HK1078696A

HK1078696A - Power control of serving and non-serving base stations

Info

Publication number: HK1078696A
Application number: HK05110588.2A
Authority: HK
Inventors: 陈道; 魏文斌; A．筒恩; E.G.小蒂德曼
Original assignee: 高通股份有限公司
Priority date: 2002-02-07
Filing date: 2003-02-07
Publication date: 2006-03-17

Description

Power control for serving and non-serving base stations

no marking

Claim priority in accordance with U.S. patent Act 35 U.S. C § 119

This patent application claims priority to provisional application No. 60/355223 entitled "METHOD and apparatus FOR FORWARD LINK POWER IN acidic recording SYSTEM", filed on day 2, month 7, 2002; also claimed is priority of provisional application No. 60/356929 entitled "METHOD AND APPARATUS FOR FORWARD LINK POWER IN a COMMUNICATION SYSTEM", filed 2002, 12/2; also claimed as priority IS provisional application No. 60/360271 entitled "POWER CONTROL office F-cpccph (forward COMMON POWER CONTROL channel) IN IS-2000rev.c (1 XEV-DV)" filed on 26.2.2002; and claim priority from provisional application No. 60/362119 entitled "POWER CONTROL USING PC BIT STREAMS OF differents", filed on 3/5/2002; all assigned to the assignee of the present invention and incorporated herein by reference.

Background

FIELD

The present invention relates generally to communications, and more particularly to a novel and improved method and apparatus for power control for serving and non-serving base stations.

Background

Wireless communication systems are widely deployed to provide various types of communication such as voice, data, and so on. These systems may be based on Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), or some other modulation technique. CDMA systems offer certain advantages over other types of systems, including increased system capacity.

A CDMA System may be designed to support one or more CDMA standards, such as (1) the "TIA/EIA-95-BMobject State-Base State Compatibility Standard for Dual-ModeWideband Spread Spectrum Cellular System", referred to herein as the IS-95 Standard, (2) the "3-mode wideband Spread Spectrum Cellular System" by the name^rdThe organization provided by Generation Partnership Project ", referred to herein as 3GPP, and included in document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, 3G TS 25.214, and 3G TS 25.302, referred to herein as the W-CDMA standard; (3) is given by the name "3^rdThe standards provided by the organization of GenerationPartnership Project 2 ", referred to herein as 3GPP2 and TR-45.5(IS-2000 standards) and (4) some other standards.

In the above named standards, the available spectrum is shared among multiple users simultaneously, and techniques such as power control and soft handoff are used to maintain sufficient quality to support delay sensitive services such as voice. Data services are also available. More recently, a system has been proposed to enhance the capability of data services by using other higher order modulations, very fast carrier-to-interference ratio (C/I) feedback from mobile stations, very fast scheduling, and scheduling of services with more relaxed delay requirements. An example of such a data-only communication system using these techniques IS a High Data Rate (HDR) system that conforms to the TIA/EIA/IS-856 standard (the IS-856 standard).

In contrast to other above-named standards, the IS-856 system uses the entire available spectrum in each cell to transmit data to a single user at a time, where the users are selected based on link quality and other considerations such as data pending, etc. In this way, the system is able to transmit data at a higher rate a greater percentage of the time when the channel is better, thereby avoiding the use of resources to support transmissions at an inefficient rate. The net efficiency is higher data capacity, higher peak data rate and higher average throughput.

The system may also include support for delay sensitive data such as voice channels or data signals supported in the IS-2000 standard and support for packet data services such as those described in the IS-856 standard. One such system is described in LG electronics, LSI Logic, lucent technologies, Nortel networks, high-traffic companies, and samsung, the recommendation submitted to third generation partnership project 2. The details of the proposal are described in the following documents: a document entitled "Updated Joint Physical Layer protocol for 1 xEV-DV" was filed 3GPP2 with document numbers C50-20010611-; "Results of L3NQS Simulation Study" filed 3GPP2 with document number C50-20010820-Asocnd 011, 20/8/2001; and "System organization Results for the L3NQS FrameworkProposal for cdma 20001 xEV-DV" filed 3GPP2 with the document number C50-20010820-012, 8/20/2001. These and related subsequently generated documents, such as revision C of the IS-2000 standard, include c.s0001.C through c.s0006.C, and hereinafter include a proposal referred to as 1 xEV-DV.

One system, such as described in the 1xEV-DV proposal, generally includes four types of channels: overhead channels, dynamically varying IS-95 and IS-2000 channels, a forward packet data channel (F-PDCH), and some spare channels. Overhead channel assignments change slowly, they may be constant for months. They typically change when there is a large network configuration change. The dynamically changing IS-95 and IS-2000 channels are allocated or used on a per call basis for IS-95 or IS-2000 release 0 to B packet services. Typically, the available base station power after the overhead channels and dynamically varying channels have been allocated is allocated to the F-PDCH for the remaining data services. The F-PDCH may be used for less delay sensitive data services while the IS-2000 channel IS used for more delay sensitive services.

The F-PDCH, similar to the traffic channel in the IS-856 standard, IS used to transmit to one user in each cell at a time at the highest supportable data rate. Within IS-856, the entire power of the base station and the entire space of Walsh functions are available at the time the data IS transmitted to the mobile stations. However, in the proposed 1xEV-DV system, some base station power and some Walsh functions are allocated to overhead channels and existing IS-95 and cdma2000 services. The data rate that can be supported depends primarily on the available power and Walsh codes after the power and Walsh codes have been allocated for the overhead, IS-95, and IS-2000 channels. Data transmitted on the F-PDCH is spread using one or more Walsh codes.

In the 1xEV-DV proposal, the base station typically transmits to one mobile station at a time on the F-PDCH, although many users may use packet services within a cell. (and possibly by scheduling transmissions for two or more users to two or more users and allocating power and/or Walsh channels to each user as appropriate). The mobile station is selected for forward link transmission based on some scheduling algorithm.

In a system similar to IS-856 or 1xEV-DV, scheduling IS based in part on channel quality feedback from the served mobile stations. For example, in IS-856, the mobile station estimates the quality of the forward link and calculates the transmission rate that IS currently conditionally supported. The desired rate from each mobile station is transmitted to the base station. For example, a scheduling algorithm may select a mobile station for transmission that can support a relatively higher transmission rate to more efficiently use the shared communication channel. As another example, in a 1xEV-DV system, each mobile station transmits a carrier-to-interference (C/I) estimate as a channel quality estimate on the reverse channel quality indicator channel or R-CQICH. A scheduling algorithm is used to determine the mobile stations that select a transmission and the appropriate rate and transmission format based on the channel quality. There are a variety of scheduling algorithms that can be implemented, such as the proportional fair algorithm detailed in U.S. patent No. 6229795.

In this system, a mobile station receives forward link data from a serving base station. As described, reverse link feedback from the mobile station to the serving base station may be used for forward link scheduling and transmission, and may also be used for serving base station power control. Soft handoff in the above listed systems is not used for this type of forward link data transmission. That is, the mobile station does not receive forward packet data channels, i.e., F-PDCHs, from more than one base station. However, the mobile station is in soft handoff on the reverse link with one or more non-serving base stations and/or sectors to provide reverse link switching diversity. Since the path loss characteristics of each path between a mobile station and multiple base stations will typically be different, the serving base station power control mechanism transmitted to the mobile station may not be suitable for non-serving base stations of the same mobile station. In order to optimize system capacity, it is desirable that the reverse link, as well as any forward link signaling, between the mobile station and the non-serving base station be power controlled. However, maintaining a power control loop for each non-serving base station may use excessive resources on the reverse link. Therefore, there is a need in the art for a method of power control for serving and non-serving base stations.

SUMMARY

Embodiments disclosed herein satisfy power control for serving and non-serving base stations. In an aspect, power control commands for multiple base stations are combined to form a single command to control multiple base stations. In another aspect, an "or-of-up" criterion is used for combining power control instructions. In another aspect, the channel quality indicator is used to implement power control for the serving base station. Various other aspects are also shown. These aspects have the benefit of providing efficient power control between the mobile station and the serving and non-serving base stations, thereby avoiding excessive interference and increased capacity.

