JP2006157956A - Temporary equipment identifier message notifying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a scanning operation of a radio subscriber station for controlling power consumption and for prolonging the lifetime of a battery to supply the power to the radio subscriber. <P>SOLUTION: Energy consumption of the radio subscriber station, to be operated in a cellular digital packet data (CDPD), is reduced by eliminating an operation to decode front direction error correction (FEC) block (69). Decoding of the FEC block is eliminated, by using a temporary equipment identifier (TEI) of start and finish, such that Hamming distances from all other TEI messages (62) are minimum. Base error rate (BER) is measured for deciding the time requiring the decoding of the FEC block. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  This application is a continuation-in-part of US patent application serial number 08 / 533,152 filed on September 25, 1995.

  The present invention generally relates to wireless communication devices. Specifically, the present invention relates to controlling the scanning operation of a wireless subscriber station to limit power consumption and extend the life of a battery that supplies power to the wireless subscriber station.

  Recent analog cellular systems for mobile radio duplex voice transmission, called “Advanced Mobile Phone Service” (AMPS), use a carrier frequency with an FCC assigned in the range of 800 MHz to 900 MHz. Automotive cellular units transmit voice signals to cellular base stations in a given cell with power up to 1 watt. A battery-powered portable cellular unit transmits audio signals to a cellular base station in a given cell with a transmission power of up to a quarter watt.

  Analog human speech was originally a signal designed for the AMPS system to communicate. AMPS has been optimized to carry as many analog voice signals as possible over a given bandwidth channel. Cellular phones with low power mobile units, FM modulation, and higher carrier frequencies (800 MHz to 900 MHz) are achieved by the base station cell configuration, in this case when the user moves outside the current cell area. The user's signal is passed to the next cell site. This signal passing between cells can cause a temporary loss in transmission or reception. The user knows that the voice information can be retransmitted when there is signal loss, so the temporary loss of the voice signal is not significant, while the signal loss is temporary Even that causes problems unique to digital data transmission. Other sources of loss of voice signal transmission include signal strength degradation, reflection, Rayleigh fading, and cell dead spots.

  When a portable computer becomes available, there is naturally a desire to wirelessly transmit digital data from a remote location. Currently, AMPS voice cellular systems are used to transmit digital data in the form of circuit switched cellular data over an AMPS carrier channel. Raw (baseband) digital data must be converted so that it can be sent and received via an analog AMPS system. One disadvantage of data transmission using the AMPS system is that the baud rate of digital data transmission / reception is limited because the channel bandwidth is narrow and there is a transmission error. Again, loss of raw digital data may occur due to other causes in the AMPS mobile cellular system.

  Therefore, it is difficult to perform efficient wireless communication of voice and data signals in the integrated package. In addition, AMPS voice transmission features can be incorporated into applications such as data transmission, e-mail, and dual paging, and circuit-switched cellular data interfaces such as wireless fax modems in one portable wireless unit that operates on a battery. It was difficult to be able to provide it. Some of these are disclosed in commonly assigned US patent application serial numbers 08 / 117,913 (filed September 8, 1993) and 08 / 152,005 (filed November 12, 1993). Has been achieved using the cellular digital packet data (CDPD) system described in the CDPD specification Version 1.1. In this specification, this CDPD specification Version 1.1 is incorporated by reference as a background material. The CDPD communication system shares the same carrier frequency as the carrier frequency assigned to the AMPS channel described in Part 405 of the CDPD specification Version 1.1 (in this specification, the CDPD specification is incorporated by reference).

  A typical base unit or mobile database station (MDBS 1 shown in FIG. 1) of the CDPD system uses a channel in the AMPS cell to establish a link with the user's wireless subscriber station for communication. The MDBS may also use other frequencies outside the AMPS that are made available to the MDBS by the service provider. A wireless subscriber station (M-ES2) is a portable computer, handset, or other portable electronic device that includes a subscriber communication station. The MDBS is from a user of the wireless subscriber station M-ES2 and from a line, microwave link, satellite link, AMPS cellular link, or other link (such as mobile data intermediate system MD-IS3 and intermediate systems 4, 5, 6). Serving as a communication link to and from one service provider's network, transferring data to another wireless subscriber station, computer network, or non-mobile or fixed end-user system (F-ES 7, 8).

  CDPD networks are designed to operate as extensions of existing communication networks such as AMPS networks and Internet networks. From the mobile subscriber side, the CDPD network is simply a wireless mobile extension of the traditional network. The CDPD network shares the transmission facilities of the existing AMPS network and provides a non-intrusive packet switching data service that does not affect the AMPS service. In practice, CDPD networks are completely transparent to AMPS networks that “do not know” CDPD functionality.

  The CDPD system uses a connectionless network service (CLNS) in which the network routes each data packet individually based on the destination address in the packet and knowledge of the current network topology. Since data transmission from M-ES2 has the property of packetizing data, many CDPD users can share a common channel, access that channel only when there is data to send, otherwise Make the channel available to other CDPD users. Due to the multi-access nature of this system, a single CDPD station can be installed in a given sector (standard AMPS base station transceiver transmission range and area) to provide substantial CDPD coverage to many users simultaneously. It becomes possible.

  The air link interface part of the CDPD network consists of a set of cells. A cell is defined by a geographical boundary within an RF transmission range from a fixed transmission site such as MDBS1 that a mobile subscriber such as M-ES2 can receive with an acceptable level of signal strength. A transmitter that supports a cell may be placed centrally within the cell. In this case, transmission takes place via an omnidirectional antenna. Alternatively, the transmitter may be located at the edge of the cell. In this case, transmission is performed through a directional antenna so as to cover only a part of a cell called a sector. In a typical configuration, transmitters for several sectors are co-located. Serviced by a set of cells so that a moving wireless subscriber station can maintain continuous service by switching from one cell to a neighboring cell in a manner similar to the standard delivery of AMPS systems. Some areas overlap. If continuous service can be maintained by switching from one cell to the other, these two cells are considered adjacent. This switching process is called cell transition and is performed independently of the normal AMPS delivery procedure.

  In FIG. 1, an interface (A) between the wireless subscriber station 2 and the MDBS 1 is an “air interface” configured by a radio frequency link using a standard AMPS frequency. The MDBS 1 is connected to other mobile database stations through a mobile data intermediate system (MD-IS) 3. Many mobile database stations can be under the control of one mobile data intermediate system. Mobile data intermediate systems are interconnected by intermediate systems such as intermediate systems 4 and 5 of FIG.

  The intermediate system is configured by at least one node connected to one or more sub-networks (such as intermediate system MD-IS3). The main role of the intermediate system is to transfer data from one subnetwork to another. Mobile data MD-IS3 routes data packets under the control of MD-IS based on the knowledge of the current location of each wireless subscriber station within range of the mobile database station. MD-IS is the only network entity that “knows” the location of all wireless subscriber stations. However, under certain circumstances (as defined in the CDPD specification Version 1.1), a particular mobile database station always tracks the operation of a particular wireless subscriber station. The Mobile Network Location Protocol (MNLP) for CDPD operates between MD-IS (via an intermediate system) to exchange location information about wireless subscriber stations.

