Methods and apparatuses for fast power control of signals transmitted on a multiple access channel

Method and apparatus for fast power control of signals transmitted on a multi-directional proximity channel

<u>Background of the invention</u>

<u>I. Field of invention</u>

SUMMARY OF THE INVENTION The present invention is generally directed to a mobile radiotelephone system. In particular, the present invention relates to a mobile radiotelephone system that controls the output transmission power of an information signal transmitted between a mobile unit and a base station. More particularly, the present invention relates to a system and method for a novel and improved system and method for rapidly controlling the output transmission power of a signal transmitted by a mobile station to a base station over a plurality of proximity channels within a mobile radiotelephone system.

<u>II. Description of related technologies</u>

In a CDMA radiotelephone system operating according to the TIAIEIA-95 standard (IS-95 standard), a Proximity Channel (R-ACH) is used when a mobile station does not specify a dedicated channel, such as a traffic channel (TCH), from a mobile station to a base station. The R-ACH carries the source, call response, login, and confirmation of the message sent by the base station on the calling channel. The R-ACH is transmitted at a constant speed of 4800 bps. This is in contrast to the traffic channel being a variable rate. For a detailed description of the CDMA example system, reference is made to U.S. Patent No. 4,901,307, the entire disclosure of which is incorporated herein by reference. The IS-95 standard is stated in the TIA/EIA Interim standard name "Mobile Station Base Station Compatibility Standard for Dual Mode Broadband Spread Spectrum Honeycomb Systems", TIA/EIA/IS-95, July 1993, the contents of which are described in This is for reference.

At R-ACH, the mobile station uses a base station-specific long code spread-frequency cover. Special base stations can have up to 7 calling channels. Each call channel incorporates one or more R-ACHs (up to 32 channels are allowed). Each R-ACH has a long code cover to determine the spread spectrum order. The cover includes the identity of the channel associated base station, the R-ACH is coupled to the calling channel, and the R-ACH number. This provides a unique long code cover that provides a unique long code sequence for a particular R-ACH.

Although it is indeed possible, R-ACH is not operated in a soft disconnection. Unlike the traffic channel, it is operated by a soft disconnect. In addition, R-ACH does not have fast power control like the IS-95 traffic channel. On the traffic channel, the base station transmits power control to the mobile station at 800 bps. BPSK modulation is used for the power control bit stream. One bit phase indicates that the mobile station is to increase the transmission power: another bit phase indicates that the mobile station is to reduce the transmission power. The base station determines whether the base station needs to increase or decrease the transmission power by controlling the energy received by the base station to the noise density to a threshold. If the received energy-to-noise density is less than the threshold, the base station can increase the transmission power of the mobile station; if the received energy-to-noise density is greater than the threshold, the base station reduces the transmission power of the mobile station. In the U.S. Patent Nos. 5,056,109 and 5,265,119, the entire disclosure of which is incorporated herein by reference in its entirety in its entirety in the the the the the the the the for reference.

One reason why R-ACH does not have fast power control is that multiple mobile stations can transmit on the same R-ACH, making it difficult to control a power control flow. In addition, if there are many power control flows controlling one channel, it is unclear how to map the power control flow to the mobile station. U.S. Patent No. 5,604,730 (the applicant of the present application) describes how the power control flow can be used to control multiple mobile stations. As described below, the teachings of this teaching are applicable to the invention described herein.

In a CDMA system operating in accordance with the IS-95 standard, the mobile station is determined based on the open loop power control estimate by a number of communication management parameter adjustments depending on the level of the R-ACH transmission. In particular in accordance with the IS-95 standard, the mobile station attempts to attempt to access the R-ACH by transmitting one or more proximity sounding signals. The proximity probe signal is a message that the mobile station attempts to send to the base station. The mobile station starts transmitting the proximity detection signal; if the mobile station does not receive the confirmation of the proximity detection signal, the mobile station increases its transmission power (the value specified by the communication management message) and transmits the detection signal again. This continues until the mobile station receives an acknowledgment, or the mobile station has reached the tolerance of the proximity detection signal.

For any multi-directional proximity system, the key aspect of system design is congestion control. In terms of R-ACH, the congestion control system responds to the number of mobile stations that receive an R-ACH in response to control. Congestion control is important because the system cannot cope when too many mobile stations pick up the system. It is especially possible to have more transmissions on the backlink than the base station can receive. This is the physical hardware limit. Second, the reverse CDMA channel has a capacity limit. When the capacity limit is reached, the transmission power of the required mobile station is infinite, in other words, communication is not allowed. This requires maintaining the channel load within limits. Since R-ACH typically shares a reverse lead with the traffic channel, some parts of the reverse capacity are typically scheduled for R-ACH. It should be noted that the overload of the R-ACH may cause a substantial load of the backlink, thus limiting the performance of the mobile station that has designated the traffic channel. It should also be noted that the R-ACH itself is slightly unstable because the actual output of the R-ACH may be reduced after the reverse link reaches a certain load. To control this load, the IS-95 standard has multiple congestion control mechanisms. Including proximity detection signal compensation, proximity sequence compensation, channel randomization and PN randomization. However, IS-95 lacks any mechanism to quickly enable and access the R-ACH to control congestion.

These problems and deficiencies are recognized by the present invention and are solved in the following manner.

