UA79233C2 - Wireless communication device for cdma communication systems - Google Patents

Abstract

A method and apparatus for call recovery in a wireless communication system (10). When the communication link between a mobile station (38) and a base station (32) is in trouble the mobile station and the infrastructure prearrange potential rescue base stations (34). The source cell base station contacts all recovery capable neghbors as potential rescuers. Each rescue base station is instructed to use a default channel for rescue transmissions. The rescue transmission is considered a call recovery operation. The mobile station establishes a soft hand-off with rescue base station wherein the FL uses the default channel and an alternate channel. Once hand-off is complete the rescue base station discontinues use of the default channel. In one embodiment the source cell base station provides the mobile station with the list of recovery-capable neighbors as overhead during transmissions and prior to development of the communication link problem.

Description

Description of the invention

The invention relates to wireless speech and data transmission. In particular, the present invention relates to a new and improved method and device for restoring a call in a wireless communication system.

A wireless communication system usually includes a plurality of base stations (BS) (B5), each of which is associated with a cell and/or sector that communicates with a plurality of mobile stations (MS) (M5). Base stations are controlled by a base station controller (BSC) (850). As the mobile station moves through the system, the quality of the signals received from the base stations fluctuates. When the communication line between the base station and the given mobile station 70 deteriorates, it is possible to prevent the loss of communication by establishing a communication line with at least one more base station. A handover process is provided to initiate such alternate line(s). In a handover situation, the infrastructure coordinates with various base stations and this mobile station. However, signal quality often degrades too quickly for such matching. 12 Therefore, there is a need for a method and apparatus for call recovery in various situations. In addition, there is a need for a reliable method of call recovery in a wireless communication system.

The disclosed implementation options offer a new and improved way of restoring calls in a wireless communication system. According to one aspect, a method in a wireless communication system with a plurality of base stations, each of which has a neighbor set containing neighboring base stations, and each of the neighboring base stations having a default channel, is to transmit channel information by default to the mobile station; detect an event that triggers call recovery; and command all base stations in the set of neighbors to transmit on the corresponding default channels.

In one aspect, the wireless device includes an antenna; processor connected to the antenna; the transmission circuit connected to the antenna and the processor; receiving circuit connected to the antenna and the processor; the first set of

Machine-readable commands executed by the processor to receive a list of neighbors of the base station, and Ge) this list includes the assignment of channels by default for each of the neighbors; a second set of machine-readable instructions executed by the processor to identify the event that triggers call recovery and block the transmission circuit in response; and a third set of machine-readable instructions, executed by the processor, to establish handover by at least one of the neighbors. at

According to another aspect, the wireless device includes a transmission circuit; control block with recovery, made with the possibility of functioning after the call recovery operation, for generating the specified power control command; and a power control unit connected to the power control unit and the transmission circuit, and the power control unit is configured to adjust the transmission circuit in response to a power control command. 3o According to yet another aspect, the computer program is embodied on a machine-readable medium containing machine-readable commands, and this program includes a first set of commands executed to identify a special event; a second set of commands executed to prevent call recovery during a special event; and a third set of commands executed to notify the wireless system of a "special event." C 70 Features, objects and advantages of the unfolding method and device will become clear from the detailed description set forth below, taken together with the drawings, in which the same reference points are indicated, respectively

From" throughout the description and on which:

Fig. 1 illustrates in the form of a block diagram a wireless communication system according to one of the implementation options;

Fig. 2 illustrates in the form of a block diagram part of the wireless communication system according to Fig. 1 according to one of the implementation options; 7 Fig. 3 illustrates in the form of a time diagram the signal quality of two base stations in the wireless system according to (se) Fig. 2 according to one of the implementation options;

Fig. A4 illustrates in the form of a block diagram a part of the wireless communication system of Fig. 1 during recovery where according to one of the implementation options; оз 20 Fig. 5 illustrates in the form of a time diagram the signal quality of two base stations in a wireless communication system according to one of the implementation options; c» Fig. bA and 6B illustrates in the form of a block diagram of the algorithm the method of restoring a call at the base station according to one of the implementation options;

Fig. 7A and 7B illustrate in the form of a block diagram of the algorithm a method of restoring a call at a mobile station 52 according to one of the implementation options;

GF) Fig. 8 illustrates in the form of a block diagram the levels of architecture in the system of Fig. 1 according to one of the implementation options;

Fig. 9 illustrates in the form of a time diagram the call recovery operation in the system of Fig. 1 according to one of the implementation options;

Fig. 10 illustrates in the form of a time diagram the initiation of the transmission power level in the mobile station 60 after call recovery according to one of the variants of the implementation of the invention;

Fig. 11 illustrates in the form of a block diagram the operation of a wireless device in the system of Fig. 1.

A method of restoring a call in a wireless communication system according to one embodiment provides information related to neighboring cells and/or sectors that are available and capable of restoring a call to a mobile station that is in a state of potential risk of losing a communication line. Each of the base stations, because it is capable of restoring a call, has a direct channel by default for restoring a call, identified by a given code. In another implementation option, one neighbor is assigned more than one direct channel by default for call recovery, and the mobile station uses a hash function with MIMS (international identification of mobile stations) (IM5I), ChMShS (temporary international identification of mobile stations)

MPM5I), ESN (Electronic Serial Number) (ESN), system time, or a combination thereof to specifically decide which channels to use to receive transmissions from each base station capable of resuming the call. The mobile station then uses this channel to receive signals from the restoring base station. The mobile station may be instructed to combine power control subchannels from a plurality of neighboring recovery base stations by service messages when the mobile station addresses 7/0 to the base station. It can also occur when a mobile station moves into the coverage area of a base station while the mobile station is in an idle state (standby state), i.e. without permanent communication lines, by traffic channel messages at call initiation or handover , when the active set changes for the mobile station.