  The entire CDPD network is controlled by a network management system (NMS) 10 having an interface with at least one mobile data intermediate system 3. Using a special protocol, programming instructions can be sent from NMS 10 via MD-IS3 to any number of mobile database stations under appropriate conditions.

  Such programming instructions can be used to communicate useful network data to the MDBS and configure the operation of the MDBS with respect to important features such as channel queue maintenance. The NMS also controls other features of the CDPD system, such as the timing of paging messages, to match the non-pause period of the M-ES handset. One advantage of CDPD is that operational instructions to the mobile database station can be sent from the NMS 10 via MD-IS3 or directly with the MDBS as described in the description of the MDBS architecture in CDPD specifications Version 1.1, Part 402 and 403. That can be given by connection.

  FIG. 2 shows a comparison between the CDPD network of FIG. 1 and a standard AMPS network. MDBS1 is equivalent to AMPS base station 21 and is intended for CDPD. Both of these serve as links to mobile users 2, 2 'and 2 "for CDPD systems and as links to 22, 22', 22" for AMPS users. Both AMPS and CDPD functions can be handled by the same handset or end system device. Further, as will be described in detail below, the MDBS 1 is preferably arranged with the AMPS base station 21.

  MD-IS3 serves as a local controller for the CDPD mobile database station and is a mobile telephone switching center (MTSO) 23 used to control a plurality of AMPS base stations 21, 21 ', 21 ". In an AMPS system, the MTSO 23 can be connected by communication links to various base stations 21, 21 ', 21 "via a dedicated land line or public switched telephone network (PSTN). Similarly, the connection between MD-IS 3 and the various mobile database stations 1, 1 ′, 1 ″ controlled thereby is made in the same manner, except for the signal transmission protocol that is different from the signal transmission protocol found in AMPS systems. A transmission protocol is used.

  Compared to AMPS, CDPD has very few infrastructure requirements. The CDPD base station device is preferably located at the cellular site of a cellular carrier having an existing AMPS base station cellular device. Due to the multiple access nature of this system, a single CDPD radio can be installed in a given sector to provide substantial CDPD coverage to many users simultaneously. This multiple access is achieved by the mobile end system accessing the CDPD channel only when there is data to send.

  The AMPS base station and the MDBS can use the same RF device if they are both located at the same location. In contrast, the AMPS system MTSO and the CDPD system MD-IS need not be co-located to share the RF link. In the AMPS system, the MTSO 23 is responsible for connecting the AMPS base station and the mobile station to another party via the PSTN 24. The CDPD intermediate system 4 corresponds to the use of PSTN by the AMPS system. Like the AMPS system, the CDPD system must use a public switched telephone network or another landline network that accomplishes calls to remote parties or systems via the telephone system terminal network 28. However, the CDPD system uses a protocol that is different from the protocol used by the AMPS system to achieve a call over the PSTN.

  The MDBS maintains a number of channel streams (within the transmission capability of the MDBS) via the air link interface in response to an instruction by the MD-IS that controls the MDBS. The MDBS instructs all wireless subscriber stations to change channels when needed, such as when AMPS communications are detected on the CDPD channel. Each terminal stream of the wireless subscriber station is carried in one channel stream at a time and is usually selected by the mobile subscriber based on data received from the MDBS, preferably regarding the optimal channel for CDPD usage. Forward and reverse traffic (MDBS terminal stream) on a given cell is carried on one signaling DS0 trunk between MDBS and MD-IS. Communication between MDBS and MD-IS via the DS0 trunk follows a standard format such as T1.

  Within a CDPD network, digital data is transmitted between MDBS and M-ES using Gaussian Minimum Shift Keying (GMSK) modulation. Transmission from the base station to the wireless subscriber station M-ES is continuous. Transmission from the wireless subscriber station M-ES to the MDBS uses a burst mode. The burst mode is a mode in which the wireless subscriber station M-ES accesses a channel not used by another mobile wireless subscriber station only when there is data to be sent. This allows a large number of mobile radio subscriber stations to share a channel and, in the case of data transmissions characterized by intermittent transactions of relatively small amounts of data, via conventional circuit-switched cellular modems. Compared to sending digital data, the connection time is significantly reduced.

  Unlike the signal transmission mechanism used in conventional cellular modems, chosen based on the need to operate within the constraints of existing voice signal transmission systems, the GMSK modulation technique used for CDPD communications is apparent In addition, it has been selected to obtain a very high bit transmission rate and excellent error performance in the cellular channel. Since the choice of modulation was not limited by the pre-existing signal structure, the CDPD system can achieve substantially higher instantaneous bit rates at very low received signal levels compared to conventional cellular modems. Become. This means that the CDPD communication system provides reliable high speed data transmission in many areas where signal quality is insufficient for good cellular modem performance. A network connection such that raw (baseband) digital data currently transferred via CDPD can be transferred as if it were an email message, digital fax data, or file is currently connected to a local area network Including other digital data.

  The mobile data intermediate system MD-IS3 handles the routing of packets for all wireless subscriber stations visiting the service area. MD-IS provides two services. That is, a registration service that maintains the information base of each M-ES currently registered at the specific location where the service is provided, and a readdressing service that decapsulates the forwarded packet and routes it to the correct cell. is there. The serving MD-IS also manages authentication, authorization, and billing services for application of network support services.

  The CDPD communication system is separate from the pool of cellular voice channels and can operate using a dedicated channel reserved for use with CDPD. In an alternative, in a more typical mode of operation, the CDPD communication system can use idle time in a channel that can also be used by AMPS communication. In this second case, the mobile database station determines “RF sniffing” to determine which channels are available and to detect the start of voice traffic on the channels currently used for CDPD communications. Can be performed. When an AMPS cellular unit starts transmitting on a channel occupied by CDPD communications, the CDPD unit stops transmitting to that channel and switches to another available channel (a process called “channel hopping”). If no other channel is available, the CDPD unit ceases transmission until the channel becomes available for use of CDPD.

  Although the CDPD system shares existing AMPS radio frequency channels, AMPS calls have the highest priority and can occupy the right to use channels used by CDPD. However, the cellular service provider may choose to dedicate one or more channels for use with CDPD. In this case, the AMPS call does not attempt to occupy a channel dedicated to the use of CDPD.