<u>Summary of invention</u>

One aspect of the present invention is directed to a method and apparatus for transmitting control signals from one or more complex mobile stations to a base station over a plurality of M multi-directional proximity channels. The power control information packets formed by the plurality of power control bits are transmitted by the base station to one or more mobile stations. Each power control bit of the power control information packet has a location that maps to a selected proximity channel and maps to one of the selected proximity channels. The power control information packet is received at the first mobile station. Then, a message is transmitted on the first proximity channel and the first time offset associated with the first proximity channel is transmitted by the first mobile station to the base station. The message is transmitted by the first mobile station at a power level determined by the first power control bit of the response power control information packet. The first power control bit is located at a first location of the power control information packet, and the first location is mapped to the first proximity channel and the first time offset.

According to yet another aspect, the present invention is directed to a method and apparatus for transmitting signals to a base station by two or more of a plurality of mobile stations in a plurality of M multi-directional proximity channel control signals. The power control information packets formed by the plurality of power control bits are transmitted by the base station to one or more mobile stations. Each of the power control bits of the power control information packet has a location that is mapped to a selected proximity channel. The power control information packet is received by the first mobile station and the second mobile station. The message is then transmitted to the base station by the first mobile station and the second mobile station simultaneously on the first proximity channel. The messages from the first and second mobile stations are transmitted on the first proximity channel only in response to the power level determined by the first power control bit in the power control information packet, wherein the first power control bit is located in the power Controlling the first location of the information packet, and the first location is mapped to the first proximity channel.

According to yet another aspect, the present invention is directed to a method and apparatus for transmitting one or more channel control signals from one or more of a plurality of multi-directional proximity channels to a base station. A power control information packet formed by the plurality of power control bits is transmitted by the base station to one or more mobile stations. The power control bit of the power control information packet uses a modulation transmission that allows each of the power control bits to assume one of the first, second, and third different states. The power control information packet is received at the first mobile station, and then the first mobile station identifies a first power control bit state associated with the first proximity channel. And then, if the state of the first power control bit corresponds to the first state, performing one of the first, second or third operations at the first mobile station, wherein the first operating system corresponds to the first proximity channel initialization message information Transmitted by the first mobile station to the base station, the second operation system is corresponding to the first proximity channel, the message information is transmitted by the first mobile station to the base station, and the third operation system corresponds to the termination message information to the first proximity channel. Transferred by the first mobile station to the base station. If the first power control bit state corresponds to the second state, the output power level of the first mobile station in the first proximity channel is increased, and if the state of the first power control bit is corresponding to the third state, the first The output power level of the mobile station on the first proximity channel is reduced.

According to still another aspect, the present invention is directed to a method and apparatus for transmitting control signals to a plurality of M multi-directional proximity channels from one or more stations of a plurality of mobile stations to a base station. A power control information packet formed by the plurality of power control bits is transmitted by the base station to one or more mobile stations. Each of the power control bits of the power control information packet has a location that is mapped to a selected proximity channel and to a time offset of the selected one of the selected proximity channels. The base station secondly determines whether the base station receives the first proximity channel during the time interval corresponding to the first time offset. If a base station accesses the first proximity channel during a time interval corresponding to the first time offset, the first power control bit having the first location in the power control information packet is mapped to the first proximity channel and the first power channel The first time is biased. If a mobile station cannot access the first proximity channel during the time interval corresponding to the first time offset, the first power control bit having the first location inside the power control information packet is mapped to the first proximity channel, And a second time offset associated with the first proximity channel.

According to still another aspect, the present invention is directed to a method for performing a proximity channel disconnection connection to a mobile wireless unit when the mobile wireless unit is moved from the first cellular unit of a mobile wireless telephone system to the second cellular unit of the mobile wireless system. Device. At least one power control bit transmitted by the first base station associated with the first hive is transmitted to the mobile radio unit. The power control bits from the first base station are transmitted at a first time interval corresponding to the first proximity channel associated with the first base station. At least one power control bit from the second base station associated with the second hive is also transmitted to the mobile radio unit. The power control bits from the second base station are transmitted at a second time interval, which may correspond to a first time interval used by each of the first base stations. The power control bit from the second base station corresponds to the proximity channel associated with the first base station. Each of the power control bits of the power control information packet has a location that maps to the selected proximity channel and maps to a base station associated with the selected proximity channel. The mobile radio unit receives the power control packet from the first base station and the power control packet from the second base station, determines the corresponding power control bit, and then determines the power control bit status. If the status indicates that a message is to be transmitted and the mobile station has a message to transmit, the mobile station transmits the message to the selected proximity channel. Each group of base stations that specify the base station attempts to receive transmissions on the selected proximity channel, and then sets the noise ratio to the corresponding bit of the power control information packet according to the received signal.

