MXPA99004638A - Method and apparatus for adjusting thresholds and measurements of received signals by anticipating power control commands yet to be executed - Google Patents

Abstract

The present invention provides a method and apparatus for providing improved quality or power control by recognizing the delays inherent in a closed-loop communication system. The mobile station (12) or receiver properly adjusts its forward link quality or power level thresholds or measurements with which it compares incoming frames or portions thereof to reflect the level it anticipates receiving (after the delay). For example, the mobile station (12) can recognize that at a given measurement time, two outstanding messages have not been executed by the transmitter (where each message indicates a corresponding increase of 1 dB). As a result, the mobile station (12) can adjust its measurement threshold down by 2 dB to more closely correspond to future power adjustments. If the currently received frame or portion thereof is still below the readjusted threshold, then the mobile station (12) sends out a new message to request a further increase in the forward link channel.

Description

METHOD AND APPARATUS FOR ADJUSTING THRESHOLDS AND MEASUREMENTS OF THE SIGNALS RECEIVED WHEN ANTICIPATING THE POWER CONTROL COMMANDS TO BE EXECUTED BACKGROUND OF THE INVENTION I. Field of the Invention The present invention relates to communication systems. More particularly, the present invention relates to a method and apparatus for providing power control in a closed circuit communications system.

II. Description of Related Art The use of code division multiple access modulation (CDMA) techniques is one of several techniques to facilitate communications in which there is a large number of users of the system. Other techniques of multiple access communication systems are known in the field, such as time division multiple access (TDMA) and frequency division multiple access (FDMA). However, CDMA-type extended spectrum modulation techniques have significant advantages over the other modulation techniques for multiple access communication systems. The use of CDMA techniques in a communication system P1312 / 99MX multiple access is disclosed in U.S. Patent No. 4,901,307, entitled "SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS "assigned to the assignee of the present invention and incorporated herein by reference The use of CDMA techniques in a multiple access communication system is further disclosed in U.S. Patent No. 5,103,459, entitled" SYSTEM AND METHOD FOR GENERATING SIGNAL WAVEFORMS IN A CDMA CELLULAR TELEPHONE SYSTEM "also assigned to the assignee of the present invention itself, which is incorporated herein by reference CDMA by its inherent nature of being a broadband signal offers a form of diversity in frequency by extending the signal energy over a wide bandwidth, therefore selective frequency fading affects only a small part of the bandwidth of the CDMA signal. provide multiple signal paths through simultaneous links from a mobile user or a mobile station through of two or more cell sites. In addition, path diversity can be obtained by exploiting the multipath environment by processing P131 / 99MX extended spectrum, by allowing a signal arriving with different propagation delays to be received and processed separately. Examples of on-track diversity are illustrated in U.S. Patent No. 5,101,501, entitled "METHOD AND SYSTEM FOR PROVIDING A SOFT HANDOFF IN COMMUNICATIONS IN A CDMA CELLULAR TELEPHONE SYSTEM" and in U.S. Patent No. 5,109,390, entitled "DIVERSITY RECEIVER IN A CDMA CELLULAR TELEPHONE SYSTEM", both assigned to the assignee of the present invention and incorporated herein by reference. If the transmission power of the signals transmitted by the base station to a mobile station is very high, it can generate problems such as interfering with other mobile stations. Alternatively, if the transmission power of the signals transmitted by the base station is very low, then the mobile station may receive multiple erroneous frames. Fading of the terrestrial channel and other known factors can affect the power of the received signals transmitted by the base station. As a result, each base station must quickly and accurately adjust the transmit power of the signals it transmits to mobile stations. In a useful method to control the transmission power of the signals transmitted by a P1312 / 99MX base station, the mobile station transmits a signal or message to the base station the moment the power of a received data frame deviates from a threshold or is received in error. In response to this message, the base station increases the transmission power of the signals transmitted by the base station. A method and apparatus for controlling transmission power is disclosed in U.S. Patent No. 5,056,109, entitled "METHOD AND APPARATUS FOR CONTROLLING TRANSMISSION POWER IN A CDMA CELLULAR TELEPHONE SYSTEM", assigned to the assignee of the present invention and incorporated here as a reference. Necessarily there is a delay in the previous closed circuit communications system, the delay includes the moment in which the base station transmits the frame with an inadequate power, the moment in which the mobile station receives the erroneous frame, the moment in which the station mobile detects the error (for example, the signal falls below the threshold or a frame erasure is declared), the moment the mobile station transmits an appropriate error message to the base station and the time the base station receives the error message and appropriately adjust its transmit power. The communications system usually transmits data packets as discrete frames. As a result, the P1312 / 99MX communications system can not quickly compensate for fluctuations in transmission power. Additionally, the mobile station could request a large increase in the transmit power of the forward link before recognizing this increase due to the inherent delay described above.

