission is set

equal to that of packet retransmission. In doing so, a transmitting side applies an

identical TPR, which is determined at the time of initially transmitting a packet, to any

packet retransmitted later, so that a retransmission packet is transmitted by the same

transmission power. Therefore, in case of retransmitting the packet in a reverse link,

the same higher transmission power of the retransmission packet, which has been set

equal to that of the initial transmission packet, increases an interference amount of the

reverse link unnecessarily.

Moreover, the increased interference of the reverse link decreases throughput and unnecessarily increases the number of packet retransmissions necessary for a successful

instance of transmission number. Therefore, in performing HARQ transmission in a

wireless mobile communication system, the transmission power of successive

retransmission packets should be controlled to improve system performance.

Disclosure of Invention

Accordingly, the present invention is directed to a method and apparatus for

controlling transmission power of a retransmission packet that substantially obviates

one or more of the problems due to limitations and disadvantages of the related art. An object of the present invention, which has been devised to solve the foregoing

problem, lies in providing an improved method of controlling the transmission power of

a retransmission packet in a wireless mobile communication system supporting HARQ

transmission, by which the transmission power of a transmitting side, e.g., a mobile

terminal, is efficiently controlled when retransmitting a packet in response to a packet

retransmission request of a receiving side, e.g., a base station.

It is another object of the present invention to provide a method of controlling

the transmission power of a retransmission packet, which reduces the interference of a

reverse link when retransmitting a packet in a wireless mobile communication system

supporting HARQ transmission. It is another object of the present invention to provide a method of controlling

the transmission power of a retransmission packet, which facilitates link adaptation

effectiveness in a forward link. It is another object of the present invention to provide a method of controlling

the transmission power of a retransmission packet, which improves system performance.

It is another object of the present invention to provide a mobile terminal suitable

for adopting the above methods. In the following description of the present invention, the term "retransmission

packet" refers to a reiterative data packet that, in a wireless mobile communication

system supporting HARQ transmission, is to be transmitted to a base station from a

specific terminal having received a NACK signal from the base station which initially

received a corresponding original packet, the NACK signal corresponding to the

original packet and indicating the presence of an error in the received packet, which was

originally transmitted from the specific terminal but failed, i.e., included an error, such

that the specific terminal should again transmit data of the erroneous packet.

Furthermore, the method of the present invention is described with respect to at

least one base station of a wireless mobile communication system and at one mobile

terminal transmitting to the base station. Thus, the base station is representative of a

receiving side and the mobile terminal is representative of a transmitting side.

Additional features and advantages of the invention will be set forth in the

description which follows, and in part will be apparent to those having ordinary skill in

the art upon examination of the following or may be learned from a practice of the

invention. The objectives and other advantages of the invention will be realized and

attained by the subject matter particularly pointed out in the specification and claims

hereof as well as in the appended drawings. To achieve these objects and other advantages in accordance with the present

invention, as embodied and broadly described herein, there is provided a method of

controlling transmission power of retransmission packets by a mobile terminal in a

wireless mobile communication system supporting hybrid automatic retransmission

request (HARQ) transmission. The method comprises steps of receiving, from a base

station, gain information associated with the sequence of the retransmission packets;

determining, using the gain information, transmission power of one of the

retransmission packets; and transmitting the retransmission packet with the determined

transmission power. In another aspect of the present invention, there is provided a method of

controlling transmission power of retransmission packets in a wireless mobile

communication system supporting hybrid automatic retransmission request (HARQ)

transmission. The method comprises steps of transmitting, to at least one mobile

terminal, gain information associated with the sequence of the retransmission packets;

and receiving, from the at least one mobile terminal, a retransmission packet transmitted

at a transmission power determined by the at least one mobile terminal using the gain

information.

In another aspect of the present invention, there is provided a mobile terminal

used in a mobile telecommunications system supporting hybrid automatic

retransmission request (HARQ) transmission. The mobile terminal comprises means

for receiving, from a base station, a plurality of adjustment gain values (or a plurality of

adjustment power reduction values) corresponding to each data transmission rate and the sequence of the retransmission packets and for transmitting packets to the base

station; means for storing a plurality of values, i.e., a plurality of nominal gain values or

a plurality of nominal power reduction values; and means for determining transmission

power of one of the retransmission packets according to one of the first and second

embodiments of the present invention. In the first embodiment, the determination is

made using one of the plurality of adjustment gain values, one of a plurality of nominal

gain values, and a pilot-channel transmission power. In the second embodiment, the

determination is made using one of the plurality of adjustment power reduction values,

one of a plurality of nominal power reduction values, and a pilot-channel transmission

power.