Fig. 1 illustrates a wireless communication system 10, which has a plurality of cells 12, 14, 16, 18, 20, 22, 24.

Cells 12, 14, 16, 18, 20, 22, 24 communicate with CBS 26 through the ether radio interface. Each of the cells 12, 14, 16, 18, 20, 22, 24 has a corresponding set of neighbors composed of cells in the geographical neighborhood and/or the transmission neighborhood. For example, cell 18 has a set of neighbors that includes cells 12, 14, 16, 20, 22, 24. In spread-spectrum transmission systems, such as a code-division multiple access (CDMA) system (CDMA) defined by the standard "Compatibility standard of mobile station - base station

PA/EIA/Z-95 for dual-mode broadband cellular system with extended spectrum", hereinafter referred to as "I5-95 standard". or "TIA/EIAL5-95 standards for MDKR2000 systems with extended spectrum", hereinafter referred to as " standard SOMA20O00", spread-spectrum signals occupy the same channel frequency band, and each signal has its own distinct pseudo-noise (PS) (PM) sequence. The operation of the MDKR system is described in US patent 4901307, entitled "Multiple Access Communication System with extended spectrum, which uses satellite or terrestrial repeaters", as well as 5103459, entitled "System and method of generating oscillations in a cellular telephone system MDKR"), the rights to which belong to i) the applicant of this patent application and which are specifically included in this description by link.At the same time, multiple users transmit messages simultaneously in the same frequency channel band.

Fig. 2 illustrates a part of the system 10 of Fig. 1, which includes a base station 32, marked BS1, which communicates with MS 38. BS1 is located in cell 18 of Fig. 1. The other two base stations 34, 36, marked as

BS2 and BSZ, respectively, are located in cells 16, 24, respectively. The ether radio interface provides i) an environment for a direct line of communication (PLZ) (RI) for transmissions from BS1 32 to MS 38, and a return line of communication (ZLI) from M 38 to BSI1 32. Note that MO 38 can move in system 10 so that the quality of the signal to BS1 32 and from it deteriorates. To initiate a call, MS 38 sends transmissions over the access channel. BS1 32, BS2 34 and BSZ Me z5 36 send channel assignment messages via the paging channel. The channel assignment identifies the number of Walsh codes for each base station.

The quality of signals is generally measured as the signal-to-noise ratio (SNR) (SNR) and can be expressed as the energy of the pilot signal per elementary signal to the total received power density (Е со).

Figure 3 illustrates a graph of the signal quality measured on the MS 38 for BS1 32 and BS2 34. The signal quality for BS2 34 begins to increase at time Y and continues to increase above the threshold level noted as P.Y. DOD, with s after moment 1. Threshold level P DOD ensures the quality of the reference signal, above which MC 38 is given a command to inform the base station about the need to add the base station to its active set (AN) with (AB). AN consists of base stations that actively communicate with MS 38 both for transmission and reception. AN is usually selected from the base stations that are in the candidate set (KN) (C5). KN includes base stations that are candidates for establishing an active connection with MS 38. KN is usually selected from -I base station in the set of neighbors (NS) (M).

In Fig.3, while the quality of the signal from BS2 34 improves, the quality of the signal from BS1 32 decreases. ise) The increase in the energy level of signals received from BS2 34 is added to the degradation of signals from BS1 32, since the quality of signals for a given base station is a comparison of the signal energy from this base station with all other available signals. At the moment of PI MS 38 measures the signal energy from BS2 34, which exceeds P DOD. This o indicates to the mobile station 38 that appropriate action is required, i.e. it is a case of initiating a transfer 4) service. At time 2, MS 38 transmits to BS1 32 and KBS 26 a pilot signal level measurement message (PVRP) (RZBMM), which contains measurement information for both BSI1 32 and BS2 34. At time IZ, KBS 26 establishes a communication line from KBS 26 to BS2 34 and for MS 38. KBS 26 has a selector. BS 26 establishes a "return" link between BS1 32, BS2 34, and BS 26 for MS 38. At time (4), BS1 32 sends a Direction of Service (DSP) message (DOM) that contains information identifying BS1 32 and BS2 34 and theirs

F) linked indicators of codes for direct communication channels (PLZ) from BS1 32 and BS2 34. This information allows MS 38 to receive and demodulate signals from BS1 32 and BS2 34. At moment 5, MS 38 receives PNP from BSI1 32 and begins to demodulate signals from BS2 34 in addition to signals from BS1 32. In this example, there is only one base station involved in handover. However, there may be any number of base stations involved in such a handover situation, and these base stations communicating with MC 38 form the AN. When the MS 38 receives signals containing symbols from a plurality of base stations in the AN, the MS 38 can combine these signals to obtain a stronger signal. The merging process is called "soft merging" of PLZ and it is usually performed when combining in the optimal ratio, ie with b5 weighting, based on signal quality. At time 16, the MS 38 sends a message to the PNP received from the BS1 32, or a Handover Completion (Handover Completion) message, indicating a successful completion of the handover.

In Fig. 3, a situation may arise when the quality of the signal from BS2 34 increases too quickly. In this case, the BS2 34 signal strength relative to the BS1 32 signal level contributes to a decrease in the quality of the BS1 32 signal. MS Z38 is held by the infrastructure from making a connection to receiving information necessary for service transmission, such as pseudorandom noise (PSN) shift (RM), required to identify BS2 34 or a channel using BS2 34 for MS 38.

In the normal process of handover of MDKR service, when a mobile station from the service area of one base station to the service area of another base station moves from the coverage area of one base 7/o station, the handover avoids the loss of the communication line. In one type of handover, namely soft handover, a mobile station simultaneously maintains a connection with two or more base stations. The current location of the mobile stations can be considered as the starting (starting) cell, while the next cell to which the mobile station moves can be called the ending cell.