SUMMARY OF THE INVENTION The present invention solves the problems of the previous communication systems and provides additional benefits by allowing a mobile station or base station to anticipate the inherent delays in the closed circuit communications systems. As indicated above, mobile stations typically send quality or error messages on the reverse link channel to the base station, where the messages indicate the quality or power level of each frame or portions of the frame received in the channel direct link If the mobile station detects a change in quality or power in the direct channel, the mobile station supplies a message to the base station to request that the direct channel increase or decrease appropriately. In the present invention, the mobile or receiver station appropriately adjusts its thresholds or energy level measurements of the direct link with which it compares frames or portions of frames P1312 / 99MX to reflect the quality or energy level, anticipate the reception (after the aforementioned delay) in response to the previously set power adjustment commands. The mobile station can recognize that in a given measurement time two pending messages have not been executed by the remote transmitter (where each message indicates a corresponding increase of 1 dB). As a result, the mobile station can adjust its measurement threshold by 2 dB to correspond more closely to future power adjustments. If the currently received frame or a portion thereof is still below the reset threshold, then the mobile station sends a new message to request an additional increase in the power of the direct link channel. Conversely, if the received frame or, a portion of the frame, is greater than the set quality threshold, the mobile station does not request an additional increase in energy. The base station, in a similar way, sends messages on the direct link to the mobile station, which indicate the quality or power level of the reverse link. As a result, the present invention can be used in a similar manner by the base station to appropriately adjust its quality thresholds of the reverse link with which it compares the incoming reverse link signals, to reflect the anticipated adjustments to the power of the reverse link. transmission in P131 / 99MX the mobile station. In a broad sense, the present invention incorporates a communication system having a base station and at least one user station. A user of the user station system transmits communication signals to the base station and receives communication signals from it. A method for controlling the power of the transmission signal of the communication signals transmitted from the base station includes the steps of: (a) transmitting a present communication signal; (b) receiving the present communication signal; (c) determining the quality level of the present communication signal; (d) adjusting the quality level threshold based on at least one prior energy control message; (e) comparing the threshold of the adjusted quality level with the quality level of the present communication signal; (f) transmitting a present energy control message based on the comparison; and (g) transmitting a new communication signal at a set power level, based on the present power control message. The present invention also incorporates a communication system having a base station and a base station and a user station. The base station transmits signals to the user station and receives signals from it. The station User P1312 / 99MX includes a receiver, a measurement circuit, a processor and a transmitter. The receiver receives a received signal present from the base station. The measurement circuit is configured to determine the level of the present signal. The processor is configured to adjust a measurement value based on at least one precontrol message and compares the adjusted measurement value with the level of the present signal. The transmitter transmits a present control message to the base station to request that the base station transmits a new signal at a level adjusted based on the present control message.

BRIEF DESCRIPTION OF THE DRAWINGS The features and advantages of the present invention will be more evident from the study of the detailed description together with the following figures. In the figures, the reference numbers are used consistently. Figure 1 illustrates a general closed circuit power control system of the present invention. Figure 2 is a block diagram of the closed circuit power control system of Figure 1. Figures 3A-3D are time diagrams that P1312 / 99MX show the inherent delays in the closed-circuit power control system of Figure 1, when a mobile station recognizes a decrease in the energy of a direct link transmission signal from a base station and shows how the that the present invention compensates for these delays. Figure 4 is a flow chart of a method for determining the energy control messages to appropriately adjust the transmission energy of the forward link transmissions from the base station according to the present invention. Figure 5 is a time diagram showing the inherent delays in the closed-loop power control system of Figure 1, according to an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES A communication system and, in particular, an apparatus and method for energy control for the system is described in detail herein. In the following description, numerous specific details are exposed, such as the specific number of bits, the energy levels of the signals, etc., in order to provide a deep compression of the P1312 / 99MX present invention. However, those skilled in the relevant art will readily recognize that the present invention can be practiced without these specific details or with other bit numbers, signal levels, etc. In other cases, well-known structures are not shown in detail to avoid confusing the present invention. Figure 1 illustrates an exemplary cellular subscriber communications system 10, in which the present invention can be implemented. The system of Figure 1 preferably uses extended spectrum modulation techniques, such as CDMA for communication between users of mobile stations (eg mobile phones) and cellular sites or base stations. In Figure 1, mobile station 12 communicates with controller 14 of the base station by means of one or more base stations 16a, 16b, etc. The controller 14 of the base station is coupled with and, typically, includes an interface and processing circuitry to provide control of the system to the base stations 16a, 16b. The controller 14 of the base station can also be coupled to and communicate with other base stations and possibly even with other base station controllers. When the system 10 is configured so that P131 / 99MX processes telephone calls, the controller 14 of the base station routes telephone calls from a public switched telephone network (PSTN) to the base station 16a or 16b for transmission to the appropriate mobile station 12. As well, the controller 14 of the base station functions to route the calls of the mobile station 12 