It is to be understood that both the foregoing explanation and the following

detailed description of the present invention are exemplary and illustrative and are

intended to provide further explanation of the invention as claimed.

Brief Description of Drawings

The accompanying drawings, which are included to provide a further

understanding of the invention and are incorporated in and constitute a part of this

application, illustrate embodiment(s) of the invention and together with the description

serve to explain the principle of the invention. In the drawings: FIG. 1 is a diagram of a method of controlling the transmission power of a

retransmission packet according to the present invention; and

FIG. 2 is a diagram of a method of controlling the transmission power of a retransmission packet according to a second embodiment of the present invention.

Best Mode for Carrying Out the Invention

Reference will now be made in detail to the preferred embodiments of the

present invention, examples of which are illustrated in the accompanying drawings.

Throughout the drawings, like elements are indicated using the same or similar

reference designations where possible.

The method of the present invention may be adopted in a wireless mobile

communication system having multiple base stations and multiple mobile terminals, and

it should be appreciated that each mobile terminal of the system may or may not provide

intrinsic support for the power reduction of a retransmission packet. Therefore, each

embodiment of the present invention can be adopted to a system comprising one or

more mobile terminals providing such support, to a system comprising one or more

mobile terminals providing no such support, and, in the more likely scenario, to a

system comprising one or more of both types, i.e., mobile terminals providing such

support as well as of mobile terminals providing no such support. Meanwhile, with

power control essentially being a reverse-link function and since the base station utilizes

two antennas to receive a signal in the reverse link, it can be presumed that the reverse

link provides a channel environment more stable than that of the forward link.

Furthermore, assuming that an energy level of the retransmitted packet that is smaller

than that of an initial packet can be received, the base station can perform normal

decoding by combining the two packets. First Embodiment

The first embodiment of the present invention is illustrated in FIG. 1 and is

directed to a method of controlling the transmission power of a retransmission packet,

in which a set of adjustment gain values stored according to sub-packet identifier

(SPID) information is transmitted, via signaling, from a base station to a mobile

terminal. Here, the adjustment gain values vary according to a plurality of data

transmission rates, and the sub-packet identifier information indicates an instance of

packet transmission, for example, an initial transmission, a first retry, or a second retry,

in a mobile communications system supporting HARQ transmission. The data

transmission rates are those available to the system, including 19,200kbps, 38,400kbps,

76,800kbps, 153,600kbps, etc.

In a step S 11, a set of adjustment gain values, preferably included in an extended

channel assignment message (ECAM) transmitted upon call establishment, is

transmitted from the base station to the mobile terminal. According to the type of call

established, it is determined, preferably by the base station in which a lookup table is

stored, whether to support power reduction for a retransmission packet, so that the

transmitted adjustment gain values may be varied accordingly. Here, if it is

determined that the established call needs no retransmission packet power reduction, the

transmitted adjustment gain values vary according to data transmission rate only. On

the other hand, if it is determined that power reduction will be needed for a

retransmission packet of the established call, the transmitted adjustment gain values

vary according to sub-packet identifier as well as data transmission rate. All of the above adjustment gain values are stored in the lookup table. Once the data of the

lookup table is received in a mobile terminal adopting the method of the present

invention in accordance with the first embodiment, a determination of transmission

power for retransmission packets is made in a step S13 as necessary, after which the

retransmission packet is transmitted in a step SI 5. That is, the steps S13 and S15 are

repeated by the mobile terminal each time a packet retransmission request is received.