A mobile station uses a comb-type receiver (rake receiver) to demodulate a plurality of signals received by the PLZ from a plurality of base stations. The two signals are combined and give a composite signal of increased quality. Although each of the plurality of base stations participating in the soft handover demodulates the received signal separately, each sends the demodulated and decoded information to the CBS. CBS has a selector that selects the best frame among the many received. For a variety of conditions and system requirements, other types of service transfer can be used.

When transferring service using a mobile station (PODM) (MANO), the mobile station measures the signal quality for the PLZ pilot signals from a number of mobile stations. This information is sent to the originating base station. Signal qualities are compared for different thresholds to decide whether to add base stations to the AN. If the signal quality of the specified pilot signal exceeds the threshold of P DOD detection of the pilot signal, then this pilot signal is added to the AN. In another embodiment, the pilot signal can first be added to the KN and then to the AN. In fact, this threshold allows the state of the base station to be transferred from one set to another.

Call recovery provides information to the mobile station in advance if handover coordination i) is not possible. Call recovery is triggered by various situations. In normal operation, the mobile station and the base station use trigger events to determine their respective operations. For example, the mobile station of the system 10 uses a plurality of thresholds to make a decision based on which information is transmitted back to the base station. One threshold already mentioned above, P DOD, indicates the quality of the signal for adding a base station to AN. When a mobile station receives a signal that is measured above i)

P DOD, this mobile station moves this base station to the KN, searches for this base station more often and reports these conditions to the system through its corresponding AN. Another threshold P OFF provides the signal quality level below which the base station will be removed from the AN. When the mobile station receives a signal about which Me is measured

Зb Below P. OFF for a time longer than P. TUKYL, the mobile station reports these conditions to the system via M existing AN. In each case, the base stations in the AN transmit this information to the base station controller.

To restore the call to the base station, the AN looks at any of a plurality of possible triggering events.

The first type of cases that trigger call recovery occurs when the PLZ3 signal quality is below a threshold level for a longer period of time than for another threshold. This type of triggering event includes “

WHAT When a base station receives continuous power control (POC) requests from a mobile station to increase the transmission rate at the base station. Often, the base station already transmits to the mobile station at . the maximum level of the limit power. For example, the transmission of PLZ traffic is maintained at a high level during a given time interval. A mobile station can send multiple power-up requests, i.e. HIGHER commands. Alternatively, the mobile station may report excess erasures. Erasure occurs when a greater number than the threshold level of bits is received without confidence in their assigned value. Otherwise, the mobile station transmits messages informing the base station that its outer loop settings are high or have been at these levels for a longer period of time. and, A second type of triggering case recovery occurs when some response is expected from the mobile station, but no response is received or another response is received. This type of triggering event

Includes no acknowledgment from the mobile station to a message sent by the base station that requires an acknowledgment. This message may be sent a specified number of times before the triggering event condition is satisfied. This number can be fixed or variable or variable over the air. Similarly, the base station may receive repeated ZLZ3 messages from the mobile station that require confirmation, and these messages were received after the confirmation was transmitted by the base station.

The third type of triggering cases refers to the low quality of the reverse line of communication, for example, when

Ф) the frequency of personnel errors (ChKP) (REK) in ZLZ exceeds the threshold level. Alternatively, ZLZ3 can be maintained at a high level for a given time interval. But another situation can have a high installation of ZLZ. The base station to be added to the AN also has call recovery triggering events that initiate the recovery action. The most important trigger case is a message from the CBS about the presence of potential problems related to the task of mobile stations. In this case, the base station starts searching for signals from this mobile station.

The mobile station may also use various call recovery triggering events to enter call recovery. The first type of triggering event occurs when the received signals have an abnormal number of errors. For example, the erosion of the PLZ on a moving window can exceed a given threshold level. In one embodiment, this threshold level is 12 consecutive frames that undergo erasure. In such a case, the mobile station can turn off the transmitting part of the mobile station and turn it on again when at least two consecutive PLZ frames have no erasures.

The second type of trigger recovery case for a mobile station occurs when the mobile station receives power control commands from the base station instructing it to increase power. The base station may have difficulties in receiving the signals from the mobile station due to significant losses in the path from the mobile station.

A third type of triggering recovery case occurs when one or more ZLU messages that require acknowledgment from the base station are not acknowledged. This is called an event that triggers a retransmission attempt. Similarly, there may be an incorrect response or no response from the base station to the mobile station's message. A similar type of triggering event occurs when receiving repeated PLZ messages that require confirmation immediately after the actual transmission of this confirmation from the mobile station.

A fourth type of trigger recovery case occurs when the mobile station transmits at a high level for a given time interval. At the same time, it is assumed that the ZLZ does not reach the base station with sufficient energy.