  In normal operation, MDBS performs channel hopping to prevent the channel from being used for AMPS communications. To do this, the MDBS performs AMPS channel monitoring activities and maintains a list of status (voice occupied or not used) for each channel available for CDPD usage in the cell. The MDBS selects a channel for CDPD usage from the unused channels in the list based on a combination of criteria (not specifically indicated in the CDPD standard). This criterion can cause the voice system in the near future to require a channel, the amount of interference present in the channel, the CDPD communication may cause other voice users in different cells, other sectors, or other factors. Consideration such as a certain amount of interference may be included. The MDBS sends a list of all available channels (whether or not currently occupied by voice communications) to the wireless subscriber station for use of CDPD. If the MDBS determines that another channel is more appropriate, the MDBS may perform a channel hop before the AMPS communication occupies the channel. In such a case, the MDBS sends a message to the wireless subscriber stations and instructs these wireless subscriber stations to change to a particular selected channel. The MDBS then performs a hop. This type of hop is much more orderly and efficient than an unplanned hop because the wireless subscriber station does not have to search for the next channel.

  When the AMPS communication occupies the current CDPD channel, the MDBS selects another channel from those not used by the AMBS communication and moves to that channel without informing the wireless subscriber station (unplanned hop). The wireless subscriber station determines that there is no CDPD signal on the current channel, searches other channels from the list, and determines any channel that CDPD communication has hopped on.

  The CDPD system has the ability to easily interface with existing AMPS systems and share some front-end device with this AMPS system. In order to take advantage of this capability, the MDBS must have the ability to physically interface with existing AMPS base stations. Therefore, the MDBS must be small, discreet and easily accessible without interrupting existing AMPS devices. The MDBS must be configured so that it can be easily connected to devices outside the MDBS that are normally shared with the AMPS system. The external devices found in AMPS base stations include antenna systems, RF power amplifiers (especially linear amplifiers that can be shared with existing AMPS), RF multicouplers, power splitters, duplexers, and optical devices. Since MDBS shares the environment of an AMPS base station, MDBS should not constitute a substantial additional burden on support systems such as environmental control and maintenance. Therefore, the MDBS must be compact and flexible and must only comprise the elements necessary to perform the necessary MDBS functions at the cell site.

  FIG. 3 is a block diagram of the portable communication terminal handset 100. In most respects, this portable communication terminal is similar to a conventional portable radiotelephone handset having a radiofrequency module 102 with at least one radiofrequency transceiver. The radio frequency transceiver uses the main antenna 104 for transmission and reception of various types of signals handled by portable terminals, such as AMPS data (circuit switched cellular data) communication, AMPS voice communication, and CDPD communication. Diversity antenna 106 is used as a backup to maintain reception under certain adverse conditions. To facilitate AMPS voice communication, a telephone type handset 112 is used.

  The portable terminal can also be temporarily connected to the local public switched telephone network (PSTN) by a digital-analog access interface (DAA) connected to the radio control processor 108. This processor, along with the control processor / modem 109, shares various control functions of the portable terminal, such as call setup, high level protocol, low level protocol, power regulation, modem operation, and data transfer with external host computer. To do. For ease of use by the subscriber, the host computer can be a personal computer (PC) or personal digital assistant (PDA), or other electronic device. The connection hardware of the portable terminal is a standard type that is usually used together with a PC external connector.

  The portable data terminal handset and wireless subscriber station shown in FIG. 3 can be configured to allow all of the modes of operation of FIG. 4 as described in US patent application serial number 08/117/913. . The mode shown as 200 in FIG. 4 represents menu mode selection by the operator or programmer of the portable data terminal handset. The operator can select either of two modes (AMPS or CDPD) using the handset keypad. If data is input to the portable terminal (handset) 100 by the host computer, the selected mode or predetermined default settings can be selected as part of the data transfer.

  Preferably, the system is normally in a low power sleep mode. This sleep or hibernation mode minimizes power consumption. Normally, the sleep mode is interrupted every 10 to 255 seconds in order to check for the presence of a message such as an incoming paging signal. If no message is received, the CDPD mode remains idle. CDPD may be activated upon receipt of a command from a host computer or handset user instructing to receive a paging signal or to initiate data transfer in CCPD mode. The advantage of maintaining the CDPD mode is that the battery burden is light, so according to current battery technology, the call time at maximum transmission power exceeds 1 hour and the waiting time while monitoring the AMPS control channel exceeds 12 hours That is.

  A sleep mode procedure is used to put the handset into sleep mode. The sleep mode is defined as the optimum mode of operation that can be requested by the wireless subscriber station M-ES during the data link establishment procedure (communication between the wireless subscriber station and the mobile data intermediate system). The sleep mode is intended to help a strategy for power saving in the wireless subscriber station. The general operation of the sleep mode allows the M-ES to disable its receiver and associated circuitry or reduce power supply. This mode is a key advantage of CDPD operation.

  The sleep mode procedure operates in the “multiframe established state”. In this operation, after the period specified by the parameter T203 has elapsed, if no frame is exchanged in the data link connection between a particular wireless subscriber station M-ES and the MDBS, the data link connection A temporary device identifier (TEI) sleep state may be placed. While in this state, the entire network does not attempt to send information destined for that M-ES. After entering the sleep state, when the new frame still exists and is waiting for the first transmission, the network sends a predetermined message at periodic intervals. This message contains a list of TEIs for which channel data is pending. The wireless subscriber station is expected to leave the sleep state (awake state) at periodic intervals, and upon exiting the sleep state, it determines if data from the wireless subscriber station is pending and Inform the network that you want to receive data. Normally, the M-ES can exit the sleep state at any time.

  Parameter T203 is the maximum time allowed in the absence of frame exchange on the data link connection prior to the time when the M-ES is expected to enter the CDPD sleep mode. On the user / subscriber (M-ES) side, when any type of data link layer frame is transmitted on the reverse channel (M-ES to MDBS), timing of parameter T203 is started or resumed. On the network side, when a (some type of) data link layer frame is received on the CDPD channel, timing of parameter T203 is started or resumed for a particular M-ES. When the value of the parameter T203 ends, the data link entity enters the TEI sleep state and issues an instruction of this state from the user side. The layer management entity may take action to save power, such as by disabling the subscriber radio receiver or other non-essential parts of its circuitry.

  The second parameter T204 represents a time interval at which the network side sends a TEI notification of pending data for a sleeping M-ES. For one channel stream, one timing operation with respect to the parameter T204 is maintained, and all user-side management entities discover a particular channel stream T204 by the TEI notification procedure described in § 6.8.8, Part 403 of the CDPD specification. Synchronize with it. The number of frames that are queued at the maximum time that the network attempts to notify the T-sleep M-ES depends on the implementation. The network releases the data link connection and discards all the queued frames involved in aborting the TEI sleep notification procedure. The maximum number of attempts to notify a TEI sleep M-ES of pending network transmissions is a specified system parameter 204. The network normally suspends the TEI sleep notification procedure for TEIs included in the number represented as parameter N204 of consecutive TEI notification messages without a response from the M-ES. Therefore, the M-ES is deregistered in the CDPD system.