by means of at least one base station 16a or 16b towards the PSTN. The controller 14 of the base station can also connect calls between mobile stations 12 and other mobile stations (not shown). The controller 14 of the base station can be coupled to the base stations 16a and 16b by various means such as dedicated telephone lines, fiber optic links or microwave communication links. The double arrow lines shown in Figure 1 define possible communication links between the mobile station 12 and the base stations 16a and 16b and between the base stations and the controller 14 of the base station. Figure 2 illustrates the situation where the mobile station 12 is in soft communication transfer between the cell covered by the base station 16a and the cell covered by the base station 16b. It will be understood that the description easily extends to the situation where only a base station 16a or 16b is in communication with the P1312 / 99MX mobile station 12 and to the case where more than two base stations are in communication with the mobile station. Referring to the block diagram of the communication system 10 in Figure 2, the mobile station 12 includes the antenna 20 that transmits signals to the base stations 16a and 16b and receives signals from these same stations. The duplexer 22 provides a direct link channel or signal from the base stations 16a and 16b to the mobile receiver system 24 (mobile RCV system). The receiver system 24 subconverts, demodulates and decodes the received signal. The receiver system 24 then provides a predetermined parameter or parameter set to the quality measurement circuit 26. Examples of parameters may include the measured signal-to-noise ratio (SNR), measured received power or decoder parameters, such as the error rate in the symbols, the Yamamoto metric or the indication of the parity bit check. The channel quality measurement circuit 26 receives the parameters of the mobile receiver system 24 and determines a quality or energy level measurement signal of the received signal. The quality measurement circuit 26 can generate energy per bit (Eb) or energy per symbol (Es) measurements of the portions or windows of each frame. Preferably, energy measurements by P1312 / 99MX bit or power per symbol are normalized (eg, Eb / No), or are normalized and include interference factors (eg Eb / Nt). Based on these measurements, the quality measurement circuit 26 produces the energy level signal. The energy control processor 28 receives the energy level signal from the quality measurement circuit 26, compares the signal with an adjustable threshold and produces an energy control message based on the comparison, as described in detail below . In sum, the energy control processor 28 adjusts the threshold based on the non-executed energy control messages. Alternatively, the energy control processor 28 supplies the adjustable threshold to the quality measurement circuit 26. The quality measurement circuit 26 in turn compares the parameters received from the mobile receiver 24 with the set threshold and produces the energy level signal of the energy control processor 28 in response to it, as described below. The energy control processor 28 produces several energy control messages (e.g., 8 or 16) in response to the various energy level signals per frame, wherein each energy control message may indicate a change in energy of the direct link signal. For example, the message of P1312 / 99MX power control could be a binary value, where a value of "1" requests the base station 16a or 16b to increase the gain of the forward link signal, while a value of "0" requests that the signal is reduced. The mobile transmission system 29 (Mobile Transmit System) encodes, modulates, amplifies and overconverts the energy control message, by means of the duplexer 22 and the antenna 20 in the exemplary embodiment, the mobile transmission system 29 provides the control message of energy in a predetermined location of an outbound reverse link frame. The mobile transmission system 29 also receives traffic data from the reverse link, which may correspond to voice data from the user of the mobile station 12. In the exemplary mode, the energy control messages are punched in the data of reverse link traffic. Each base station 16a and 16b includes a receiving antenna 30 that receives the reverse link frames from the mobile station 12. The receiving systems 32 of the base stations 16a and 16b subvert, amplify, demodulate and decode the reverse link traffic. In addition, the receiver system 32 separates the power control messages from each reverse link traffic frame and provides the power control messages to the power control processor 34. Thereafter, most of P1312 / 99MX The description of the present invention will be described with respect to only a single base station 16a. Unless otherwise indicated herein, the description equally applies to the second base station 16b. The energy control processor 34 monitors energy control messages and produces a power signal from the direct link transmitter to the transmit system 36 of the forward link. The direct link transmitter system 36, in response thereto, increases or maintains or decreases the energy of the direct link signal. The forward link signal is then transmitted by the transmit antenna 38. The direct link transmitter system 36 also receives direct link traffic data which codes, modulates and transmits via the antenna 38. The mobile receiver system 24, the system mobile transmission 29, the receiving system 32 and the transmitting system 36 are either a receiver or a CDMA transmitter, as described in the aforementioned US Patents Nos. 4,901,307 and 5, -103,459, under the modality ej emplificativa . Unless otherwise described below, the construction and operation of the various blocks shown in Figure 2 are of conventional design. As a result, these blocks do not P1312 / 99MX need to be described herein in further detail, as they will be understood by those skilled in the relevant art. This description is omitted for reasons of brevity and, so as not to confuse the description of the present invention. Any necessary modifications to the blocks of the communication system 10 of Figure 2 can be easily realized by those skilled in the art, based on the detailed description provided herein. Referring to Figures 2A to 3D, the typical delays in the closed circuit power control system 10 will be described. Figure 3A shows multiple windows in the first and second frames, m and n, respectively, transmitted by the base station 16a. As shown in Figure 3A (and also in Figures 3B-3D), each frame is divided into eight exemplary windows (for example, the m frame consists of the windows go ^ a m.). With respect to each window of Figure 3A a deviation of the desired transmission energy level (eg, 6 dB) is shown. For example, the value of -4 dB corresponds to a 4 dB drop from the desired reception energy level in the mobile station 12, while a value of 0 dB corresponds to a value equal to the desired reception energy level. in the mobile station 12.