The present invention provides methods and system elements that implement various aspects, embodiments, and features of the present invention, as described in detail below.

Brief description of the drawings

The features, nature, and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout and wherein:

FIG. 1 is a general block diagram of a wireless communication system capable of supporting multiple users;

fig. 2 depicts an example of a mobile station and a base station for use in a system adapted for data communication;

FIG. 3 is a block diagram of a wireless communication device, such as a mobile station or base station;

fig. 4 depicts an example embodiment of a system using a first reverse link power control flow for controlling a serving base station and a second reverse link power control flow for controlling a non-serving base station;

FIG. 5 is a flow diagram of an example embodiment of a method of implementing reverse link power control;

FIG. 6 depicts an example timing diagram for reverse link power control;

FIG. 7 depicts a flow diagram of an example embodiment of a method of forward link power control;

FIG. 8 depicts an exemplary timing diagram for forward link power control;

FIG. 9 is a flow diagram of an example embodiment using R-CQICH repetition;

FIG. 10 is a flow diagram of an example embodiment using R-PCSCH repetition; and

fig. 11 depicts an example of the interrelationship between power control commands and the F-CPCCH channel.

Detailed Description

Fig. 1 IS an illustration of a wireless communication system 100 (e.g., W-CDMA standard, IS-95 standard, CDMA2000 standard, HDR specification, 1xEV-DV proposal) designed to support one or more CDMA standards and/or designs. In another embodiment, system 100 may use any wireless standard and design other than a CDMA system.

For simplicity, system 100 is shown to include three base stations 104 in communication with two mobile stations 106. The mobile station and its coverage area are often collectively referred to as a "cell". In an IS-95 system, a cell may include one or more sectors. In the W-CDMA specification, each sector of a base station and the sector's coverage area is referred to as a cell. As used herein, the term base station is used interchangeably with access point or node B. The mobile station terminology may be used interchangeably with the corresponding terminology in the User Equipment (UE), subscriber unit, subscriber station, access terminal, remote station, or other fields. The term mobile station includes fixed wireless applications.

Depending on the CDMA system implemented, each mobile station 106 may communicate with one (or possibly more) base stations 104 on the forward link at any given moment, and with one or more base stations on the reverse link depending on soft handoff. The forward link (i.e., downlink) refers to transmission from the base station to the mobile station, and the reverse link (i.e., uplink) refers to transmission from the mobile station to the base station.

For clarity, the examples used in describing the present invention may assume that the base station is the originator of signals and the mobile station is the recipient and acquirer of those signals, i.e., the signals are forward link signals. Those skilled in the art will appreciate that mobile stations as well as base stations may be used to transmit data as described herein and that aspects of the present invention may be applied in these situations as well. The word "exemplary" is used 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.

As described herein, the wireless communication system 100 may support multiple users sharing communication resources simultaneously, such as an IS-95 system, may allocate the entire communication resource to one user at a time, such as an IS-856 communication system, or may allocate communication resources proportionally to allow various types of access. A 1xEV-DV system is an example of a system that allocates communication resources in two access types, and dynamically allocates according to user needs. The following is a brief background on how communication resources are allocated to conform to individual users within two types of access systems. Power control IS described for simultaneous access by multiple users, such as IS-95 type channels. Rate determination and scheduling IS discussed for time-shared access for multiple users, such as the data-only portion (i.e., F-PDCH) of an IS-856 system or a 1xEV-DV type system. It is noted that "outer loop" is a term referring to both access types, but in both cases the meaning may be different.

Capacity in a system such as an IS-95CDMA system IS determined in part by interference generated by signals transmitted by various users in the system. A feature of a typical CDMA system is that signals to and from a mobile station are coded and modulated so that the signals are perceived as interference by other mobile stations. For example, on the forward link, the channel quality between a base station and a mobile station is determined in part by other user interference. To maintain a desired level of performance in communication with a mobile station, the transmit power of the mobile station must be large enough to exceed the power transmitted to other mobile stations served by the base station and to exceed other interference and degradation experienced within the channel. Therefore, to increase capacity, it is desirable to transmit the minimum power required by each served mobile station.

In a typical CDMA system, when multiple mobile stations transmit to a base station, it is desirable to receive multiple mobile station signals at the base station at a normalized power level. Thus, for example, the reverse link power control system may adjust the transmit power from each mobile station so that signals from neighboring mobile stations do not exceed signals from more distant mobile stations. On the forward link, the transmit power of each mobile station is maintained at the minimum power level required to maintain the desired performance level to maximize capacity, while still achieving other power saving benefits such as increased talk and standby battery requirements.

Capacity in a typical CDMA system, such as IS-95, IS limited by interference factors including interference from other users. Other user interference may be mitigated by using power control. The overall performance of the system, including capacity, voice quality, data transmission rate, and throughput, depends on the station transmitting at the lowest power level to support the desired level of performance possible. To achieve this, various power control techniques are well known in the art.

One class of techniques includes closed loop power control. For example, closed loop power control may be used on the forward link. The system may use an inner and outer power control loop within the mobile station. The outer loop determines the target received power level based on the desired error rate. For example, a target frame error rate of 1% may be predetermined as the desired error rate. The outer loop may update the target received power level at a relatively low rate, such as once per frame or module. In response, the inner loop then sends an up or down power control message to the base station until the received power meets the target. These inner loop power control commands occur relatively frequently so that the transmit power quickly adapts to the level needed to achieve the desired received signal to noise and interference ratio for efficient communication. As described above, maintaining the forward link transmit power of each mobile station at a minimum level reduces interference to other users at each mobile station and allows the remaining available transmit power to be reserved for other purposes. In systems such as IS-95, the remaining available transmit power may be used to support communication with additional users. In systems such as 1xEV-DV, the remaining available transmit power may be used to support additional users, or to increase the throughput of the data-only portion of the system. The outer or inner loop for power control described above may be different from a similarly numbered control loop defined for use with a pure data channel, as described below.

In a "data-only" system, such as IS-856, or in a "data-only" portion of the system, such as 1xEV-DV, the control loop may be used to manage transmissions from the base station to the mobile station in a time-shared manner. For clarity, in the following discussion, a transmission to one mobile station at a time is described. This IS to distinguish from simultaneous access systems, one example of which IS individual channels within an IS-95 or cdma2000 or 1xEV-DV system. There are now two types of comments.

First, the term "data-only" or "data channel" IS used to distinguish it from an IS-95 type voice or data channel (i.e., a simultaneous access channel using power control, as described above), for clarity of discussion. It will be apparent to those skilled in the art that the data-only or data channel described herein may be used to transmit any type of data, including voice (e.g., voice over internet protocol, VOIP). The usefulness of any particular type of embodiment for any particular type of data may be determined in part by throughput requirements, latency requirements, and the like. Those skilled in the art may combine various embodiments with any one access type and selected parameters to provide a desired level of latency, throughput, quality of service, etc.

Second, the data-only portion of the system, such as that described for 1xEV-DV, which is described as a time-shared communication resource, can be used to provide simultaneous access to more than one user. In the examples herein, where the communication resources are described as time-shared to provide communication with one mobile station or user over a period of time, those skilled in the art may use these examples for time-shared transmissions to or from more than one mobile station or user over the period of time.

A typical data communication system may include one or more channels of various types. In particular, one or more data channels are commonly used. Also, one or more control channels are normally used, although in-band control signaling may be included on the data channel. For example, in a 1xEV-DV system, a forward packet data control channel (F-PDCCH) and a forward packet data channel (F-PDCH) are defined for transmission of control and data on the forward link, respectively.

Fig. 2 depicts an example mobile station 106 and base station 104 within system 100 for data communication. Base stations 104 and mobile stations 106 are shown communicating on the forward and reverse links. The mobile station 106 receives the forward link signal in the receive subsystem 220. The base station 104 communicates data and control channels as described below and may be referred to herein as a serving station for the mobile station 106. An example receiving subsystem is described in detail below with respect to fig. 3. A carrier-to-interference (C/I) estimate is made of the forward link signal received from the serving base station within the mobile station 106. C/I measurements are an example of a channel quality metric used as a channel estimate, and other channel quality metrics may be used in other embodiments. The C/I measurements are sent to a transmission subsystem 210 within the base station 104, an example of which is described in detail below with respect to fig. 3.

