HK1083970B - Methods and apparatus for operating mobile nodes in multiple states - Google Patents

Description

Method and apparatus for operating a mobile node in multiple states

RELATED APPLICATIONS

Priority is claimed in this application in accordance with U.S. patent application 10/324,194 entitled "Methods and apparatus for Operating Mobile Nodes in Multiple States" filed on 12/20/2002 and U.S. provisional patent application 60/401,920 entitled "Methods and apparatus for imaging Mobile Communications System" filed on 8/2002, which are hereby expressly incorporated by reference.

Technical Field

The present invention relates to wireless communication systems, and more particularly, to a method and apparatus for supporting multiple mobile nodes in a resource-limited communication cell.

Background

Wireless communication systems are often implemented as one or more communication cells. Each cell typically includes a base station that supports communication with mobile nodes that are within, or come within, the communication range of the cell's base station. The unit of communication resources is a symbol inside a cell or inside a sector in a cell, for example, in an Orthogonal Frequency Division Multiplexing (OFDM) system, the symbol is QPSK or QAM transmitted in one frequency tone of one slot. The total available communication resource is divided into a number of symbols (units) that can be used to communicate control and data information between the base station and one or more mobile nodes in the cell, and these symbols tend to be limited. Control signals transmitted between the base station and the mobile node may be transmitted in two possible directions, respectively from the base station to the mobile node or from the mobile node to the base station. Wherein the transmission of signals from the base station to the mobile node is commonly referred to as the downlink. In contrast, transmissions from a mobile node to a base station are typically referred to as uplink.

To efficiently use limited communication resources, the base station may allocate different numbers of tones to different mobile nodes depending on the bandwidth requirements of the device. For example, in a multiple access system, several nodes may simultaneously use different tones to transmit data in the form of symbols to a base station. In OFDM systems, this operation is very common. It is very important that in such systems, symbols from different mobile nodes arrive at the base station in a synchronized manner, so that the base station can correctly determine the symbol period to which the received symbol belongs, and signals from different mobile nodes do not interfere with each other. When a mobile node enters a cell, the transmission delay will vary as a function of the distance between the mobile node and the base station. To ensure that the transmitted symbols from different mobile nodes arrive at the base station in a synchronized manner, timing control signals, such as feedback signals, are in many cases transmitted to each active mobile node in the cellular system. Typically, the timing control signal is specific to the respective device, and represents, for example, a timing offset correction used by the device to determine the timing of the transmission of the symbol. The timing control signaling operations include, for example, monitoring for timing control signals, decoding received timing control signals, and performing timing control update operations in response to the decoded received timing control signals.

Timing control signals are very important in systems with a large number of mobile nodes. To avoid interference from the mobile node due to timing loss, it is necessary to establish timing synchronization and control before allowing the mobile node to transmit voice data, IP packets containing data, and other data to the base station.

In addition to managing limited resources such as bandwidth, power management is also often a concern in wireless communication systems. Mobile nodes, such as wireless terminals, are typically battery powered. Since battery power is limited, power needs to be reduced, thereby increasing the operating time of the mobile node without charging or replacing the battery. To minimize power consumption, the amount of power used to transmit signals to the base station needs to be limited to the minimum amount of power required. Another advantage of minimizing the mobile node transmission power is that: it has the advantage of limiting the interference generated by the transmission in neighbouring cells, which typically use the same frequency as neighbouring cells.

To simplify transmission power control, power control signaling, such as a feedback loop, may be established between the base station and the mobile node. Power control signaling is typically performed at a much faster rate than timing control signaling. This is because power control signaling attempts to track signal strength changes between the base station and the mobile node, and this signaling typically changes on the millisecond scale. Timing control, however, only needs to take into account the distance change between the base station and the mobile node and typically changes on the basis of a very low range of hundreds of milliseconds to seconds. Therefore, the amount of control signaling overhead for power control tends to be much greater than the overhead for timing control.

In addition to timing and power control signaling, other types of signaling may be used. For example, the mobile node may additionally advertise downlink channel quality on the uplink. The base station may use the quality report to determine a communication resource allocation, thereby allowing transmission of data packets from the base station to the mobile node. Such downlink channel quality reports allow the base station to determine the mobile nodes to transmit and, if one is selected, the base station can determine the amount of forward error correction protection to apply to the data. As with power control signaling, these downlink channel quality reports are typically announced on a similar timescale. As another example, signaling may be used periodically to announce the presence of a mobile node in a cell to a base station. The signaling may also be used to request allocation of uplink resources for transmitting user data in a communication session, for example. Shared resources as opposed to dedicated resources may be used for such advertisements and/or resource requests.

The signaling resources, such as time slots or tones, may be shared or dedicated. In the case of shared slots or tones, multiple devices may attempt to communicate information at the same time using resources such as segments or slots. In the case of shared resources, each node in the system typically attempts to use the resource as needed. Such processing sometimes causes a conflict. For example, in the case of dedicated resources, time slots and/or tones may be allocated to a particular communication device or group of devices during a particular time period, thereby excluding other devices, in which case the problem of causing collisions may be avoided or reduced. The dedicated resources may be part of a common resource, such as a common channel, where channel segments are dedicated, e.g., allocated, to individual devices or groups of devices, where the groups contain fewer mobile nodes than the total number of mobile nodes in a cell. For example, for the uplink, time segments may be dedicated to individual mobile nodes, thereby avoiding possible collisions. For the downlink, time slots may be dedicated to individual devices, while for multicast messages or control signals, time slots may be allocated to a group of devices receiving the same message and/or control signal. Although common channel segments may be dedicated to individual nodes at different times, multiple nodes use different channel segments over time, thereby making all channels common to multiple nodes.

The logical control channels dedicated to individual mobile nodes may comprise common channel segments dedicated to individual mobile nodes.

Dedicated resources that are not used are very wasteful. However, the shared uplink resources that can be accessed by multiple users simultaneously can suffer from a large number of collisions, which can result in wasted bandwidth and unpredictable time required for communication.

Although timing and power control signals and downlink channel quality reports are useful in managing communications in a wireless communication system, due to limited resources, a base station is unable to support a large number of nodes when power control and other types of signaling support are required to be continually provided for each node in the system.

From the foregoing discussion, it should be apparent that a need exists for an improved method of allocating limited resources to a mobile node, thereby allowing a single base station to support a relatively large number of nodes using limited communication resources. It is highly desirable that at least some of the communication resource allocation and mobile node management methods take into account timing control signaling needs as well as power control signaling needs in the mobile communication system.