  A complete description of the above operation can be found in §6.8, Part 403 of the CDPD specification. The parallel operation of M-ES and MD-IS is shown in the flowchart of FIG. Both units recognize when the last CDPD communication at the M-ES by a particular subscriber was. In this regard, the M-ES and MD-IS can be synchronized with each other. As shown in step 702, both units always use the internal clock to keep track of the elapsed time since the most recent CDPD communication between M-ES and MD-IS. In operation according to the above part of the CDPD specification, if no data is sent over the air link for a certain amount of time (parameter T203), the M-ES sleeps as shown in step 703. Entering mode, the network assumes that the M-ES is in the sleep state. Once the M-ES enters sleep mode, another timekeeping operation is performed in the M-ES and MD-IS.

  As previously mentioned, the total length of this period is defined by the product of parameters T204 and N204. If the network has data to send to an M-ES that it believes to be sleeping, the network will send a TEI for that M-ES to the sleeping unit in a particular channel stream, and Add to the list of units that have data waiting for them. However, the network does not send the data (step 704). For each time frame measured by parameter T204, the network sends a TEI indication for a particular wireless subscriber station M-ES, indicating that there is data waiting for that wireless subscriber station. Therefore, a wireless subscriber station must monitor the CDPD channel at any time during the time frame specified in T204 to determine whether a message is waiting for that wireless subscriber station. Don't be.

  A list of wireless subscriber stations with waiting messages is periodically sent to all stations in the channel stream in TEI notification messages. The time interval for such notification is defined by parameter T204. This parameter is the length of time that the M-ES is expected to be asleep before it awakes and receives the message. When the M-ES enters the awake state, the M-ES waits until receiving a notification message. If the TEI of the M-ES is in the list, the M-ES informs the network that data can be received. If a particular M-ES's TEI is not in the list, the M-ES will typically go back to sleep for the additional time specified by parameter T204. When the target M-ES does not indicate that data can be received and notification of a continuous number (specified by the parameter N204) is made for the TEI, as shown in step 705, the network Assuming the M-ES is not in the CDPD system, discard the data that was pending for the M-ES.

  If a particular M-ES continues to handle normal AMPS communication for a time longer than that contained in the product of parameter N204 and parameter T204, the network discards the data held for that M-ES. As a result, CDPD communication is lost due to normal operation of AMPS communication. Thus, the subscriber station M-ES must remain in the CDPD channel for long enough to monitor for that TEI. This inevitably leads to a further time awake state, resulting in further battery consumption.

  Since AMPS mode operation is recognized as being preferred over CDPD mode operation, the handset preferably spends most of its time to monitor the presence or absence of AMPS communication and in CDPD mode, the wireless subscriber Only enough time is spent to pick up the message instructions for the station and prevent deregistration. One mode of operating the wireless subscriber station M-ES includes periodically leaving the AMPS mode and polling the CDPD network while maintaining the AMPS mode to monitor the AMPS control channel. When the wireless subscriber station M-ES exits the AMPS mode, it sends a polling signal to the CDPD network, prompts for a response, and determines whether the CDPD network has data waiting to be transmitted to that wireless subscriber station. After paying attention to whether there is no return message from the CDPD network for an appropriate time after response (usually T203), the wireless subscriber station switches mode and returns to the AMPS channel. Preferably, this switching occurs before the associated AMPS page that may have been missed while the wireless subscriber station was in CDPD mode is retransmitted.

  Performing the operations described above will inevitably require the wireless subscriber station to maintain a relatively high power state in order to receive the messages described above. Therefore, the power consumption of the wireless subscriber station is considerably increased and the battery life is shortened. This is an important factor in the operation of the wireless subscriber station.

  To overcome this drawback, the wireless subscriber station has no temporary equipment identifier (TEI), or other transmitted from MD-IS or MDBS to control the operation of the wireless subscriber station. The time to pay attention to whether there is a control message needs to be minimized.

  One important factor that contributes to the time a wireless subscriber station must maintain a high power state in order to receive a TEI message is the predictability of the time at which the TEI signal is sent (on the wireless subscriber station side). ). As a result, wireless subscriber stations are forced to waste time and power during long communication cycles in order to wait for transmission of TEI signals. This is also true for other necessary control signals. The timing of the TEI signal is regular and can be predicted by the Mobile Data Link Protocol (MDLP) layer described in Part 403 of the Cellular Digital Packet Data Specification Version 1.1, but such predictability depends on the cellular digital packet data. It is not converted to the medium access control (MAC) layer described in Part 402 of the specification. This is important because it is the MAC layer that ultimately controls the timing between the MDBS and the wireless subscriber station.

  Examples of factors contributing to this uncertainty include the following.

(I) propagation delay through the processing element;
(Ii) queuing delay in the return network (write delay), and (iii) queuing delay in the base station.
Although these factors cannot be evaluated directly, experience with the CDPD system shows that these delays cause an uncertainty of about ± 3 seconds. Thus, a wireless subscriber station can receive approximately 60 blocks or frames of message flow time (one block is approximately 50 milliseconds) and the three blocks required to process the appropriate TEI notification when it appears. Must be awake for hours. This is a substantial time of operation of the wireless device, and is particularly important considering that when an appropriate TEI notification appears, it only takes 3 frames to process it. Thus, in conventional operation, the time that must be in the high power awake mode is about 2100% (63/3 × 100) of the time actually required.

  Another problem in conventional use of CCPD systems is that further monitoring by the wireless subscriber station is required for the reception of control messages other than TEI messages. Examples of control messages include the following.

(I) a channel configuration message that gives information necessary to perform cell transition by channels used in neighboring cells;
(Ii) timing information, parameters for control of the MAC layer, and other identification parameters for channeling use by the subscriber,
(Iii) channel access parameters (iv) a switching channel message used to control the subscriber to switch to another channel, and (v) an alternative service provider that informs the subscriber of other service providers that may be available. message.

  Normally, these messages are distributed at quasi-regular intervals and suffer a queuing delay at the MDLP level. There is also internal propagation delay in MDBS. This additional monitoring time of the wireless subscriber station is required because these messages are required to gain access to the network when the mobile wireless subscriber station enters a new cell. Therefore, the wireless subscriber station must keep paying attention until it receives all the above control messages. Typically, the time required is about 5 seconds to about 10 seconds. Thus, the time spent monitoring the presence or absence of these control messages is the time required to receive and process the control messages (typically a few blocks, one block being about 50 milliseconds). Much longer than.

  In order to extend the battery life of a mobile radio subscriber station, the time that the radio subscriber station must monitor the CDPD channel to receive TEI and other necessary control messages needs to be substantially reduced. . However, there is a major problem in that all the above control messages are necessary for the operation of the wireless subscriber station in the CDPD mode.