The transmission subsystem 210 transmits the C/I estimate to the serving base station on the reverse link. It is noted that the reverse link signals transmitted from the mobile stations may be received by one or more base stations other than the serving base station, which are referred to as non-serving base stations, as is well known in the art. A receive subsystem 230 within the base station 104 receives C/I information from the mobile station 106.

A scheduler 240 within the base station 104 is used to determine whether and how data is to be transmitted to one or more mobile stations within the coverage area of the serving cell. Any type of scheduling algorithm may be used within the scope of the present invention. An example is disclosed in U.S. patent application No. 08/798951 entitled "METHOD and apparatus FOR FORWARD LINK pipeline", filed on 1997, month 2 and day 11, assigned to the assignee of the present invention.

When the C/I measurements received from a mobile station indicate that data may be transmitted at a certain rate, the mobile station is selected for forward link transmission in the example 1xEV-DV embodiment. It is advantageous to select a target mobile station such that the shared communication resource is used at the maximum supportable rate in terms of system capacity. Thus, the general target mobile station selected may be the one with the largest reported C/I. Other factors may also be considered in the scheduling decision. For example, there is a minimum quality of service guarantee for each user. A mobile station reporting a relatively low C/I is selected for transmission to maintain a minimum data transmission to the user.

In the example 1xEV-DV system, the scheduler 240 determines which mobile station to send to, and which data rate, modulation format, and power level of transmission. In other embodiments, such as an IS-856 system, for example, supportable rate/modulation format decisions may be made at the mobile station based on channel quality measured at the mobile station, and the transmission format may be sent to the serving base station instead of the C/I measurements. Those skilled in the art will recognize that various combinations of supportable rates, modulation formats, power levels, etc. may be used within the scope of the present invention. Additionally, although in various embodiments described herein, scheduling tasks are implemented within a base station, in other embodiments, some or all of the scheduling process may occur within a mobile station.

Scheduler 240 instructs transmission subsystem 250 to transmit on the forward link to the selected mobile station using the selected rate, modulation format, power level, etc.

In an example embodiment, a message on the control channel, i.e., F-PDCCH, is sent along with data on the data channel, i.e., F-PDCH. The control channel may be used to identify the receiving mobile station for data on the F-PDCH and to identify other communication parameters useful during the communication session. When the F-PDCCH indicates that the mobile station is the target of a transmission, the mobile station should be able to receive and demodulate data from the F-PDCH. The mobile station, upon receiving such data, responds on the reverse link with a message indicating the success or failure of the transmission. Retransmission techniques, well known in the art, are also commonly used in data communication systems.

A mobile station may communicate with more than one base station, a situation referred to as soft handoff. A soft handoff may include multiple sectors (or one Base Transceiver Subsystem (BTS)) from one base station, known as a soft handoff, with sectors from multiple BTSs. Base station sectors in soft handoff are typically stored in the mobile station active set. In systems that simultaneously share communication resources, such as IS-95, IS-2000, or the corresponding portions of a 1xEV-DV system, a mobile station may combine forward link signals transmitted from all sectors in the active set. In a data-only system, such as IS-856, or a corresponding portion of a 1xEV-DV system, a mobile station receives a forward link data signal from one of the base stations in the active set, serving the base station (determined according to a mobile station selection algorithm, such as those described in the c.s0002.c standard). Other forward link signals may also be received from non-serving base stations, examples of which are described in detail below.

Reverse link signals from the mobile station may be received at multiple base stations, and the quality of the reverse link is typically maintained for the base stations in the active set. It is possible to combine reverse link signals received at multiple base stations. In general, soft combining of reverse link signals from non-co-located base stations can require a lot of network communication bandwidth with little delay, which is not supported by the example systems listed above. In soft handoff, reverse link signals received at multiple sectors within a single BTS may be combined without the need for network signaling. In the exemplary system described above, reverse link power control maintains quality so that reverse link frames are successfully decoded at one BTS (switch diversity), although any type of reverse link combination may be used within the scope of the present invention.

In a simultaneously shared communication resource system, such as the corresponding part of an IS-95, IS-2000 or 1xEV-DV system, each base station in soft handoff with a mobile station (i.e., within the mobile station's active set) measures the reverse link pilot quality of the mobile station and transmits a stream of power control commands. In IS-95 or IS-2000 modification B, each stream IS punctured on either the forward fundamental channel (F-FCH) or the forward dedicated control channel (F-DCCH), if one of the two channels IS allocated. The command stream for a mobile station is referred to as the forward power control subchannel (F-PCSCH) for that mobile station. The mobile station receives parallel command streams from all its active set members of each base station (the same command is sent to the mobile station from multiple sectors of a BTS (if all are in the mobile station's active set)) and determines whether an "up" or "down" command is sent. The mobile station modifies the reverse link transmit power level accordingly using the "or-of-downs" rule, i.e., if a "down" command is received, the transmit power level is decreased, otherwise it is increased.

The transmit power level of the F-PCSCH is typically associated with the level of the primary F-FCH or F-DCCH carrying the sub-channel. The primary F-FCH or F-DCCH transmit power level at the base station is determined by feedback on the reverse power control subchannel (R-PCSCH), which occupies the last quarter of the reverse pilot channel (R-PICH). Since the F-FCH or F-FDCCH from each base station forms a single stream of traffic channel frames, the R-PCSCH reports the combined decoding results for these legs (legs). Erasure of the F-FCH or F-DCCH determines the Eb/Nt set point required for the outer-loop, which in turn drives the inner-loop instructions on the R-PCSCH, driving the base station transmit level of the F-FCH, F-DCCH on it.

Some base stations in the active set may not reliably receive the R-PCSCH and may not properly control the forward link power of the F-FCH, F-DCCH, and F-PCSCH due to potential differences in reverse link path loss from a single mobile station to each base station in soft handoff. The base station may need to realign the transmit levels among them so that the mobile station retains the spatial diversity gain of the soft handoff. Otherwise, some forward link legs (leg) may carry little or no traffic signal energy due to feedback errors from the mobile station.

Since different base stations may require different mobile station transmit powers for the same reverse link set point or reception quality, the power control commands from different base stations may be different and cannot be soft combined at the MS. When a new member is added to the active set (i.e., no soft handoff to unidirectional soft handoff, or from unidirectional to bidirectional, etc.), the F-PCSCH transmit power is increased relative to its primary F-FCH or F-DCCH. This may be because the latter has more spatial diversity (less total Eb/Nt required) and load sharing (less energy per leg), while the former cannot.

In contrast, in a 1xEV-DV system, the forward common power control channel (F-CPCCH) transmits reverse link power control commands for the mobile station without the need for the forward fundamental channel (F-FCH) or the forward dedicated control channel (F-DCCH). In earlier versions of the 1xEV-DV proposal, it was assumed that the base station transmit power level of the F-CPCCH was determined by the reverse channel quality indicator channel (R-CQICH) received from the mobile station. The R-CQICH may be used for scheduling to determine the appropriate forward link transmission format and rate based on forward link channel quality measurements.

However, when the mobile station is in soft handoff, the R-CQICH only reports the forward link pilot quality of the serving base station sector and therefore cannot be used to directly power control the F-CPCCH from the non-serving base station. Various methods of solving this problem are discussed below. One example method is as follows: reverse link power control is maintained for all active set members. The mobile station uses the "or-of-down" criterion to change the reverse link transmission level. The R-CQICH is used for power control of the serving base station. Another criterion, such as "or-of-up," is described below, and is used at the mobile station to generate a single power control feedback stream for all non-serving base stations.

Fig. 3 is a block diagram of a wireless communication device, such as mobile station 106 or base station 104. The modules depicted in this exemplary embodiment are generally a subset of the components included in either the base station 104 or the mobile station 106. Those skilled in the art will appreciate that the embodiment of fig. 3 may be used with any number of base station or mobile station configurations.