<u>Detailed description of preferred embodiments</u>

<u>Basic fast proximity channel power control</u>

Referring now to Figure 1, there is shown a schematic diagram showing the construction of a bit stream 100 formed by a plurality of power control information packets 110 in accordance with the present invention. As described in detail later, in the present invention, the information included in the power control information packet 110 is transmitted from the base station to the mobile station in the wireless telephone system, and is controlled by the mobile station to be transmitted to the one or more multi-directional proximity channels. The output power of the base station, for example, the reverse proximity channel (R-ACH) of a CDMA cellular system operating in accordance with the IS-95 standard. In addition, the information contained in the power control information packet is used to adjust the access from the mobile station to the plurality of proximity channels. The power control packet can be sequenced on separate channels, as shown in FIG. 1; or can be mixed with the information of the separate channels. This cross is well known to the industry. Each power control information packet 110 is comprised of N power control bits 120. In the specific example shown in FIG. 1, each power control bit 120 of the power control information packet 110 is mapped to a single R-ACH and used to control the output power of the R-ACH. The power control bit 120 thus labeled 1 controls the output power level of one of the mobile stations transmitted on the R-ACH (1), and the power control bit indicated as 2 controls one of the transmissions on the R-ACH (2). The output power of the mobile station and so on. In a specific example, each of the power control bits is modulated according to a combination of OOK (switch keying) and BPSK modulation, so that three states, that is, off, 0 degrees, and 180 degrees are obtained. The second and third states (ie, 0 and 180 degrees) are used to transmit state and power up and power down commands to the mobile station, respectively, and the mobile station, for example, will increase its output transmission power by 1 dB in response to the command (if received) Go to the power up command) or reduce its output transmission power by 1 dB (if a power down command is received). Other power control step sizes are ideally suited for tuning the system to be optimal. In the first state (i.e., 0 degrees), the transmission power control bit 120 is used by the mobile station for adjusting the access to the power control bit association (i.e., mapped to) to the R-ACH. In a preferred embodiment, each power control information packet 110 has a duration of 1.25 milliseconds, and the control packet 110 is transmitted by the base station to the mobile station served by the base station in a forward link shared control or power control channel.

In a simplified version of the invention, the power control bit 120 is continuously transmitted by the base station in a BPSK modulated symbol stream. When the mobile station begins to pick up a particular R-ACH, the mobile station begins to pay attention to the power control bitstream 100, with particular attention to the power control bit 120 mapped to that particular R-ACH that the mobile station begins to pick up. If the power control bit 120 corresponding to the R-ACH received by the mobile station indicates that the mobile station must increase its transmission power, the mobile station increases: Similarly, several power control bits 120 indicate that the mobile station must reduce its transmission power. , the mobile station also follows. In a preferred embodiment, when the base station does not receive any transmission associated with the power control bit of the R-ACH (i.e., before the mobile station attempts to access the R-ACH corresponding to the special power control bit 120) The base station transmits power control bit 120 as a power supply command. When the base station does not receive any transmission of the associated power control unit on the R-ACH, the base station transmits the power control bit 120 as a power-up command, causing the mobile station to increase its power level at the beginning of the access, for example, if The mobile station is sent at a low power level.

Using the fast power control described herein allows a similar CDMA system to allow for accurate power control of the R-ACH in the reverse traffic channel (R-TCH). Such fast power control is important to achieve the maximum capacity of a mobile radiotelephone system. Another advantage of fast control is that it allows the mobile station to begin receiving R-ACH by transmitting a signal having a higher power than required, and then quickly correcting to a predetermined power level once the base station has received the transmission of the mobile station. Bit.

Referring now to Figure 2, a timing diagram is shown illustrating the use of the power control information packet 110 of the present invention for example access by the mobile station to the R-ACH. As shown in FIG. 2, the slot takes place by the mobile unit to access the R-ACH during a close channel. Although the preferred embodiment uses the R-ACH time slot, it should be noted that this innovative teaching does not require the R-ACH to be defined as a time slot, and thus can be applied to systems without timed slots.

At the beginning of the slot when the channel is connected, the mobile station first transmits a message preamble at the initial power level P0. In a specific example, the initial power level used during the transmission of the preamble signal corresponds to a power level that is used by the mobile station to access the R-ACH of the IS-95 standard. The power level of the received probe signal is about 3 dB higher. After transmitting the message preamble signal, the mobile station begins demodulating the power control information packet 110, and the special mobile station begins monitoring the value of the power control bit 120 corresponding to each of the power control information packets of the R-ACH being used by the mobile station. In response to the value stored in the power control bits, the mobile station responds up or down (ie, plus or minus 1 dB) its transmission output power in response to each of the power control bits 120 associated with the R-ACH used by the mobile station. .

According to another aspect, the base station will wait until it detects a transmission from the mobile station (ie, the mobile station will wait until its detected message preamble) and has received transmissions from the mobile station before transmitting the power control bits. Yuan stream. The base station will determine whether to instruct the mobile station to increase power or reduce power based on the received power level of the signal from the mobile station. In particular, the base station will compare the power level of the received signal with the threshold; if the received signal is below the threshold, the base station will use the power control information packet to send a power boost command to the mobile station, otherwise the base station will use the power. Control the information packet to send a power down command to the mobile station.

In the foregoing specific example, each power control bit 120 of the power control information packet 110 is mapped to a single R-ACH. In this specific example, if there are N power control bits 120 in each power control information packet 110, then the information packets can be considered to form N bit streams, each of which is used to control the aforementioned one R-ACH. One of the multi-directional proximity channels, such as R-ACH, simultaneously accesses and transmits to multiple mobile stations on such channels. U.S. Patent No. 5,604, 730, the disclosure of which is incorporated herein by reference in its entirety in its entirety in its entirety in the the the the the the the the the the the the Thus, the teachings of U.S. Patent No. 5,604,730 can combine the specific examples of the aforementioned power control information packet 110 (i.e., when the power control bit 120 maps the R-ACH from one to one), allowing multiple actions on the same R-ACH. The power level of the station is simultaneously controlled using a single power control bit stream.