Disclosure of Invention

The present invention relates to methods and apparatus for supporting multiple wireless terminals, such as mobile nodes, by transmitting signals between a base station and a mobile node using limited resources, such as bandwidth and a single base station in a communication cell. A system may also be implemented and embodied in accordance with the invention as a plurality of cells, each cell including at least one base station and the base station serving a plurality of mobile nodes. The mobile node may, but need not, move within or between cells.

In accordance with the present invention, the mobile node supports a plurality of operating states. The control signaling resources used by the mobile node are varied according to the operating state. Thus, depending on the state of the mobile node, a large amount of signaling resources may be required, while in other states only minimal resources may be required. For example, in addition to being a data transmission resource, the control signaling resource is also a bandwidth for communicating payload data such as voice, data files, and the like. The amount of base station/mobile node control communications resources that are required for control purposes, which may be signal bandwidth, are different for different mobile node operating states, and by supporting different mobile node operating states, the base station can support more mobile nodes than if all mobile nodes were allocated the same amount of communications resources for control signaling purposes.

The bandwidth allocated to a mobile device for communicating control signals between the particular mobile device and the base station is known as the dedicated control bandwidth. The dedicated control bandwidth may comprise a plurality of dedicated logical or physical control channels. In some embodiments, each dedicated control channel corresponds to one or more dedicated segments in the common control channel. For example, a control channel segment may be a channel slot used to transmit and/or receive control signals. The dedicated uplink control channel segment is different from a shared uplink control channel segment in which multiple devices share the same bandwidth for uplink signaling.

With a shared communication channel, collisions may occur when multiple nodes simultaneously attempt to transmit control signals using the shared communication channel.

A mobile node implemented in accordance with one exemplary embodiment supports four states, such as an operational mode. The four states are a sleep state, a hold state, an access state and an on state. Among these states, the access state is a transition state, the other states are stable states, and the mobile node can be in these states for an extended period of time.

Of these four states, the on state requires the maximum amount of control signaling resources, e.g., bandwidth for control signaling. In this state, bandwidth is allocated to the mobile node as needed to transmit and receive traffic data, such as payload information such as text or video. Thus, at any given time in the on state, the mobile node may be allocated a dedicated data channel for conveying payload data. In addition, a dedicated uplink control signaling channel is allocated to the mobile node in the on state.

In various embodiments, during the on state, the MN uses a dedicated uplink control channel to generate downlink quality reports, communicate resource requests, and perform session signaling, among other things. Downlink channel quality reports are typically advertised frequently enough to track signal strength changes between the base station and the mobile node.

In the on state, the base station and the mobile node exchange timing control signals using one or more dedicated control channels, thereby allowing the mobile node to periodically adjust its transmission timing to account for distance variations, and from the perspective of the base station, to account for other factors that cause the transmission signal timing to drift, such as symbol timing. As described above, many systems use orthogonal frequency division multiple access in the uplink to prevent transmission signals generated by a plurality of nodes in the same cell from interfering with each other, and it is important for these systems to use timing control signaling and perform timing control signaling operations such as updating transmission timing.

To provide transmission power control, transmission power control signaling is used in the on state to provide a feedback mechanism so that the mobile node can effectively control the transmission power level based on signals periodically received from the base stations with which it is in communication. In various embodiments, the base station periodically transmits power control signals on a dedicated control downlink. As part of the transmission power control signaling process, the mobile node performs various transmission power control signaling operations including, for example, monitoring transmission power control signals to a particular mobile node, decoding received transmission power control signals, and updating transmission power levels based on the received and decoded transmission power control signals. Thus, if a power control signal is received in a dedicated downlink segment corresponding to a particular mobile node, the mobile node adjusts its transmission power level in response to the received signal. In this way, the mobile node can increase or decrease its transmission power to enable the base station to successfully receive signals without additional wasted power, and in addition, reduce interference and extend battery life. Power control signaling is typically performed frequently enough to track rapid changes in signal strength between the base station and the mobile node. The power control interval is a function of the minimum channel coherence time designed for the system. In general, power control signaling and downlink channel quality reporting have similar time scales, and the signaling is typically performed at a much higher frequency than timing control signaling. However, in accordance with a feature of the present invention, the base station varies the rate at which it transmits power control signals to the mobile node as a function of the operating state of the mobile node. Thus, in this embodiment, the rate at which the mobile node performs transmission power control adjustments varies as a function of the operating state of the mobile node. In one exemplary embodiment, no power control updates are performed in the sleep state, but are typically performed at a lower rate when performing power control updates in the hold state than in the on state.

The mobile node operation in the hold state requires relatively fewer control communication resources than resources such as bandwidth required to support the mobile node operation in the on state. Furthermore, in various embodiments, when in the hold state, the mobile node is not provided with bandwidth for transmitting payload data, but may be allocated bandwidth for receiving payload data. In such embodiments, the mobile node is not provided with a dedicated data uplink communications channel in the hold state. The bandwidth allocated for receiving data may be, for example, a data downlink channel shared with other mobile nodes. Timing control signaling is maintained in the hold state and the mobile node is allocated a dedicated control uplink communications resource, e.g., a dedicated uplink control communications channel, which the mobile node can use to request to change to another state. This would allow the mobile node to acquire additional communication resources by, for example, requesting a transition to an on state in which payload data may be transmitted. In some, but not all embodiments, in the hold state, the dedicated uplink control channel is limited to communicating only those signals that request permission to change the operating state of the mobile node from the hold state to the on state. In the hold state, the bandwidth allocated to the mobile node for control signalling, e.g. dedicated to the mobile node, is relatively small compared to the bandwidth in the on state.

By maintaining timing control while in the hold state, the mobile node may be allowed to transmit its uplink request, but this does not interfere with other mobile nodes in the same cell, and furthermore, if there is a dedicated uplink control resource, it may be ensured that the delay of the state transition is minimal since the state transition request does not collide with similar requests from other mobile nodes as in the case of shared uplink resources. Since timing control signaling is maintained, once the mobile node is provided with the requested uplink resources, for example, while transitioning from the hold state to the on state, it can transmit data without much delay, regardless of the uplink symbol timing offset which may cause interference to other mobile nodes in the cell. In the hold state, transmission of power control signaling is rarely stopped or performed at greater intervals than in the on-state operation. In this way dedicated control resources for power control signalling can be eliminated or reduced, allowing for a reduction in resources dedicated for this purpose, compared to the case where power control signalling for all nodes in the holding state is performed at the same rate as in the on state.