The signal is received at antenna 310 and transmitted to receiver 320. Receiver 320 implements processing in accordance with wireless system standards, such as those listed above. Receiver 320 performs various processing such as Radio Frequency (RF) to baseband conversion, amplification, analog to digital conversion, filtering, and so forth. Various techniques for receiving are known in the art. Receiver 320 may also be used to measure the channel quality of the forward or reverse link when the device is a mobile station or base station, respectively, although a separate channel quality estimator 335 is shown for clarity of discussion, as described in more detail below.

Signals from receiver 320 are demodulated in demodulator 325 according to one or more communication standards. In an example embodiment, a demodulator capable of demodulating a 1xEV-DV signal is used. In another embodiment, other standards may be supported, and embodiments may support multiple communication formats. Demodulator 330 may perform rake reception, equalization, combining, deinterleaving, decoding, and other functions, such as required by the format of the received signal. Various demodulation techniques are known in the art. Within base station 104, a demodulator 325 may demodulate based on the reverse link. Within mobile station 106, demodulator 325 may demodulate according to the forward link. The data and control channels described herein are examples of channels that may be received and demodulated in receiver 320 and demodulator 325. Demodulation of the forward data channel may occur in accordance with signaling on the control channel, as described above.

Message decoder 330 receives the demodulated data and extracts signals or messages directed to mobile station 106 or base station 104 on the forward or reverse link, respectively. Message decoder 330 decodes various messages used to set up, maintain and terminate calls (including voice or data sessions) on the system. The message may include a channel quality indication including a C/I measurement, a power control message, or a control channel message for demodulating the forward data channel. Various other message types are also known in the art and may be specified within the various communication standards supported. The messages are sent to processor 350 for subsequent processing. Some or all of the functions of message decoder 330 may be performed within processor 350, although discrete modules are shown for clarity of discussion. Alternatively, demodulator 325 may decode certain information and send it directly to processor 350 (an example is a single bit message such as an ACK/NAK or power control up/down instruction).

Channel quality estimator 335 may also be coupled to receiver 320 and used to perform various power level estimates for the processes described herein, as well as for various other processing for communications, such as demodulation. Within the mobile station 106, C/I measurements may be made. Additionally, measurements of any signal or channel used within the system may be made within channel quality estimator 335 of a given embodiment. As will be fully described below, a power control channel is another example. Within the base station 104 or the mobile station 106, channel strength estimates, such as received pilot power, are made. For simplicity of discussion, channel quality estimator 335 is shown as a discrete block. Such a module is often included within another module, such as receiver 320 or demodulator 325. Various types of signal strength estimation may be performed depending on which signal or which system type is implemented. In general, any type of channel quality metric estimation module may be used in place of channel quality estimator 335 within the scope of the present invention. Within base station 104, the channel quality estimates are sent to a processor 350 for use in scheduling or determining reverse link quality, as further described below. The channel quality estimate may be used to determine whether up or down power control commands are needed to drive either the forward or reverse link power to a desired set point. The desired set point may be determined using an outer-loop power control mechanism, as described above.

The signal is transmitted through an antenna 310. The transmitted signal is formatted in accordance with one or more wireless system standards, such as those listed above. Examples of components that may be included within transmitter 370 are amplifiers, filters, digital-to-analog (D/a) converters, Radio Frequency (RF) converters, and so forth. Data for transmission is provided to transmitter 370 by modulator 365. The data and control channels may be formatted for transmission according to various formats. Data transmitted on the forward link data channel may be formatted in modulator 365 according to a rate and modulation format specified by a scheduling algorithm based on a C/I or other channel quality measurement. A scheduler, such as scheduler 240, as described above, may reside within processor 350. Likewise, transmitter 370 may be used to transmit power levels according to a scheduling algorithm. Examples of components that may be included in modulator 365 include various types of encoders, interleavers, spreaders, and modulators.

Message generator 360 may be used to prepare various types of messages, as described herein. For example, the C/I message may be generated within the mobile station for transmission on the reverse link. Various types of control messages may be generated in either the base station 104 or the mobile station 106 for transmission on the respective forward or reverse links.

Data received and demodulated in demodulator 325 may be sent to processor 350 for use in voice or data communications, as well as for use in various other components. Likewise, data for transmission may be directed from processor 350 to modulator 365 and transmitter 370. For example, various data applications may be present on the processor 350 or another processor included within the wireless communication device 104 or 106 (not shown). The base station 104 may be connected to one or more external networks, such as the internet (not shown), through another device not shown. The mobile station 106 may include a link to an external device, such as a laptop computer (not shown).

Processor 350 is a general purpose processor, a Digital Signal Processor (DSP), or a special purpose processor. Processor 350 may perform some or all of the functions of receiver 320, demodulator 325, message decoder 330, channel quality estimator 335, message generator 360, modulator 365, or transmitter 370, as well as any other processing required by the wireless communication device. Processor 350 may be connected with special purpose hardware to assist in these tasks (details not shown). The data or voice applications may be external, such as an externally connected handheld computer or connection to a network, may run on an additional processor within the wireless device 104 or 106, or may run on the processor 350 itself. The processor 350 is coupled to a memory 355 that may be used to store data and instructions for implementing the various processes and methods described herein. Those skilled in the art will appreciate that memory 355 may comprise one or more of various types of memory components, and may be embedded in whole or in part within processor 350.

As described above, in data systems such as 1xEV-DV, it is desirable that reverse link traffic channels be decoded with a high probability within at least one base station (switch diversity) and that interference to all reverse link base stations should be minimized. In addition, it is desirable to obtain reliable R-CQICH reception at the serving base station. The R-CQICH provides fast forward link channel condition updates for the BTS to efficiently operate the F-PDCH.

The mobile station receives a single F-CPCCH from the serving BTS when the mobile station is not in soft handoff, and the BTS may be transmitting by more than the serving sector if the mobile station is in soft handoff with the BTS. The forward link transmit power of the F-CPCCH may be determined without an outer loop based on the R-CQICH from the mobile station via a table lookup (as a variation of the outer loop power control method described above).

There are a number of ways to perform reverse link power control design when a mobile station is in soft handoff with multiple BTSs. Several methods are described below.

One approach is to use only a single reverse link power control feedback from the serving base station to the mobile station, such as when the mobile station is not in soft handoff. The benefit of this approach is that no forward link power or capacity is consumed by introducing the F-CPCCH from the non-serving base station. In other words, the non-serving base station does not power control the transmit power of the mobile station. Also, the mobile station need not measure forward link measurements, and need not transmit feedback on the reverse link for additional base stations, except for the R-CQICH. In addition, the mobile station follows only one power command stream. The main drawback of this approach is that the capacity can be severely reduced when there is an imbalance between the forward and reverse links. For example, from time to time the reverse link loss from a mobile station to a non-serving base station may be less than the path loss from the same mobile station to the serving base station. When this occurs, the non-serving base station may have higher interference from the mobile station and there is no way to reduce this interference.

Another approach is to maintain reverse link power control feedback from each active set member BTS, one for each non-serving BTS, with a time-division multiplexed R-PCSCH command stream. This approach alleviates the forward/reverse link imbalance problem, but since the multiple reverse link feedback signals are time multiplexed, the supportable rate can be reduced or the reverse link data and associated interference increased. The rate may be further reduced if symbol repetition requires that the transmit power be maintained at a desired level for the R-PCSCH to reach all active set member base stations. The increase in rate may require additional reverse link power and thus reduce capacity.

Fig. 4 depicts an example embodiment using a first reverse link power control flow for controlling a serving base station and a second reverse link power control flow for controlling a non-serving base station. The mobile station 106 receives the F-CPCCH from each active set base station 104A-104C. In this example, each base station 104A-104C, BS₁-BS₃Two sectors 1 and 2 are included, labeled 410A, 1-410C, 2 and 410C, respectively. This is an example of what is known as soft-softer handoff because the mobile station is in soft handoff with multiple base stations (soft) and multiple sectors within one or more base stations (softer). Each active set sector transmits the F-CPCCH to the mobile station 106. The F-CPCCHs of the sectors of a single base station transmit the same information to be combined at the mobile station. The reverse links at the base stations may be combined via sectors, and thus may use common workThe rate controls the instruction stream.

