HK1075141B - Method and apparatus for power control in a wireless communication system - Google Patents

Description

Method and apparatus for power control in a wireless communication system

Background

FIELD

The present invention relates generally to communications, and more particularly to power control in a wireless communication system.

Background

The increasing demand for wireless data transmission and the expansion of services available through wireless communication technology has led to the development of systems capable of handling voice and data services. One spread spectrum system designed to handle the various requirements of both services IS the Code Division Multiple Access (CDMA) system known as CDMA2000, the specifications of which are specified in the "TIA/EIA/IS-2000 standard for CDMA2000 spread spectrum systems".

As the amount of data transmitted and the number of transmissions increases, the limited bandwidth available for radio transmission becomes a decisive resource. Accordingly, there is a need for an efficient and accurate method of transmitting information in a communication system that optimizes the use of available bandwidth.

SUMMARY

Embodiments disclosed herein address the above stated needs by a remote station apparatus having a link quality estimation unit operable to generate a link quality estimate from a first power control command received on a common channel, and a power control unit coupled to the link quality estimation unit to generate a second power control command from the link quality estimate.

According to a further aspect, a base station apparatus includes a decoder, and a decision unit coupled to the decoder, and an adjustment unit coupled to the decision unit for determining a power control command for transmission by the base station on a common channel, the adjustment unit operable to adjust a power level of the power control command.

According to yet another aspect, a base station apparatus includes a control processor for power controlling transmission of power control instructions on a common channel and an amplifier operable to adjust a power level of the power control instructions.

In yet another aspect, a wireless communication system includes a first power control unit operable to transmit reverse link power control commands on a common channel and a second power control unit operable to adjust a transmit power of the reverse link power control commands based on forward link power control commands received on a Reverse Link (RL).

In yet another aspect, a method for power control in a wireless device operable in a wireless communication system having a Forward Link (FL) and a Reverse Link (RL), transmitting power control instructions on a Forward Link (FL) common channel, includes measuring an SNR of at least one power control bit used to control the Reverse Link (RL) and determining a power control decision for the Forward Link (FL) based on the SNR.

In yet another aspect, a method for power control in a wireless communication system having a Forward Link (FL) and a Reverse Link (RL) and transmitting power control commands on a Forward Link (FL) common channel includes determining a first power control command for controlling the Reverse Link (RL) based on a second power control command received on the Reverse Link (RL), determining a second power control command for controlling the Forward Link (FL) for a first transmit power, and transmitting the first power control command at the first transmit power level on the common channel, the system

In yet another aspect, a method for power control in a wireless communication system having a Forward Link (FL) and a Reverse Link (RL) transmitting power control commands on a Forward Link (FL) common channel includes generating reverse link power control commands, generating forward link power control commands, and adjusting a power level at which the forward link power control commands are transmitted based on the reverse link power control commands.

Brief Description of Drawings

FIG. 1 is a diagram of a communication system having a wired subsystem and a wireless subsystem;

FIG. 2 is a diagram of a structural model of a Reverse Link (RL) channel in a communication system;

fig. 3 is a diagram of a structural model of logical channels in a communication system;

FIG. 4 is a timing diagram for power control on a dedicated channel in a communication system;

FIG. 5 is a timing diagram for power control on a shared control channel in a communication system;

fig. 6 is a flow chart of a method of power control in a communication system;

FIG. 7 is a timing diagram for power control of power control bits on a shared control channel in a communication system;

FIG. 8 is an illustration of a wireless device compatible with a communication system protocol that performs power control on a common channel of a forward link; and

fig. 9 is a diagram of a communication system compatible base station apparatus that performs power control on a common channel of a forward link.

Detailed Description

The word "exemplary" is used exclusively herein to mean "serving as an example, instance, or illustration". Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

In a spread spectrum wireless communication system, such as cdma2000, multiple users transmit to a transceiver, typically a base station, in the same bandwidth at the same time. A base station may be any data device that communicates through a wireless channel or through a wired channel, for example using fiber optic or coaxial cables. The user may be any of a variety of devices including, but not limited to, a PC card, a compact flash, an external or internal modem, or a wireless or wireline phone. The user is also referred to as a remote station. The communication link through which a user sends signals to the transceiver is called a reverse link, RL. The communication link through which a transceiver sends signals to a user is called a forward link, FL. As each user transmits to and receives from the base station, other users simultaneously communicate with the base station. The transmission of each user on the Forward Link (FL) and/or the Reverse Link (RL) introduces interference to other users. To overcome interference in the received signal, the demodulator tries to maintain a sufficient ratio E of bit energy to interference power spectral density_b/N_oTo demodulate the signal with an acceptable probability of error. Power control, PC, is a process that adjusts the transmit power of one or both of the Forward Link (FL) and Reverse Link (RL) to meet a given error criterion. Ideally, the power control process adjusts transmitter power to achieve at least a minimum requirement E at a given receiver_b/N_o. This ensures that the benefit from one user through the power control process is not at the expense of any unnecessary cost to the other user.