Table 1 is an exemplary lookup table stored in the base station. The table

includes a set of adjustment gain values (ADJ_GAIN SPID RATE) determined

according to data transmission rate for each instance of packet transmission, i.e., its first

transmission and a predetermined number of subsequent retries, as well as one bit

(ADJ_GALN_SPID_LNCL), for each instance of transmission, respectively indicating

whether the currently transmitted message, e.g., the ECAM, contains an adjustment gain

value for a specific instance of transmission. Preferably, for a given data transmission

rate, the stored adjustment gain values decrease according to the transmission sequence

(successive retries) of a retransmission packet. The data of the lookup table is

transmitted to a mobile terminal in each of steps S 11 and S 17 of FIG. 1.

Table 1

As packet transmission continues after completion of a call establishment between the base station and mobile according to step Sll and steps S13 and 15 as necessary. In doing so, if a change in the channel status warrants a change of the adjustment gain values, the base station transmits to the mobile terminal a new set of adjustment gain values, i.e., a new lookup table, which may be included in any one of a variety of existing messages, for example, a universal handoff direction message (UHDM) or a power control message (PCNM). In a step SI 7, the new set of values is preferably included in either the UHDM or PCNM, after which a determination of transmission power for retransmission packets is newly made in a step S 19 as necessary, after which the corresponding retransmission packet is transmitted in a step S21.

Meanwhile, the base station and mobile terminal each store a set of nominal gain values (G_n0m) corresponding to a specific or "nominal" situation, according to one of three conditions, namely, an Equation Condition 1 or an Equation Condition 2, which are applied depending on the mobile terminal's support characteristics for retransmission packet power reduction, or an selective application of Equation Conditions 1 and 2, in which the base station and mobile terminal each store both sets of nominal gain values. In Equation Condition 1, the stored nominal gain values comprise a first set of values (NOM_GAIN_RATE) that varies according to the data

transmission rate only, whereby there can be no intrinsic support for the power

reduction of a retransmission packet by the mobile terminal, since there is no variation

in the nominal gain values according to sub-packet identifier. In Equation Condition 2,

the stored nominal gain values comprise a second set of values

(NOM_GAIN_SPID_RATE) that varies according to the sub-packet identifier as well as

the data transmission rate, which enables a mobile terminal's intrinsic support of

retransmission packet power reduction. In the selective application, the system

comprises at least one mobile terminal storing both sets of nominal gain values. According to the condition of the stored set of nominal gains, the transmission

power of a retransmission packet is determined in the mobile terminal by an Equation 1.

That is, to control the transmission power of a packet (traffic), i.e., an initially

transmitted packet or a retransmission packet, the mobile terminal, which has received

the adjustment gain values (G_adj) of Table 1, applies in each of the steps S13 and S 19 the

data transmission rate and sub-packet identifier of the packet to be transmitted, to

determine its transmission power thus:

Ptraffic = Ppilot + 0.125(G_nom+Gadj) . . . Eq. 1 where P_traffi_c is the transmission power of a specific packet to be transmitted or

retransmitted by the mobile terminal and where P_Pji₀t is the transmission power of the

pilot signal at the time of transmission of the specific packet. The multiplying factor

0.125 is a value for converting the sum of G_n0m and G_adj into a decibel unit.

When transmitting a specific packet having a specific sub-packet identifier at a specific data rate, the mobile terminal first calculates the traffic-to-pilot ratio using the corresponding adjustment gain value (ADJ_GAiN_SPID_RATE) and nominal gain value (NOM_GAIN_RATE and/or NOM_GAIN_SPID_RATE) according to the condition of the stored nominal gain values, i.e., according to Equation Condition 1 or 2.

5 The mobile terminal then determines the transmission power of the traffic channel, to transmit or retransmit the packet based on the calculated traffic-to-pilot ratio and the transmission power of the pilot signal.

In applying Equation Condition 1, utilizing the first set of nominal gain values (stored according to data transmission rate only), the value of G_nom is based on data o transmission rate only, for cases where the mobile terminal of the system provides no intrinsic support for retransmission packet power reduction. In other words, power reduction of a retransmission packet is achieved using the value of G_adj. For reference, application of Equation Condition 1 to Equation 1 may be represented as P_tr_affi_c ⁼ Ppii_ot +

0.125(Gnom_Rate+G_adj_SPID_Rate)- s In applying Equation Condition 2, whereby the mobile terminal of the system utilizes the second set of nominal gain values (stored according to sup-packet identifier as well as data transmission rate), the value of G_nom is based on the sup-packet identifier in addition to data transmission rate, for case where the power reduction of a retransmission packet can be achieved in the mobile terminal intrinsically, i.e., without o using the value of G_adj. Therefore, at the time of call establishment, the base station has an option, according to the type of call established, in transmitting adjustment gain values to the mobile terminal. That is, since power reduction of a retransmission packet can be achieved in the mobile terminal using the value of G_n0m only, the base

station may transmit a set of adjustment gain values based on data transmission rate only.