  Another power consumption source is the decoding operation of the forward error correction (FEC) block. As in the case of digital systems, CDPD communication error correction is required. The basic transmission unit to the CDPD channel stream is an error control block having a fixed length of 278 bits. The transmission includes an integer number of blocks interleaved with various control flags and sync words as described in detail in the forward channel formatting and reverse channel formatting sections of the CDPD specification. Composed of bursts.

  Each block is encoded using the systematic Reed-Solomon error correcting code (CDPD specification Version 1.1 § 4.31, extracted from FIGS. 402 to 404 of Part 402) shown in FIG. This encoding is performed based on the (63, 47) Reed-Solomon code generated in the Galois field GF (64). Codewords are based on 6-bit symbols. The information field consists of 47 6-bit symbols (bidirectional 2 bits), and the generated parity field consists of 16 6-bit symbols. Thus, 282 bits are encoded into a 378 bit block. This (63, 47) Reed-Solomon encoding is common to both forward and reverse channels of CDPD communications. In normal CDPD, a considerable amount of time and energy is consumed to encode the FEC block.

The first advantage of the BRIEF SUMMARY OF THE INVENTION The present invention uses the predictive power of the transmission time of the control message is to further reduce the power consumption of CDPD subscriber station.

  Another advantage of the present invention is that wireless subscriber stations operating in a CDPD system are reduced in time to monitor the CDPD channel.

  Another advantage of the present invention is that the reliability of control message monitoring is improved.

  Yet another advantage of the present invention is that time and energy are prevented from being consumed in decoding the FEC block.

  The above and other advantages of the present invention are achieved in a wireless communication system by a method of operating a wireless subscriber station to limit power consumption of the wireless subscriber station. The wireless communication system includes at least one base station for transmitting a communication stream of message blocks to a plurality of wireless subscriber stations. The method includes monitoring the communication stream for the presence of a temporary device identifier (TEI) message block that includes a TEI message and a plurality of forward error correction (FEC) bits. The method further includes determining a base error rate (BER). The method further includes decoding the FEC bits only when the BER is above a predetermined level.

  A second aspect of the present invention includes a method for performing communication between a base station and a plurality of wireless subscriber stations in a wireless communication system. The base station controls a stream of message blocks including a plurality of TEI messages corresponding to each of the plurality of subscriber stations. The method includes arranging all TEI messages in successive groups, starting a group of TEI messages with a unique TEI message, and ending the group of TEI messages with a second unique TEI message. Include. The unique TEI message differs from all other TEI messages by at least 6 characters.

Detailed Description of the Preferred Embodiment FIG. 6 is a time flow diagram illustrating an arrangement of message blocks that facilitates increasing battery life through reduced power usage according to the present invention. As with most CDPD control functions, the timing array shown in FIG. 6 is generated by MD-IS using the Mobile Data Link Protocol (MDLP) shown in CDPD Specification Version 1.1, Part 403. As mentioned above, operation and time adjustment at the MDLP level is not possible to achieve acceptable reliability due to variations at the medium access control (MAC) level (described in CDPD specification Version 1.1, Part 402). Is appropriate. Therefore, this approach is overcome using the approach described below.

  The present invention applies to the two-way paging variant of the CDPD system and its prior art. The bi-directional paging variant is essentially the same as a standard CDPD system, but there are numerous variants to allow bi-directional paging as described below. The CDPD bi-directional paging variant can share channels with AMPS communications, as in standard CDPD systems. However, bi-directional paging variants are not limited to AMPS channel sharing and can be used on dedicated channels outside the AMPS band range.

  In the operation of the bidirectional paging variant, the subscriber station must obtain a channel identification message before the subscriber station can initiate a registration procedure that is normally performed as specified in Part 407 of the CDPD specification. This is done by a subscriber station that performs indefinite time monitoring. In addition, the subscriber station must acquire a channel identification message after the cell transition as done in normal CDPD operation. This acquisition preferably ends in time for the subscriber station to take action to prevent MD-IS (3 in FIG. 1) from starting retransmissions in the old channel stream using MDLP.

  Further, at the time of initial acquisition, the subscriber station acquires to the RF network and cell using the channel identification message because the channel identification message includes the epoch or segment length for the current epoch. The definition of the epoch structure must be given. Normally, the transmission of the TEI notification message is started from the first data holding block of the forward channel time slot with the end of the TEI notification message timing counter (indicated by N210). Cell configuration, cell access parameters, and alternate identifier messages are all sent in this order immediately after sending each TEI notification message. If necessary, the base station (MDBS1 in FIG. 1) may send a number of cell configuration messages before sending the channel access parameters and the alternative service identifier message. If a switching channel message is required, it is sent immediately after the TEI notification message and before the cell configuration message. Arranging TEI and other control messages in this manner facilitates one aspect of the present invention as described below.

  The timing arrangement of FIG. 6 enables highly reliable timing even if the queue and timing of the MAC layer vary. This is accomplished by allowing the MAC layer and wireless subscriber stations to predict the location of TEI and other control messages within the overall message flow. In order to obtain such predictability, the communication message flow needs to be divided into a number of segments 60 as shown in FIG. Each epoch has a reference block 61 that identifies the start of the epoch. Thus, the message flow is divided into a series of epochs, such as 60, each epoch starting with a reference block 61, 61 ', 61 ", .... Preferably, each epoch is established with a fixed number of blocks. As described below, the duration of an epoch must be an integer number of Reed-Solomon blocks (Reed-Solomon blocks specified in the CDPD specification), based on traffic levels and other requirements for the system. Can be coordinated by the CDPD system provider.

  Normally, the MAC layer does not read MDLP entity messages. Thus, according to the present invention, a standard is established that the MAC layer recognizes as defining a reference frame 61 for all epochs 60 of N message blocks. The location of each reference frame is selected to match an external time standard such as the Global Positioning System (GPS), although other timing standards can be used. After a wireless subscriber station enters awake mode to this timing standard and receives a TEI message and other necessary control messages, it immediately enters sleep mode if no TEI message directed to that wireless subscriber station is found. It is important to go back.

  Timing information that the wireless subscriber station conforms to the standard is communicated to the wireless subscriber station via a channel identification message frame 66. The channel identification message includes the time at which the ongoing reference block occurred. This frame provides timing information, MAC layer control parameters, and other identification parameters for the channel in use, as described in Part 402 of the CDPD specification Version 1.1.

  In order to accurately predict where the TEI message and other control messages will occur in the communication flow, it must know exactly where the subject message occurs relative to the reference block 1. The MAC layer and the wireless subscriber station may use the TEI message 62 and other necessary control messages based on a set of parameters configured at the “start” (when the wireless subscriber station first registers with the CDPD system). Know the arrangement of 63.

  In order for the present invention to maintain the required predictability, the local timing standard or reference must maintain an accuracy of ± 20 milliseconds relative to the external absolute time reference. If the MDBS cannot guarantee that the local time reference is within ± 20 milliseconds of the external absolute time reference, the mobile database station typically stops sending.