For clarity, power control PC information transmitted via the Forward Link (FL) is referred to as "FL PC commands (forward link power control commands)" and power control information transmitted via the Reverse Link (RL) is referred to as "RL PC commands (reverse link power control commands)". The FL PC commands provide power control information for controlling Reverse Link (RL) transmit power. The reverse link power control commands provide power control information for controlling Forward Link (FL) transmit power.

In spread spectrum systems, such as CDMA systems, the performance of the system is interference limited. Thus, the capacity of the system and the quality of the system are limited by the amount of interference power present in the transmission. Capacity is defined as the total number of users that the system can simultaneously support, while quality is defined as the condition of the communication link perceived by the receiver. Power control impacts the capacity of the system by ensuring that each transmitter only causes the other users to introduce a minimal amount of interference and thus increases the "processing gain". The processing gain is the ratio of the transmission bandwidth W to the data rate R. The quality measure of the transmission link can be defined as E corresponding to the signal-to-noise ratio SNR_b/N_oTo the ratio of W/R. The processing gain overcomes a limited amount of interference from other users, i.e., the total noise. Therefore, the system capacity is proportional to the processing gain and SNR.

Fig. 1 illustrates a wireless communication system 20, which in one embodiment is a cdma2000 system in system 20. The system 20 includes two parts: a wired subsystem and a wireless subsystem. The wired subsystems are the public switched telephone network, PTSN 26, and the internet 22. The internet 22 portion of the wired subsystem interfaces with the wireless subsystem via an interworking function internet IWF 24. Increasing data communication requirements are generally associated with the internet to facilitate access to available data. Advanced video and audio applications, however, increase the requirements for transmission bandwidth.

The wired subsystem may include, but is not limited to, other modules such as a test unit, a video unit, and the like. The radio subsystems include a base station subsystem comprising a mobile switching center MSC 28, a base station controller BSC 30, base transceiver stations BTS32, 34 and mobile stations MS36, 38. MSC 28 is the interface between the wireless subsystem and the wired subsystem. The switch dialogues with a plurality of wireless devices. The BSC 30 is the control and management system for one or more BTSs 32, 34. The BSC 30 exchanges messages with the BTSs 32, 34 and the MSC 28. Each BTS32, 34 includes one or more transceivers located at separate locations. Each BTS32, 34 terminates the radio path on the network side. The BTSs 32, 34 may be located at the same location as the BSC 30 or may be located at separate locations.

The system 20 includes radio air interface physical channels 40, 42 between the BTSs 32, 34 and the MSs 36, 38. The physical channels 40, 42 are communication paths described in terms of digital coding and RF (radio frequency) characteristics. According to one embodiment, system 20 contains logical channels in addition to physical channels 40, 42, such as shown in FIG. 2. Each logical channel is a communication path in a protocol layer of the BTS32, 34 or MS36, 38. The information on the logical channels is grouped according to criteria such as number of users, type of transmission, direction of delivery, etc. The information on the logical channels is eventually transferred to one or more physical channels. A mapping is defined between logical and physical channels. These mappings may be permanent or may be defined only for a given communication duration. In the example logical channel of fig. 2, the forward common signaling channel F-CSCH 50 conveys information that may be mapped to a forward synchronization channel F-SYNCH 52, a forward paging channel F-PCH 54, and a forward broadcast control channel F-BCCH 56.