In one embodiment, flexible thresholds are implemented for one or more different instances that trigger call recovery. These triggering call recovery cases can be based on multiple transmission attempts in the system 10. These attempts are often performed at the level of communication lines between the signaling and the physical communication line. The level of communication lines is called level 2 and it is considered below in relation to Fig.8. In recovery-capable systems, such as system 10 of FIG. 1 , the MS 38 performs a recovery procedure to maintain the call when a communication line, such as the PLZ, deteriorates. A trigger event often initiates a recovery operation, with this trigger event indicating when a parameter or metric crosses a threshold. These thresholds can be dynamic, adapted to the conditions of the system 10 and the environment. In the same way, the thresholds can be adjusted based on the history or statistical record of the functioning of the system 10. sch

In one embodiment, the number of retransmissions on the ZLZ or the time between erasures that follow each other, or the shutdown of the transmitter in the MS 38 may occur in response to a command transmitted from the infrastructure of the system 10, such as the BS 32 and/or the CBS 26. In an alternative embodiment, a fixed parameter is defined for a particular action, for example, the maximum number of retransmissions allowed. In another embodiment, the condition and/or location of the mobile station sets the triggering event. Proximity of co

The MS 38 can initiate call recovery from the current transmission level up to the specified maximum value. Other triggering cases include PL quality as measured by gear wears in the current AN, lack of internal loop power control, preferably for MC 38 ZSSh different from that provided by the internal loop, etc. Other implementation options may combine a specific parameter and conditions of the mobile station as a triggering event. Me

System infrastructure 10 may provide MC 38 with operational type information that is useful in determining M thresholds for triggering case recovery and may use such information to select fixed parameters provided to MC 38 to use as trigger case thresholds. In one embodiment, a typical number of call retries that are challenged or dropped.

An alternative version of the execution uses the loading of the ZLZ to set and adjust the thresholds "

Alternative embodiments may use the location of the MC 38 in the system 10, such as sector c of a given cell. Other implementations consider the day of the week and/or time of day compatible with known mobile traffic patterns. A combination of any of these mechanisms can be used if necessary. ;" In the system 10 according to Fig. 1 and 2, each BS 32, 34, 36 transmits additional service information to mobile stations with which it communicates. This additional service information for each BS 32, 34, 36 includes its corresponding list of neighbors. This list of neighbors identifies the corresponding shifts of the pseudorandom noise (PSN)-I code of the neighbors.

In Fig.A4, the CBS 26 responds to any of a plurality of triggering events by establishing a reverse delivery connection with BS1 32 and BS2 34. According to one embodiment, call recovery method 100 is initiated, as illustrated in Fig.b . A specific graph of signal quality for one example is illustrated in Fig.5. In this example, there is time to identify MS 38 as having a potential problem. o In the call recovery method 100 of one embodiment shown in Fig.bA and 6B, in operation 102 4) BS1 32 sends to the MS 38 the assignment of default channels for a set of neighboring base stations. The base stations in the set are reproducible units having the necessary software and/or hardware, and have a coverage area(s) that overlaps the area of the base station sending the set of neighbors. The default channel assignment identifies the default channel code indicator used by the base stations in the neighbor set, including the code for BS2 34. Each of the base stations in

F) the set of neighbors capable of restoration has an extended code by default, which will be used to identify the mobile station that needs to restore the call. This extended code, in one embodiment, is a specific Walsh code. BS2 34 during operation 104 sends to MS 38 a case that triggers retransmission attempts. This case, which triggers a retry attempt, dictates the number of retries that are allowed for

Me 38 before initiating call recovery operations. After that, BS1 32 determines in the resolution diamond 106 whether a recovery-triggering event has occurred. If the recovery triggering event has not occurred, processing waits for the triggering event to occur. When the triggering case of another case appears, the processing continues at operation 108 to issue a command to all base stations in the NS for BS1 32 to transmit on their channels on b5 the default corresponding to MS 38. Note that some of the base stations in the NS may not be capable to establish a communication line due to the weakness of the PLZ or ZLZ, however, each emergency base station starts transmitting to MO 38. Multiple transmitters provide stronger PLZ signals to MS 38 and more reliable ZLZ to KBS 26.

It should be noted that according to this version of execution, the number of attempts to transmit a message to the ZLZ3 or the amount of time allowed for successive erasures are determined in the KBS 26 and sent to the MS 38 through messages and broadcasts on dedicated radio lines. An alternative embodiment uses a fixed parameter that is different from the other parameters.

One embodiment includes a mobile conditions feature. Mobile conditions may take into account how close the actual transmission level of the MS 38 is to the maximum transmission level. Similarly, another mobile condition takes into account the quality of the ZLZ, such as attrition in the current AN. Another mobile condition takes into account the 70 intra-loop deficit. This in-loop deficit is the difference between the specified VSS and the VSS provided by the in-loop power control. Another embodiment combines the mobile condition with the transfer type.

The allowable number of attempts can be adjusted according to the statistics of lost calls or calls with difficulties. For example, there may be an average number of attempts above which most hard calls do not recover. Other considerations include the payload of the missile, the location of the MC 38, and/or the time of day or date. In the latter case, some mobile traffic patterns affect the number of mobile stations requiring fast call recovery.

Returning to Fig.bA, the CBS 26 determines the current AN for the mobile stations in operation 110. After that

The CBS 26 initiates the PNP timer in operation 112 and transmits the PNP in operation 114. At this point, the system 10 wishes to transfer the communication lines from the default channels. These channels by default are available for use by any of the mobile stations of the system 10 and therefore their use should be optimized. Since MS 38 uses a given channel by default, this channel is not available for use by another base station.

Base stations in NS are instructed to initiate transmissions on an alternative or new channel in parallel with transmissions on the default channel. This is the initiation of the terms of service transfer. high school

If the CBS 26 in the resolution diamond 118 has received a message from the MS 38 indicating that the handover is complete, processing continues at operation 120 to disconnect the communication lines of the MS 38 with i) members of the NS on the default channels. Processing then continues at operation 124. In contrast, if the handover completion message has not been received, the CBS 26 checks in resolution diamond 118 whether the PNP timer has expired. If so, the corresponding default channel terminates transmission to MS 38, the call recovery is canceled in operation 124, and use of both the default channel and the new channel is terminated in operation 125. Operation 126 resumes normal operation. If the timer has not worked in the solving rhombus 118, processing returns to waiting for a message about the completion of communication transmission from the MS 38 in the solving rhombus 118.