  The mobile database station can use two sources as external absolute time references: a GPS receiver or an NTP time server based on the GPS reference. In order to predict the beginning of a TEI message transmission, it is necessary to ascertain both the duration of the epoch (eg, epoch 60 in FIG. 6) and the start time of the epoch. The parameter shown as N212 is used to define the duration of the epoch. Preferably, the value of N212 is predefined and assigned by the NMS. The epoch start time, which is also the start time of the reference block (eg, reference block 61), is determined by calculating the number of epochs that have occurred since the absolute start reference (eg, Oh 1995) by the base station. Both the epoch start time and duration are communicated to the subscriber station via a channel identification message located at the end of the epoch currently being received by the subscriber station.

  Preferably, the mobile database station and subscriber station can maintain synchronization with the forward channel transmission window using the N212 counter. The N212 counter is set to the duration of the forward transmission window in units of 8 times the Reed-Solomon block duration. The duration of the forward channel transmission frame is defined by the NMS (10 in FIG. 1) and communicated to the mobile database station. This parameter is also communicated to the subscriber station via a channel identification message as described above. It is necessary for the mobile database station transmission window to maintain a precise time alignment with the local mobile database station clock. Otherwise, it would be impossible to maintain the predictability of TEI message transmission.

  FIG. 7 shows the operation of the CDPD system and the subscriber station. The location of the TEI and other control messages are programmed into this MDBS when the mobile database station (MDBS1 in FIG. 1) is placed online at step 711. At step 712, the CDPD system (MD-IS in FIG. 1) sends the exact interval to send the TEI notification message. This second timing data is incorporated into the TEI message sent from MD-IS to MDBS. In step 713, the MDBS reads the TEI message and obtains second timing data. As shown in step 714, information regarding the first timing data (including epoch or segment length and control message placement data) is incorporated into the channel identification message 66. (Note that the second timing data is transmitted to the subscriber station in a TEI overhead message.) This data is generated based on the timing represented by the message block sequence of FIG. ES2).

  To obtain all control messages and TEI timing data necessary for the subscriber to operate in the new cell, the subscriber station monitors the CDPD channel in awake mode until all control messages are received ( Step 720). In this step, the subscriber station also adjusts to the external time standard. Typically this takes about 5 seconds to about 10 seconds. When the subscriber station receives the timing standard associating the reference block and the TEI message with the timing standard, the subscriber station can enter sleep mode until about one block or frame before the expected transmission time of the TEI message. Acquisition of this timing data requires continuous monitoring, but this monitoring is only required once, regardless of which cell the subscriber moves to. The time saved by grouping all other control messages following the TEI message is about 5 seconds. This is the time that the subscriber station does not have to be in awake mode, and considering the overall lifetime of the subscriber station, battery life will be saved considerably.

  The subscriber station (M-ES2 in FIG. 1) must time the arrival of the next reference block based on the first and second timing data and input from an external timing standard such as GPS (steps). 721). Therefore, as shown in step 722, the subscriber station must enter the awake mode in synchronization with the occurrence of the reference block 61, even in the sleep mode. In step 723, the subscriber station performs a detection operation to determine whether a unique TEI has been sent to the subscriber station. If a unique TEI has been sent, at step 724, the subscriber station begins a communication operation. However, if no TEI specific to the subscriber station is detected, the next step (725) of the process is performed. This step includes determining whether another control message is required for operation of the subscriber station. Usually, such acquisition only needs to be done once, and is done when the subscriber station first registers with the MDBS. However, under certain circumstances, the subscriber station may have to acquire a control message again. If there is such a need, the subscriber station operates as shown in step 726 to maintain the awake state and monitor the control message 63. On the other hand, if it is not necessary to acquire another control message again, the subscriber station can enter sleep mode immediately after receipt of the TEI message 62, as shown in step 727. The timing process shown in step 721 continues to predict the occurrence of the next reference block for subsequent segments or epochs of the same length as segment 60.

  When the wireless subscriber station establishes an adjustment with an external timing device to know the exact transmission time of the reference block 61, the wireless subscriber station maintains an awake mode to transmit such necessary control messages. Monitor the presence or absence of TEI messages only during the time. Thereafter, if the wireless subscriber station does not receive a TEI message 62 directed to the subscriber station, it immediately returns to sleep mode. This is possible because the wireless subscriber station already “knows” the exact number of blocks between TEI messages and the maximum duration of those messages.

  Another advantage of this level of predictability of the control message block is that the wireless subscriber station does not spend unnecessarily time in awake mode, but without other control messages 63 (channel configuration, channel access parameters, cell configuration, Switching channels, alternative service providers, etc.). This is achieved by arranging all control messages in a predictable manner. As shown in FIG. 6, another control message 63 can be placed immediately after the TEI message. However, other arrangements of TEI messages are possible.

  The channel identification message 66 must be placed at a different location. However, due to the precise frame alignment of the present invention, this location is easily predictable by the MAC layer and the wireless subscriber station. Accordingly, the wireless subscriber station does not have to waste time waiting for the occurrence of the channel identification block 66 in the awake mode. The location of the channel identification block 66 is particularly important because timing information (relative to the external time standard) is incorporated into the channel identification message.

  In order to maintain the predictability obtained by the present invention, the normal message flow 64 is controlled to keep the segment or epoch length 60 uniform. A stationary measurement process (step 715) is performed to measure the time between the current message flow block 64 and the next reference block 61 '. This value is compared at step 717 with the length of the message to be transmitted (measured at step 716). If the message to be sent is longer than the remaining time of the existing segment, the message is suspended at step 718 and dummy data 65 is inserted until the next incoming channel identification frame 66 is indicated. The message is resumed again in the normal message flow 64 'after transmission of the TEI message 62' and other control messages 63 '. On the other hand, if the remaining portion of the normal message flow 64 fits into the space that exists before the next reference block 61 'occurs, the normal message flow is executed as indicated at step 719. This timing operation is performed for each part of the normal message flow handled by the MDBS3. Thus, all normal communication messages that are identified as being too long for the remaining space of the segment or epoch, such as 60, are suspended and retransmitted on the next segment.

  Variations of the present invention are specific to the specific block or frame assigned to each subscriber station served by a particular MDBS. This is accomplished by MD-IS sending a message to each subscriber station before it enters sleep mode. The message includes the exact location of the TEI message for that subscriber. Because most subscriber stations or pagers are not paged at any given time, the notification message for a particular subscriber has many “dummy” values to fill the space between other TEI messages. Is included.

  Other techniques can be used to limit the battery consumption of the subscriber station. FIG. 6 also shows a breakdown of the TEI block 62. The arrangement shown as blocks 1 and 2 in FIG. 6 is a well-known arrangement according to the CDPD specification. Of particular note are the forward error correction (FEC) bits shown as 69 and 69 'in blocks 1 and 2, respectively. In each block of 378 bits, the redundant segment for FEC occupies a substantial part of the block. The relative time and energy spent reading and decoding FEC bits constitutes a substantial consumption of mobile subscriber station battery resources. However, it has always been considered that the FEC bit is necessary for the operation of the CDPD system because errors can occur. However, if the need to decode the FEC bits can be eliminated, considerable time and energy will be saved and the battery life of the wireless subscriber station will be extended.