P1312 / 99MX In general, the exemplary timelines of Figures 3A-3D and the following analysis relate to the energy deviations of the forward link signal of the desired energy level or of the adjustable threshold energy level PTH. The present invention is equally applicable to measurements of the absolute energy level, rather than changes of a certain energy level, as described below. Figure 3B shows the windows of the frames m and n of the direct link signal that are received by the mobile station 12. Figure 3B shows several energy control messages not executed (due to the delay) under the corresponding window. A positive number indicates a total increase value of between one and three energy control messages of +1 dB of non-executed increase (for example, +3 equals +3 dB of increase of three non-executed messages). A negative number indicates a total decrease value (for example, (+ 1-2) is equal to a total decrease value of -1 dB of one +1 dB and two -2 dB decrease messages). Figure 3C shows the windows transmitted along the reverse link signal by the mobile station 12 to the base station 16a. Figure 3C shows, above these windows, the energy control messages (P) transmitted in the P1312 / 99MX reverse link signal, where the message subscript indicates which window of the forward link signal the message was generated. For example, a power control message Pml corresponds to a window of the direct link signal, although the mobile station 12 does not transmit the message P ^ to two windows afterwards during a window m3, as discussed in detail below. Figure 3D shows the windows received in the reverse link signal by the base station 16a. Figure 3D shows the energy control messages P received in the base station 16a during the corresponding window, regardless of whether the message has a binary value of 1 or 0 e, regardless of whether the message indicates an increase or decrease of 1. dB (+ or -1 dB) of the direct link signal. The inherent exemplary delays in the communication system 10 will be discussed first with respect to Figures 3A-3D. After this, the operation of the communication system 10 will be analyzed with respect to the example of Figures 3A-3D. Referring first to Figure 3A, if the base station 16a transmits a first window vc? 1 during the m frame, the mobile station 12 subsequently receives the window m? with a small delay in the propagation of a pathway (Figure 3B). As shown in Figure 3B, P1312 / 99MX the mobile station 12 does not normally process the energy level of the window m to a window after (i.e., during the second window m) During the second window m2, the mobile station 12 generates a power control message that corresponds to the previous window (tx). During this processing, the mobile station 12 compares the received energy level of the direct link signal with the threshold of the adjustable power level PTH to determine how far away from the desired energy level it will presumably be the level of energy received after the station base 16a executes the previous energy control messages not executed, as will be described more fully below. During a third window m3, the mobile station 12 transmits a first energy control message (Pml) corresponding to the first window m1. As indicated above, the energy control messages P in the exemplary embodiment indicate in which direction the energy level of the forward link signal must be changed. If the energy control message has a value of 1 or 0, then the base station 16a determines that the energy level of the forward link signal must be increased or decreased by a predetermined value (eg, +1 dB or - 1 dB), respectively. As shown in Figure 3A, the forward link signal received by the P1312 / 99MX mobile station 12 during the first window m1, suffers a -4 dB drop in energy from the desired energy level, mobile station 12 will not recognize this drop in energy until the second window m2 and will not transmit the energy control message Pml = 1 requesting an increase in energy up to the third window m3. The energy drop results from a degradation of the propagation path as a result of overshadowing or fading. During a fourth window m4 (Figure 3D), the base station 16a receives and processes the power control message Pml of the first window m1. In the exemplary embodiment, where each energy control message has only a single bit, the message Pm, i will have a binary value of 1 and - * the base station 16a increases the forward link transmission signals by 1 dB, in response to it. Therefore, the base station 16a increases the energy of a fifth window m5 by 1 dB to provide a deviation of only -3 dB of the desired energy level (Figure 3). In sum, the communication system 10 undergoes an exemplary delay of three windows between the time it receives the fall in the direct link signal from the mobile station 12 (window m and at the time when the base station 16a supplies a Subsequent increase in the direct link signal (window m5) Mobile station 12 does not recognize the P1312 / 99MX increase in the direct link signal to the sixth window m6. Importantly, the energy control processor 28 of the mobile station 12, under the routine 100 described below, generates energy control messages based on the previous energy control messages not executed, so as to avoid overcompensating the Power adjustment of the direct link signal. Therefore, during the third window m3 (Figure 3B), the mobile station adjusts the threshold of the PTH energy level, based on the 1 dB unexecuted increase provided by the first power control message Pml. Since the fall of -4 dB of the level of. desired energy in the forward link signal during the window m2 is still not equal to or greater than a setting of -1 dB at the threshold of the power level PTH, the mobile station 12 during the fourth window m4 transmits a second control message of Pm2 energy for the window m2 (Figure 3C), which indicates to the base station 16a that it increases the transmission energy of its direct link signal (Pm2 = 1). The mobile station 12 repeats the same process for the windows m3 and m4 transmitted by the base station 16a, processed by the mobile station during windows m4 and m5 and transmitted as third energy control messages and four Pm3 and Pm4 = 1, during the m5 windows and ItL.