The mobile node may start with an initially high power at the time of transition from the hold state to the on state, so that, as part of the on state operation, the process ensures that the base station can receive its signal at a reduced power level when transmission power control signaling resumes at a normal rate. In one exemplary embodiment, when a mobile node in a hold state wants to transition to an on state, it transmits a state transition request using a dedicated uplink communication resource that is not shared with other mobile nodes. The base station then responds with a broadcast message indicating its response to the mobile node's state transition request. The mobile node receives the base station message assigned to it and responds with an acknowledgement. The acknowledgement is transmitted via a shared resource on the uplink and is subordinate to the broadcast message on the downlink.

The mobile node may transition to the dormant state by transmitting an appropriate state transition request. In one exemplary embodiment, when the mobile node does not want to transition to another state, the mobile node may not transmit any signal on the dedicated uplink communication channel, but other mobile nodes will not use the channel because the dedicated channel is allocated to the mobile node. In another embodiment, the mobile node uses an on/off signaling in its dedicated uplink communication channel, which sends a fixed signal (on) when the mobile node intends to transition to another state and does not send any signal (off) when it does not want to transition to any other state. In this case, if transmission is performed at a specific point in time, the transmission fixing signal may be interpreted as a request for transition to the on state, and if transmission is performed at another point in time, the transmission may be interpreted as a request for transition to the sleep state.

To support a large number of mobile nodes, it is necessary to support a dormant state that requires relatively few communication resources. In one exemplary embodiment, timing control signals and power control signaling are not supported in the sleep state. Thus, in the dormant state, the mobile node typically does not perform transmission timing control or transmission power control signaling operations such as receiving, decoding, and using timing and transmission power control signals. In addition, no dedicated uplink control resource, such as an uplink control communication channel, is allocated for the mobile node to generate the state transition request or payload transmission request. In addition, in the dormant state, the mobile node is not allocated dedicated bandwidth, a data transmission resource used in transmitting payload data that is part of a communication session with another node via the base station.

Assuming there is no dedicated uplink control channel in the dormant state, a shared communication channel is used to reach the base station and request the resources needed for the mobile node to start transitioning from the dormant state to another state.

In some embodiments, a mobile node in a dormant state may advertise its presence in a cell, for example, using shared communication resources, on command of a base station serving the cell. However, as described above, only a small amount of other signaling is supported in this operating state. Thus, only a small amount of control signaling bandwidth is used to communicate control information between a mobile node in a dormant state and a base station serving the node.

The access state is a state through which the mobile node in the dormant state transitions to one of the other supportable states. The transition between states may be triggered by the mobile node user performing an action, such as an attempt to transmit data to another mobile node. At the time of entering the access state, transmission power control and timing control signaling is not yet established. While in access state operation timing control signaling will be established and in various embodiments all or part of the transmission power control signaling will be established. The mobile node may transition from the access state to the on state or the hold state.

Establishing timing synchronization and transmission power control may take a certain time during which data transfer will be delayed. Also, access processing is performed over a shared medium, where contention among mobile nodes needs to be resolved. Since the transition from the hold state to the on state does not pass through the access state, according to the present invention, by supporting the hold state in addition to the dormant state, such delay can be eliminated for a large number of mobile nodes, while the number of nodes supported by a single base station is relatively large in this case compared to the case where no reduced mobile node operation signaling state is used.

In some embodiments, the maximum number of mobile nodes that can be dormant at any given time is set for an individual cell to be greater than the maximum number of mobile nodes that can be on hold at any given time. The maximum number of mobile nodes that can be on hold at any given time is set to be greater than the maximum number of mobile nodes that can be on at any given time.

In accordance with the power saving features of the present invention, downlink control signaling from a base station to a mobile node is divided among a plurality of control channels. The mobile node monitors different numbers of downlink control channels depending on the node operating state. Wherein a maximum number of downlink control channels are monitored in the on state. The number of downlink control channels monitored in the hold state is relatively small compared to the on state. While in the dormant state, the number of downlink control channels being monitored is minimal.

To further reduce power consumption associated with monitoring control signals in the mobile node, in accordance with one feature of the present invention, the control channels being monitored in the hold and sleep states are implemented as periodic control channels. In other words, the signal is not continuously broadcast on the channel being monitored in the hold and sleep states. Thus, in the hold and sleep states, the mobile node monitors the control signals at periodic intervals and does not monitor the control signals at those times when no control signals are transmitted on the monitored channels, thereby conserving power. To further shorten the time required for a particular mobile node to monitor control signals in the hold and sleep states, segmented such periodic control channel portions may be dedicated to one or a group of mobile nodes. Instead of monitoring all segments in the control channel, the mobile nodes learn their dedicated control channel segments and then monitor only their dedicated segments. This approach allows individual mobile nodes to monitor control signals in the hold and sleep states at greater periodic intervals than if the mobile node had to monitor all segments in the periodic control channel.

In a particular embodiment, in the on state, the mobile node continuously monitors segments in the assignment channel, and also monitors segments in the periodic quick paging and slow paging control channels. While in the hold state, the mobile node monitors the quick paging and slow paging control channels. The monitoring may include monitoring a subset of periodic fast and slow paging channel segments, such as segments dedicated to a particular mobile node. In a particular exemplary embodiment, a slow paging channel is monitored in the hold state instead of a fast paging channel or an assignment channel. The paging control channel may also be used to instruct the mobile node to change states.

By limiting the number of control channels and the rate at which control channels are monitored as a function of operating state, power resources can be conserved in accordance with the present invention when operating in the hold and sleep states.

Numerous additional features, advantages and details of the method and apparatus of the present invention are set forth in the detailed description which follows.

Drawings

Fig. 1 illustrates an exemplary communication cell implemented in accordance with the present invention, which may be part of a communication system.

Fig. 2 illustrates a base station implemented in accordance with the present invention.

Fig. 3 illustrates a mobile node implemented in accordance with the present invention.

Fig. 4 is a state diagram illustrating the different states a mobile node may enter while operating in accordance with the present invention.

Fig. 5 is a diagram illustrating different control and signaling modules executed by the mobile node in each of the different states shown in fig. 4.

Fig. 6 illustrates transmissions associated with three exemplary downlink control channels used in accordance with one embodiment of the present invention.