  In another embodiment of the invention, the FEC block is obtained by obtaining a significant Hamming distance between the unique TEI at the beginning of message block 62 (immediately after reference block 61) and the other TEI message blocks in group 62. Eliminates the need for decryption. The final block of the group of TEI messages 62 is also given a unique configuration. Thus, the unique TEI value is clearly distinguished from other TEI values and one source of error is eliminated.

  In order for the present invention to operate even if the beginning and beginning TEI blocks of segment 62 (FIG. 6) have a unique configuration, the occurrence of unique TEI blocks must be predictable. One way to achieve this is by the techniques described above. However, it is possible to perform this embodiment using other prediction techniques so that this embodiment of the present invention may not use the techniques described above. It should be noted that it would be impossible in practice to eliminate the FEC decoding operation by the subscriber station without the ability to predict the transmission time of the unique start TEI.

As mentioned above, this embodiment of the present invention takes advantage of significant Hamming distances between unique beginning and ending TEI and other regular TEI messages. However, this is not necessarily true between normal TEI messages. The Hamming distance is a measurement of the number of different bits between any two TEIs. Since the TEI includes 32 bits, this embodiment assumes that a difference of at least 6 bits constitutes an appropriate Hamming distance. This means that a unique TEI message differs from any regular TEI message at at least 6 different locations out of a total of 32 locations. As a result, in order to ensure that the 6-bit Hamming difference relationship is maintained, typically a substantial number of TEI out of the possible number of 2 ³² combinations is rejected.

  However, in this embodiment, since the TEI arrangement is assigned randomly, it is very unlikely that any two TEIs with a Hamming distance close to 6 are at the same cell site at any time. This operation is controlled by a random assignment algorithm that also checks the Hamming distance. If the hamming distance of the unique TEI message from the normal TEI message is insufficient, MD-IS (1 in FIG. 1) can detect this condition and, optionally, the subscription in that cell. The TEI of one of the subscriber stations can be reassigned. Combining this with the guaranteed Hamming distance from the unique TEI value combined with the random TEI assignment described above eliminates the need to decode the FEC block of the TEI notification message.

  If the subscriber station no longer decodes the FEC block, a sufficient hamming distance is likely to be maintained, but the problem is that errors may not be detected. One technique for determining errors without decoding the FEC block is to measure the base error rate (BER) using bits already known to the subscriber station before receiving the message to be examined. Because about one eighth of these bits are transmitted to the subscriber station in a TEI overhead message, about one eighth of these bits are already known.

  By comparing the known bits with the received bits, it is possible to obtain the underlying BER. If the subscriber station determines that the BER is high, the subscriber station can compare the BER to a predetermined threshold to determine whether time and energy is required to decode the FEC. If the subscriber station decides to decode the FEC, it will ensure that errors do not interfere with the scanning process as long as the message can be decoded. As described above for techniques for predicting the beginning of a TEI message, the BER inspection process is facilitated because the distance between the unique TEIs of successive epochs or segments (60 in FIG. 6) is already known.

  When the BER is at an acceptable level, the subscriber station must know exactly where the boundaries of the TEI message are because the scan is performed on undecoded blocks. It is therefore very important to defer the HDLC zero insertion function. This is because the predicted boundary portion of the TEI message moves when this operation is performed. Furthermore, the use of the HDLC zero insertion function reduces the need for all TEIs to have the same number of bytes. The requirements for HDLC frames are fully explained in the literature and are described in more detail in Part 402 of the CDPD Specification Version 1.1.

  One aspect of the requirements for HDLC frames is “zero stuffing” technology. Zero stuff is to insert “0” after five consecutive “1” s. Typically this is used to distinguish the data from the frame delimiter sequence “01111110”. Normally, the receiving station or subscriber station removes the stuffed zeros. However, in this embodiment of the invention, padded zeros are not reliably detected or removed before scanning is performed without decoding the FEC block. Therefore, to prevent this problem, zero stuff technology for HDLC framing should not be used in the present invention.

  When a channel error occurs, the subscriber station may mistake the normal TEI for a unique beginning or ending TEI. In this system, this error occurs if there are 6 errors. This is an unlikely event, but if it happens, the mistake is corrected at the next notification interval or epoch. There is some chance that the error will be repeated at the next notification interval, but it is very low.

  There is also some chance that a subscriber station will mistake another subscriber station's TEI for its own. This occurs by scanning for errors, and also because the minimum Hamming distance may not be fully guaranteed using the random assignment algorithm described above. This is not a serious problem. However, other actions can be used if the system operator wishes to reduce the likelihood of this event occurring. Using this operation, MD-IS (3 in FIG. 1) can detect when two or more TEIs have a Hamming distance of 6 or less and are in the same service area. When MD-IS detects this, it reassigns at least one of the TEIs to achieve a better Hamming distance.

  The problem of missing a unique end TEI is not a serious problem. This is because the subscriber station already knows the maximum length of the TEI message segment 62 (FIG. 6). If a unique end TEI is not found based on the known timing, the subscriber station simply stops searching and continues the timekeeping operation to predict the transmission time for the reference block 61 'that starts its next segment or epoch. . From this timing operation, the occurrence of the next unique TEI message (in block group 62 ') can be predicted.

  In order to implement the present invention, the MDBS (1 in FIG. 1) must be able to store the TEI notification message sent from the MD-IS (3 in FIG. 1). At the end of the epoch or segment 60 (FIG. 6), the MDBS must send the latest TEI message as shown in segment 63 of FIG. To do this, the MDBS uses a special buffer to hold the received TEI message. Furthermore, as explained above, the MDBS has the ability to defer normal operation of the communication message in order to insert the TEI message at the exact time that the subscriber station predicted transmission.

  This embodiment has other constraints on normal CDPD operation. This is because there are more subscriber stations that can enter the awake state at any notification interval (62 in FIG. 6) than can be listed in one 136 byte HDLC frame, and the TEI list is Then it must continue with the subsequent HDLC frame. A unique start TEI must occur only at the beginning of the first HDLC frame. This unique end TEI must not occur until the end of the last HDLC frame. Because the subscriber station may not recognize the unique end TEI message, the subscriber station must know the upper limit of the HDLC frame for one notification. From this, the subscriber station can determine which is the last block that needs to be examined. Each maximum length HDLC frame in the notification period must occupy exactly 4 blocks. Only the last HDLC frame of the notification period can be shorter than this maximum length. In order to maintain the conditions necessary for the operation of embodiments of the present invention, the MDBS must follow these standards.