P1312 / 99MX In sum, the mobile station 12 in the exemplary mode, preferably, receives continuously the direct link signal at the desired energy level. The energy control processor 28 therefore adjusts the threshold of the power level PTH of the desired energy level to compensate for the non-executed energy control messages that remain without being executed in a given time, due to the delay of three exemplary windows. Therefore, if there are two pending control messages of +1 dB of power and a pending control message of -1 dB of power, resulting in a total of +1 dB of increase, the mobile station 12 adjusts the threshold of the PTH energy level in a corresponding amount or opposite amount (-1 dB). If the energy of the forward link signal is less than the threshold of the adjusted PTH energy level, then the mobile station 12 provides an energy control message requesting an increase of +1 dB, whereas if the received energy is equal or greater than the threshold, the mobile station 12 a -1 dB decrease. During the sixth window m6 (Figure 3B), the mobile station 12 determines that three non-executed energy control messages (corresponding to an increase of +3 dB) have been sent. Therefore, mobile station 12 adjusts its power level threshold PTH by a corresponding -3 dB and compares the threshold P1312 / 99MX adjusted with the energy of the direct link signal received during window m5 to determine if the received energy is equal to or less than the threshold. Since the similarly received energy differs by -3 dB from the desired level and thus is equal to the threshold of the adjusted PTH energy level, the mobile station 12 transmits during a seventh window m7 (Figure 3C), a fifth message of power control Pm? of 0, which requests a 1 dB decrease in the direct link signal. It should be noted that the case in which the measured energy level is equal to the threshold is rare, given the sufficient quantization of the received quality but which is provided for illustrative reasons. When the received energy is equal to the threshold, the mobile station 12 could alternatively request an increase in the transmission energy or randomly send an energy control signal. Since the exemplary mode uses single-bit energy control messages, the energy of the forward link signal preferably ranges between approximately +1 and -1 dB, with respect to the desired energy level. Therefore, during the sixth window m6 (Figure 3B), when the mobile station 12 recognizes that the deviation of -3 dB present in the received signal is equal to the threshold of the adjusted PTH energy level of -3 dB (based on three +1 dB energy control messages not executed), P1312 / 99MX the mobile station 12 anticipates that three subsequent windows to the energy of the received forward link signal will be at approximately +1 dB above the desired energy level. Consequently, during the seventh window m7 (Figure 3C), the mobile station 12 supplies the fifth energy control message Pm5 requesting a 1 dB decrease to the base station 16a (PmS = 0). In the present example, the seventh window m7 of Figure 3A reflects a further degradation or decrease of the forward link signal, as compared to the previous window m6 (i.e., -2 dB to -3 dB). In this example, a degradation of 2 dB has occurred in the propagation path during the time period of the m7 window. This degradation is the result of external factors, such as the shadowing of the mobile station 12. The deviation of the energy of the direct link signal during the m7 window, of -3 dB, is equal to the energy deviation in the window previous m6 (-2 dB), modified by the cumulative effect of the additional loss on the radio channel (-2 dB) and the adjustment by the base station due to the power control command Pm3 (+1 dB). During the eighth window m8 (Figure 3B), when the mobile station 12 processes the received m7 window, the mobile station 12 recognizes only one P1312 / 99MX total of +1 dB in the energy control messages not executed and expects the power of the forward link signal received by the previous messages to be improved (ie suffers a -1 dB drop only. In this mode, the mobile station 12 adjusts the threshold of the PTH energy level by -1 dB, however, during the eighth window mg (Figure 3B), the mobile station 12 determines that the deviation of -3 dB of the energy level of the received direct link signal is less than the threshold of the set PTH energy level of -1 dB, and thus determines that the energy of the forward link signal must be further increased by 1 dB, consequently, during the first window nx of the second frame n (Figure 3C), the mobile station 12 provides a seventh power control message Pm7 to the base station 16a which requests that the forward link signal be increased again by 1 dB (ie, Pm7 = 1) From the eighth window m8 of the first frame ma the first window n ± of the second frame n (Figure 3A), the energy of the received forward link signal is further degraded from -2 dB to -3 dB, because the fifth control message of power Pm5 causes the base station 16a to attenuate the direct link signal by 1 dB, even when the signal itself suffers no further degradation in the present example.

(Remember, mobile station 12 anticipated a correction P1312 / 99MX completes the initial -4 dB decrease in the forward link signal during the sixth window m6 (Figure 3B) and thus generated the fifth energy control message Pm5 which requested the -1 dB decrease. ) After this, the direct link signal * is increased gradually by increments and then oscillates between 0 and -1 dB during windows n2 to n7, as shown in Figure 3A. This improvement in the forward link signal is due to the mobile station 12 which adjusts the threshold of the PTH energy level by -3 dB during the window n2 (Figure 3B) and thus produces an increase of +1 dB in the command of power control during window n (FIG. 3C) The oscillation of the forward link signal around the desired level during windows n4 through n7 (FIG. 3A) results from mobile station 12 adjusting the energy level threshold P ^ at -3 dB, -1 dB and +1 dB, during windows n2 to n4, respectively (Figure 3B) and, thereby producing a series of energy control messages Pnl, Pn2 and Pn3 having values of 0, 1 and 0 respectively (Figure 3D) Referring to the flow diagram of Figure 4, the routine 100 executed by the energy control processor 28 in the mobile station 12, considers the delay of several windows when generating energy control messages in response to the direct link signals received. the P1312 / 99MX experienced in the relevant technique can create a source code based on the flow chart of Figure 4 and the detailed description provided here. The routine 100 is preferably stored in a memory (not shown) that is part of the processor 28 of the power control. In step 102, the channel quality measurement circuit 26 receives the present window of the direct link signal from the base station 16a. The channel quality measurement circuit 26 in response thereto supplies the energy measurement signal to the power control processor 28 in step 102 which indicates the energy level of the present window. In step 104, the energy control processor 28 adjusts the power level threshold PTH, based on the previous energy control messages not executed. Therefore, as described above with respect to Figures 3A to 3D, if, for example, three +1 dB increase commands have not been executed, then the power control processor 28 in step 104 reduces the threshold of the PTH energy level at -3 dB, to compensate for the three energy control messages not executed. Alternatively, the power control processor 28 may provide the threshold of the adjusted PTH energy level or other instructions appropriate to the quality measurement circuit 26. The measuring circuit 26 