The mobile station 106 provides reverse link power control feedback from each active set member BTS. The R-CQICH is used for the serving base station. One reverse power control subchannel (R-PCSCH) command stream is used to control the non-serving base stations.

As depicted, each member sector in the mobile station's active set transmits an F-CPCCH for reverse link power control. The mobile station transmits the R-PCSCH in addition to the R-CQICH because the non-serving base station cannot deduce information about the forward link condition or F-CPCCH reception at the mobile station from the R-CQICH. The R-PCSCH is used to carry F-CPCCH feedback from non-serving base stations, where the R-CQICH may be used by the serving base station to determine the transmit power level on the F-CPCCH.

It is noted that there is only one reverse link power control bit stream from each BTS to the mobile station through all of its sectors. In this way, there is no need to provide additional power control feedback on the F-CPCCH from the non-serving sector of the serving BTS. As shown, reception of the reverse link at a sectorized BTS will be performed by all sectors. It is noteworthy that BS₃Sector 2 of 410C, 2 is not in the active set, in this example, but is still able to receive the R-PCSCH, if desired.

Fig. 5 is an exemplary embodiment of a method of implementing reverse link power control. The process begins at step 510, where each base station in the active set measures the received reverse link pilot from the mobile station. Proceed to step 520. Each sector transmits the F-CPCCH with power control commands generated based on the measured pilot power, step 520. It is noted that any power control procedure may be used to determine the power control instruction, examples of which are given above. In another embodiment, signals other than the reverse link pilot may be used for power control. Proceed to step 530. In step 530, the mobile station soft-combines the power control commands received from the sectors of one base station. Proceed to step 540. In step 540, the mobile station changes the reverse link transmission power based on the instruction "or-of-down" from each base station. The process then stops. This process is typically repeated once during each power control group.

Fig. 6 depicts an example timing diagram for reverse link power control. This example corresponds to the system example embodiment shown in fig. 4, and the steps described with respect to fig. 5 are described within an ellipse with corresponding step numbers. Reverse link pilot at each base station BS₁-BS₃Is received. The power control groups are labeled PCG_i、PCG_i+1、PCG_i+2And the like. Base station in PCG_iDuring which the reverse link pilot is measured as described in step 510. Each sector then sends power control commands for corresponding pilot measurements on its respective F-CPCCH during bbb, as described in step 520. The mobile station soft combines the instructions from each base station as described in step 530. In this example, the mobile station soft combines from the BS₁Sector 1 and sector 2, and soft-combines from the BS₂Sector 1 and sector 2. The mobile station then determines to increase or decrease the transmit power based on an "or-of-down" criterion. In this example, from the BS₁And BS₂With combined commands at the F-CPCCH slave BS₃As shown, sector 1 receives the ORed of the instruction. These steps are detailed for one cycle in fig. 6, but the process may repeat for each PCG, as described above with reference to fig. 5.

Since the best forward link generally implies the best reverse link, the "or-of-down" criterion provides adequate R-CQICH reception at the serving base station. When a forward/reverse link imbalance occurs, i.e., the reverse link to the serving base station is less than the reverse link to one or more non-serving base stations, the serving base station can detect an insufficient R-PICH or R-CQICH level as part of its reverse link power control operation. The serving base station may then activate the R-CQICH repetition feature via the F-PDCH or F-CACH without much reverse link capacity loss. Such repetition techniques are well known in the art.

Fig. 7 depicts a flowchart of an example embodiment of a method of forward link power control. The process begins at step 710. In step 710, the mobile station measures the power of each F-CPCCH from the active set members. In an embodiment, the serving base station may be power controlled based on the forward link channel quality, as indicated by the R-CQICH, and thus the F-CPCCH need only be measured for non-serving base stations. This is shown in step 720. In another embodiment, power control of the serving base station may be achieved based on measurements of the serving base station F-CPCCH. It is noted that steps 710 and 720 may be performed in any order, or may be implemented in parallel. Proceed to step 730.

At step 730, the R-CQICH is transmitted to the serving base station to indicate the measured quality of the serving base station forward link. The R-CQICH may be used for power control. An example is to implement a table query, as described above. Proceed to step 740.

At step 740, power control commands are determined for each non-serving base station. In this example, a "raise" or "lower" instruction is generated for each. If there are multiple non-serving base stations in the active set, the mobile station applies the "or-of-up" criterion to generate a single instruction. I.e. if any F-CPCCH measurement results in an "up" instruction, the power control instruction is "up", otherwise the instruction is "down". Power control commands for one or more non-serving base stations are transmitted on a single R-PCSCH, which may be received by all non-serving base stations, as described above with reference to fig. 4. The non-serving base station adjusts the transmit power of the F-CPCCH (and any forward link channels, as desired) based on the R-PCSCH. The technique allows the non-serving base station to transmit at a lower level than without the feedback mechanism. It is noted that other logic within the transmit command decision based on a single decision by the non-serving base station may also be used herein in place of the "or-of-up" logic.

In one embodiment, the mobile station may exclude signals from non-serving base stations that are deemed inadequate. For example, if a rake receiver is used, there are a limited number of fingers to lock onto and track non-serving base stations. The usual technique is to assign the fingers to the strongest forward link paths. In this case, the rake receiver may lock onto the most important active set member. The "or-of-up" criterion may be modified to include only non-serving base stations with a predetermined quality level, or a predetermined number of "best" base stations. These may correspond to the active set member with the highest pilot Ec/Io. In addition, limiting the "or-of-up" criterion to a subset of active set members should not increase the F-CPCCH bit error rate, since the reverse link power control criterion "or-of-down", as described above with respect to fig. 5, is generally limited to the same subset of the active set, since the mobile station considers the other members of the active set to be too weak to be used. It is noted that, in general, the weakest received F-CPCCH will determine to send either a "up" or "down" command, and therefore, the F-CPCCH bit error rate is kept low on all F-CPCCHs.

Other embodiments may be used to reduce the excess transmit power of the F-CPCCH that is not the weakest. For example, the F-CPCCH transmit level may be limited for the better located base stations whose forward link path loss to the mobile station is not the largest.

In another embodiment, the base station instructs the mobile station to send a Pilot Strength Measurement Message (PSMM), or equivalent, wherein the forward link pilot quality at the mobile station is reported to the base station. From this message, the forward link path differences between the active set members of the mobile station may be evaluated. Each non-serving base station may adjust the transmit level based on its path loss difference relative to the maximum forward link path loss. Thus, the starting transmission level from the non-serving base station that is better than the worst forward link path loss can be reduced by a delta set to the path loss difference between that base station and the worst base station (in the active set or a subset thereof), as described above. Upon receiving the first or successive PSMMs, a Base Station Controller (BSC) or other system component may also determine the deltas used for such non-serving base stations.

An example of this other method is as follows: from the PSMM or other mobile station report, the base station is the BS₁、BS₂And BS₃The forward link pilot Ec/Io values at the mobile station are determined to be-9 dB, -10dB, and-13 dB, respectively. For this example, assume that the BS₁Is a serving base station, BS₂And worst forward link Base Station (BS)₃) The difference in path loss will be 3 dB. To the BS₂The initial transmit level of the F-CPCCH for the mobile station sending the report may be lower than the worst Base Station (BS)₃) Approximately 3 dB. In this way, the signal from the BS can be removed₂Since the mobile station will be either the BS or the F-CPCCH₂Or BS₃Similar received F-CPCCHs are measured.

In another embodiment, each non-serving base station may determine its corresponding path loss difference from the path loss of the worst base station by measuring the reverse link pilot for other channels with and without PSMM. This may be part of a closed loop reverse link power control mechanism. Because there is only one power level from the mobile station and the reverse link path loss may be correlated to the forward link path loss, the base station may know the path loss difference from the worst base station. The same set of delta values can be determined and used.

