JP5307168B2 - Updating overhead messages with distributed control - Google Patents

Description

Background of the Invention

TECHNICAL FIELD OF THE INVENTION

  The present invention relates generally to wireless communication systems, and more particularly to the distribution of overhead channel information in wireless communication systems.

Conventional technology

  In cellular communication systems, the area to be covered is divided into many small areas called cells, and one base station (BS) is arranged to provide service or coverage for mobile units in the cell. Each BS is connected to a base station controller (BSC), which is used to control several BSs, and mobile units move as one mobile unit moves from one cell to another. Used for control to provide communication services. The BSC is then connected to a mobile switching center (MSC), which is typically a telephone switch with special software that handles the mobility aspects of the mobile unit. Most cellular communication systems consist of a number of MSCs, each MSC having its own MS and interconnected by fixed links. The MSC interconnects to the public switched telephone network (PSTN) for both outgoing calls to the fixed telephone and incoming calls from the fixed telephone.

  The mobile unit is ultimately connected to the MSC through a radio frequency (RF) radio reverse (mobile unit to BS) link to the BS and an RF forward (BS to mobile unit) link from the BS. RF signals are exchanged between a particular mobile unit and one or more base stations through these links. Mobile units do not communicate directly with each other. Communication from mobile unit to mobile unit over one or more spans of cells occurs through a base station serving a mobile unit that desires communication. The base station communicates with the BSC using various media such as ground based wired or microwave links. The BSC can route calls to the PSTN through the MSC and can route packets to a packet switch network such as the Internet. The base station controller also coordinates the operation of the base stations in the system, for example during handoff.

A common feature of RF forward and reverse links in many cellular systems is multiple users using a single communication channel that occupies a limited frequency range. Cellular systems utilize a variety of technologies that allow multiple users to use a single communication channel that occupies a limited frequency range. Code division multiple access (CDMA) is one such technique. A popular standard for CDMA can be found in the TIA / EIA standard TIA / EIA-95-B entitled “Mobile Station-Base Station Compatibility Standard for Dual Mode Wideband Spread Spectrum Cellular Systems”. In CDMA, a plurality of users can use the entire communication channel at the same time without having to adjust the transmission timing or a part of the communication channel used by each user. A more detailed description of CDMA and spread spectrum communications can be found in Addison-Wesley Publishing Company, Reader, M.C. A. In 1996, Andrew J. It can be found in the CDMA principle of spread spectrum communication by Viterbi. In contrast to CDMA, the other two multiple access techniques adjust the timing of user transmissions (Time Division Multiple Access (TDMA)) or adjust some of the communication channels used by users (Frequency Division Multiplexing). Connection (FDMA)).

  Regardless of the technology used to provide multiple access in a typical cellular system, the forward communication link includes one or more data channels, a pilot channel, one or more paging channels, All of these are transmitted from the base station to the mobile unit. The pilot channel or pilot signal functions to define the boundaries of the cell area handled by the base station. In a CDMA cellular system according to IS-95, the pilot signal functions for other purposes as well. For example, the pilot signal provides a time reference, provides amplitude and phase tracking, and allows the mobile unit to identify and synchronize with various base stations that are within its communication capabilities. A set of data channels carry data related to various communication sessions (typically telephone calls) and are directed to individual mobile units. These data channels are often referred to as traffic channels. The paging channel is used by the base station to notify the mobile unit when a communication request is received. The paging channel is also used to send overhead messages. The overhead message includes information that enables communication from the mobile unit to the base station.

  The overhead message is not addressed to any particular mobile unit, but is intended to be distributed to each mobile unit in the corresponding coverage area. In an IS-95 CDMA cellular system, there are four types of overhead messages: system parameters, access parameters, channel list overhead messages, and neighbor list overhead messages. Each type of overhead message must be broadcast at least once every second. For example, the neighbor list overhead message continuously broadcasts a list of neighboring base stations with which communication is possible. When the mobile unit enters the coverage area of the neighboring base station, the mobile unit uses this neighbor list to monitor signals from neighboring base stations. Cellular systems using other communication standards may use other types of overhead messages.

  Overhead messages are typically received and processed by the mobile unit when the mobile unit is not in a call or is not trying to connect (ie, when the mobile unit is “idle”). The term idle state is somewhat misleading because mobile stations can be very busy during idle state.