Fig. 7 illustrates the control channel shown in fig. 6 being monitored in each of four states in which the mobile node of the present invention can operate.

Detailed Description

Fig. 1 illustrates a communication cell 10 implemented in accordance with the present invention. The communication system may comprise a plurality of cells of the type described in figure 1. The communication cell 10 comprises a base station 12 and a number of mobile nodes 14, 16, for example N, which exchange data and signals with the base station by radio, as indicated by arrows 13, 15. In accordance with the present invention, the base station 12 and the mobile nodes 14, 16 are capable of performing and/or maintaining control signaling independently of communicated data signaling, such as voice or other payload information. Examples of control signaling include power control, downlink channel quality reporting, and timing control signaling.

Fig. 2 illustrates a base station implemented in accordance with the present invention. As shown, the exemplary BS 12 includes receiver circuitry 202, transmitter circuitry 204, a processor 206, a memory 210, and a network interface 208, which are coupled together by a bus 207. Receiver circuitry 202 is coupled to antenna 203 to receive signals from the mobile node. The transmitter circuitry 204 is coupled to a transmitter antenna 205 that can be used to broadcast signals to mobile nodes. Network interface 208 is used to couple base station 12 to one or more network components, such as a router and/or the internet. In this way, the base station 12 may act as a communication element between mobile nodes served by the base station 12 and other network elements.

The operation of the base station 12 is controlled by the processor 206 under the direction of one or more routines stored in the memory 210. Memory 210 includes communications routines 223, data 220, session management/resource allocation routines 222, session and resource signaling subroutines 224, and active user information 212. The communications routines 223 include different communications applications, such as IP telephony services or interactive games, that may provide particular services to one or more mobile node users. Data 220 comprises data to be transmitted to or received from one or more mobile nodes. Data 220 may include, for example, voice data, email messages, video images, game data, and so forth.

The session management and resource allocation routine 222 operates in conjunction with the subroutine 224, the valid user information 212, and the data 220. Where the routine 222 is responsible for determining whether and when a mobile node can transition between states, and which resources to allocate to a mobile node in a state. The routine may make the determination based on different criteria, such as requests from mobile nodes that require a transition between states, idle time/time spent by the mobile node in a particular state, available resources, available data, mobile node priority, etc. These criteria will allow the base station to support different quality of service (QoS) across the mobile nodes to which it is connected.

The session management routine 222 calls the session and resource signaling subroutine 224 when a signaling operation is required. This signaling is used to indicate that transitions between states are allowed. The signaling may also be used to allocate resources, for example, while in a particular state. For example, in the on state, it may provide resources for the mobile node to transmit or receive data.

The active user information 212 contains information for each active user and/or mobile node served by the base station 12. This information includes a set of state information 213, 213' for each mobile node and/or user. The state information 213, 213' includes, for example, whether the mobile node is in an on state, a hold state, a dormant state, or an access state supported in accordance with the present invention, the number and type of data packets that may be currently transmitted to or received from the mobile node, and information regarding the communication resources used by the mobile node.

Fig. 3 illustrates an exemplary mobile node 14 implemented in accordance with the present invention. The mobile node 14 includes a receiver 302, a transmitter 304, antennas 303, 305, a memory 210, and a processor, which are also coupled together as shown in fig. 3. The mobile node uses its transmitter 306, receiver 302 and antennas 303, 305 to transmit information to the base station 12 or to receive information from the base station 12.

Memory 210 includes user/device information 312, data 320, a power control and power control signaling module 322, a timing control and timing control signaling module 324, a device state control and state signaling module 326, and a data control and data signaling module 328. The mobile node 14 operates under the control of these modules, which are executed by the processor 306. User/device information 312 includes device information such as a device identifier, a network address, or a telephone number. The base station 12 may use this information to identify the mobile node, for example, when allocating a communication channel. The user/device information 312 also includes information related to the current state of the mobile device 14. And data 320 includes, for example, voice, text, and/or other data received from or to be transmitted to the base station as part of the communication session.

A device state control and status signaling module 326 is used for device state control and status signaling. The device state control module 326 determines the mode of operation, e.g., state, of the mobile node 14 at any given time by combining signals received from the base station 12. For example, in response to user input, mobile node 14 may make a request to base station 12 to allow transitioning from one state to another and be granted resources associated with a given state. The state control and status signaling module 326 then determines what signaling will occur and which signaling modules will be active based upon the operating state at any given time and the communication resources allocated to the mobile node 14. For example, in response to a shortened period of signal activity, such as control signal activity, state control and state signaling module 326 determines to transition from the current operating state to an operating state that requires less control resources and/or less power. Module 326 may, but need not, advertise the state transition to the base station. The state control and status signaling module 326 controls, among other things, the number of downlink control channels that are monitored in each operating state, and in various embodiments, the rate at which one or more downlink control channels are monitored.

As part of the process of controlling the state of mobile node 14, the signaling module is responsible for signaling base station 12 when mobile node 14 first enters a cell and/or when base station 12 requires mobile node 14 to indicate its presence, omitting conventional signaling between mobile node 14 and base station 12. Mobile node 14 may use the shared communication resources to announce its presence to cell base station 12 while also using dedicated communication resources for other communication signals, such as the upload and download of data files as part of a communication session.

The transmission power control and power control signaling module 322 is used to control the generation, processing, and reception of transmission power control signals. Module 322 controls signaling for implementing transmission power control by interacting with base station 12. Signals transmitted to and received from base station 12 are used to control the transmission power level of the mobile node, as directed by module 322. The base station 12 and the mobile nodes 14, 16 adjust the power output by using power control when transmitting signals. Where the base station 12 transmits signals to the mobile node which are then used by the mobile node in adjusting the transmission power output. The optimum power level for transmitting signals varies with several factors including the transmission burst rate, channel conditions, and distance from base station 12, e.g., the closer mobile node 14 is to base station 12, the less power mobile node 14 needs to transmit signals to base station 12. Using maximum power output for all transmissions is also disadvantageous, as the battery life of the mobile node 14 may be reduced and the high power output may increase the transmission signal potential, thereby causing collisions with transmissions in adjacent or overlapping cells. Transmission power control signaling allows the mobile node to reduce and/or minimize transmission output power, thereby extending battery life.