As an alternative to the foregoing specific example, more than one power control bit stream can be used to control the operating power of multiple mobile stations operating on the same R-ACH. In an alternative embodiment, different mapping structures are used to map the power control bit 120 to a mobile station that is admitted to a particular R-ACH. In particular, in this alternative embodiment, the slot for the proximity channel transmitted by the mobile unit is interleaved in time by the complex offset within each R-ACH, as shown in FIG. Each offset indicates the time when a mobile station starts transmitting on a particular R-ACH. Preferably, the time interval between the two time offsets is greater than the maximum path delay range (including the maximum multipath delay) associated with the base station transmission to the mobile station, in order to determine which power control bit stream corresponds to a particular R-ACH And the confusion of bias. In one embodiment of the present invention, the proximity channel slot is divided into multiple frames as IS-95. Taking IS-95 as an example, the duration of one frame is 20 milliseconds. In this case, the slot is composed of S frames, so the duration of the time slot is 20×S milliseconds, where S is a fixed value or transmitted to the mobile station in system management information. In order to simplify the system design, it is preferable to select the time interval between time offsets as an integer W frame, where W is less than S.

In this specific example, the power control bit 120 is used to control the mobile station power, and the mobile station starts at the designated R-ACH transmission in the first access time slot (ie, after the offset 1), and the other power control bit 120 For controlling the mobile station power 120, the mobile station starts at the same R-ACH transmission and the like in the second access time slot (ie, after the offset 2). Although Figure 3 shows four interleaved connections for a given R-ACH, the industry must be aware that any number of interleaved connections can be used for a single channel.

Still referring to the specific example discussed in the previous paragraph, where each R-ACH is divided by a complex offset to generate a complex interleaved time for transmission by the mobile station, and the power control bit 120 is mapped to a complex R-ACH that can be used for mobile station transmission. An example mapping of the interleaved access times mapped to the available transmissions is shown in Table I below. The map shown in Table I shows that the M R-ACHs can be utilized by the mobile station and each of the R-ACHs has K interlaces (or offsets), and each of the power control bits 120 and a designated R-ACH. The offset has a one-to-one correspondence. Assuming such a one-to-one mapping, in this particular embodiment of the invention, an M x K power control bit 120 is required for each power control information packet 110.

<img file="TW453058B_D0001.tif" />

In order to mitigate the load on the forward link and slightly increase the capacity, a base station uses a power control system that conforms to the mapping shown in Table I. In a preferred embodiment, the base station will avoid transmitting power control bits associated with a particular R-ACH. The element and the specified offset until the base station receives the transmission from a mobile station for the particular R-ACH and the offset. In this case, if the base station uses BPSK modulation to transmit the power control bit, the base station transmits the modulation symbol of the specified power control bit only to the base station and receives the power from the mobile station. Controls the transmission of specific R-ACHs and offsets associated with the bit. Referring to FIG. 2 as such, the base station will not begin transmitting the corresponding power control bit until it detects that the R-ACH transmits the previous synchronization signal. The R-ACH preamble is for example defined in section 6.1.3.2.2.1 of the IS-95 standard.

In the slight modification of the specific example discussed in the previous paragraph, the base station starts transmitting the power control bit associated with the specific R-ACID and the offset at the beginning of the slot of the near-channel; if the base station does not detect the specified time interval When the specific R-ACH and the offset are received, the base station stops transmitting the power control bit associated with the specific R-ACH and the offset. This specific example allows the base station to increase its transmission power level at the slot transmission starting point of the mobile station in the proximity channel. The special base station will start transmitting the power boost command with a 0 degree phase shift at the start of the time slot. If the detection is received, the base station will send a series of power boost and power down commands as needed to control the received mobile station power. If no access is detected, the base station will abort the transmit power control bit, thereby reducing its transmit power and thus increasing its capacity.

<u>Use power control bits to enable/disable access to the proximity channel</u>

In accordance with a further aspect of the present invention, the power control bit 120 of the power control information packet can be used for congestion control of the R-ACH, that is, the power control bit can be used by the mobile station to enable/disable access to the R-ACH. In this specific example, when no mobile station receives the designated R-ACH, the base station does not transmit a power control bit corresponding to the specific R-ACH, thus indicating that the channel is idle. When an acceptable number of mobile stations pick up the designated R-ACH, the base station begins transmitting the power control bit associated with the designated R-ACH and the system using the bit to indicate that the mobile station must increase/decrease the transmission power ( That is, if the base station uses BPSK modulation to transmit the power control bit, the base station will simply send a plus or minus 180 degree BPSK modulation symbol to the designated power control bit). When, for example, the designated R-ACH becomes congested due to too many mobile stations operating on the channel, the base station does not start or stops transmitting the power control bit associated with the designated R-ACH, thus indicating that the mobile station must stop at the R - ACH transmission. This aspect of the invention is readily extended to the case where each R-ACH system is divided by a plurality of offsets (as shown in Figure 3). In this case, when no mobile station uses the specified offset to access the designated R-ACH, the base station does not transmit the power control bit corresponding to the specific R-ACH and the offset, thus indicating that the R-ACH and the offset are Idle. When an acceptable number of mobile stations pick up the designated R-ACH and the offset, the base station starts transmitting the power control bit associated with the designated R-ACH and the offset, and uses the message to indicate the mobile station of the access system. The transmission power must be increased/decreased. When the designated R-ACH and the offset are caused by too many mobile stations in the R-ACH and the result of the misalignment, the base station stops transmitting the power control bit associated with the designated R-ACH and the offset to indicate the mobile station. Must stop at this R-ACH and offset transmission.