  During the idle state, the mobile station periodically wakes up, listens to the paging channel, and processes messages on that channel. Overhead messages may remain the same for a significant period of time when the mobile station periodically wakes up and listens to the paging channel. From the point of view of conserving and using battery power, just let the mobile station wake up and receive the overhead message and decode it just to determine that the overhead message is the same as the previous message that was previously decoded Since this is not preferable, the sequence number is transmitted together with the overhead message. When the mobile station wakes up, it receives the sequence number of the overhead message and decides whether to receive the overhead message while waked up. In many instances, the mobile unit goes back to sleep after receiving the sequence number. The reason is that the received sequence number has the same sequence number that was received when the mobile unit was last woken up.

  The amount of time that the mobile unit performs the listening function because it requires a certain amount of power to listen to overhead messages and because the listening function is performed frequently (such as once every second) Limiting the overall power consumption of the mobile unit, thus increasing the life of any battery or other power storage system utilized by the mobile unit. In many cases, overhead messages remain the same for a significant time period, resulting in significant power savings.

  In many cellular systems, overhead messages and sequence numbers transmitted by the base station are controlled from a central location such as BSM. One reason for providing this centralized control stems from the nature of the services typically provided by cellular systems. Cellular systems typically provide voice services or connections to / from ground-based PSTN. PSTN generally has a highly centralized switching structure. As a result, cellular services that wish to interface to the PSTN must use a central switch to route calls. In many cellular systems that provide voice service through the PSTN, telephone calls are bundled at the central switch (MSC) for transmission through the PSTN and unbundled for transmission through the wireless network. As a result, there is a central location (BSM or MSC) where links from many BSs terminate, so this central location is used to centralize overhead message and sequence number programming at each base station in the cellular system. Remote control from the position was inevitable.

  In contrast, cellular systems that provide packet data services rather than voice services typically interface with highly distributed networks. An example of a decentralized network is the Internet. A cellular system that provides packet data services provides a wireless link from a user of the cellular system to the router, which links the user to the distributed network. Technically, the Internet is a collection of standard protocols such as Transmission Control Protocol / Internet Protocol (TCP / IP) that allow dissimilar computer systems and networks to send and receive information. Some of the more popular protocols are e-mail (electronic message transmission), file transfer protocol (file transfer processing), world wide web (link using graphic interface by hypertext document), telnet (phone network connection), IRC (Internet connection). Relay chat) and Gopher (information organization) are included.

  Messages received from mobile users of packet data cellular systems are forwarded by the base station to the router. The router breaks down the message into smaller pieces known as packets. The packets travel separately across the network, but are eventually reshaped together when all pieces of the message arrive at their destination. During transmission, packets flow from one router along the other and through bridges and switches. A specific route is not selected from the beginning. Each router or switch looks at the destination address of the packet, but does not look at its contents and determines the best route to send it.

  Routers typically connect directly to a decentralized network and typically send data along multiple paths to a destination, so the need for a centrally located switch to set up a single path to and from the destination There is often no. As a result, wireless data systems that provide access to distributed networks may not have a central location like BSM or MSC that can also be used to control base stations and update cellular system overhead messages. There is sex.

  Accordingly, there is a need to deliver overhead messages in a wireless communication system such as a cellular system that provides access to a distributed network. The present invention satisfies this need.

Overview

  The systems and methods of the present invention provide a simple but effective technique for communicating overhead messages in a wireless communication system that provides access to a distributed network while conserving bandwidth and minimizing power consumption.

  In one embodiment, a wireless base station connected to a distributed network transmits a series of overhead message signatures to a mobile unit. The mobile unit wakes up and receives the signatures and compares them with the signatures stored in the mobile unit. If the signature received by the mobile unit is different from the signature stored in the mobile unit, the mobile unit receives an overhead message transmitted by the wireless base station while awake. If the signature received by the mobile unit is the same as the signature stored in the mobile unit, the mobile unit goes back to sleep.

  In other embodiments, the mobile unit wakes up to receive a message from the wireless base station. The mobile unit uses the message to generate a signature. The mobile unit compares this signature with the signature of the previous message received by the mobile unit. If the signature generated for the received message is the same as the signature of the previously received message, the mobile unit goes back to sleep. If the signature generated for the received message is different from the signature of the previously received message, the mobile unit updates the operating parameters for use in communication with the base station.