As described herein above, the Forward Link (FL) is defined as the communication link for transmissions from one of the BTSs 32, 34 to one of the MSs 36, 38. A Reverse Link (RL) is defined as the communication link for transmissions from one of the MSs 36, 38 to one of the BTSs 32, 34. According to one embodiment, power control in system 20 includes controlling the transmit power of both the Reverse Link (RL) and the Forward Link (FL). Various power control mechanisms may be applied to the Forward Link (FL) and Reverse Link (RL) in system 20, including reverse open-loop power control, reverse closed-loop power control, forward closed-loop power control, and so on. Reverse open loop power control adjusts the initial access channel transmit power of the MSs 36, 38 and compensates for changes in the path loss attenuation of the Reverse Link (RL). The Reverse Link (RL) uses two types of code channels: traffic channels and access channels. The Forward Link (FL) and Reverse Link (RL) traffic channels typically comprise a base code channel FCCH and a plurality of supplemental code channels SCCH. The fundamental code channel serves as the primary channel for all traffic communication in the Forward Link (FL) and Reverse Link (RL). In one embodiment, each base code channel is associated with one instance of a spreading code, such as a walsh code. Each of the reverse link access channels (RACH) is associated with a Paging Channel (PCH). Fig. 3 illustrates a Reverse Link (RL) channel structure in accordance with one embodiment.

In system 20, closed loop power control compensates for fading environments of both the Forward Link (FL) and the Reverse Link (RL), according to one embodiment. During closed loop power control, the receiver measures the input E_b/N_oAnd providing feedback to the transmitter commanding an increase or decrease in transmit power. In one embodiment, the changes are made in 1dB steps. Further embodiments may use further values of constant value step size, or may implement dynamic step size values, for example, as a function of power control history. Still other embodiments may vary the step size depending on the performance and/or requirements of system 20. Power control of the Reverse Link (RL) is performed by the BTSs 32, 34, where the received signal is measured and compared to a threshold value. A determination is then made whether the received power is above or below a threshold value. The decisions are sent as FL PC commands to a given user, such as MSs 36, 38, respectively. Reverse Link (RL) transmit power is adjusted according to the command. During closed loop power control of the Reverse Link (RL), FL PC commands may be periodically interspersed into Forward Link (FL) transmissions to provide feedback to the MSs 36, 38. Instead of transmitting a signal, FL PC commands are interspersed. Puncturing may be done in each of a number of frames that split a transmission into a given time duration.

System 20 is designed to transmit voice information, data information, and/or both voice and data. Fig. 4 shows a Fundamental Channel (FCH) for communications containing voice. The signal strength of the fundamental channel is shown as a function of time. Showing the slave time t₀To t₃The first frame of (2). Respectively showFrom time t₃To t₆And from time t₆To t₉The subsequent frame of (2). The first frame comprises a break-in time t₁To t₂FL PC command of. The punctured power control bits replace the information transmitted during that time. Similarly, the power control bits are punctured from t₄To t₅In subsequent frames of and from t₇To t₈In the next frame. Note that the power control instruction may be done over multiple frames. In one embodiment, the FL PC commands are placed in a pseudo-random manner. In alternative embodiments, the FL PC commands may be placed in a fixed time slot or an opposite time slot.

Power control of forward link and reverse link power control commands are provided from the MSs 36, 38 to the BTSs 32, 34, respectively. Closed loop power control of the forward link counts the number of bad frames received during a given period and sends a report to the BTSs 32, 34. The message may be sent periodically or when the error rate reaches a threshold value, which is set by system 20. In one embodiment, each frame transmitted by the MS36, 38 includes an Erasure Indicator Bit (EIB) set to indicate an erasure. Forward Link (FL) power is adjusted based on the EIB history.

Closed loop power control includes two feedback loops: an inner loop and an outer loop. The outer loop measures the frame error rate and periodically adjusts the set point up or down to maintain the target frame error rate. The set point is increased if the frame error rate is too high and decreased if the frame error rate is too low. The inner loop measures the received signal level and compares it to a set point. Power control commands are then sent to increase or decrease the power as needed to maintain the received signal level near the setpoint. The two loops operate in concert to ensure sufficient signal strength, demodulate the signal with an acceptable probability of error, and minimize interference to other users.

The Forward Link (FL) includes common channels including, but not limited to, a pilot channel, a common Control Channel (CCH), a Broadcast Channel (BCH), and a Common Power Control Channel (CPCCH). The common control channel carries mobile-specific messages for compatible mobile stations, and the Broadcast Channel (BCH) carries broadcast messages for compatible mobile stations, including overhead messages. A common power control channel is used to transmit Power Control (PC) bits to the mobile stations such that messages are transmitted under power control.