P1312 / 99MX quality can, in turn, appropriately measure the received direct link signal based on the threshold of the adjusted PTH energy level and provide the results of these measurements to the energy control processor 28. The energy control processor 28, in response thereto, then generates the appropriate energy control messages. In step 106, the energy control processor 28 compares the energy level of the present window received in step 102 with the energy level threshold set in step 104. In step 108, the control processor 28 energy supplies the base station 16a with the appropriate energy control message, based on the comparison between the energy level of the present window and the set threshold. Several alternative modalities of the exemplary modality described above are possible. In a first alternative mode, a smaller number of energy control messages may be sent by the mobile station 12 during each frame. For example, instead of using the relatively fast reporting rate on the reverse link of 8 or 16 bits per frame (for example, the 8 energy control messages per frame of Figures 3A-3D), only one bit could be used per plot. This single bit could indicate the quality of the currently received frame, instead of its deviation in the level of energy of a level P1312 / 9-9MX desired energy, such as using a one-bit message frame draft indicator (EIB) transmitted as the energy control message. The EIB message implicitly indicates an energy level of the currently received frame, because if the EIB indicates that a present frame was deleted, it is likely that the direct link signal received by the mobile station 12 has insufficient power. For example, the quality measurement circuit 26 can determine whether a complete frame in the received direct link signal contains errors or was erased. In response thereto, the energy control processor 28 can produce an EIB message for each frame indicating whether a frame currently received contains an erasure. An EIB binary value of "0" may indicate an acceptable received frame, while a value of "1" may indicate an erased frame. Referring to the timeline of Figure 5, the typical inherent delays in accordance with the first alternative mode will be described. If the base station 16a transmits a present frame (frame n), the mobile station 12 subsequently receives that frame with a small delay in the propagation of a path, as indicated above. Due to the time required to demodulate and to attempt to decode the frames, the mobile station 12 P1312 / 99MX does not determine that the frame n is erroneous until a frame after (frame n + 1), at that moment it generates an EIB message or error bit En = 1. A frame after this (frame n + 2), the mobile station 12 transmits the error bit En = 1. During the next frame (frame n + 3), the base station 16a processes the error bit En = 1 and increases the energy of the forward link signal by 1 dB. Therefore, as shown in Figure 5, if any error occurs during the reception of the mobile station 12 of the frame n, it is not up to three frames later (frame n + 3) that the base station 16a increases the gain in the the direct link signal. As a result, the subsequent frame (frame n + 4) is transmitted by the base station 16a at the increased energy level. The energy control processor 28 of the mobile station 12 compensates for this delay of three frames according to the routine 100. For example, if errors occurred during the frames n + 1 and n + 2, the mobile station provides an EIB value of 1 during the frame of n + 1 but, provides a value of zero during the frame n + 2, anticipating that the bits 1 during the frames n and n + 1 (1En and - * Enx + l1 = 1) * will increase the energy adequately of the direct link signal. This alternative mode of one bit per frame is acceptable for small drops or reductions in the direct link signal. However, fading P1312 / 99MX strong in the direct link signal of 20 to 30 dB, can not be corrected quickly and acceptable at a rate of 1 dB per frame. The controller 14 of the base station in the first alternative mode can monitor and confirm changes in the power performed by the base station 16a in response to the EIB messages. In this way, during the same frame in which the base station 16a processes the error bit En = 1 (frame n + 3), the base station also transmits the error bit to the controller 14 of the base station. The controller 14 of the base station, however, does not process the increase in the gain of the direct link signal to a frame after it (frame n + 4). Still one frame later (frame n + 5), the controller 14 of the base station communicates with the base station 16a and confirms that the increase in gain was appropriate or supplies the appropriate setting (if this is necessary). As shown in Figure 5, there is a delay of 5 frames between the time the first error occurs during the frame n and the increase in the gain of the forward link signal is confirmed by the station 16a during the frame n + 5 The adjustment to transmit power in response to some commands from controller 14 of the base station will not apply until frame n + 6. The time diagram in Figure 5 illustrates the typical additional delay of P1312 / 99MX two frames that would result from allowing the controller 14 of the base station to control the transmit power of the base stations 16a and 16b, as described more fully below. In the second alternative embodiment, the present invention is applied in a substantially similar manner to control the energy of the reverse link, therefore, the power control processor 34 of the base station 16a can execute the routine 100 and adjust the threshold of the energy level of the reverse link. For example, the base station 16a transmits power control messages over the direct link channel to the mobile station, wherein the messages indicate the quality of each frame or frame portions received in the reverse link channel. The base station 16a appropriately adjusts its reverse link energy level thresholds, with which it compares the arrival frames or portions thereof, to reflect the energy level anticipating the reception of the reverse link channel, then of a delay practically similar to the aforementioned delay. As a result, the base station 16a can adjust its measurement threshold to correspond more closely to future energy adjustments. In addition, the details on this second alternative modality were omitted for reasons of brevity, because this modality is easily compressible P1312 / 99MX by those skilled in the relevant art, based on the detailed description of the first embodiment provided above. In a third alternative mode, the controller 14 of the base station controls the adjustment of the energy level of the direct link signal of each base station 16a, 16b, etc. Referring again in Figure 2, according to the third alternative embodiment, the back-up routing transceiver 39 in the base stations 16a and 16b, supplies signals, including energy control messages, to the selector receiving system 40 in the controller 14 of the Base station. The energy control messages transmitted by the mobile station 12 may represent the change or the difference of the desired level. The selector control processor 42 receives the power control messages from the selector receiver system 40 and, under the routine 100, determines whether the forward link signal transmitted by the base stations 16a or 16b is increased or attenuated. The selector transmitting system 44 receives the power control commands from the selector control processor 42 and supplies them to one or more of the reverse route transceivers 39 in the base stations 16a and / or 16b. In response to this, the backward routing transceiver 39 provides the power control commands to the control processor 34.