FIG. 1 is a block diagram of a wireless communication system according to a preferred embodiment of the present invention. FIG. 2 shows a forward link structure of a wireless communication system according to the present invention. FIG. 3 illustrates a process for communicating overhead messages using the forward link structure illustrated in FIG. FIG. 4 shows another structure of the forward link of a wireless communication system according to the present invention. FIG. 5 illustrates another process for communicating overhead messages using the forward link structure illustrated in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

  FIG. 1 shows a system block diagram of a wireless communication system (CS or system) 200 according to a presently preferred embodiment of the present invention. The system 200 includes a plurality of base stations (BS) 210, 220 (only two are shown) with a mobile unit (MU) 202 in a geographical area covered by the base station. Each base station 210, 220 can communicate wirelessly with the mobile unit 202. The MU 202 includes a terminal device (TE) 206 and a mobile terminal (MT) 204.

  The MU is used to refer to a composite entity composed of a terminal device and a mobile terminal. In this description, the term “mobile unit” is used to generally refer to a remote subscriber station for purposes of this description. However, it should be noted that the mobile unit may be fixed in a certain position. The mobile unit may be part of a subscriber system where multiple users are gathered. The mobile unit may be used to convey a combination of voice, data or signal type. The term “mobile unit” is a technical term and is not meant to limit the scope or function of the unit.

  Base stations 210, 220 include base station transceiver subsystems (BTS) 212, 222 and radio link protocol and signaling managers (RSM) 214, 224. Base station is used to refer to a composite entity consisting of BTS and RSM.

  The TE 206 is a device that provides a user interface, typically a laptop or notebook computer, or a personal digital assistant (PDA). TE 206 is connected to MT 204, which is a wireless device that provides data modulation and demodulation capabilities. The BTS 214 is connected to the MT 204 through a radio frequency (RF) radio interface. The BTS 214 provides data modulation / demodulation capability for connection with the MT 206. RSMs 214, 224 function as radio link protocol (RLP) endpoints and signaling endpoints and map Internet protocol addresses and mobile station identifiers to each other. There may be a single RSM or an RSM located in the same location as each BTS.

  System 200 also includes a router 230. Router 230 connects RSMs 214, 224 to a distributed network 250 comprised of routers (not shown) and other networks (not shown). One example of a distributed network is the Internet. System 200 may be connected to other types of distributed and / or centralized networks.

  The RF radio interface between the BTS 212 and the MT 204 includes a BTS forward link for mobile unit communication and a mobile unit reverse link for BTS communication. In one embodiment, the forward link of system 200 is entirely dedicated to a single mobile unit at any moment, and a single forward channel is transmitted to one mobile unit at any moment. There are many types of communication standards, and the present invention may be used with these communication standards. One standard for the forward and reverse links in a wireless communication system is the TIA / EIA standard TIA / EIA-95 entitled “Mobile Station-Base Station Compatibility Standard for Dual Mode Wideband Spread Spectrum Cellular Systems”. -B (ie IS-95). In other embodiments, the forward link of system 200 may be the same as the IS-95 forward channel. In IS-95, multiple forward channels are received by one mobile unit.

  The forward link of system 200 may be different from IS-95, in which case the pilot channel is burst transmitted and data is transmitted as opposed to the pilot channel being transmitted continuously as in IS-95. It may be embedded in the channel. Other overhead channels may also be different, and IS-95 continuous synchronization and paging channels are combined into a single control channel in system 200, and this single control channel message is "single user" forwarded. Time multiplexed on the link. Multiplexing is desirable because it avoids dividing the base station power into two or more consecutively transmitted channels. Higher data rates can be used if substantially all base station power is used to transmit the data channel.

  System 200 is designed to operate on independent CDMA channels (i.e., different frequencies) other than existing IS-95 systems. The system 200 can be deployed independently of an existing IS-95 system (or where such a system does not exist) and in such cases has no interaction with the underlying audio system. The system 200 can also be deployed where a coordinated IS-95 system is present, in which case the IS-95 system related information is transmitted over the control channel of the system 200 that supports handoff. And information distribution from the IS-95 system to the system 200 is performed with support for call distribution notification.

  In system 200, an overhead channel, such as a paging channel, is time multiplexed with the forward data channel, and the less time is spent transmitting the paging channel, the more time is available to transmit the forward data channel. . For a given constant data rate, the data throughput for the mobile unit is directly related to the amount of time that the forward data channel is transmitted to and received by the mobile unit, so the time spent transmitting the paging channel. It is highly desirable to reduce the amount.