Most wireless multiple-access communication systems, such as spread spectrum systems, capable of voice and data transmission seek to optimize the physical channels to serve users at high data rates. Such systems may use a low rate channel known as a Fundamental Channel (FCH). The fundamental channel is used for voice and signaling transmission. Each fundamental channel is associated with a plurality of high-rate channels known as supplemental channels. The supplemental channel is used for data transmission. Where the fundamental channel uses less energy, a dedicated walsh code is required for each fundamental channel, resulting in a larger energy being aggregated over multiple fundamental channels. The fundamental channel is idle for data communication most of the time. Under this condition, the fundamental channel wastes walsh codes and power that can be used to increase the capacity and performance of the system. To avoid this waste, one embodiment allocates a number of fundamental channels to one or more common channels shared by all users. The use of walsh codes, or walsh space, is reduced to one walsh code, reducing the power otherwise consumed by an idle fundamental channel.

The introduction of a shared common channel facilitates the use of a Common Power Control Channel (CPCCH) when power control commands are previously transmitted on each allocated fundamental channel. The common power control channel is used for power control of a Reverse Link (RL), in which different users share the channel in a time-division manner. The FL PC commands are transmitted over the common power control channel.

Fig. 5 shows an alternative to FL PC commands for mobile users labeled a and B. FL PC commands are transmitted on the common power control channel and plotted as a function of time. The FL PC commands are transmitted on the common power control channel at full power or at a predetermined power level. Commands intended for users a and B are time division multiplexed together on a common power control channel. The replacement of the individual FL PC commands may be at a fixed time or may be replaced in another manner, such as a pseudo-random manner.

In the system 20 of fig. 1, the FL PC commands are transmitted over a Common Power Control Channel (CPCCH), or on a dedicated channel such as a Fundamental Channel (FCH). FL PC commands are sent to the MSs 36, 38 using the forward common power control channel (F-CPCCH) for controlling the reverse common control channel (R-CCH). As described herein above, open loop power control is used on the reverse access channel (R-ACH). Each MS36, 38 repeats the transmission with increasing power until it receives an acknowledgement from the BTS32, 34, respectively, or until a maximum number of probes and probe sequences is reached.

It is often desirable to continue power control of the Forward Link (FL) even when no data is being transmitted. For example, if only a few data frames are transmitted on the supplemental channel, updating the power control of the Forward Link (FL) enhances the transmission of the supplemental channel to transmit at the required power and conserving power. Further, for data transmission, continuing power control of the Forward Link (FL) provides a data scheduler with information about the link quality at a given time. This information allows the scheduler to take advantage of the channel using a given scheduling scheme.

In addition, it is desirable for the mobile station to determine the base station's response to RL PC commands (reverse link power control commands). Using the shared common channel, the mobile station can see the effect of the RL PC command. For example, the mobile station may know the E of the Forward Link (FL) following a series of RL PC commands_b/N_o. At the base station receiver, the RL PC commands may already be unreliable. Ideally, the Forward Link (FL) includes one power indication in response to RL PC commands received at the base station. Using the Fundamental Channel (FCH), the mobile station can measure the Fundamental Channel (FCH) of this feedback. In one embodiment using a shared channel, feedback is provided as a function of the power level commanded by the RL PC.

Fig. 6 illustrates a method 100 of power control in a system 20 in which FL PC commands (forward link power control commands) controlling the Reverse Link (RL) are transmitted on a Common Power Control Channel (CPCCH) for the Forward Link (FL). According to the method 100, RL PC commands (reverse link power control commands) are used to adjust the power level of the FL PC commands. Initially, at step 102, the method 100 sets the FLPC commanded transmit power for the Forward Link (FL) to a predetermined reference power level. At step 104, a determination is made whether an up or down instruction is received based on the RL PC command received from the mobile station MS. If an up command is received, the FL PC command power level is incremented at step 106. The increment amount may be a step value or a function of a transmit power control bit previously sent on the Forward Link (FL). If the received RL PC command is a down command, the FL PC command power level FL is decremented at step 108. The amount of decrement may be a function of a step value or a transmit power control bit previously sent on the Forward Link (FL), or may be a function of a received command. Following either step 108 or step 106, processing continues at step 110 with the next FLPC command being sent at the adjusted power level. If an RL PC command is received at step 112, the process returns to step 104 to determine the instruction. The method 100 efficiently performs FL PC commanded forward link power control. Note that the power control of method 100 does not attenuate FL PC command information. Power control of the Reverse Link (RL) is performed using FL PC command information.