Timing control and timing control signaling module 324 is used for timing and timing signaling. Timing control is used in wireless networking schemes, for example, with an uplink based on orthogonal frequency division multiple access. Tone hopping may also be used here in order to reduce the effect of noise. Tone hopping can be a function of time in which different mobile nodes are assigned different tones in different symbol transmission time periods, referred to as symbol times. It is desirable for the base station 12 to receive information from mobile nodes in a synchronized manner so that the base station 12 in a multiple access system can track and distinguish signals from different mobile nodes. Timing offsets between the mobile nodes 14 and the base station 12 may cause transmission collisions, whereby it is difficult for the base station to distinguish between symbols transmitted by different mobile nodes using the same tone in different symbol periods or different tones in the same symbol period.

For example, the effect on the distance of a mobile node from a base station is a factor since transmissions from mobile nodes that are further away from the base station 12 take more time to reach the base station 12. A late arriving signal may interfere with another connection that hops to the frequency of the late arriving signal in a later period. In order to maintain symbol timing synchronization, it is necessary to instruct a node to advance or delay its symbol transmission start time, thereby taking into account variations in the time at which signals are propagated to the base station.

The data and data signaling module 328 is used to control the transmission and reception of payload data, such as controlling channels or time slots dedicated to the mobile node for signaling purposes. This includes, for example, data packets in an internet file transfer operation.

In accordance with the present invention, the mobile node 14 may be in one of four states. The signaling, power and communication resources required by the mobile node vary depending upon the operating state of the mobile node. Because multiple states are used in a mobile node, the base station 12 can allocate different degrees of communication resources, such as control and data signaling resources, to different mobile nodes as a function of the node's operating state. This process enables the base station 12 to support more mobile nodes than if all nodes were continuously on. The particular state in which the mobile node 14 is located determines the control signaling and data signaling modules that are performed at any given time, and also determines the level of control signaling between the mobile node and the base station 12. In addition, the mobile node 14 may also utilize different levels of activity in different states to conserve power and extend battery life.

The operation of the mobile node 14 in different states in accordance with the present invention will now be described with reference to fig. 4 and 5. Fig. 4 depicts a state diagram 400 containing four possible states that a mobile node 14 may enter, including an access state 402, an on state 404, a hold state 410, and a dormant state 408. Arrows are also used in fig. 4 to describe possible transitions between the four states.

Fig. 5 illustrates the mobile node modules 322, 324, 326, 328 in different states as shown in fig. 4. Each row in the graph 500 corresponds to a different state. The first through fourth rows 502, 504, 506, 508 correspond to a sleep state, an access state, an on state, and a hold state, respectively. Each column of the graph 500 corresponds to a different module within the mobile node 14. For example, a first column 510 corresponds to the transmission power control and power control signaling module 322, a second column 512 corresponds to the timing control and timing control signaling module 324, a third column 514 corresponds to the device state control and state signaling module 326, and a last column 516 corresponds to the data and data signaling module 328. In fig. 5, solid lines are used to indicate modules that are active in a particular state. Assuming that the module is not yet fully active, the short dashed line will be used to indicate those modules that may transition from an inactive or reduced-activity level to a fully active state before leaving the access state. The long dashed line is used to indicate a module that is active in one state, but that is capable of performing signaling at a reduced rate, opposite to the signaling rate implemented in the on state, when in the indicated state.

As can be seen in fig. 5, in the dormant state, the device state control and status signaling module 326 is still active, but the other modules are inactive, allowing for power savings and significantly limiting the activity of the mobile node. In the access state 402, which acts as a transition state, the transmission power control and power control signaling module 322, the timing control and timing control signaling module 324 are fully active (in some embodiments, active at a reduced rate for the transmission power control and power control signaling module 322) before leaving the access state 402 to enter the on state 404 or the hold state 410. In the on state, all signaling modules 322, 324, 326, 328 are fully active, which requires the most power from the mobile node's perspective and the most communication resource allocation, e.g., bandwidth, from the base station's perspective. In the hold state, the transmit power control and power control signaling module 322 may be inactive, but may also be active at a much reduced signaling rate. The timing control and timing control signaling module 324 remains active as the device state control and state signaling module 326. The data and data signaling module 326 is either inactive or operates to implement reduced functionality, such as receiving data but not transmitting data, as part of a communication session between different nodes. In this way, the hold state allows bandwidth and other communication resources to be conserved, while in some cases, the state also allows the mobile node to receive multicast signals and/or messages, for example.

Each state and possible transitions between states will now be described in detail with reference to the state diagram in fig. 4.

Of these four states 402, 404, 410, 408, the on state 404 allows the mobile node to perform a number of communication activities that may be supported, but which require the greatest amount of signaling resources, such as bandwidth. In this state 404, which may be considered an "all-on" state, mobile node 14 is allocated bandwidth as needed to transmit and receive data, such as payload information, e.g., text or video. The mobile node 14 is also assigned a dedicated uplink signaling channel that the mobile node can use to generate downlink channel quality reports, communication resource requests, and implement session signaling, among other things. To assist, these downlink channel quality reports should be advertised frequently enough to track changes in the signal strength received by the mobile node.

In the on state 404, the base station 12 exchanges timing control signals with the mobile node 14 under control of the module 324. Thereby allowing the mobile node 14 to periodically adjust its transmission timing, e.g., symbol timing, to account for variations in distance and other factors that may cause timing offsets at the base station receiver for signals transmitted by the mobile node relative to signals transmitted by other mobile nodes 16. As mentioned above, many systems use orthogonal frequency division multiple access in the uplink and in these systems use the application of symbol timing control signalling to avoid collision with transmission signals generated by multiple nodes in the same cell 10.

To provide transmission power control, transmission power control signaling is used in the on state 404 to provide a feedback mechanism, as directed by block 322, so that the mobile node can effectively control its transmission power based on signals periodically received from the base stations with which it is in communication. Thus, the mobile node 14 may increase and/or decrease its transmission power to enable the base station 12 to successfully receive signals without additional wasted power and without shortening battery life. Power control signaling is typically performed frequently enough to track changes in signal strength between the base station 12 and the mobile nodes 14, 16. The power control interval is a function of the channel coherence time. Power control signaling and downlink channel quality reporting have similar timescales and are typically performed at much higher rates than the timing control signaling required to support vehicle mobility.

The mobile node 14 may transition from the on state 14 to the dormant state 408 or the hold state 410. Each of these states requires only reduced communication resources to provide support, e.g., bandwidth, as compared to the on state 404. The transition may be in response to a user input, such as a user terminating the communication session, but the transition may also be in response to a loss of communication resources, such as bandwidth required to transmit and/or receive communicated information, such as voice or data information.