  In TIA / EIA-95, the paging channel is transmitted continuously and takes part of the total available bandwidth on the forward channel and the total available power of the base station. The forward data channel can use less power because some of the total available power of the base station is taken by the paging channel. The maximum data transmission rate on the forward data channel for a given signal-to-noise ratio (SNR) and a given bit error rate (BER) is a function of the power available to the forward data channel. In particular, for a given SNR, when less power is available for the forward data channel, the maximum data transmission rate on the forward data channel must be reduced to satisfy the requirement for a given BER.

  For many systems and applications, if a high data transmission rate is desired, it may not be possible to increase the power available to the forward data channel by increasing the power at the base station transmitter. As a result, to achieve a high transmission data rate, it is necessary to take power from other channels so that the forward data channel can make use of that power.

  Unfortunately, if too much power is taken from the paging channel and applied to the forward data channel, the SNR on the paging channel is adversely affected and hence the BER on the paging channel is also adversely affected. It may obscure the information transmitted on the channel. However, if the transmitter power cannot be increased to significantly increase the data transmission rate, a significant amount of power can be taken from the paging channel (or some other channel) to make available power for the forward data channel. A substantial increase is required.

  In order to increase the data transmission rate considerably, it is necessary to take all power from the paging channel, give it to the forward data channel, and time multiplex the paging channel and the data channel. For a given transmitter power, a system in which the paging channel and the data channel are time-multiplexed has a higher transmission data rate than the system in which the paging channel and the data channel are simultaneously transmitted to share the given transmitter power. Can be provided.

  Although it is true that a higher maximum transmission data rate is possible when the paging channel and the forward data channel are time multiplexed, the paging channel must be transmitted to achieve a high effective transmission data rate. The time spent on should be minimized as suggested by the following equation:

Effective transmission data rate = Tr _Max * Tfd / (Tfd + Tpc)
Tr _Max is the maximum transmission data rate, Tfd is the transmission duration of the forward data channel during one period, and Tpc is the transmission duration of the paging channel during one period.

  FIG. 2 generally illustrates the structure of an embodiment forward link according to the present invention. The forward link is a data stream having a periodic cycle, and the data stream includes a paging channel multiplexed with a forward data channel. The paging channel includes a signature capsule and an overhead message capsule. In the embodiment shown in FIG. 2, the signature capsule and the overhead message capsule are transmitted in a period having a duration of 400 milliseconds. In other embodiments, this period may have other durations. The signature capsule includes at least one signature. The signature may represent just one overhead message, or may represent a group of more than one message (ie if at least one message in the group of more than one message is changed) The signature changes at any time).

  The overhead message capsule contains at least one overhead message. The overhead message is not addressed to any particular mobile unit, but is intended to be distributed to each mobile unit in the corresponding coverage area.

  Possible overhead messages include system parameters, access parameters, channel list overhead messages and neighbor list overhead messages. Each type of overhead message must be broadcast at least once every second. In the preferred embodiment, the message is broadcast every 400 milliseconds. For example, the neighbor list overhead message can continuously broadcast a list of neighboring base stations and communicate through this neighboring base station. The mobile unit uses the neighbor list to monitor signals from neighboring base stations when the mobile unit enters the coverage area of the neighboring base station. The cellular system may have other types of overhead messages. It is well known in the art that many different parameters that are necessary to establish and maintain communication between a mobile unit and a base station may be included in an overhead message.

  Overhead messages are typically received and processed by the mobile unit when the mobile unit is not in a call or is not trying to connect (ie, when the mobile unit is “idle”). The term idle state is somewhat misleading because mobile stations can be very busy during idle state.

  During the idle state, the mobile station periodically wakes up, listens to the paging channel, and processes messages on that channel. Overhead messages may remain the same for a significant period of time when the mobile station periodically wakes up and listens to the paging channel. From the point of view of conserving and using battery power, just let the mobile station wake up and receive the overhead message and decode it just to determine that the overhead message is the same as the previous message that was previously decoded Since this is not preferable, the sequence number is transmitted together with the overhead message. When the mobile station wakes up, it receives the signature of the overhead message that will be received later, and decides whether to receive the overhead message while it remains wake. In many instances, the mobile unit goes back to sleep after receiving the signature. This is because the received signature has the same sequence number that was received when the mobile unit was last woken up.

  The amount of time that the mobile unit performs the listening function because it requires a certain amount of power to listen to overhead messages and because the listening function is performed frequently (such as once every second) Limiting the overall power consumption of the mobile unit, thus increasing the life of any battery or other power storage system utilized by the mobile unit. In many cases, overhead messages remain the same for a significant period of time, resulting in significant power savings.