The specific examples discussed in the previous paragraph are schematically illustrated in Figures 7 and 7A, which illustrate a flow chart for a system for adjusting access to a proximity channel using power control bits that can be used in three different states. In step 710, the power control information packet formed by the plurality of power control bits is transmitted by the base station to one or more mobile stations. The power control bit of the power control information packet uses a modulation including OOK and BPSK, which allows each power control bit to obtain one of the first, second, and third different states (ie, state 1 = off state) , state 2 = 0 degrees and state 3 = 180 degrees). At step 720, the power control information packet is received at the mobile station; at step 730, the mobile station identifies the power control bit status associated with the designated proximity channel. In step 740, if the power control bit state corresponds to the first state, performing one of the first, second, or third jobs at the mobile station, where the first job corresponds to the designated proximity channel, and the mobile station transmits the message information to the base. The second operation corresponds to the initialization of the designated proximity channel suppression message information transmitted by the mobile station to the base station, and the third operation corresponds to the designated proximity channel stop message information transmitted by the mobile station to the base station. In the preferred embodiment shown in FIG. 7A (labeled as steps 741a-743a), if the power control bit is in the first state (not transmitted) and the mobile station has not begun to transmit on the designated proximity channel, then in step 742a, the action is taken. The station is allowed to pick up the channel; otherwise the mobile station is ordered to stop at the designated proximity channel transmission (step 743a). Referring again to FIG. 7, if the mobile station transmits on the designated proximity channel, and the base station transmits the power control bit of the channel in the second or third state, when the power control bit state corresponds to the second state, the mobile station The output power level of the proximity channel is increased (step 750), and if the power control bit state corresponds to the third state, the output power rate bit of the mobile station of the proximity channel is decreased (step 760).

As indicated above, some alternatives to the present invention do not require the base station to transmit during the synchronization signal portion prior to transmission of the proximity channel. Thus in the preferred embodiment shown in FIG. 7A (labeled as steps 741a-743a), if the power control bit is in the first state (the power control bit has not been transmitted yet) and the mobile station has not yet started transmitting on the designated proximity channel, then In step 742a, the mobile station is allowed to be in close proximity to the channel; if the power control bit is in the first state (the power control bit is not transmitted) and the mobile station is transmitting the preamble signal on the designated proximity channel, then in step 742a, the mobile station is allowed. Continuing with the designated proximity channel transmission: otherwise the mobile station is ordered to stop at the designated proximity channel transmission (step 743a). Referring again to FIG. 7, if the mobile station is in the designated near-channel transmission and the base station transmits the power control bit of the channel in the second or third state, then when the power control bit state corresponds to the second state, the mobile station The output power level of the proximity channel is increased (step 750), and if the power control bit corresponds to the third state, the mobile station drops the output power level of the proximity channel (step 760).

Referring now to FIG. 4, according to still another aspect, the small idle interval is preferably included in the slot end of each of the proximity channels, so that the base station can turn off the power control bit, thus indicating that the channel is idle and the mobile station can be in the next slot. Pick up the channel. If the base station does not turn off the power control bit of the corresponding channel during this idle interval, the mobile station is not allowed to transmit in the next time slot. In this specific example, the base station typically does not transmit the power control bit of the designated R-ACH to the mobile station during the idle interval, and the base station can accept the R-ACH for the next time slot. If one or more mobile stations start to receive the R-ACH during the next close channel, the base station starts transmitting the power control bit corresponding to the R-ACH (for example, the base station transmits the power control unit 0 or 180) Degree BPSK symbol), so that the mobile station increases or decreases its transmission power. Still referring to FIG. 4, in the case where the base station does not wish to allow access to the R-ACH, or when the base station desires that one or more mobile stations stop transmitting in the R-ACH, the base station will transmit the power control bit during the idle interval. The element (e.g., the base station transmits a 0 or 180 degree BPSK symbol of the power control bit), thus indicating that the mobile station is incapable of receiving the R-ACH in the next slot. This specific example of the present invention is schematically shown in Fig. 8. A further alternative embodiment is shown in Figure 8A. Other aspects of the specific example of Fig. 8A are the same as those of Fig. 8. However, in Figure 8A, the base station transmits a power control bit during the idle interval to indicate that the mobile station is allowed to pick up the R-ACH in the next time slot.