According to the invention, the mobile node is not provided with bandwidth for transmitting payload data in the holding state. However, timing control signalling will be maintained in this state and the mobile node will also be allocated dedicated uplink communications resources which the mobile node can use to request a change to its state. This would allow the mobile node to acquire additional communication resources by requesting to transition to an on state in which payload data may be transmitted. In the hold state 410, by maintaining timing control, the mobile node 14 may be allowed to transmit its uplink request without colliding with other mobile nodes 16 within the same cell 10. Furthermore, if there are resources dedicated to transmitting requests to the base station 12, these resources help to ensure that the delay of state transitions is minimal when these requests do not collide with the same requests from other mobile nodes.

For example, the mobile node may transition from the hold state 410 to the on state 404 when granted the requested communication resources. Alternatively, the mobile node may transition to the dormant state 408. Since the timing control signaling is maintained in the hold state 410, when the mobile node transitions to the on state, for example, once it is granted the requested bandwidth, it can transmit data without much delay without fear of collision with the uplink transmissions of other mobile nodes in the cell due to timing offsets of the mobile node.

The transmission of power control signaling may be stopped in the hold state 410 or performed at larger intervals, e.g., at a similar rate as timing control. In this way resources for transmitting power control signalling, such as base station-mobile node control resources, can be eliminated or resources dedicated for this purpose reduced compared to the case where the power control signalling for all nodes 14, 16 in the holding state is performed at the same rate as in the on state. In the hold state, transmission power control updates of the mobile nodes 14, 16 are performed at a reduced rate in the mobile nodes in a manner corresponding to reduced transmission power control signaling, but the updates may not be performed at all. Upon transitioning from the hold state 410 to the on state 404, the mobile node 14 may begin at an initial high power level to ensure that its signal is received by the base station 12. Then, as part of the on state operation, the power level is reduced once transmission power control signaling resumes at the normal (full) rate.

The transition from the hold state may be initiated by the base station or the mobile node. The base station may initiate a transition by sending a page on the paging channel assigned to the hold state user. In one embodiment, the mobile node decodes the paging channel according to a pre-scheduled period to check for base station messages. Upon discovering the paging message assigned to it, the mobile node responds with an acknowledgement. In various embodiments, the acknowledgement is transmitted via a shared resource on the uplink, and the acknowledgement is subordinate to a paging or grant message on the downlink. The mobile node 14 responds to the state change message by moving to the specified state specified in the received state change message.

In one embodiment, when the mobile node 14 intends to transition from the hold state 410 to the on state 404, it transmits a state transition request using a dedicated uplink communication channel that is not shared with other mobile nodes 16. Since there is no shared channel, the base station 12 can receive requests without conflict, and if the required resources are available, the base station will quickly grant the requests, thereby taking into account user priorities and/or applications that the user may be using. Upon receiving the grant message assigned to it, the mobile node will respond with an acknowledgement. The acknowledgement is transmitted via a shared resource on the uplink and is subordinate to the grant message on the downlink.

In one exemplary embodiment, when a mobile node does not want to transition from a hold state to another state, the mobile node may not transmit any signal in its dedicated uplink communications resources, but other mobile nodes will not use the resources because dedicated resources are allocated to the mobile node. In this case, the mobile node may temporarily turn off the transmission module and related functions, thereby saving power.

In another embodiment, the mobile node uses on/off signaling in its dedicated uplink communication resources, and when the mobile node intends to transition to another state, it sends a fixed signal (on) and when it does not want to transition to another state, it does not send any signal (off). In this case, if transmission is performed at a specific point in time, the transmission fixing signal may be interpreted as a request for transition to the on state, and if transmission is performed at another point in time, the transmission may be interpreted as a request for transition to the sleep state.

In order to provide reachability to a large number of mobile nodes 14, 16, it is necessary to provide support for a dormant state, which requires relatively few communication resources. Mobile node 14 may transition to dormant state 408 from any other state 404, 410 that may be supported, such as in response to a user input, an inactivity period, or a signal from base station 12.

In dormant state 408, mobile node 14 may announce its presence in the cell upon command of base station 12 serving cell 10. However, this operational state 408 supports only a small amount of other signaling. In the exemplary embodiment, timing control signaling and power control signaling are not supported in sleep state 408. The mobile node is also not allocated a dedicated uplink for generating resource requests and is not allocated bandwidth for use in transmitting payload data, for example, as part of a communication session with another node 16 via the base station 12.

The transition from the dormant state 408 to the other state 404, 410 is made across the access state 402. In contrast to dedicated uplinks, a shared (contention-based) communication channel is used to reach the base station 12, requesting the resources needed to transition from the dormant state 408 to another state 402, 404, 410. These transitions may be initiated by the base station on the paging channel or by the mobile nodes 14, 16. Because the communication channel used to request resources to transition from the dormant state is shared, mobile node 14 may experience a delay before successfully transmitting a resource request to base station 12. Since the request may collide with similar requests from other mobile nodes. The above delay does not occur for the transition from the hold state 410 to the on state while in the hold state 410 because dedicated uplink resources are used for the request.

The access state 420 is a state in which the mobile node 14 in the dormant state 408 may transition to one of the other supportable states 404, 410. The transition out of the dormant state may be triggered by the user of the mobile node 14 through an operation, such as an attempt to transmit data to another mobile node 16, but may also be triggered by the base station 12. At the time of entering the access state 402, transmission power control and timing control signaling is not yet established. Timing control signaling will be established during access state operation and in various embodiments all or a portion of the transmission power control signaling will be established with corresponding adjustments to the mobile node's transmission output power level. The mobile node may also transition from the access state 402 back to the dormant state 408 and may also transition to the on state 404 or the hold state 410. If the user cancels the transmission request or the base station 12 refuses to allocate resources for the node to transition to the hold or on state 404, 410, a transition back to the sleep state 408 may occur in response. Generally, the transition from the access state to the on state 404 or the hold state 410 is made when the mobile node 14 resumes its power and timing synchronization signaling with the base station 12 and is given one or more communication resources needed to maintain the state in which the mobile node is transitioning.

In the access state 402, establishing timing synchronization and transmitting power control signaling may take a significant amount of time during which data transmission may be delayed. Furthermore, as described above, delays may be caused by using shared resource request transitions, and thus contention may be generated between mobile nodes that may take time to resolve. Furthermore, since shared resources are used in requesting state transitions, it is difficult to prioritize between different nodes requesting state transitions.