When the base station adjusts the power level of the FL PC command based on the RL PC command, such as according to the method 110 of fig. 6, the mobile station may use the FL PC commanded power level to make a power control decision to estimate the quality of the Forward Link (FL). The mobile station may then use this information to generate power control commands. According to one embodiment, the mobile station measures the SNR of forward link power control bits on a Common Power Control Channel (CPCCH). The SNR is then compared to a threshold value. And transmitting the corresponding power control command according to the comparison. The Forward Link (FL) is prepared to transmit at the correct power level and the base station may use the transmit power as an indication of the channel quality. According to one embodiment, the RL PC command is included in the DRC transmit data rate channel.

Fig. 7 shows a timing scheme for implementing the method 100 of fig. 6. RL PC command transmission and FL PC command transmission are shown as a function of time. From time t at a first power level A₁To t₂A first FL PC command is sent. Following the first FL PC command, from time t₃To t₄The RL PC command is sent. The RL PC command corresponds to a down command. In response to the down command, the base station decrements the power level of the next transmit FL PC command. As shown, from time t at an adjusted power level B₅To t₆The next FL PC command is sent.

With continued reference to FIG. 7, at time t₇Here, the RL PC command denotes an up command. In response to the up command, the base station increments the power level of the next transmit FL PC command. As shown, from time t₉To t₁₀The power level of the transmitted FL PC command returns to level a.

The method 100 is applicable to a variety of systems and schemes. For example, the method 100 may be applied to data transmission in which a base station receives more data from a mobile station than is transmitted on a Forward Link (FL). In one embodiment, the wireless financial system incorporates the method 100 of FIG. 6. A central processing center, similar to BTSs 32, 34, receives information about financial transactions or credit purchases over a Reverse Link (RL). Performing most of the transmissions on the Reverse Link (RL); therefore, power control is typically performed exclusively on the Reverse Link (RL). In this scheme, power control is also performed on the Forward Link (FL) and serves to enhance reverse link power control. In further embodiments, the method 110 is applied to a distributed billing reporting system, such as a utility billing reporting system. In this case, the central processing center receives information from a plurality of units or meters.

Fig. 8 illustrates one embodiment of a wireless device 200, such as a remote station or mobile station, compatible with a spread spectrum system implementing common channels on the Forward Link (FL) that transmits power control decisions for the Reverse Link (RL). Wireless device 200 is an integral part of power control for both the Reverse Link (RL) and the Forward Link (FL). As shown, FL PC commands are transmitted over a Common Power Control Channel (CPCCH). In further embodiments, the FL PC commands may be transmitted over another control channel. The FL PC command provides information including Reverse Link (RL) power control instructions. The FL PC commands have been power controlled to reflect instructions transmitted by the wireless device 200 to a base station (not shown) as RL PC commands that control the Forward Link (FL). In this manner, the RL PC command effectively performs power control of the FL PC command. Wireless device 200 receives FL PC commands and other information at receive circuitry 202 over a Common Power Control Channel (CPCCH). The receive circuitry 202 may include, but is not limited to, an antenna or antennas, a pre-processing unit for multiple access communication, a frequency spreading unit, and a demodulator.

Coupling the receive circuitry 202 to E operable to estimate the received signal_b/N_oTo the SNR estimator 204. The SNR estimator 204 generates E_b/N_oAnd provides the estimate to threshold comparator 206. Threshold comparator 206 pair E_b/N_oThe estimate is compared to a predetermined or pre-calculated threshold value called the set point. The set point is monitored and updated by a set point adjustment unit 212 coupled to the threshold comparator 206. As described herein above, the setpoint adjustment is part of the power control outer loop and is a function of the frame error rate. There are many decision criteria and methods for performing the operation of the setpoint adjustment unit 212. The result of the comparison by the threshold comparator 206 is provided to a power control bit decision unit 208 to determine the next power control command to send to the base station. The wireless device 200 can provide the correct power control commands to the base station by determining the quality of the Forward Link (FL) via forward link power control bits received on the Common Power Control Channel (CPCCH).