Fig. 6B details a part of the method 100, which illustrates the operation 110 as the initiation of the timer in the operation Me

130. The CBS 26 checks the PVRP in resolution diamond 132. If the PVRP is accepted, processing is performed at M operation 134 to set the AN to include neighbors that were included in the PVRP. If the PVRP is not accepted, processing continues in resolution diamond 138 to determine if the timer (initiated by operation 130) has expired. If yes, processing continues in solving diamond 144. If not, processing returns to solving diamond 132.

After the AN is established in operation 134, if the ZLZ is to be improved in the solving diamond with s 136, the KBS 26 determines if there are any neighbors not included in the PVRP that have received the signal(s) of the MS 38 in the solution "jazuval rhombus 140. These neighbors are called listening neighbors (SS) and they are added to AN at ;" operation 142. Then processing returns to operation 112 of Fig. bA.

If the timer has run out and the PVRP was not accepted, the KBS 26 determines in the solving diamond 144

The presence of neighbors who received the MS 38 signal(s), i.e. SS. In this case, AN is established during operation 146 -I to include these SS. If no CCs are found in the resolving diamond 144, call recovery is terminated at operation 148 and the call is terminated. and, In the resolving diamond 110, the method determines whether the transmitter of the MC 38 was turned on. If it is turned off, the CBS 26 commands the MC 38 to turn on the transmitter during the software operation.

The method 200 of restoring a call to a mobile station for one embodiment is illustrated in Fig.7. During operation 202, MC 38 communicates with AN(0) base stations. This identifies the current AN. If 4) a recovery-triggering event occurred in resolver diamond 204, processing continues at resolver diamond 208. The recovery-triggering event may be one of those discussed above, or an alternative indication that MC 38 needs a crash recovery type operation, ie MC 38, maybe ov Loses the PLZ communication line. If no triggering event occurs, normal operation continues at operation 206. Resolution diamond 208 determines whether transmitter operation is permitted in MC 38.

F) If transmitter operation is permitted, processing continues at step 214, if not, MC 38 checks the triggering event condition in resolution diamond 210. If the triggering event condition is present, this indicates that MC 38 should prohibit (block) transmitter operation, then at operation 212 the appropriate actions are performed and processing continues at operation 214. The absence of a triggering event indicates that transmitter operation should be prohibited, then processing continues at operation 214. At operation 214 a wait timer is set.

This wait timer is checked in resolution block 216, and a recovery timer expiration is initiated at step 218. If the wait timer has not expired, processing continues in resolution block 222 to determine whether MC 38 has returned to normal operation. Normal 65 operation continues from operation 206, otherwise processing returns to waiting or transitions back to waiting for the wait timer to expire.

Next in Fig. 7, from operation 218, if the transmitter in MS 38 is blocked, operation 220 unlocks the transmitter. The MS 38 transmits a given header during the time interval U. This header provides information about the transmission of the MS 38, but not the actual data or symbols. In the resolution diamond 228, if the PVRP is accepted or if some message confirming the PVRP is received, the MS 38 goes to wait for a given time interval X, after which the AN is updated. If neither PNP nor PVSP was accepted in resolution diamond 230, processing continues in resolution diamond 232 to verify that the PVRP has not been transmitted more than the maximum number of times allowed. If the PVRP can be transmitted again, that is, this maximum has not been reached, processing returns to operation 228 and the PVRP is transmitted again. However, 7/0 if the maximum has been reached, processing continues at operation 236 and call recovery is terminated.

According to the alternative method of call restoration, the CBS 26 informs all neighbors capable of restoration

BS1 32 about a potential problem. The CBS 26 commands the MC 38 to turn on the transmitting part of the MC 38 and commands the base station(s) in the neighbor set to listen to the MC 38. When a signal from the MC 38 is detected or requested, each base station in the neighbor set transmits a report. Reports are received from a subset of base stations, /5 and this subset may include all base stations in a set of neighbors or a portion of base stations.

The CBS 26 informs the MS 38 about the default channels of each base station in this sub-set. Base stations then use an acceptable default channel to initiate communication with MS 38.

According to yet another method, a subset of the set of neighbors is determined based on the most recently transmitted

PVRP The problem is that the last transmitted PVR may be taken incorrectly, and in this case the PVR used to identify the subset is incorrect. As an example, when the last received PVRP identifies BSI1 32 and BSZ 36, and MO 38 sent the next PVRP identifying BSP1 32 and BSP2 34, which was not accepted, call recovery is aborted. KBS 26 is establishing a return delivery network with

BOZ 36, and BSZ 36 starts transmitting to MS 38 on the default channel. But MS 38 believes that the connection will be established with BS2 34 to restore the call, and prepares to disconnect on another channel by default. high school

Excess transmission from BSZ 36 is wasted and effectively creates additional noise in system 10.

When the call recovery is initiated by the MC 38, a timer can be used to delay this initiation i) after the event that triggers the call recovery. The time period for this timer can be set by KBS 26.

After this timer has expired, MS 38 transmits the ZLZ3 pilot signal in the header on the channel. This header includes the call recovery message. In one embodiment, the header is a predetermined constant that can be set by the base station controller 26. In an alternative implementation, the header has a variable length that is determined by the system operator. After the transfer of the header, MS 38 sends a message regarding the change(s) of PLZ3. This message can be a message of measuring the level of the pilot signal (PVRP). This message can be sent several times for reliable reception by the second BS2 base station 34. Me

Combinations of the above methods provide different advantages for call recovery. In one embodiment M, the call recovery method is based on the radio transmission environment of the base station of the originating cell.