For an individual cell 10, the maximum number of mobile nodes 14, 16 that can be in the dormant state 408 at any given time is set in some embodiments to be greater than the maximum number of mobile nodes 14, 16 that can be in the holding state 410 at any given time. The maximum number of mobile nodes 14, 16 that can be in the hold state 410 at any given time is set to be greater than the maximum number of mobile nodes that can be in the on state 404 at a given time.

Since the transition from the hold state 410 to the on state 404 does not pass through the access state, this delay can be eliminated for a large number of mobile nodes 14, 16 by supporting hold states other than the dormant state in accordance with the present invention, while in this case the number of nodes supported by a single base station 12 is relatively large compared to the case where no reduced signaling hold state is used.

From a power perspective, it is desirable to minimize the time and power consumed by the mobile node to monitor the control signals. To minimize the time and power consumed by the mobile node to monitor the control signals, a plurality of control channels are used to perform at least some downlink control signaling, i.e., signaling from the base station to one or more mobile nodes. In one embodiment of the present invention, which is particularly suited for use in conjunction with a mobile node capable of supporting multiple operating states, multiple control channels are provided for communicating control signals from the base station to the mobile node. Each of the plurality of common control channels is divided into a plurality of segments, e.g., time slots, where each segment is dedicated, e.g., assigned, to one or a group of mobile nodes for use thereby. In this case, for example, a group of mobile nodes in the system may be a subset of mobile nodes corresponding to a multicast message group. In this embodiment, the control channel is common to a plurality of nodes, but each segment in the channel is dedicated, e.g., corresponding to a particular mobile node or mobile group with a plurality of mobile nodes, and other mobile nodes are denied access to the dedicated segments. The dedicated segment of the common control channel corresponds to an individual mobile node and represents the dedicated control channel assigned to the individual mobile node.

For example, individual mobile nodes 14, 16 may learn the control channel segment allocation pattern based on information communicated from the base station 12 to each particular node 14, 16.

To provide particularly efficient control channel signaling, base station to mobile node control signaling may be performed at several different rates, with different control channels being used for each different control channel signaling rate.

To minimize the amount of power and resources consumed by the task of monitoring the control channel to obtain information concerning the mobile node, each mobile node need only monitor to detect signals in the control channel segment allocated for that particular node. This allows the mobile node to schedule control channel monitoring operations, thereby eliminating the need to continuously monitor the control channel while still allowing the mobile node to receive control signals in a timely manner.

In one embodiment that is particularly well suited for use with mobile nodes that support at least an on state, a hold state, and a dormant state, three different segmented control channels are used. The three control channels include an assignment control channel, a quick paging control channel, and a slow paging control channel.

In practice, both the quick paging control channel and the slow paging control channel are periodic, e.g., in which control signals are not transmitted continuously in time. Thus, the mobile node does not have to expend power and resources to continuously monitor these channels. In some embodiments, to further reduce the time and power consumed by a mobile node monitoring the fast and slow paging channels, the channels are segmented and the segments are dedicated to a particular mobile node or group of mobile nodes.

To minimize the power and resources expended in monitoring the control channel for the task of obtaining information concerning the mobile nodes, each mobile node need only monitor to detect signals in the fast and slow paging control channel segments assigned to that particular node. This allows the mobile node to schedule control channel monitoring operations so that the control channel does not have to be monitored as often as the number of operations that may be performed if all segments need to be monitored for control signals.

Fig. 6 illustrates control signals 602, 620, 630 corresponding to exemplary assignment channels, quick paging, and slow paging downlink control channels, respectively. The quick paging control channel signal 602 is divided into segments, which may be, for example, slots of 1 millisecond in size. In the embodiment of fig. 6, the transmission in these allocation channels is ongoing. For each slot, there are one or more corresponding traffic channel segments. Traffic channel segments are assigned to mobile nodes 14, 16 by base station 12 transmitting a mobile node identifier or mobile node group identifier in a time slot indicating that one or more mobile nodes corresponding to the transmitted identifier have been assigned a corresponding one or more traffic segments for use thereby. While in the on state, the mobile node 14, 16 continuously monitors the assignment channel at a rate sufficient to detect the identifiers contained in the segments of the control channel for traffic assignment purposes.

In the on state, each mobile node 14, 16 monitors periodic fast paging and slow paging channels in addition to the assignment channel.

As can be seen in fig. 6, the quick paging signal 620 is periodic in nature. Each exemplary quick paging signal cycle 622, 626, 630, 634 is 10 milliseconds in duration. However, in this 10 ms period, the quick paging signal is actually transmitted only a small fraction of the full period, e.g., 2 ms. The periods 623, 627, 631, 635 during which the quick paging signal is transmitted are segmented into time slots. While the remaining portions 624, 628, 632, 636 represent times when the base station 12 is not broadcasting the quick paging control signal. Although only two 1 millisecond segments are shown in each quick page turn-on period 623, 627, 631, 635, it should be understood that there are typically several segments at each turn-on time.

In some embodiments, to reduce the time required for the mobile nodes 14, 16 to monitor the quick paging control signal, the quick paging control channel segments are dedicated to individual mobile nodes or groups of mobile nodes. For example, typically, information of which segments are dedicated to which mobile nodes is communicated from the base station 12 to the mobile nodes 14, 16. Once the dedicated information is known, the mobile nodes 14, 16 may limit their operation of monitoring the quick paging channel segments to only monitoring the segments that are dedicated to them. In this embodiment, the mobile node may monitor the quick paging channel at periodic intervals greater than the quick paging cycle without risking loss of control information transmitted to the mobile node via the quick paging channel.

The quick paging channel segment is used to convey information, such as commands, that control the transition of the mobile node between states. The quick paging channel segment may also be used to instruct the mobile node to monitor the allocation channel, for example, when the mobile node is in a state such that it stops monitoring the allocation channel. Since the mobile nodes of the system know which segments of the quick paging channel are allocated to them, commands can be included in quick paging channel segments without a mobile node identifier, thereby achieving an efficient transmission scheme.

The slow paging channel is segmented in the same manner as the fast paging channel and is used to convey information. The information communicated using the slow paging channel may be the same or similar to the information and commands communicated using the fast paging channel.