For reference, application of Equation Condition 2 to Equation 1 may be represented as

Ptraffic ⁼ Ppilot + 0.125(G_nom_SPID_Rate+G_adj). When the mobile terminal has access to both sets of nominal gain values, the

value of G_n0m is selectively based on data transmission rate only or the sup-packet

identifier in addition to data transmission rate, i.e., based on Equation Condition 1 or 2.

Here, too, the mobile terminal of the system intrinsically supports power reduction for

packet retransmission. In this case, the base station may transmit to the mobile

terminal, preferably via the ECAM containing the adjustment gain values transmitted

upon call establishment, a nominal gain value indicator for determining which nominal

gain value is be used, thereby enabling the mobile terminal to determine the

transmission power of a retransmission packet based on either one of the first and

second conditions. Second Embodiment

The second embodiment of the present invention is illustrated in FIG. 2, in which

Table 2 is transmitted from the base station in lieu of Table 1. As shown in Table 2,

the data stored in the lookup table includes a set of adjustment gain values stored

according to the data transmission rate of the initial packet transmission and a set of

adjustment power reduction values stored according to data transmission rate and sub-

packet identifier information. Thus, the mobile terminal determines transmission

power by applying the adjustment gain values for the initial transmission packet and applying the adjustment power reduction values for any retransmission packets.

The second embodiment is completely analogous to the first embodiment, in that

steps S31, S33, and S35 of the second embodiment respectively correspond to the steps

Sll, SI 3, and S15 of the first embodiment, which may be executed upon call

establishment. At the same time, the steps S37, S39, and S41 of the second

embodiment respectively correspond to the steps SI 7, SI 9, and S21 of the first

embodiment, which may be executed in the event that a subsequent change in channel

status warrants a change of the originally transmitted values of Table 2.

Table 2 is an exemplary lookup table stored in the base station and includes a set

of adjustment gain values (ADJ_GALN_RATE) determined according to data

transmission rate for the first instance of packet transmission only and a set of reduction

gain values (ADJ_RTX_DELTA_SPID_RATE) determined according to data

transmission rate for a predetermined number of subsequent retries. Preferably, for a

given data transmission rate, the stored adjustment power reduction values decrease

according to the transmission sequence (successive retries) of a retransmission packet.

Also included is one bit, for each instance of transmission, respectively indicating

whether the currently transmitted message contains an adjustment gain value for the

first instance of packet transmission and an adjustment power reduction value for a

subsequent retry. Table 2

Meanwhile, the base station and mobile terminal each store a set of nominal gain values (G_n0m) and a set of nominal power reduction values (R_n0m) corresponding to a specific or "nominal" situation. The nominal gain values are stored according to data transmission rate, and the nominal power reduction values are stored according to sub- packet identifier information as well as data transmission rate.

Therefore, the transmission power of a retransmission packet can be determined in the mobile terminal by an Equation 2. That is, to control the transmission power of a packet (traffic), i.e., an initially transmitted packet or a retransmission packet, the terminal, which has received the adjustment gain values (G_adj) and adjustment power reduction values (R_adj) of Table 2, applies in each of the steps S33 and S39 the data transmission rate and sub-packet identifier of the packet to be transmitted, to determine its transmission power thus:

Ptraffic = Ppilot + 0.125{(G_nOm+G_adj) ^~ ( R_n0m+Radj)} Eq. 2 where P_traffi_c is the transmission power of a specific packet to be transmitted or retransmitted by the mobile terminal, where Ppiiot is the transmission power of the pilot signal at the time of transmission of the specific packet, and where α is equal to zero or one according to whether the mobile terminal provides intrinsic support for retransmission packet power reduction. As in the case of Equation 1, the multiplying

factor 0.125 is a value for producing a decibel unit.