  FIG. 3 illustrates a process for updating overhead messages for an embodiment having a forward link having the structure shown in FIG. 2 in accordance with the present invention. Referring to FIG. 3, the overhead message is modified at BS 210 at step 302. In step 304, a signature is generated for the overhead message modified in BS 210.

  Signatures can be generated by hashing the message using well-known hashing functions that generate 16 or 32 bit signatures. Hashing a message to generate a signature can be performed by a signature generator using well-known computational logic (not shown) or a general purpose microprocessor (not shown), here There is no need to explain. Those skilled in the art will recognize that other forms of logic not described herein may be used to generate the signature. The bit length of the signature depends on the system requirement that two consecutive messages separate different signatures (ie avoid collisions). There is a limited but small probability that two different consecutive messages may share the same signature. The reason is that hashing only serves to compress the message space into a smaller signature space, and more than one message may have the same signature.

  If two consecutive messages are different, but hashing produces the same signature for both, then in step 304, until a signature is generated that is different from the signature of the predetermined number of previous messages, The hashing may be repeated using a random number. Alternatively, the signature can be generated by incrementing the counter.

  In step 306, MU 202 wakes up and listens. In step 308, BS 210 transmits the signature to MU 202. In step 310, the MU 202 receives the signature. In step 312, MU 202 retrieves the previous signature from memory (not shown). In step 312, MU 202 compares the signature received in step 310 with the previous signature. The circuit or signature comparison element required to perform the comparison in step 312 can be implemented by various components including combinational logic circuits and other logic circuits as well as microprocessors. If the signature received at step 310 is the same as the previous signature, at step 314 MU 202 goes back to sleep. If the signature received at step 310 is different from the previous signature, at step 316, the MU 202 remains awake and listens to receive the message. After receiving the message, the MU 202 updates the operating parameters of the MT 204 so that it can effectively communicate with the system 200.

  The overhead message structure on the paging channel may follow the structure required by a technique known as slotted paging. Slotted paging is useful for reducing power consumption by mobile units. Further information on slotted mode operation was issued on February 21, 1995 and assigned to the assignee of the present invention, US Pat. No. 5, entitled “Apparatus and Method for Reducing Power Consumption of Mobile Communications Receivers”. 392,287, which is hereby incorporated by reference.

  FIG. 4 generally illustrates the structure of another embodiment of the forward link according to the present invention. The forward link is a data stream with a periodic cycle, which includes a paging channel multiplexed with a forward data channel. The paging channel contains an overhead message capsule. In the embodiment shown in FIG. 4, the overhead message capsule is transmitted in a period having a duration of 400 milliseconds. In other embodiments, this period may be other durations.

  FIG. 5 illustrates a process for updating overhead messages for another embodiment having a forward link having the structure shown in FIG. 4 in accordance with the present invention. Referring to FIG. 5, the overhead message is modified at BS 210 at step 502. In step 504, MU 202 wakes up and listens. In step 506, the BS sends a message to the MU 202, which receives the message. In step 508, the MU 202 generates a signature for the message using a hashing function as described with respect to the process 300 in FIG.

  Hashing a message to generate a signature can be performed by a signature generator using well-known computational logic (not shown) or a general purpose microprocessor (not shown), here There is no need to explain. Those skilled in the art will recognize that other forms of logic not described herein may be used to generate the signature.

  In step 512, MU 202 retrieves the previous signature from MU 202's storage (not shown). In step 512, the MU 202 compares the signature generated in step 508 with the previous signature. The circuit or signature comparison element required to perform the comparison in step 512 can be implemented by various components including a combinational logic circuit and other logic circuits as well as a microprocessor. If the signature generated at step 508 is the same as the previous signature, at step 514, the MU 202 returns to sleep. If the signature generated at step 508 is different from the previous signature, at step 516, the MU 202 updates its operating parameters with the information contained in the message received at step 506.

  The generation and reception of CDMA signals is described in U.S. Pat. No. 4,401,307 entitled “Spread Spectrum Multiple Access Communication System Using Satellite or Terrestrial Repeaters” and “System and Method for Generating Waveforms in a CDMA Cellular Telephone System”. No. 5,103,459, both assigned to the assignee of the present invention and incorporated herein by reference.