The preferred length of the idle interval used in the foregoing specific example is the allowable processing time of at least some of the power control information packets plus the slot before the next close channel, so the mobile station can determine whether it is allowed to transmit in the time slot. This length is derived from the fact that a single power control bit is not encoded with error correction or detection information, but is relatively low power transmission to increase system capacity. The transmission of such a single power control bit is not extremely reliable. This is quite acceptable for power control purposes during the transmission of message information (for example, in the middle of a close channel) because a single bit error during this interval will cause the mobile station to change its power in the wrong direction. It will be quickly corrected by the next power control bit. However, since the mobile station cannot reliably detect whether a single power control bit is transmitted, a number of power control bits corresponding to the designated R-ACH are accumulated during the idle interval, and the mobile station is reliably determined whether the mobile station is allowed to access the R- The ACH is either ordered to stop at the R-ACH transmission.

In accordance with a further aspect of the present invention, FIG. 5 illustrates a system for accessing the R-ACH in the center of the control slot. If the slot has a more than the scheduled access of the base station for a predetermined number of R-ACHs, the base station preferably turns off the power control bit corresponding to the R-ACH after a certain time interval T in the center of the time slot. . The time interval T is the time required for the base station to determine whether there is more access than the predetermined time. After accumulating a number of such bits, the mobile station determines that the base station has not transmitted the power control bit corresponding to the R-ACH, and the base station can transmit it to the R-ACH (in the middle of the time slot).

It should be noted that in the alternative example, the idle interval may be during the preamble transmission, so that no invalid time is required on the channel. In this example, the base station not transmits a notification to the mobile station during the preamble signal period. However, the disadvantage of this specific example is that the mobile station cannot perform power control during the preamble. A further alternative would allow the mobile station to transmit during the preamble if the mobile station is allowed to pick up the system. Thus, the base station does not transmit during the preamble indicating that the mobile station is not allowed to transmit in the one-time slot.

The foregoing specific example uses a three-state of a single power control bit: off, increasing power, and reducing power. In addition, a power control bit transmits at different times to indicate whether the designated R-ACH is idle and the mobile station can pick up the R-ACH, whether the mobile station is not allowed to access the R-ACH, and whether the mobile station terminates at R. - ACH transmission. In the foregoing specific example, BPSK modulation is used to achieve this tristate using a single aforementioned power control bit. It should be noted that other modulation schemes can be used to indicate various states. For example, each power control bit can use QPSK modulation coding. This provides up to four different indications. Industry insiders must be aware that other modulation schemes can be used to encode power control bits. In a further alternative embodiment, a single power control bit can be used to manage all R-ACHs and will indicate if any mobile stations are allowed to access the system. This single bit is used to manage all R-ACHs. This approach can be used to avoid the aforementioned idle time.

<u>Reusing power control bits</u>

Figure 3 (as described above) shows the arrangement using interlaced R-ACHs. Using these interleaved R-ACHs, a power control bit can be assigned (or mapped) to each interleaved time slot of each R-ACH. According to a further aspect of the present invention, a power control bit that is not used for an interleaved time slot (i.e., a time slot associated with a particular offset) can be used again to control access to a subsequent interleaved time slot (i.e., associated later). Bit time slot).

FIG. 6 shows a case where there are four possible start times for each R-ACH power control bit and the R-ACH (that is, each R-ACH has four associated time offsets, that is, offset 1 , offset 2, offset 3 and offset 4). The power control bits 1 and 2 that originally designated R-ACH are assigned to the offset 1 and offset 2 of the R-ACH, respectively. If a mobile station picks up the designated R-ACH during the time interval corresponding to the offset 1, the power control bit 1 is used to specify the offset 1 of the R-ACH. In addition, if a mobile station does not receive the designated R-ACH at the time interval corresponding to the offset 1, the power control bit 1 is used to control the transmission starting from the offset 3 of the R-ACH association. Similarly, the power control bit for the offset 2 can be used for the offset 4 if it does not receive the R-ACH during the offset 2. According to this aspect of the invention, one of the mobile stations scheduled to receive the designated R-ACH at offset 2 will check whether the power control bit of the corresponding offset 2 is transmitting at the offset 2 idle time. If the power control bit is transmitting (eg, if the base station transmits a 0 or 180 degree BPSK symbol to the power control bit), the mobile station will not pick up during the offset 2 period. This is an extension of the aforementioned rules, in other words, if the power control bit is not transmitted, then the mobile station is picked up during the offset 2 . The foregoing method of reusing the power control bit is schematically shown in FIG. 9 in the form of a flowchart.

<u>Soft disconnected link of the control channel</u>

In the COMA system according to the IS-95 standard, the R-ACH is received by a single base station. In such a system, a number of base stations will not receive R-ACH from a specific mobile station in a soft disconnected manner (ie, first making a link and then breaking the link), as in the CDMA traffic channel as a mobile station by the first base. The soft disconnection made when the station moves to the second base station. An example of a CDMA system for performing a soft disconnection on a CDMA traffic channel is described in U.S. Patent No. 5,101,501, entitled "Method and Apparatus for Providing a Soft Decoupled Connection in a CDMA Cellular Telephone System Communication", to the assignee of the present invention and This is hereby incorporated by reference. Although the soft disconnection of R-ACH is not prohibited by the IS-95 standard, it is not known to perform such disconnection. There are two major drawbacks to the fact that R-ACH does not perform soft disconnection. The first drawback is the lack of location diversity, which reduces channel performance. The second drawback is that reverse power control is not used by multiple locations. As a result, the mobile station will send more power than needed.