Accordingly, depending on the mobile terminal's intrinsic support for

retransmission packet power reduction, i.e., the value of α, Equation 2 may also be

applied according to any one of three conditions, namely, an Equation Condition 3 or an

Equation Condition 4, which are applied depending on the mobile terminal's support

characteristics for retransmission packet power reduction, or a selective application of

Equation Conditions 3 and 4. Here, Equation Conditions 3 and 4 of the second

embodiment correspond to Equation Conditions 1 and 2 of the first embodiment,

respectively, whereby Equation Conditions 1 and 3 each consider a mobile terminal

having no intrinsic support for retransmission packet power reduction and Equation

Conditions 2 and 4 each consider a mobile terminal intrinsically supporting

retransmission packet power reduction. The selective application of the above sets of

Equation Conditions each consider a system in which one or more of both types of

mobile terminals are present.

In a contemporary wireless mobile communication system, transmission power

of a traffic channel is calculated by simply adding the pilot signal transmission power to

a gain value expressed in decibels. In many cases, however, the level of the above

traffic channel transmission power (hereinafter referred to as a "simplified traffic power

level") is inappropriate or unnecessarily high for a retransmission packet. Therefore,

by employing Equation 2 of the present invention, in accordance with either of Equation

Conditions 3 and 4, calculation of the traffic channel transmission power is enhanced by applying sub-packet identifier information.

In applying Equation Condition 3, the value of α is zero, such that the term R_nom

is removed from the equation for cases where there is no intrinsic support in the mobile

terminal for retransmission packet power reduction. Thus, when transmitting a

specific packet having a specific sub-packet identifier at a specific data rate, the mobile

terminal first calculates the traffic-to-pilot ratio using the corresponding adjustment gain

value (ADJ_GALN_RATE) and nominal gain value (NOM_GAIN_RATE). The

mobile terminal then determines traffic channel transmission power by an application of

Equation Condition 3 to Equation 2, by which only the adjustment power reduction

value (ADJ RTX DELTAJSPID RATE) corresponding to the specific sub-packet

identifier and the specific data transmission rate is subtracted from a simplified traffic

power level based on the calculated traffic-to-pilot ratio and the transmission power of

the pilot signal. For reference, application of Equation Condition 3 to Equation 2

gives Ptraffic ⁼ Ppilot + 0.125{(G_nom_Rate+G_adj_Rate) ^_ Radj_SPID_Rate}- In applying Equation Condition 4, the value of α is one, such that the term R_nom

is included in the equation for cases where the mobile terminal intrinsically supports

retransmission packet power reduction. Here, too, the mobile terminal first calculates

the traffic-to-pilot ratio using the corresponding adjustment gain value

(ADJ_GALN_RATE) and nominal gain value (NOM_GALN_RATE). In this case,

however, the mobile terminal determines traffic channel transmission power by an

application of Equation Condition 4 to Equation 2, by which the sum of the nominal

power reduction value (NOM_RTX_DELTA_SPID_RATE) corresponding to the specific sub-packet identifier and the specific data transmission rate and the adjustment

power reduction value (ADJ_RTX_DELTA_SPID_RATE) corresponding to the specific

sub-packet identifier and the specific data transmission rate is subtracted from a

simplified traffic power level based on the calculated traffic-to-pilot ratio and the

transmission power of the pilot signal. For reference, application of Equation

Condition 4 to Equation 2 gives Ptraffic = P_Piiot + 0.125 { (G_nom__Rate+Gadj_Rate) -

(Rnom_SPID_Rate+Radj_SPID_Rate)} •

To implement the selective application of Equation Conditions 3 and 4, the value

of α is determined by an α value indicator transmitted from the base station, preferably

via the ECAM containing the adjustment gain values transmitted upon call

establishment, such that the term R_n0m may or may not be included in the equation,

according to whether the mobile terminal is one providing intrinsic support for

retransmission packet power reduction or one providing no such support. Hence, the

mobile terminal may, as necessary, apply either of Equation Conditions 3 and 4 to

determine the transmission power of a retransmission packet.