P1312 / 99MX energy to control the energy of the direct link signal. The selector control processor 42 must, of course, take into account the additional delay caused during the transmission of the power control messages from the base station 16a to the controller 14 of the base station and a delay caused by the sending of the commands from the controller of the base station back to the base station, as shown in Figure 5. Because the controller 14 of the base station is coupled and can receive the power control messages from the base stations 16a, 16b , etc. can provide more precise commands to base stations, especially during smooth transfer conditions. In a fourth alternative embodiment, the energy control processor 28 may provide more than a single bit per window or frame in each energy control message. For example, if two bits are sent per energy control message, the energy control message may indicate either an increase of +1 dB or an increase of +2 dB, a decrease of -1 dB or a command to maintain the current energy level of the direct link signal. While longer energy control messages under this fourth alternative mode will require the increase in bandwidth along with the reverse link signal, these P1312 / 99MX energy control messages could more quickly adjust and maintain the direct link signal at the desired level. In a fifth alternative mode, the energy control processor 28 of the mobile station 12 can "fine tune" its energy control messages over a multi-period period. For example, the power control processor 28 can monitor its performance and determine whether the power control messages that are fed back to the base station 16a regularly and incorrectly request a +1 dB increase over a period of 10 windows. Therefore, the energy control processor 28 can automatically request a decrease of -1 dB every 10 windows to compensate for this error. Alternatively, the energy control threshold can be adjusted by a fractional amount. For example, if the power control processor 28 recognizes that 20% of its energy control messages request an incorrect increase in the forward link signal, then, the threshold can be adjusted by 20% downward. In a generalized mode, the mobile station 12 determines the quality of the received direct link signal. For example, the mobile station can measure the error rate of the symbols of the received forward link signal. The mobile stationP1312 / 99MX would compare this error rate in the symbols received from the frame or frame portion with an adjustable threshold value. The quality of the threshold is adjusted based on the previous non-executed control commands, which had previously transmitted the mobile station 12 to the base station 16a. The mobile station can adjust the speed of errors in the frame by means of a look-up table, which would predict the effect on the future measurement of the error rate in the symbols that the commands previously not executed would have. Similarly, the mobile station could measure the signal to noise ratio of the forward link signal. In a simplified mode, the mobile station would adjust the threshold of the signal-to-noise ratio under the assumption that the noise level remains constant. In this way, the generalized invention would measure the quality indication in the received signal and compare this quality measurement with an adjustable threshold that is adjusted in accordance with an estimate of how the quality measurement will be performed by the control commands of energy not yet executed by the remote station. Although specific embodiments and examples of the present invention were described herein for illustrative purposes, various equivalent modifications can be made without departing from the spirit P1312 / 99MX and scope of the invention, as will be recognized by those skilled in the relevant art. For example, the various embodiments described herein may be combined to provide additional modalities. In general, the energy control routine described above in detail is exemplary and those skilled in the relevant art can create similar routines in accordance with the teachings and concepts of the present invention. The teachings of the present invention provided herein may be applied to other communication systems, not necessarily to the CDMA communication system described above. For example, while in a general manner the present invention has been described above as being used in the CDMA communication system 10, the present invention is equally applicable to other digital or analog cellular communications systems. The present invention may also be modified, if necessary, to utilize the systems, circuits and concepts of the various patents described above, all of which were incorporated herein by reference, as if they were set forth in their entirety. These and other changes can be made to the invention in light of the above detailed description. In general, in the following claims the terms should not be interpreted P1312 / 99MX limit the invention to the specific embodiments disclosed in this specification and claims but must be construed as including any communication system that operates or functions in accordance with the claims to provide control of the transmission energy. Accordingly, the invention is not limited to the foregoing disclosure but its scope will be fully determined by the following claims.

P1312 / 99MX

Claims (25)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property. A communication system comprising: a base station means for transmitting a present communication signal; at least one user station means for receiving the communication signal and for determining the energy level of the communication signal in order to adjust the energy level threshold based on at least one prior energy control message, for comparing the threshold of the adjusted energy level with the energy level of the present communication signal and for transmitting a present energy control message; and wherein the base station means includes a means for transmitting a new communication signal at a set energy level, based on the present energy control message. The communication system according to claim 1, wherein the user station means includes means for receiving one of multiple windows of the present communication signal, a means for determining the energy level of the signal window of present communication and a P1312 / 99MX means for adjusting the threshold of the energy level based on a plurality of energy control messages prior to the previous windows of the communication signal. The communication system according to claim 1, wherein the user station means includes a means for transmitting the present energy control message having a bit and wherein the base station means includes a means for transmitting the new one. communication signal at a new energy level increased by a selected amount, if the bit has a first value. The communication system according to claim 1, wherein the user station means includes a means for analyzing a plurality of previous energy control messages with respect to a plurality of corresponding prior energy levels, a means for determining the error value based on the analysis and a means to adjust the energy level threshold based on the error value. 5. In a communication system having a base station and a user station, the base station transmits signals to the user station and receives signals therefrom, the user station comprises: a receiver receiving the present signal from the P1312 / 99MX base station; a measuring circuit coupled to receive the present and configured signal to determine the level of the present signal; a processor coupled to the receiver and to the measurement circuit, the processor is configured to adjust the measurement value based on at least one precontrol message and to compare the adjusted measurement value with the level of the present signal; and a transmitter coupled to the processor that transmits a present control message to the base station. to request that the base station transmit a new signal at a level adjusted based on the present control message. The user station according to claim 5, wherein the receiver receives one of multiple windows of the present signal, wherein the measurement circuit is configured to determine the energy level of the window of the present signal and wherein the The processor is configured to adjust the value of the measurement based on at least one pre-control message of the at least one previous window. The user station according to claim 5, wherein the transmitter is configured to transmit the present control message having a bit and wherein the bit commands the P1312 / 99MX base station to transmit the new signal to a new energy level increased by a selected amount, if the bit has a first value. The user station according to claim 5, wherein the processor is configured to analyze a plurality of previous control messages with respect to a plurality of corresponding levels of previous signals transmitted by the base station, determines the value of the error based on the analysis and adjusts the measurement value based on the value of the error. 