The power control bit decisions are then provided to a generation unit 210 to generate RL PC bits (reverse link power control bits) or RL PC messages (reverse link power control messages) for transmission on the Reverse Link (RL). The generation unit 210 is coupled to an amplifier 214 that receives the RL PC bits from the generation unit 210. The amplifier 214 passes the RL PC bits and to the transmit circuit 216. The level of amplification is provided by power control of the Reverse Link (RL) as a result of instructions from the base station. Signal information is provided from the receive circuitry 202 to a decoder 218 that obtains Reverse Link (RL) power control commands. The decoder 218 decodes information received on the Common Power Control Channel (CPCCH) and determines the corresponding FL PC commands. The FL PC command is then provided to an adjustment unit 222 that adjusts the transmit power of the Reverse Link (RL). The adjustment is provided as a control input to amplifier 214, which applies the appropriate amplification factor to the data and control information transmitted on the Reverse Link (RL). The amplifier 214 also applies power control to the RL PC commands for transmission.

One embodiment of a base station 300 compatible with wireless device 200 is shown in fig. 9. At the base station 300, RL PC bits are received at a receive circuit 302 over a Reverse Link (RL). The receive circuitry 302 may include, but is not limited to, an antenna or antennas, a pre-processing unit for multiple access communication, a frequency spreading unit, and a demodulator. The receive circuit 302 is coupled to a decoder 304 that obtains the RL PC command from the received signal. Commands are then provided to adjustment unit 308 to adjust the Forward Link (FL) traffic transmit power. The adjustment is provided as control information to amplifier 312. The power control commands from decoder 304 are also provided to power control adjust unit 310. Adjustment unit 310 adjusts the transmit power level of the power control bits sent on the Common Power Control Channel (CPCCH) based on RL PC commands. Amplifier 312 applies the appropriate amplification factor to the data and/or control information and FLPC commands transmitted by base station 300. Note that the base station 300 determines power control commands for transmission to the wireless device 200, where the power control commands are power control bits transmitted on a Common Power Control Channel (CPCCH). A multiple access power control decision mechanism may be implemented to determine the appropriate power control commands to control the Reverse Link (RL).

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any other combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The method steps or algorithms described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be combined with the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

The previous description of the preferred embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. A remote station apparatus, comprising:

a link quality estimation unit for generating a link quality estimation value according to a first power control command received on a common channel; and

a power control unit coupled to the link quality estimation unit, the power control unit generating a second power control instruction based on the link quality estimation, wherein the second power control instruction comprises one or more commands used to adjust the transmit power of the common channel at a base station.

2. The remote station apparatus according to claim 1, wherein said remote station apparatus controls transmission power according to said first power control instruction.

3. The remote station apparatus of claim 1, wherein the remote station apparatus transmits the second power control instruction.

4. A base station apparatus, comprising:

a decoder; and

a decision unit coupled to the decoder; the decision unit to determine a first power control command received from a remote station for transmission by a base station on a common channel; and

an adjustment unit coupled to the determination unit, the adjustment unit to adjust a transmit power level of a second power control command sent to the remote station on a common channel based on the received first power control command;

wherein the received first power control command is generated by the remote station based on a link quality estimate of a second power control command transmitted by the base station to the remote station on a common channel.

5. A base station apparatus, comprising:

a control processor for power controlling a first power control command transmission by a base station to a remote station on a common channel, wherein a transmit power level of said first power control command is initially set to a reference value; and

an amplifier to adjust a transmit power level of the first power control command on a common channel in accordance with a second power control command received on a common channel from the remote station;

wherein the received second power control commands are generated by the remote station based on a link quality estimate of the first power control commands transmitted by the base station to the remote station on a common channel.

6. A method for power control in a wireless device operating in a communication system having a forward link and a reverse link, the system transmitting power control bits on a forward link common channel, the method comprising the steps of:

measuring SNR of at least one power control bit from the forward link common channel, the power control bit being used for controlling a reverse link; and

determining a power control decision for the forward link based on the SNR, wherein the power control decision comprises one or more commands used to adjust the transmit power of the common channel at a base station.

7. A method for power control in a wireless communication system having a forward link and a reverse link between a base station and a remote station, the system transmitting power control commands on a forward link common channel, the method comprising the steps of:

determining, at a base station, a first power control command transmitted by the base station to the remote station on the forward link common channel for controlling a reverse link;

determining a first transmit power level based on a second power control command received on a reverse link from the remote station, the second power control command being used for control of the forward link common channel, wherein the second power control command is generated by the remote station based on a link quality estimate of the first power control command transmitted by the base station to the remote station on a forward link common channel; and

transmitting the first power control command at the first transmit power level on the forward link common channel.

8. The base station apparatus of claim 4 wherein the transmit power level of said power control commands is initially set to a reference value.

9. The remote station apparatus of claim 1, wherein the link quality estimate is an SNR.