A mobile terminal of a wireless mobile communication system comprises a

microprocessor using a memory, e.g. a flash memory, ROM, and/or SRAM, for storing

a plurality of values according to the first or second embodiment. A transceiving

means, provided for communication with the base station of the system including an

antenna, comprises an RF module and an antenna. By adopting the method of the

present invention, the microprocessor determines transmission power of one of the

retransmission packets by executing either Equation 1 or Equation 2 in accordance with the first or second embodiments, respectively.

Accordingly, the retransmission packet transmission power control method

according to the present invention reduces the reverse link interference, thereby

enabling an increase in packet throughput in a reverse link. Such reduction reverse

link interference facilitates link adaptation (e.g., AMC) effectiveness in a forward link.

It will be apparent to those skilled in the art that various modifications and

variations can be made in the present invention without departing from the spirit or

scope of the invention. Thus, it is intended that the present invention cover such

modifications and variations, provided they come within the scope of the appended

claims and their equivalents.

Industrial Applicability

The present invention can be applicable to a wireless mobile communication

system supporting hybrid automatic retransmission request (HARQ) transmission

Claims

What is claimed is:

1. A method of controlling transmission power of retransmission packets by a

mobile terminal in a wireless mobile communication system supporting hybrid

automatic retransmission request (HARQ) transmission, the method comprising steps

of: receiving, from a base station, gain information associated with the sequence of

the retransmission packets; determining, using the gain information, transmission power of one of the

retransmission packets; and transmitting the retransmission packet with the determined transmission power.

2. The method of claim 1 , wherein the gain information includes a plurality of

adjustment gain values corresponding to each one of data transmission rates and the

sequence of the retransmission packets.

3. The method of claim 2, wherein the transmission power of the

retransmission packet is determined using one of the plurality of adjustment gain values,

one of a plurality of nominal gain values which are already known to the mobile

terminal, and a pilot-channel transmission power.

4. The method of claim 2, wherein the plurality of adjustment gain values are

included in an extended channel assignment message (ECAM).

5. The method of claim 3, further comprising the step of receiving a plurality

of adjustment gain values which are changed after completion of call establishment with

the base station.

6. The method of claim 5, wherein the changed adjustment gain values are

included in a universal hand-off direction message (UHDM) or a power control

message (PCNM).

7. The method of claim 2, wherein, for each data transmission rate, the

adjustment gain values sequentially decrease according to the sequence of

retransmission packets.

8. The method of claim 3, wherein the nominal gain values vary according to

the data transmission rates.

9. The method of claim 3, wherein the nominal gain values vary according to

the data transmission rates and the sequence of the retransmission packets.

10. The method of claim 9, wherein, for each data transmission rate, the

nominal gain values decrease with the sequence of the retransmission packets.

11. The method of claim 3, wherein the plurality of nominal gain values

comprise a first set of nominal gain values varying according to the data transmission

rates and a second set of nominal gain values varying according to the data transmission

rates and the sequence of the retransmission packets.

12. The method of claim 11, further comprising a step of receiving a nominal

gain value indicator indicating whether to use the first set of nominal gain values or the

second set of nominal gain values.

13. The method of claim 12, wherein the nominal gain value indicator is

included in an extended channel assignment message (ECAM).

14. The method of claim 11, wherein, for each data transmission rate, the

second set of nominal gain values decrease with the sequence of the retransmission

packets.

15. The method of claim 1, wherein the gain information includes a plurality

of adjustment power reduction values corresponding to each data transmission rate and

the sequence of the retransmission packets.

16. The method of claim 15, wherein the transmission power of the

retransmission packet is determined using one of the plurality of adjustment power

reduction values and one of a plurality of nominal power reduction values which are

already known to the mobile terminal.

17. The method of claim 15, wherein the plurality of adjustment power

reduction values are included in an extended channel assignment message (ECAM).

18. The method of claim 15, further comprising a step of receiving a plurality

of adjustment power reduction values which are changed after completion of call

establishment with the base station.

19. The method of claim 18, wherein the changed adjustment power reduction

values are included in a universal hand-off direction message (UHDM) or a power

control message (PCNM).

20. The method of claim 16, wherein the plurality of nominal power reduction

values vary according to the data transmission rates and the sequence of the

retransmission packets.

21. The method of claim 20, further comprising a step of receiving an

indicator indicating whether the nominal power reduction values is to be used in

determining the transmission power of the retransmission packet.