9. In a communication system having a base station and a user station, the base station and the user station transmit signals to each other, a method for controlling the transmitted signals, comprising the steps of: determining the present level based on a first transmitted signal; adjust the threshold level based on at least one pre-control message; measure the present level determined based on the adjusted threshold level; and providing a control message present based on the step of the measurement, wherein the present control message requests that a second signal be transmitted at a level adjusted based on the present control message. P1312 / 99MX 10. The method according to claim 9, wherein the step of determining the present level determines the present quality level of the first signal and wherein the step of adjusting the threshold level adjusts the threshold quality level based on at least one pre-control message. The method according to claim 9, wherein the step of determining the present level determines the present energy level of the first signal and wherein the step of adjusting the threshold level adjusts the threshold energy level based on at least one Prior control message. The method according to claim 9, further comprising the step of executing the steps of determining, adjusting, measuring and providing in the user station. The method according to claim 9, further comprising the step of performing the steps of determining, adjusting, measuring and providing in the base station. The method according to claim 9, wherein the communication system includes a base station controller coupled to at least the base station and wherein the method further includes the step of executing the steps of determining, adjusting, measuring and providing in the controller of the base station. P1312 / 99MX 15. The method according to claim 9, wherein the step of determining the present level includes receiving an energy signal including one of multiple windows of the first signal and determining the energy level of a window of the first signal; and wherein the step of adjusting the threshold of the level includes adjusting the threshold of the energy level based on at least one pre-control message of a corresponding pre-window of the first signal. The method according to claim 9, further comprising the steps of: analyzing a plurality of previous control messages with respect to a plurality of corresponding prior levels of the first signal; determine the error value based on the step of the analysis; and adjust the threshold of the level based on the value of the error. 17. In a communication system having a base station and a user station, the base station transmits signals to the user station and receives signals therefrom, a control apparatus comprising: a receiving circuit receiving a signal; and a processor coupled to the receiver circuit and configured to adjust the threshold level based on at least one pre-control message, measure the signal P1312 / 99MX received based on the set threshold level and produce a control message present based on the measurement of the received signal and, where the present control message indicates the transmission of a second signal at a set level based on the control message present. The control apparatus according to claim 17, wherein the receiving circuit receives a quality signal and wherein the processor adjusts the threshold quality level based on at least one pre-control message and measures the quality signal based on at the adjusted quality threshold level. The control apparatus according to claim 17, wherein the receiver circuit receives an energy signal and wherein the processor adjusts the energy level based on at least one pre-control message and measures the energy signal based on the energy level adjusted. The control apparatus according to claim 17, wherein the user station includes the receiver circuit and the processor, wherein the receiver circuit includes a measurement circuit configured to determine the level of the first signal and to supply the level as received signal to the processor. 21. The control apparatus according to claim 17, wherein the base station includes the P1312 / 99MX receiver circuit, to the processor and a transmitter coupled to the processor, wherein the received signal corresponds to the level of a first signal measured by the user station and transmitted to the base station, where the processor provides the present control message to the transmitter and wherein the transmitter transmits the second signal to the user station at the level set in response to the present control message. 22. The control apparatus according to claim 17, wherein the communication system includes a base station controller coupled with at least the base station, wherein the controller of the base station includes the receiver circuit, the processor and a transmitter coupled to the processor, wherein the received signal corresponds to the level of a first signal measured by the user station, wherein the processor provides the present control message to the transmitter and wherein the transmitter transmits the present control message to the base station. The control apparatus according to claim 17, wherein the receiving circuit receives an energy signal corresponding to one of multiple windows of the received signal transmitted by the base station, wherein the processor is configured the energy level of a window of the received signal P1312 / 99MX and is configured to adjust the threshold of the energy level based on at least one pre-control message of a previous window of the received signal. The control apparatus according to claim 17, wherein the processor is configured to analyze a plurality of previous control messages with respect to a plurality of corresponding previous levels of the received signal, determining the error value based on the analysis of the previous control messages and adjust the level threshold based on the error value. 25. In a communication system having a first communication station and a remote station, wherein a user of the remote station transmits signals to the first communication station and receives communication signals from this station, where the communication system it has, in it, inherent communication and processing delays, a method for controlling the energy of the transmission signal of the communication signals transmitted by the first communication station, the method comprising the steps of: in the first communication station; communication, transmit a present communication signal; at the remote station, receive the present communication signal from the base station; at the remote station, determine the level of P1312 / 99MX quality of the communication signal present; in the user station, adjusting the threshold of the quality level based on at least one previous energy control message that was previously transmitted by the remote station to the first communication station; at the remote station, buy the threshold of the adjusted quality level with the energy level of the present communication signal; in the remote station, transmitting a present energy control message based on the comparison step; and in the first communication station, transmitting a new communication signal at a set energy level based on the present energy control message. P1312 / 99MX