There are several difficulties in performing soft disconnection on R-ACH. One difficulty is that the system is not required to predict which base station is needed for the mobile station to pick up the system during the disconnection period, so the system will be required to support all of the soft delinks around the base station surrounding the current base station. This point is illustrated in Figure 10. Tested in sector A₁The R-ACH soft disconnection example of the mobile station. In order to complete this disconnection, sector B₃And C₂May receive R-ACH, and sector B₂, C₃, D₁, E₁, A₂, A₃, D₃And E₂May receive sector A₁R-ACH. It is true that other cellular locations require a significant amount of additional demodulator, but it is quite possible that each sector has a demodulation zone or a subset thereof. Although so in order to achieve a complete effect, a considerable number of power cavity bits are needed for forward link. But pay attention to the sector at the same location, such as sector A.₂And A₃No additional power control bits are required. The reason is that the same set of hardware receives the R-ACH, so that a single power control bit value can be calculated based on the reception of the hive position. So in sector A₁The base station can indicate that the kit power control bit is also transmitted by other sectors, and the command is indicated to the communication management message along with the location of the power control bit. For example, consider the power control bitstream shown in Figures 11A, 11B, and 11C. Here specific R-ACH is used for sector A₁Position 1 power control bit in sector B₃Position 2 power control bit, and sector C₂The power control bit of position 4. It should be noted that these power control bits will arrive at the mobile station at different times and can be de-skewed. This point is different from the power control bit of the CDMA system traffic channel, which is reached by all base stations simultaneously to the mobile station.

Referring now to Figure 12, there is shown a flow chart of a method of soft disconnection of a proximity channel in accordance with the present invention. At step 1210, at least one power control bit from the first base station is transmitted to the mobile radio unit. The power control bit from the first base station is transmitted at a first time interval in the power control information packet, the time interval being corresponding to the interval associated with the first base station. At step 1220, at least one power control bit from the second base station is also sent to the mobile radio unit. The power control bits from the second base station are transmitted at different locations of the power control information packet at a second time interval, which corresponds to the same proximity channel of the first base station, but is associated with the second base station. The first power control packet is transmitted by the first base station and the second power control packet is transmitted by the second base station. In step 1230, the mobile radio unit receives the power control bit from the first base station of the power control information packet (as shown in FIG. 11A), and receives the power control bit from the second base station in the second power control information packet. Yuan (as shown in Figure 11B). At step 1240, the mobile station receives the skew of the bit via the release step 1230 to form a power control bit result.

The power control bit is handled in much the same way as described above. But there are a few differences. In the example where the mobile station detects whether the channel is transmitting, in a preferred embodiment, the mobile station must individually detect whether the power control bit is being transmitted in the separate power control flow. As mentioned above, this is done by looking at the bit order. If all base stations indicate that the mobile station is allowed to transmit (by the power control bit not transmitting an indication), the mobile station can enable its transmitter in the aforementioned method. In a preferred embodiment, the mobile station is required to check the power control flow separate from each base station. The reason is that a particular base station cannot receive the R-ACH transmission from the mobile station. For example, referring to Figure 10, the mobile station is approached by base station A.₂The hive center covered, so cannot be used by any other base station (eg B₃, C₂, B₂, C₃, D₁, E₁, A₂, A₃, D₃And E₂)receive. Similarly, when the mobile station is in the R-ACH transmission, the specific base station will not transmit the corresponding R-ACH bit, so that the mobile station cannot be combined and transmitted by the base station to the bit. It should be noted that the following test focus should be slightly different from the transmission of the IS-95 system on the traffic channel. In the IS-95 system, the mobile station does know the set of base stations that are transmitting R-ACH. In this case, however, the mobile station must detect if the message stream is being transmitted. Once the mobile station has de-skewed and determines the power control bit phase (and whether it is transmitting), the mobile station determines whether to increase or decrease its transmission power. This extends to the IS-95 method. If all base stations transmitting the power control bit indicate that the mobile station must increase its transmission power, the mobile station will increase its transmission power; if any base station transmitting the power control bit indicates that the mobile station must reduce the transmission power, Then the mobile station will reduce its transmission power. At step 1260, the message is sent by the mobile wireless unit during the disconnection. The message is received by the first and second base stations on the proximity channel.

<u>System details</u>

Referring now to Figure 13, there is shown a block diagram showing the components of an example mobile station 1300 for performing the fast proximity channel power control system of the present invention. The mobile station includes an antenna 1330 that is coupled to an analog receiver 1334 and a transmit power amplifier 1336 through a duplexer 1332. Antenna 1330 and duplexer 1332 are of a standard design and allow simultaneous reception and transmission through a single antenna. Antenna 1330 collects signals transmitted by one or more base stations to the mobile station and provides signals to analog receiver 1334 via duplexer 1332. Receiver 1334 is also provided with an analog to digital converter (not shown). Receiver 1334 receives the RF signal from duplexer 1332, amplifies the signal and downconverts the signal frequency, and provides a digitized output signal to digital data receivers 1340, 1342 and to search receiver 1344. It should be understood that although in the specific example of FIG. 13, only two digital data receivers are displayed, the low performance mobile station may have only a single digital data receiver, and the higher performance unit may have two or more digital data receivers. Allow for diverse reception. The outputs of the receivers 1340 and 1342 are supplied to the diversification and combiner circuit 1338. At this time, the data streams received from the receivers 1340 and 1342 are adjusted, the two data streams are added together and the result is decoded. The operation of the digital data receiver 1340, 1342 search receiver 1344 and the diversified combiner and decoder circuit 1348 is described in U.S. Patent No. 5,101,501, entitled "Method and Apparatus for Providing Communication Soft Disengagement in a CDMA Honeycomb Telephone System" The assignee of the present invention is hereby incorporated by reference.