22. The method of claim 21, wherein the indicator is included in an extended

channel assignment message (ECAM).

23. A method of controlling transmission power of retransmission packets in

a wireless mobile communication system supporting hybrid automatic retransmission

request (HARQ) transmission, the method comprising steps of: transmitting, to at least one mobile terminal, gain information associated with

the sequence of the retransmission packets; and receiving, from the at least one mobile terminal, a retransmission packet

transmitted at a transmission power determined by the at least one mobile terminal

using the gain information.

24. The method of claim 23, wherein the gain information includes a plurality

of adjustment gain values corresponding to each one of data transmission rates and the

sequence of the retransmission packets.

25. The method of claim 24, wherein the transmission power of the

one of a plurality of nominal gain values which are already known to the mobile

terminal, and a pilot-channel transmission power.

26. The method of claim 24, further comprising a step of transmitting a

plurality of adjustment gain values which are changed after completion of call

establishment with the at least one mobile terminal.

27. The method of claim 24, wherein, for each data transmission rate, the

plurality of adjustment gain values decrease with the sequence of the retransmission

packets.

28. The method of claim 25, wherein the plurality of nominal gain values vary

according to the data transmission rates.

29. The method of claim 25, wherein the plurality of nominal gain values vary

according to the data transmission rates and the sequence of the retransmission packets.

30. The method of claim 29, wherein, for each data transmission rate, the

plurality of nominal gain values decrease with the sequence of the retransmission

packets.

31. The method of claim 25, wherein the plurality of nominal gain values

rates and the sequence of the retransmission packets.

32. The method of claim 31, further comprising a step of transmitting a

nominal gain value indicator indicating which set of nominal gain values is to be used

as the plurality of the nominal gains.

33. The method of claim 31, wherein, for each data transmission rate, the

packets.

34. The method of claim 23, wherein the gain information includes a plurality

the sequence of the retransmission packets.

35. The method of claim 34, wherein the transmission power of the

already known to the mobile terminal.

36. The method of claim 35, further comprising a step of transmitting a

plurality of adjustment power reduction values which are changed after completion of

call establishment with the base station.

37. The method of claim 35, wherein the plurality of nominal power reduction

values vary according to the data transmission rates and the sequence of the

retransmission packets.

38. The method of claim 37, further comprising a step of transmitting an

determining the transmission power of the retransmission packet.

39. A mobile terminal used in a mobile telecommunications system

supporting hybrid automatic retransmission request (HARQ) transmission, the mobile

terminal comprising: means for receiving, from a base station, a plurality of adjustment power

reduction values corresponding to each data transmission rate and the sequence of the

retransmission packets and for transmitting packets to the base station; means for storing a plurality of nominal gain values; and means for determining transmission power of one of the retransmission packets

using one of the plurality of adjustment gain values, one of a plurality of nominal gain

values, and a pilot-channel transmission power.

40. The mobile terminal of claim 39, wherein, for each data transmission rate,

the adjustment gain values sequentially decrease according to the sequence of

retransmission packets.

41. The mobile terminal of claim 39, wherein the nominal gain values vary

according to the data transmission rates.

42. The mobile terminal of claim 39, wherein the nominal gain values vary

43. The mobile terminal of claim 39, wherein, for each data transmission rate,

the nominal gain values decrease with the sequence of the retransmission packets.

44. The mobile terminal of claim 39, wherein the plurality of nominal gain

values comprise a first set of nominal gain values varying according to the data

transmission rates and a second set of nominal gain values varying according to the data

transmission rates and the sequence of the retransmission packets.

45. The mobile terminal of claim 44, wherein, for each data transmission rate,

the second set of nominal gain values decrease with the sequence of the retransmission

packets.

46. A mobile terminal used in a mobile telecommunications system

reduction values corresponding to each one of data transmission rates and the sequence

of retransmission packets and for transmitting packets to the base station; means for storing a plurality of nominal power reduction values; and means for determining transmission power of one of the retransmission packets

using one of the plurality of adjustment power reduction values and one of the plurality

of nominal power reduction values .

47. The mobile terminal of claim 46, wherein the plurality of nominal power

reduction values vary according to the data transmission rates and the sequence of the

retransmission packets.