When the number of neighbors capable of restoring the call is small, for example 2, the KOS 26 instructs all neighbors to transmit on their respective default channels. AN is updated and the MC 38 transmitter is unlocked without delay. For larger sets of neighbors that are capable of resuming the call, the CBS 26 instructs the neighbors to "listen for signals from the MS 38. After the delay spent waiting for the neighbors to report whether they can receive signals from the MS 38 from c, those that hear the neighbors, give the command to use the default channels. In the same way, if the PVRP is received from MS 38 in a given time interval, the base stations identified by the PVRP are commanded to use the default channels.

Note that when the PLZ works properly, which is determined by a fixed number of consecutive frames,

Power control (CP) commands sent through the CP subchannel are considered valid. - And Fig. 8 illustrates the architecture of the wireless communication system 10 of Fig. 1 in the format of a structure of levels.

The architecture 700 includes three layers: a signaling layer 702, a link layer 704, and a physical layer 706. And, the signaling layer 702 provides upper-layer signaling 708, data transmission services 710, and voice transmission services 712. The signaling layer 702 provides voice, packet data, simple circuit data, and simultaneous voice and packet data services. Protocols and services are provided at this level, which corresponds to the two lower levels. The level 704 of the communication line is divided into the sub-level 714 of the access control to 4) the communication line (KDL) (GAS) and the sub-level 716 of the control of access to the environment (KDS). Applications and protocols of the signaling layer 712 use the services provided by the KDL layer 714. The communication line layer 704 serves as an interface between the upper layer protocols and applications of the signaling layer 702 and the physical layer 706. The sublayer 716 of the CDS includes a multiplexing and quality of service (QoS) unit 722. The communication line level 704 connects the signaling level 702 with the physical level 706. The physical level 706 is formed by the physical (F. transmission channel 724. Fig. 9 contains a clocking scenario for the operation of the system 10 of Fig. 1 according to one of the implementation options .

Reference is made to the methods in Fig. bA, 6B, 7. The horizontal axis corresponds to time, the vertical axis - different transmission channels. The base station of the source cell BS1 32 is shown in the middle, and the information is transmitted to the MC 38 through the traffic channel. Two channels are illustrated for the MS 38: the Thx transmission channel and the Xx reception channel. Two scenarios are shown for the reception channel: EX. and Kho. The neighboring base station, which is the final base station, is also shown. BS2 34. Both the default channel and the new channel are shown. The new channel is a channel to be used for communication with MS 38 after handover. Processing begins with 65 Me z8 receiving transmissions from the first AN identified as AN(O). MC 38 simultaneously transmits on the traffic channel to BS1 32 the source cell. At the moment of WE, an event occurs that triggers the recovery of the call. And BS1 32 and

MO 38 recognize this triggering event. Note that the triggering event may be a general event, such as continuous KP requests from MS 38 to BST1 32 to increase transmission power in the PLZ, or may be separate events for MS 38 and BS1 32. In addition, MS 38 and BS1 32 may not recognize the trigger

The case at the same time. Often, the MC 38 may be in a position to recognize a triggering event to the BS1 32 during PLD failures.

When the triggering case is identified at time 1, the KVS 26 BS1 initiates the transmission from the neighboring BS2 34 of the default channel. At moment (2 BS2 34 starts transmitting in the default channel to MS 38. This transmission is carried out in parallel with the same transmission from BS1 32. When a triggering event occurs, MS 38 70 blocks the transmitter for a given waiting time interval. At moment IZ the waiting interval ends and MS 38 transmits the header during time slot Y. At the same time, the AN in MS 38 changes from AN(O) to AN(1). The base stations identified in AN(1) are all base stations listed in the last PSRP. In the alternative in the execution variant AN(1) can also be a set with all neighbors for BST1 32 and BS1 32 itself.

At moment (4), the header ends and MS 38 starts transmitting the current PVRP. In response to receiving PVRP /5 At moment B, BSI 32 and BS2 34 transmit PNP at moment 6. PNP signals the change of AN to AN(2) at moment 18.

It should be noted that the next PVRP is transmitted at the moment y7, and the PVRP is transmitted periodically to identify the signals received by the MS 38.

At time 8, BS2 34 begins transmission on a new channel for MS 38. MS 38 transmits a PNP that triggers termination of transmissions for MS 38 on the default channel at time (U. In one embodiment, PNP 2o is transmitted periodically or continuously until until their correct reception is confirmed by the base station. In the scenario illustrated in Fig.9, call recovery starts at time 2 and ends at time (9. At time (9), the handover ends and BS2 34 is the current base station of the source cell for the MS 38.

An alternative scenario is illustrated for the receiving channel Kh". Here AN(0O) remains active until the end of Moment 15. After moment 5, MS 38 continues to receive from AN(O) during the given time interval X, after which a change to AN(1) occurs. This provides additional time for the base station side to determine i) a subset of capable call recovery neighbors BST1 32 to transmit to MS 38 for recovery. At moment i8, the following change occurs in response to PNP from AN(1) to AN(2). This scenario corresponds to the way in which only those neighbors that are able to receive signals from the MS 38 are given the command to transmit through the corresponding channels sozo by default.

Upon completion of call restoration and completion of service handover, MS 38 shall determine the initial transmission power level. According to one embodiment, the system 10 of FIG. 1 uses a closed loop power control (feedback system) to adjust transmission power levels. Alternative execution options can use an additional method of open b"

From the power control loop (system without feedback). Open loop refers to operation M controlled by the transmitter (or mobile or base station) when the receiver is not directly involved.