An example of this other method is as follows: from the reverse link measurements, the base station may be a BS₁、BS₂、BS₃The reverse link pilot Ec/(Io + No) values are determined to be-21 dB, -22dB, and-24 dB, respectively. In this example, it is assumed that the BS₁Is the serving base station. BS₂And worst forward link Base Station (BS)₃) The difference in path loss between them is 3 dB. Is BS₂The initial transmit level of the F-CPCCH to the mobile station may be greater than the worst Base Station (BS)₃) Is approximately 3dB lower. In this way, the signal from the BS can be removed₂Since the mobile station will be either the BS or the F-CPCCH₂Or BS₃Similar received F-CPCCHs are measured.

Turning now to fig. 7. Proceed to decision block 750. At decision block 750, if the R-PCSCH is to be repeated, then proceed to step 760 and repeat the "or-of-down" instruction loop on the R-PCSCH a predetermined number of times N. If not, the process stops. As in fig. 5, the process may repeat every power control group. The repetition feature of steps 750 and 760 is optional. This may be useful when repetition is necessary to reach all non-serving base stations, which may have variable reverse link path loss. Repetition can increase the signal-to-noise ratio without a corresponding increase in transmit power. This is the case when the reverse link benefits from repetition, as does the forward link. In this case, the F-CPCCH may also be repeated. This variation is described below in fig. 10. As described above, the R-CQICH to the serving base station (and not shown in fig. 7) may also be repeated and the serving base station F-CPCCH is needed. This option is further detailed in fig. 10.

Fig. 8 depicts an example timing diagram for forward link power control. This example corresponds to the example embodiment of the system shown in fig. 4, and the steps detailed in fig. 7 are described within the corresponding step number ellipses. The F-CPCCH is transmitted from each active set sector. In this example, the F-CPCCH is from the base station BS₃And BS₂Sectors 1 and 2 and base station BS₃Sector 1 is transmitted. The power control groups are labeled PCG_iBbb, ccc, etc. During bbb, the mobile station measures the forward link pilot and/or the F-CPCCH, as depicted in steps 710 and 720. During ccc, the mobile station transmits the R-PCSCH as described in step 740. May be repeated as necessary, as described in step 760. The mobile station also transmits the R-CQICH as described in step 730. These steps are detailed for one loop in fig. 8, but the process may repeat for each PCG, as described above with respect to fig. 7. In this example, the non-serving base station adjusts its forward link transmit power within the ccc according to the R-CQICH. The non-serving base station adjusts its transmit power in accordance with the R-PCSCH after receiving the R-PCSCH, which includes any repeated symbols.

As noted above, in some instances, it may be desirable to repeat the R-CQICH to maintain a sufficient signal-to-noise ratio for a given transmit level. Fig. 9 is a flow diagram of an example embodiment using R-CQICH repetition. The process begins at step 910, where the serving base station receives R-CQICH for 1 to N slots, where N is the number of repetitions. If N > 1, the received symbols are combined. Proceed to step 920. The transmit power level of the serving base station F-CPCCH is set according to the R-CQICH at step 920. Each unique command on the F-CPCCH may be transmitted in 1 to N time slots based on the repetition of the R-CQICH. This repetition enables a sufficiently low bit error rate to be achieved on the R-CQICH and F-CPCCH without increasing the transmit power of any one channel beyond a desired threshold.

Also, in some instances, it may be desirable to repeat the R-PCSCH to maintain a sufficient signal-to-noise ratio for a given transmit level. Figure 10 is a flow diagram of an example embodiment using PCSCH repetition. The process begins at step 1010, where the serving base station receives the R-PCSCH for 1 to N slots, where N is the number of repetitions. The symbols may be combined when N > 1. Proceed to step 1020. At step 1020, the transmit power level of each non-serving base station F-CPCCH is set according to the R-PCSCH. Each unique command on the F-CPCCH is sent between 1 and N slots based on the repetition of the R-PCSCH. This repetition enables a sufficiently low bit error rate to be maintained on the R-PCSCH and the F-CPCCH without increasing the transmit power of either channel beyond a desired threshold.

As described above, in some embodiments, the reverse link power control commands from each base station are carried on the corresponding F-CPCCH channel when the mobile station is in soft handoff, but the power control streams are carried on the F-CPCCH channel at different rates. For example, there is one serving base station and one or more non-serving base stations in the active set member. The power control commands are sent by the serving base station at a higher rate (e.g., 800Hz) while the power control commands sent by the non-serving base stations are repeated or repeated multiple times and, therefore, at a lower rate (e.g., 400Hz or 200 Hz). In general, each F-CPCCH channel may be transmitted at any rate. The "or-of-down" criterion may be modified to account for different rates of the F-CPCCH.

Fig. 11 illustrates an example of the relationship between power control commands and the F-CPCCH channel. In this example, the active set size is three. The power control bits from the serving base station arrive at a rate of 800Hz and the reverse link (RF) power control bits from the two non-serving base stations (non-serving base stations 1 and 2) arrive at a rate of 200 Hz. The Power Control Group (PCG) period is labeled n, n +1, n +2, etc. The F-CPCCH from the serving base station is sent once per PCG and each transmission contains a unique value. Mobile station extracting RL power control command C during successive PCGs_n、C_n+1、C_n+2And the like. The F-CPCCH for non-serving base stations 1 and 2 is also transmitted during each PCG. However, in this example, one value is sent for four consecutive power control groups. The mobile station combines the received F-CPCCH values for four PCG periods and sends RL power control commands once every four PCGs. This allows the F-CPCCH to be transmitted at a lower power, thus preserving the forward link capacity. The non-serving base station 1 generates an RL power control command B_n+3、B_n+7、B_n+11And the like. The non-serving base station 2 generates an RL power control command D_n+3、D_n+7、D_n+11And the like. For example, F-CPCCH symbols from non-serving station 1 during power control groups n, n +1, n +2, and n +3 carry the same RL power control symbols, and RL power control instruction B_n+3Is decimated at the end of PCG n + 3.

In current CDMA systems, power control commands from different base stations arrive at the mobile station at the same rate, and the commands within the PCG are combined according to the "or-of-downs" criterion to provide a decision for the mobile station to adjust its transmit power. I.e. if any power control command is a down command, the mobile station reduces its transmission power. The mobile station only increases its transmission power when all power control commands are up. Given the RL Power control Command C described above_i、B_jAnd D_kThese instructions are generated at varying frequencies and the mobile station must determine how to adjust its transmission power accordingly. The "or-of-down" criterion cannot be applied directly because the power control commands arrive at different rates. Various example embodiments of the solution are described below. Three solutions are provided: biased serving base stations, biased non-serving base stations, and balanced solutions between serving and non-serving base stations. Those skilled in the art can apply these principles to various solutions for transmit power control based on multiple streams of rate power control instructions.

First, consider an example embodiment biased toward a serving base station. In this example, instructions from the serving base station are used to adjust the RL power during each PCG. During the PCG, where the instructions are generated from one or more serving base stations,the serving and non-serving base station commands are combined according to the "or-of-down" criterion, as described above. For example, C of i ═ n, n +1, n +2, n +4, n +5, n +6, n +8_iFor adjusting RL power during the corresponding PCG. C of i ═ n +3, n +7, n +11_i、B_iAnd D_iAre combined using the "or-of-downs" criterion during the corresponding remaining PCGs. This approach is biased towards the serving base station because the RL power is more controlled by the serving base station than the non-serving base station. As will be clear to a person skilled in the art, the solution just described is only an example. Any number of base stations may be supported using power control command streams and each stream may be at any rate.

Second, consider an example embodiment biased toward a non-serving base station. In this example, all instructions from the serving base station are combined with the most recently received non-serving base station instruction using the "or-of-downs" instruction, as described above. E.g. C of i ═ n +3, n +4, n +5_iUsing "or-of-down" and B accordingly_n+3And D_n+3Combined to adjust RL power for the corresponding PCG. This scheme is biased towards non-serving base stations because RL power is more controlled by non-serving base stations than serving base stations. As will be clear to a person skilled in the art, the solution just described is only an example. Any number of base stations may be supported using power control command streams and each stream may be at any rate.