  Demodulating multiple signals is described in US Pat. No. 5,490,165 entitled “Assignment of Demodulator Elements in a System capable of Receiving Multiple Signals” and US Patent titled “Diversity Receiver in CDMA Cellular Telephone System”. No. 5,109,390, both of which are assigned to the assignee of the present invention and incorporated herein by reference.

  Although the invention has been described in connection with specific embodiments, it will be understood that various modifications and variations can be made by those skilled in the art without departing from the spirit and scope of the invention. The present invention should not be limited by the foregoing exemplary detailed description, but should be defined by the following claims.

Claims (12)

In a method of communicating a signature from a base station to a mobile station by a wireless communication system that provides access to a distributed data network, including the base station and the mobile station ,
Generating a signature for the message at the base station;
Transmitting at the base station the signature to a mobile station;
Receiving the signature at a mobile station; and
At the mobile station, comparing the received signature with a stored signature;
If the received signature matches the stored signature, the mobile station sleeps the mobile station; and
The signature is generated by hashing the message at a base station,
The method wherein the stored signature is a signature generated for a message prior to the message. In a method of communicating a signature from a base station to a mobile station by a wireless communication system that provides access to a distributed data network, including the base station and the mobile station,
Generating a signature for the message at the base station;
Transmitting at the base station the signature to a mobile station;
Receiving the signature at a mobile station; and
At the mobile station, comparing the received signature with a stored signature;
Listening to the message at a mobile station if the received signature does not match the stored signature;
The signature is generated by hashing the message at a base station,
The method wherein the stored signature is a signature generated for a message prior to the message. The method according to claim 2, further comprising the step of updating the operating parameters of the mobile station with information contained in the message at the mobile station. In a wireless communication system providing access to a distributed data network, including a base station and a mobile station, in a method for receiving a signature from a base station at a mobile station,
Receiving a signature from the base station at the mobile station;
At the mobile station, comparing the received signature with a stored signature;
If the received signature matches the stored signature, the mobile station sleeps the mobile station; and
The signature is generated by hashing the message at a base station;
The method wherein the stored signature is a signature generated for a message prior to the message. In a wireless communication system providing access to a distributed data network, including a base station and a mobile station, in a method for receiving a signature from a base station at a mobile station,
Receiving a signature from the base station at the mobile station;
At the mobile station, comparing the received signature with a stored signature;
Listening to the message at a mobile station if the received signature does not match the stored signature;
The signature is generated by hashing the message at a base station;
The method wherein the stored signature is a signature generated for a message prior to the message. 6. The method according to claim 5, further comprising the step of updating operating parameters of the mobile station with information contained in the message at the mobile station. In a wireless communication system providing access to a distributed data network, including a base station and a mobile station,
Means at the base station to generate a signature for the message;
Means at the base station for transmitting the signature to a mobile station;
Means at the mobile station for receiving the signature;
Means at the mobile station for comparing the received signature with a stored signature;
Means at the mobile station for causing the mobile station to sleep if the received signature matches the stored signature;
The signature is generated by hashing the message at a base station,
The system wherein the stored signature is a signature generated for a message prior to the message. In a wireless communication system providing access to a distributed data network, including a base station and a mobile station,
Means at the base station to generate a signature for the message;
Means at the base station for transmitting the signature to a mobile station;
Means at the mobile station for receiving the signature;
Means at the mobile station for comparing the received signature with a stored signature;
Means at the mobile station for listening to the message if the received signature does not match the stored signature;
The signature is generated by hashing the message at a base station,
The system wherein the stored signature is a signature generated for a message prior to the message. 9. The system according to claim 8, further comprising means in the mobile station for updating mobile station operating parameters with information contained in the message. In a wireless communication system providing access to a distributed data network, including a base station and a mobile station, in a mobile station receiving a signature from the base station,
Means for receiving a signature from the base station;
Means for comparing the received signature with a stored signature;
Means for causing the mobile station to sleep if the received signature matches the stored signature;
The signature is generated by hashing the message at a base station;
The stored signature is a mobile station that is a signature generated for a message prior to the message. In a wireless communication system providing access to a distributed data network, including a base station and a mobile station, in a mobile station receiving a signature from the base station,
Means for receiving a signature from the base station;
Means for comparing the received signature with a stored signature;
Means for listening to the message if the received signature does not match the stored signature;
The signature is generated by hashing the message at a base station;
The stored signature is a mobile station that is a signature generated for a message prior to the message. The mobile station according to claim 11, further comprising means for updating operation parameters of the mobile station with information included in the message.

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