  As mentioned above, although many structures of this invention were demonstrated, this is an illustration and this invention is not necessarily limited to these structures. For example, the present invention can be adapted to use control message transmission prediction configurations other than those described above. Accordingly, the invention is to be construed as including any and all configurations, modifications, changes, combinations, or equivalent configurations that fall within the scope of the appended claims.

FIG. 1 is a block diagram of a conventional CDPD system. FIG. 2 is a block diagram in which a CDPD system is correlated with a conventional AMPS system. FIG. 3 is a block diagram of a portable radiotelephone handset. FIG. 4 is a block diagram of the MDBS architecture. FIG. 5 is a flowchart showing the parallel operation of the wireless subscriber station and the associated MDIS. FIG. 6 is a diagram showing a message block array used in a method for predicting a control message transmission time including a message block configuration. FIG. 7 is a flowchart showing an operation sequence of the system using the data array of FIG. FIG. 8 is a diagram showing the arrangement of FEC blocks.

Claims (19)

In a wireless communication system, a method for communicating between a base station and a plurality of wireless subscriber stations, the base station comprising a plurality of temporary device identifiers (TEI) corresponding to each of the plurality of subscriber stations. Controlling a stream of message blocks including a message, the message block including a plurality of forward error correction (FEC) bits, the plurality of forward error correction (FEC) bits being corrected by the plurality of TEI messages. Decrypted by the plurality of wireless subscriber stations to ensure that they were received as none
The method
(A) arranging the plurality of TEI messages in successive groups;
(B) starting the TEI message group with a unique TEI message and ending the TEI message group with a second unique TEI message, the unique TEI message including at least all other TEI messages Differing by six characters, thereby eliminating the need to decode the plurality of FET bits.   Further comprising assigning a TEI to all radio subscriber stations of the plurality of radio subscriber stations located in a particular cell, wherein the TEI for all radio subscriber stations in the particular cell is at least 6; The method of claim 1, wherein the method differs by characters.   The method of claim 2, wherein the TEI for all wireless subscriber stations is randomly assigned. Checking if the TEI for all wireless subscriber stations in a particular cell differs by at least 6 characters;
Reassigning the TEI to at least one of all wireless subscriber stations in the particular cell such that the TEI for all wireless subscriber stations in the particular cell differs by at least 6 characters; The method of claim 2 comprising. Checking if the TEI for all wireless subscriber stations in a particular cell differs by at least 6 characters;
Randomly reassigning a TEI to at least one of all wireless subscriber stations in the particular cell such that the TEI for all wireless subscriber stations in the particular cell differs by at least 6 characters; The method of claim 2 further comprising:   The method of claim 5, wherein TEIs for all the wireless subscriber stations are randomly assigned. In a wireless communication system, a method for communicating between a base station and a plurality of wireless subscriber stations, the base station comprising a plurality of temporary device identifiers (TEI) corresponding to each of the plurality of subscriber stations. Controlling a stream of message blocks including a message, the message block including a plurality of forward error correction (FEC) bits, wherein the plurality of forward error correction (FEC) bits are corrected by the plurality of TEI messages. Is decrypted by the plurality of wireless subscriber stations to ensure that
The method
(A) arranging the plurality of TEI messages in successive groups;
(B) starting the TEI message group with a unique TEI message and ending the TEI message group with a second unique TEI message, the unique TEI message including at least all other TEI messages (C) monitoring the communication stream for a temporary device identifier (TEI) block; and
(D) determining a base error rate (BER);
(E) decoding the FEC bit only if the BER is above a predetermined level.   The method of claim 7, wherein the BER of step (d) is determined by comparing a known bit of the communication stream with a received bit of the communication stream.   The method of claim 7, wherein the BER of step (d) is determined by comparing a known bit of the TEI overhead message with a received bit of the TEI overhead message.   Further comprising assigning a TEI to all wireless subscriber stations of the plurality of wireless subscriber stations located in a particular cell, wherein the TEI of all wireless subscriber stations in the particular cell is at least 6 characters long 8. The method of claim 7, wherein the method differs by minutes.   The method of claim 10, wherein TEIs for all the wireless subscriber stations are randomly assigned. Checking if the TEI for all wireless subscriber stations in a particular cell differs by at least 6 characters;
Reassigning the TEI to at least one of all wireless subscriber stations in the particular cell such that the TEI for all wireless subscriber stations in the particular cell differs by at least 6 characters; 11. The method of claim 10, comprising. Checking if the TEI for all wireless subscriber stations in a particular cell differs by at least 6 characters;
Randomly reassigning a TEI to at least one of all wireless subscriber stations in the particular cell such that the TEI for all wireless subscriber stations in the particular cell differs by at least 6 characters; The method of claim 10, further comprising:   The method of claim 13, wherein TEIs for all the wireless subscriber stations are randomly assigned.   The method of claim 14, wherein the BER of step (d) is determined by comparing a known bit of the communication stream with a received bit of the communication stream.   16. The method of claim 15, wherein the BER of step (d) is determined by comparing known bits of a TEI overhead message with received bits of the TEI overhead message. A base station that controls a stream of message blocks including a plurality of temporary equipment identifier (TEI) messages corresponding to each of a plurality of subscriber stations;
The base station
(A) A transmission control mechanism that arranges the plurality of TEI messages in successive groups, starting the TEI message group with a unique TEI message and ending the TEI message group with a second unique TEI message. With a transmission control mechanism,
The unique TEI message is at least six characters different from all other TEI messages, thereby eliminating the need to decode the plurality of FET bits. (A) at least one wireless subscriber station;
(B) a communication system comprising: a base station that controls a stream of message blocks including a plurality of temporary device identifier (TEI) messages corresponding to each of a plurality of subscriber stations;
The at least one wireless subscriber station is
(1) a monitor for monitoring a communication stream for a temporary device identifier (TEI) message block, wherein the TEI includes a TEI message and a plurality of forward error correction (FEC) bits;
(2) an error rate detector for determining a base error rate (BER);
(3) a decoder that decodes the FEC bit only when the BER exceeds a predetermined level;
The base station
(1) A transmission control mechanism that arranges the plurality of TEI messages in successive groups, and starts the TEI message group with a unique TEI message and ends the TEI message group with a second unique TEI message. With a transmission control mechanism,
The communication system, wherein the unique TEI message differs from all other TEI messages by at least six characters, thereby eliminating the need to decode the plurality of FET bits. A memory medium storing a program for controlling a base station,
The base station controls a stream of message blocks including a plurality of temporary device identifier (TEI) messages corresponding to each of a plurality of subscriber stations;
The program
Instructions for arranging the plurality of TEI messages in successive groups;
An instruction to start the TEI message group with a unique TEI message and end the TEI message group with a second unique TEI message, the unique TEI message being at least 6 characters from all other TEI messages Unlike, a memory medium that can eliminate the need to decode the plurality of FET bits.

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