For example, specific open-loop power control refers to the mobile station to adjust the transmission power of the reverse link based on the power level of signals received from the base station on the forward link. Closed-loop power control "extends open-loop operation, as a result of which the receiver actively participates in decision-making about 7s power regulation. For example, in order to control the power of the closed circuit of the ZLZ, the base station compares the power level of signals received from a given mobile station with a threshold value. Then the basic ;" the station commands the mobile station to increase or decrease the transmission power of the reverse link based on this comparison. On the contrary, the mobile station monitors the power level of the signals received on the PLZ, 1 provides feedback on the quality of the PLZ for the base station. Closed-loop operation is used -And to compensate for power fluctuations associated with a dead-out, for example, a Relay dead-out, of a given communication line. and, Immediately after the wait timer expires and before power control is established, the 38 ko MC starts transmitting at the initial power level. The transmission power level of the ZLZ3 can be reset from 5p of that which occurred before the blocking of the transmitter MC 38. The power level can remain at this initial level until the closed loop power control is resumed. 4) In an alternative embodiment, the power level is initiated at the last level before the transmitter is blocked and then gradually increased at a given rate until closed-loop power control is resumed. The rate of increase is usually set by BS1 32 and/or BS2 34 and can be constant or variable. These increases continue until power control is restored in the closed circuit of the LZ.

F) Another embodiment initiates open-loop control recovery based on the total received ka power in the frequency band. This procedure is similar to the access procedure in I5-95 and I5-2000. This can be adjusted for a plurality of forward link base stations visible on MS 38. Open-loop control continues until closed-loop power control resumes. Fig. 1o illustrates power regulation according to this embodiment. The horizontal axis represents time, and the vertical axis represents the transmission power level. At the first moment of MI, the transmission power has an initial level. After the first time interval, at the moment Y2, the transmission power is increased by the specified increment value. This amount of increment can be fixed or it can be variable, increasing or decreasing with increasing b5 time. In one embodiment, the amount of increment is adaptive and depends on the conditions in the system 10, and the amount of increment can increase or decrease from one time interval to the next time interval. Finally, a given maximum transmission power level can be reached after a given number of time slots. The transmit power is then at the limit value pending the recovery of the closed-loop power control.

In yet another embodiment, the initial transmission power is based on the quality of the received pilot signals. The quality of the signals is measured by the ratio E Lo of the pilot signal or the value of Es of the pilot signal for the designated AN. When controlling the power in an open circuit, the transmission power usually has a ratio given as: 70 Tx t Sv) as, (1) where K is constant, T is the transmission energy of the HLZ, and K is the received energy of the HLZ3. For the closed-loop power control method, the transmission power usually has a relationship given by:

Х т (Х я К ку, (2) where у(0 is a cumulative correction variable based on all valid power control commands received up to the moment ( Expression (K ж у()) is denoted as Д. In an alternative form, the following relation is valid :

Tk i kh "Kk x U, (3)

The initial transmission power determination applies the p value of the previous transmissions to the new transmissions.

The new power level is calculated when: p

Х(9 - ХХ and Хx(0) - BEH), (4) where ХХ(0) is the transmission energy before the call is restored, К (0) is the received energy before the call is restored. In this case, the transmission power is adjusted according to the previous ratio of the transmission power level to the reception power level. co

An MS 38 with a wireless device operating in the system 10 of FIG. 1 , such as a cellular phone or a personal digital assistant (PDA) (PSA), is illustrated in FIG. 11 . MS 38 includes an antenna 300 for reception and transmission. The antenna 300 is connected to the duplexer 302 to isolate the receiving path from the He transmission path. The duplexer is connected to the receiving circuit 308, which forms the receiving path, and to the amplifier 304 and the transmission circuit, which forms the transmission path. The amplifier 304 is additionally connected to the power control unit 310, which provides control of the amplifier 304. The amplifier 304 receives transmission signals from the transmission circuit 306.

Received signals through the antenna Z0O0 enter the power control unit 314, which implements the power control scheme in a closed loop. The power control unit 314 is connected to the communication bus 318. This communication bus 318 provides a common connection between the modules in the MC 38. The communication bus 318 is also connected to the memory 322 and the recovery control unit 316. The memory 322 stores machine-readable commands for various operations and functions of the MC 38. The processor 320 executes the commands stored in the memory 322. Under normal operating conditions, the power control unit generates a CP signal for the power control unit 310 via a multiplexer 312. The power control unit 310 then transfers the KP signal as a gain level to the amplifier 304.

When resuming a call, the MS 38 may block the transmitter. When the transmitter is unlocked, the service transmission completion signal is applied to the recovery control unit 316. This service completion signal instructs the recovery control unit 316 to generate the specified KP signal. The KP signal generated in this way can implement any of the schemes for the co-generation of the initial transmission power of the ZLZ discussed above, or can implement an alternative method. Signal c 50 completion of service transfer is also provided to multiplexer 312. After the call is restored, the signal

KP. generated by the recovery control unit 316 is sent to the power control unit 310. syu" In parallel, power control in a closed circuit begins. When the closed-loop power control is fully restored, the end-of-service signal is canceled and the multiplexer 312 selects the CP signal generated by the power control unit 314 to be applied to the power control unit 310 . The operation of the recovery control unit 316 can be performed by the microprocessor 320, operating according to program commands, or can be implemented in hardware for efficient and reliable operation. o In one implementation option, specific operations of MS 38 or BS1 32 are considered as special events. These special events include a variety of conditions and procedures that can cause triggering events to occur.

In other words, special events can create a situation where the event that triggers call recovery 60 occurs, but the call is not suppressed. One special event is finding a mobile station location locator. MC 38 receives a command to conduct a search on an alternative frequency of the global positioning system (GPS) signal (35P). The HSP provides the location of MC 38 or partial location information of MC 38. The mobile station location locator search is carried out periodically or aperiodically. Of course, MC 38 has a priori information regarding the timing of such searches. Other events may include searching for candidate frequencies 65 in preparation for inter-frequency hardware handover, where the mobile station tunes to a different frequency to search for a signal from base stations on other frequencies.