Third, consider embodiments in which the transmit power is controlled in a manner that balances between the serving and non-serving base stations. Since the instructions from the serving base station arrive more frequently than the instructions from the non-serving base station, they are processed differently to maintain the balance of the serving and non-serving base stations in controlling RL power. Especially when the R power is adjusted according to commands from the non-serving base station, the power adjustment may be larger than if the adjustment is based only on instructions from the serving base station.

The first balanced embodiment uses a scheme similar to the first example, biased towards the serving base station as described above. During PCG, where only instructions from the serving base station are received, the serving base station instructions are used to determine whether the transmit power should be increased or decreased. However, the up or down step size of the power change is proportional to the first parameter ST. During a PCG, during which commands from serving and non-serving base stations arrive, the commands from the serving and non-serving base stations are combined (using the "or-of-downs" rule) to form a combined command. The up or down decision is made by using the "or-of-downs" criterion on the serving base station commands and the combined commands. When the combined command is the same as the serving base station command, the power is adjusted with an up or down step size proportional to the second parameter. When the combined command is different from the serving base station command, the power is adjusted with an up or down step size proportional to the third parameter.

In the example of fig. 11, the second parameter may be set to 4 ST and the third parameter to 3 ST due to the relative frequency of the instruction stream. This example can be extended to any rate of control instruction flow. In general, when the ratio between the serving base station rate and one or more non-serving base stations is K (K ≧ 1), the second parameter may be set to K × ST, and the third parameter may be set to (K-1) × ST.

The second balanced embodiment also uses a similar scheme to the first example, biased towards the serving base station as described above. As above, during PCG, where only instructions from the serving base station are received, the serving base station instructions are used to determine whether the transmit power should be increased or decreased. Also, the up or down step size of the power change is made in proportion to the first parameter ST. During PCGs arriving from serving and non-serving base station instructions, the non-serving base station instructions (using the "or-of-downs" rule) are combined to form a combined instruction. The up or down decision is made by using the "or-of-downs" criterion for the serving base station command and the combined command. In this example, the combined instruction and the serving base station instruction are combined in a weighted manner to form a metric M. The power is adjusted with an up or down step size proportional to the second parameter, calculated as M ST.

Using the relative frequency of the instruction stream, metric M can be calculated as follows, as shown in fig. 11. A +1 is assigned toThe up instruction, a-1, is assigned to the down instruction (those skilled in the art will appreciate that these values are examples only). The combined instruction ("or-of-downs" for the non-serving base station) is multiplied by four and added to the sum of the four previous instructions from the serving base station to form the metric M. For example, at PCG n +3, M is calculated as follows: m-4 (or-of-downs (B)_n+3，D_n+3))+C_n+3+C_n+2+C_n+1+C_n。

This example can be extended to any rate of power control instruction flow. Typically, when the ratio between the serving base station rate and one or more non-serving base stations is K (K ≧ 1), the metric M can be calculated as M ═ (combined command from non-serving base stations) × K + (sum of K previous serving base station commands).

It is noted that the terms service and non-service are used only for clarity of the example embodiments. The disclosed flow control of transmit power based on received multi-rate power indications may be applied to any set of base stations, whether they are serving or non-serving base stations. Embodiments may be described with "serving" replaced with "primary" and "non-serving" replaced with "other" or "secondary" base stations, and the disclosed principles are equally applicable.

It is noted that in all embodiments described above, method steps may be interchanged without departing from the scope of the invention. The description disclosed herein refers in many cases to signals, parameters, and processes associated with the 1xEV-DV standard, although the scope of the invention is not so limited. Those skilled in the art will be able to apply the principles to various other communication systems. These and other modifications will be apparent to those of ordinary skill in the art.

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, circuits, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any 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) or other processor, 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, to implement the functions described herein. A general purpose processor is preferably a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may 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 steps of a method or algorithm 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 processor is preferably 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 integral to the processor. The processor and the storage medium may reside in an application specific integrated circuit, 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 the use of the inventive faculty. 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

1. An apparatus, comprising:

a receiver for receiving a plurality of transmitted signals from a plurality of remote stations;

a power estimator for measuring power of a plurality of received signals and generating a plurality of signal power measurements;

a processor to:

generating a plurality of power control commands; and

generating a combined power control instruction from the plurality of power control instructions; and

a transmitter for transmitting the combined power control instruction.

2. The apparatus of claim 1, wherein each of the plurality of power control commands indicates an increase or decrease in a transmit power level of the corresponding remote station.

3. The apparatus of claim 2, wherein the combined power control instruction indicates an increase if one or more of the plurality of power control instructions is an increase, and a decrease otherwise.

4. The apparatus of claim 1, wherein:

the plurality of received signals include reverse link power control instructions; and

the power level of the transmitter is adjusted accordingly.

5. The apparatus of claim 4 wherein said transmitter power level is decreased if one or more of the reverse link power control commands indicate a decrease in power level and increased otherwise.

6. The apparatus of claim 1, wherein:

one or more of the plurality of received signals comprises symbols transmitted sequentially within the time slot; and

one or more symbols from sequential slots are combined prior to generating power control instructions for the respective signals.

7. The apparatus of claim 1, wherein:

the combined power control commands are transmitted sequentially within a time slot; and

the combined power control instruction is repeated for one or more time slots.

8. The apparatus of claim 1, wherein:

the receiver further receiving a second plurality of signals transmitted from a second plurality of remote stations;

the power estimator further measuring power of a second plurality of received signals and generating a second plurality of signal power measurements;

the processor further generates a second plurality of power control instructions corresponding to a second plurality of signal power measurements; and

the transmitter transmits a stream of power control instructions to each of the second plurality of remote stations accordingly.

9. The apparatus of claim 8, wherein each of the second plurality of power control commands is a channel quality indicator.

10. The apparatus of claim 8, wherein each of said second plurality of power control instructions indicates an increase or decrease in a transmit power level associated with a respective remote station.

11. An apparatus, comprising:

a receiver for receiving a plurality of power control channels, each power control channel comprising a sequence of time slots, one or more of the plurality of power control channels comprising power control instructions transmitted within one or more subsets of the sequence of time slots;

a transmitter for transmitting a signal at a transmit power level; and

a processor configured to adjust a transmit power level during each time slot based on a plurality of power control channels.

12. The apparatus of claim 11 wherein the processor decreases the transmit power level of each slot when one or more power control commands received in the slot on one or more of the plurality of power control channels indicate a decrease, and increases the transmit power level of the slot otherwise.

13. The apparatus of claim 11, wherein the processor decreases the transmit power level of each slot when one or more of the most recently received power control commands from each of the plurality of power control channels indicate a decrease, and increases the transmit power level of the slot otherwise.

14. The apparatus of claim 11, wherein:

the first power control channel includes power control commands within each of the sequence of each time slot; and

a processor:

combining any power control commands received from the remaining time slots of the plurality of power control channels to form a combined power control command;

when the remainder of the plurality of power control channels does not contain a power control instruction for the time slot, adjusting the transmit power level of the time slot in proportion to the first parameter according to the power control instruction for the first power control channel;

when the combined power control command (if any) for the slot is the same as the power control command for the first power control channel, adjusting the transmit power level for the slot in proportion to the second parameter according to the combined power control command; and

otherwise the transmit power level of the time slot is reduced in proportion to the third parameter.

15. The apparatus of claim 14, wherein:

the ratio of the power control command rate in the remainder of the plurality of power control channels to the power control command rate in the first power control channel is K;

the second parameter is set to K multiplied by the first parameter; and

the third parameter is set to K-1 multiplied by the first parameter.

16. The apparatus of claim 11, wherein:

the first power control channel comprises power control commands within each of the sequence of time slots;

the remainder of the plurality of power control channels comprises power control commands in every K time slots; and

a processor:

otherwise, the transmit power level of the slot is adjusted in proportion to a second parameter calculated as the sum of the K most recent power control commands received on the first power control channel and K multiplied by the combined power control command.