The output signal is supplied to the control processor 1346 by the decoder 1348. In response to this output signal, control processor 1346 determines the value of power control bit 120 supplied to the mobile station by one or more base stations. Control processor 1346 uses the received power control bits in accordance with the present invention to enable, disable, and power control the signals of the R-ACHs. Thus responding to the received power control bit indicating that the mobile station is to increase power or down power (as described above), the control processor 1346 will signal the transmit power controller 1338 to command the controller 1338, for example by adding or subtracting 1 db. The output power level of the transmission amplifier 1336 is increased or decreased.

Referring now to Figure 14, there is shown a block diagram of components of an exemplary base station 1400 for performing the fast proximity channel power control system of the present invention. At the base station, two receiver systems are utilized, each with a separate antenna and analog receiver for diverse reception. In each receiver system, the signals are processed in the same way to the signal for a diverse combination process. The dashed internal components correspond to the corresponding components of the communication between the base station and the mobile station. Still referring to FIG. 14, the first receiver system is comprised of an antenna 1460, an analog receiver 1462, a search receiver 1464, and digital data receivers 1466 and 1468. The second receiver system includes an antenna 1470, an analog receiver 1472, a search receiver 1474, and a digital data receiver 1476. The hive position control processor 1478 is used for signal processing and control during disconnection. The two receiver system is coupled to a diversified combiner and decoder circuit 1480. The digital link 1482 is used to control the mobile telephone switching center (MTSO) communication signal under the control of the control processor 1478.

The signal received at antenna 1460 is supplied to analog receiver 1462, where the signal is amplified, the frequency is translated and digitized, and the processing is the same as described for the mobile station analog receiver. The output from analog receiver 1462 is supplied to digital data receivers 1466 and 1468 and search receiver 1464. The second receiver system (i.e., analog receiver 1472, search receiver 1474, and digital data receiver 1476) processes the received signals in a manner similar to the first receiver system. The outputs of the digital data receivers 1466, 1476 are supplied to a diversified combiner and decoder circuit 1480 which processes the signals in accordance with the Vilerbi algorithm. Details of the operation of the first and second receiver systems and the diversified combiner and decoder 1480 are described in U.S. Patent No. 5,101,501, entitled "Method and Apparatus for Providing Soft Disengagement of Communication in a CDMA Honeycomb Telephone System", and As mentioned before. The signal sent to the mobile unit is supplied to the transmission modulator 1484 under the control of the processor 1478. The transmission modulator 1484 modulates the data for transmission to the intended receiving mobile station. The data signals output by the transmission modulator 1484 also include power control information bits 120 that form the subject of the present invention.

While the foregoing specific examples are illustrative of R-ACH channels for CDMA mobile radio systems, those skilled in the art will appreciate that the teachings of the present invention can be applied to any type of mobile radiotelephone system having proximity channels that can be accessed by multiple users.

The foregoing description of the preferred embodiments is intended to enable any person skilled in the art to make or use the invention. Many modifications to these specific examples are apparent to those skilled in the art, and the generic principles defined herein may be applied to other specific examples without the need for innovation. The present invention is not intended to be limited to the methods and devices shown herein.

The features, objects and advantages of the present invention will be described in detail below with reference to the accompanying drawings.

Obviously, the similar reference symbols in the drawings indicate the corresponding elements in each figure.

Piece, in the drawing:

1 is a schematic diagram showing a bit stream structure formed from a plurality of power control information packets in accordance with the present invention.

2 is a timing diagram illustrating an example of receiving a channel from a mobile station using the power control information packet of the present invention.

3 is a timing diagram showing the interleaving of slots in a proximity channel with different offsets in accordance with the present invention.

Figure 4 is a schematic diagram showing the slot structure of a proximity channel having an idle interval in accordance with the present invention.

Figure 5 is a timing diagram showing a method of being able to be accessed by a mobile station to a proximity channel in accordance with the present invention.

6 is a timing diagram showing a plurality of interleaved proximity channel slots in accordance with the present invention, each time slot having an associated idle time interval for adjusting the slot of the proximity channel that is coupled to each of the interlaces.

7, 7A, 8 and 8A are system flow diagrams in accordance with the present invention for adjusting access to a proximity channel using one of three different states of power control.

9 is a flow diagram of a re-use power control bit system in accordance with the present invention.

Figure 10 is a schematic diagram showing several honeycombs of a cellular telephone system in accordance with the present invention, each of which is divided into a plurality of segments.

11A, 11B and 11C show a bit stream structure formed by a plurality of power control information packets in accordance with the present invention for transmission from a first base station to a connected proximity channel to a second base station.

Figure 12 is a flow diagram of a method for disconnecting a near-channel transmission from a first base station to a second base station in accordance with the present invention.

Figure 13 is a block diagram showing the components of an example mobile station for performing the fast proximity channel power control system of the present invention.

14 is a block diagram showing components of an exemplary base station for performing the fast proximity channel power control system of the present invention.