Other events may include actions of MC 38 at a time when the triggering event should be ignored. In such cases, MS 38 informs BSI1 32 of the source cell about a special event. In one embodiment, the special event is to search for a candidate frequency, whereby the MS 38 tunes to another frequency to view signals from neighboring base stations on that frequency. This provides better handover between coverages on different frequencies, for example, switching between a personal communications system (PSC) frequency (POS) and a cellular frequency. When this type of special event, initiated by the mobile station, MS

C8 informs BS1 32 of the source cell to ignore triggering events relative to MS 38 during a specific time interval or until further notice. 70 According to one embodiment, to eliminate such false starts during special events, the base station of the source cell, such as BS1 32, authorizes the event and informs the MS 38 of the timing of the event, including at least when the event should start , and the length of time allocated for this event.

MO 38 and base stations in its AN are prohibited from initiating call recovery trigger(s) during a special event.

In an alternative version of implementation, MS 38 notifies BSI1 32 about the occurrence of a special event or a set of 7/5 THESE special events. In response to this notification, BSIT 32 may authorize a special event or reschedule the event. Again, this provides MS 38 and the base stations in its AN with sufficient information to block call recovery starts during a special event.

So, a new and improved method of maintaining communication in a wireless communication system was proposed. When the communication line between the mobile station and the corresponding base station of the original cell is broken, the mobile station and the infrastructure pre-establish potential base stations for emergency recovery. The base station of the originating cell contacts all call-recovery neighbors as potential failover stations. A neighbor capable of restoring a call has a given channel by default, made with the possibility of soft handover of service with a mobile station. This default channel is used only temporarily during the initial part of the handover. Each s g5 disaster recovery base station is commanded to use the default channel for disaster recovery transmissions. A call recovery operation is considered an emergency recovery transfer. The mobile i) station establishes a soft handover with the emergency recovery base station, while the PLZ uses the default channel. The failover base station then initiates transmissions on the alternate channel. When the handover is completed, the failover base station stops using the default channel for transmissions to the mobile station. In one embodiment, the base station of the source cell provides the mobile station with a list of callable neighbors as spares during transmissions and before the communication line problem is resolved. In this case, and for situations in which the PLZ is lost before receiving the handover information, the mobile station has enough information to perform the handover. Me

In an alternative implementation, more than one M channel is assigned to BS2 34 neighbors by default. The use of multiple default or failover channels increases the call recovery capability of the system 10. Each neighbor is then able to contribute to the call recovery by more than one mobile station, such as the MS 38. In operation, prior to call recovery, BS1 32 of the originating cell provides BS2 34 identifier corresponding to the set of channels associated with BS2 34. MS 38 and BS2 34 "

Each store a deterministic function, such as a hash function, to map identifiers to a specific c channel. Using a hash function. in particular, is a pseudorandom procedure. In addition to this, MS 38 is assigned an electronic serial number. The electronic serial number can be stored in MS 38 or it can;" to be provided to MS 38 when resuming the call. When the call is restored, the BSI1 32 of the originating cell provides the electronic serial number of the MS 38 to the BS2 34. The BS2 34 and the MS 38 both apply a given function to calculate the acceptable default channel. -And a hash function for a data structure allows you to recognize a keyword in a set of words with just one access to the data structure. A hash function maps its argument to a result of a given type. and, Hash function with deterministic and does not have its own state. That is, the return value depends only on the argument, and the same arguments give the same results. For a hash function, it is important to minimize collisions, where a collision is defined as two different arguments hashing to the same value. It is also important that the distribution of hash values is uniform; that is, the probability that a hash function will return some particular value of a given type should be approximately the same as the probability that it will return any other value. In alternative implementations, other types of cryptographic functions can be implemented to identify a set of channels by default for call recovery.

By way of example, various illustrative logic blocks, modules, circuits, and algorithm operations described in connection with the embodiments disclosed herein may be embodied and executed by a digital signal processor (DSP).

F) (O5P), application specialized integrated circuit (PSIC) (ABIS), user programmable logic matrix (PCLM) (ERSA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components such as, for example, registers and elements with a request-and-arrive service algorithm (RIPO), a processor executing a set of hardware and software instructions, any programmable software module and processor, or any combination thereof, designed to perform the functions described herein. Program modules can be in memory

RAM, flash memory, PZP memory, SPPZP memory, ESPPZHT memory, hard disk registers, removable disk,

PPZPP-KD (SO-KOM) or in any other type of storage medium known from the prior art. Processor b5 May be in PSIS (not shown). The PSIS may be in the phone (not shown). Alternatively, the processor may reside in the phone. The processor can be embodied in a combination of a CPU and a microprocessor or as two microprocessors together with a CPU core, etc.

The foregoing description of preferred embodiments is intended to enable one skilled in the art to make or use the present invention. Various modifications of these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be applied to other embodiments without the use of inventive step. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (2)

The formula of the invention 1. A wireless communication device for the SOMA communication system, which contains a transmission circuit, a power control unit connected to the transmission circuit, and the power control unit is made with the possibility of adjusting the gain level of the transmission circuit, and a power control unit in a closed loop , which is characterized by the fact that it contains a multiplexer and a call recovery control unit, and the signal from the output of the power control unit in the closed loop reaches the power control unit through the multiplexer after canceling the end of service signal, which controls the multiplexer also connected to the control unit recovery of a call designed to generate a given power control command and performed with the possibility of functioning upon receipt of a signal of completion of service transfer. 2. Device according to claim 1, characterized in that the specified power control command is based on the transmission power level sch before the call is restored. o (ze) (ze) s (o) and - - I.Y and? -i se) ime) (95) syu» ime) 60 b5