17. An apparatus, configurable in a first mode or a second mode, comprising:

a receiver for:

when operating in a first mode, receiving a first channel from a remote station, the first channel comprising a channel quality indicator; and

receiving a second channel from the remote station while operating in a second mode, the second channel comprising power control instructions;

a processor to:

configuring the device in the first or second mode;

determining a transmit power level from the channel quality indicator when configured in the first mode; and

when configured in the second mode, determining a transmit power level according to the power control command; and a transmitter for transmitting to the remote station in accordance with the transmit power level.

18. The apparatus of claim 17, further comprising:

a power estimator for measuring the power of the first or second channel and generating a signal power measurement; and wherein:

the processor also generates a reverse link power control command based on the signal power measurement; and

the transmitter transmits one or more reverse link power control commands to the remote station.

19. A wireless communication device, comprising:

a processor to:

generating a plurality of power control commands; and

generating a combined power control instruction from the plurality of power control instructions; and a transmitter for transmitting the combined power control instruction.

20. A wireless communication device configured in a first mode or a second mode, comprising:

a receiver for:

receiving a first channel from a remote station when operating in a first mode, the first channel comprising a channel quality indicator; and

a processor to:

means configured in a first or second mode;

determining a transmit power level from the power control command when configured in the second mode; and a transmitter for transmitting to the remote station in accordance with the transmit power level.

21. A wireless communication system comprising a wireless communication device, the wireless communication device comprising:

a power estimator for measuring a plurality of received signal powers and generating a plurality of signal power measurements;

a processor to:

generating a plurality of power control commands; and

22. A wireless communication system including a wireless communication device configured in a first mode or a second mode, comprising:

a receiver to:

a processor to:

configuring the device in a first or second mode;

23. A method of power control, comprising:

receiving a plurality of signals from a plurality of remote stations;

measuring a power of each of the plurality of received signals;

generating a plurality of power control commands according to the plurality of measured powers; and

combining the plurality of power control instructions to form a single power control instruction.

24. The method of claim 23, further comprising transmitting a series of combined power control commands for reception by a plurality of remote stations.

25. The method of claim 23, wherein a plurality of power control commands indicate an increase or decrease, and the combined power control command is generated as an increase when one or more of the plurality of power control commands is an increase and a decrease otherwise.

26. The method of claim 23, further comprising:

receiving an additional signal from an additional remote station;

measuring the additional signal and generating therefrom a channel quality indicator; and

the channel quality indicator is transmitted for reception by the additional remote station.

27. The method of claim 24, wherein one or more of the combined power control commands are transmitted two or more times in successive transmission gaps.

28. The method of claim 26, wherein the channel quality indicator is transmitted two or more times in successive transmission gaps.

29. The method of claim 23, wherein:

the plurality of signals includes power control instructions transmitted within a sequence of time slots; and

implementing transmission according to the transmit power level; and further comprising:

the transmit power level is decreased when one or more of the plurality of power control commands within the time slot indicate a decrease, and increased otherwise.

30. The method of claim 29, wherein one or more power control commands are repeated in successive time slots, and wherein the repeated power control commands are combined prior to adjusting the transmit power level accordingly.

31. A method of power control, comprising:

receiving a plurality of power control channels, each power control channel comprising a sequence of time slots, one or more of the plurality of power control channels comprising power control instructions transmitted within one or more subsets of the sequence of time slots;

transmitting a signal at a transmit power level; and

the transmit power level is adjusted during each time slot according to a plurality of power control channels.

32. The method of claim 31, wherein the transmit power adjustment comprises decreasing the transmit power level of each slot when one or more power control commands received in the slot on one or more of the plurality of power control channels indicate a decrease, and increasing the transmit power level of the slot otherwise.

33. The method of claim 31, wherein the transmit power adjustment comprises decreasing the transmit power level of each slot when one or more of the most recently received power control commands from each of the plurality of power control channels indicates a decrease, and increasing the transmit power level of the slot otherwise.

34. The method of claim 31, wherein:

the first power control channel comprises power control commands within each of the sequence of time slots; and

the transmission power adjustment comprises:

when the combined power control command (if any) for the timeslot is the same as the power control command for the first power control channel, adjusting the transmit power level for the timeslot in proportion to the second parameter according to the combined power control command; and

35. The method of claim 34, wherein:

the second parameter is set to K multiplied by the first parameter; and

the third parameter is set to K-1 multiplied by the first parameter.

36. The method of claim 31, wherein:

the transmission power adjustment comprises:

37. A power control method for operating in a first mode or a second mode, comprising:

：

when configured in the second mode, determining a transmit power level according to the power control command; and

and transmitting to the remote station based on the transmit power level.

38. The method of claim 37, further comprising:

measuring the power of the first or second channel and generating a signal power measurement; and

generating a reverse link power control command according to the signal power measurement; and

one or more reverse link power control commands are transmitted to the remote station.

39. An apparatus, comprising:

means for receiving a plurality of transmitted signals from a plurality of remote stations;

means for measuring power of a plurality of received signals;

means for generating a plurality of signal power measurements from the plurality of measured powers;

means for combining the plurality of power control instructions to generate a single power control instruction.

40. The apparatus of claim 39, further comprising means for transmitting a series of combined power control commands for reception by a plurality of remote stations.

41. The apparatus of claim 39, further comprising:

means for receiving an additional signal from an additional remote station;

means for measuring the additional signal and generating therefrom a channel quality indicator; and

means for transmitting a channel quality indicator for reception by an additional remote station.

42. An apparatus, comprising:

means for receiving a plurality of power control channels, each power control channel comprising a sequence of time slots, one or more of the plurality of power control channels comprising power control instructions transmitted within one or more subsets of the sequence of time slots;

means for transmitting a signal at a transmit power level; and

means for adjusting a transmit power level during each time slot based on a plurality of power control channels.

43. An apparatus operable in a first mode or a second mode, comprising:

means for receiving a first channel from a remote station when operating in a first mode, the first channel comprising a channel quality indicator; and

means for receiving a second channel from a remote station when operating in a second mode, the second channel comprising power control instructions;

means for determining a transmit power level from a channel quality indicator when operating in a first mode; and

means for determining a transmit power level from the power control command when operating in the second mode; and

means for transmitting to the remote station based on the transmit power level.

44. The apparatus of claim 43, further comprising:

means for measuring the power of the first or second channel and generating a signal power measurement;

means for generating a reverse link power control command based on the signal power measurements; and

means for transmitting one or more reverse link power control commands to the remote station.

45. A wireless communication system, comprising:

means for receiving a plurality of signals from a plurality of remote stations;

means for measuring a power of each of a plurality of received signals;

means for generating a plurality of power control commands based on the plurality of measured powers; and

means for combining a plurality of power control instructions to form a single power control instruction.

46. The wireless communication system of claim 45, further comprising means for transmitting a series of combined power control commands, said commands being received by a plurality of remote stations.

47. The wireless communication system of claim 45, further comprising:

means for receiving an additional signal from an additional remote station;

means for measuring the additional signal and generating a signal quality indicator therefrom; and

48. A wireless communication system, comprising:

means for receiving a plurality of power control channels, each power control channel comprising a sequence of time slots, and one or more of the plurality of power control channels comprising power control instructions transmitted in one or more subsets within the sequence of time slots;

means for transmitting a signal at a transmit power level; and

49. A processor-readable medium for implementing the steps of:

receiving a plurality of signals from a plurality of remote stations;

measuring a power of each of the plurality of received signals;

generating a plurality of power control commands based on the plurality of measured powers; and

50. A media as in claim 49 further adapted to perform the steps of:

receiving an additional signal from an additional remote station;

measuring the additional signal and generating a channel quality indicator therefrom; and

51. A processor-readable medium for implementing the steps of:

receiving a plurality of power control channels, each power control channel comprising a sequence of time slots, and one or more of the plurality of power control channels comprising power control instructions transmitted within one or more subsets of the sequence of time slots;

transmitting a signal at a transmit power level; and

52. A processor-readable medium for implementing the steps of:

determining a transmit power level from the channel quality indicator when operating in the first mode; and

determining a transmit power level from the power control command when operating in the second mode; and

and transmitting to the remote station based on the transmit power level.