In fig. 6, signal 630 represents an exemplary slow paging channel signal. It should be noted that the full slow paging signal period 632 is longer than the paging period 622 of the fast paging channel. Reference numerals 631 and 634 are used in fig. 6 to show a portion of the slow paging cycle. Given that the slow paging cycle is longer than the fast paging cycle, the time between performing control signal transmissions in the slow paging cycle is often greater than in the fast paging channel. This means that the mobile node may stop monitoring the slow paging channel for a longer time interval than the fast paging channel. However, it also means that, on average, control signals transmitted on the slow paging channel may take longer to be received by the intended mobile node.

Two slow paging signal transmissions are shown in fig. 6 at signal periods 640 and 642. The signal periods 639, 641, 643 correspond to slow paging channel signal periods during which no slow paging signals are transmitted.

Since both the fast and slow paging channels are periodic in nature, if the transmissions on a period are staggered so that they do not overlap, the fast and slow paging channels may be implemented using the same physical transmission resources, e.g., tones, which are interpreted as corresponding to either the fast or slow paging channels according to the time period to which the tones correspond.

The interval between segments allocated to a particular mobile node in the slow paging channel is typically, but not necessarily, greater than the interval in the fast paging channel. This typically means that in terms of time, the mobile device needs to monitor the slow paging channel over several time intervals, where the intervals are wider than the intervals at which the fast paging channel is monitored. Since the slow paging channel segments have a larger interval, the power required to monitor the channel is often less than the power required to monitor the fast paging channel.

According to one embodiment of the invention, different numbers of downlink control channels are monitored in different states. In this embodiment, the assignment channel, the fast paging channel, and the slow paging channel are not monitored in all states. In contrast, in the on state, the number of monitored downlink control channels is the largest, in the holding state, the number of monitored downlink control channels is relatively small, and in the dormant state, the number of monitored downlink control channels is the smallest.

Fig. 7 shows a table 700 depicting three exemplary base station-mobile node (downlink) control signaling channels, and the corresponding four exemplary mobile node operating states as described above. In table 700, a tick mark is used to indicate those control channels that are monitored in the designated state, while an X is used to indicate those control channels that are not monitored. A dashed tick is used to indicate a control channel that is not necessarily monitored during a portion of the state, but is monitored during at least a portion of the state.

According to fig. 7, the first row 702 corresponds to the on state, the second row 704 corresponds to the on state, the third row 706 corresponds to the hold state, and the fourth row 708 corresponds to the sleep state. The columns in table 700 correspond to different segmented control channels. The first column 710 corresponds to the assignment channel, the second column 712 corresponds to the quick paging channel, and the third column 714 corresponds to the slow paging channel.

As can be seen from the table 700, the mobile nodes 14, 16 monitor the assignment channel, the quick paging control channel, and the slow paging control channel while in the on state. The allocation channel and the quick paging channel are monitored for a portion of the access state indicating a transition between an on state and a hold state or a sleep state. While the slow paging channel is monitored throughout the period of time that the mobile node is in the access state. As described above, monitoring the fast paging and slow paging channels requires the mobile node to effectively perform periodic monitoring rather than continuous monitoring.

While in the hold state, where no monitoring of the allocation channel is performed. However, the quick paging channel and the slow paging channel are monitored at this time. Accordingly, a mobile node in a hold state may be instructed to change states and/or monitor the assignment channel for a relatively short period of time to find traffic channel segment assignment information.

In the dormant state, only the slow paging channel is monitored by the mobile node for the three control channels shown in fig. 6. Accordingly, the mobile node 14, 16 in the hold state may be instructed to change states and/or monitor the assignment channel to discover traffic channel segment assignment information, but on average, such instructions may take longer to detect than while in the hold state.

By reducing the number of control channels being monitored when operation proceeds from an on state to a less efficient dormant state, active control of the mobile node monitoring and processing resources and power consumption may be achieved. Thus, the dormant state requires less mobile node resources, including power, than the hold state. Also, the hold state requires less mobile node resources, including power, than the on state.

The transition of the mobile node from the active operating state to the less active operating state may be in response to a command received from the base station to change state. However, in different embodiments of the present invention, such a transition may also be initiated by the mobile node 14, 16 in response to detecting a downlink control signal inactivity period or reducing activity involving the mobile node.

In one embodiment of the present invention, if the mobile node decreases its activity state by one level, it will cease monitoring the control channel for activities associated with the mobile node 14, 16 that will be used to determine when the mobile node should itself switch to an operating state with a lower level of activity. For example, for the on state, the mobile node monitors the assigned channel for signals associated therewith. Upon failure to detect a signal on the assignment channel for a preselected period of time or upon detection of a reduced message level for a period of time, the mobile node 14, 16 switches from the on state to the hold state and ceases monitoring the assignment channel.

While in the hold state, the mobile node 14, 16 monitors the quick paging channel for activity, and in particular determines whether it should switch to a less active operating state, such as a dormant state. Upon failure to detect a signal in a preselected period of time or a reduced signal level in a certain period of time, the mobile node 14, 16 switches from the hold state to the dormant state and ceases monitoring the quick paging channel.

With the above approach, signal processing and power resources may be conserved in the mobile nodes 14, 16 by using multiple operating states and using multiple segmented control channels. Furthermore, since a plurality of control channels, such as the segmented control channels of the type described above, are used, bandwidth, a limited control resource for communicating control information from the base station to the mobile node, can be efficiently used.

Many variations on the above-described methods and apparatus will be apparent to those skilled in the art in light of the above description of the invention. And all such variations are intended to be included within the scope of the present invention.

Claims (55)

1. A method of communication, the method comprising:

operating the first wireless terminal at different times and in each of three different operating states, the three different operating states including a first state, a second state, and a third state,

wherein operating the first wireless terminal in the first state comprises: communicating control information between the first wireless terminal and a base station using a first number of control communications resources and performing power control signalling at a first rate using some of the first number of control communications resources;

wherein operating the first wireless terminal in the second state comprises: communicating control information between the first wireless terminal and a base station using a second number of control communications resources and performing power control signalling at a second rate using some of the second number of control communications resources, wherein the second rate is lower than the first rate;

wherein operating the first wireless terminal in the second state comprises: using fewer control communication resources than the first wireless terminal uses in the first state,

wherein operating the first wireless terminal in the third state comprises: using fewer control communication resources than the first wireless terminal uses in the first or second state, an

Operating a first wireless terminal to transition from one of said first and second states to said third state, the step of transitioning from one of said first and second states to said third state comprising reducing the rate of power control signaling.

2. The method of claim 1, wherein operating the first wireless terminal in the first state to use the first number of control communications resources comprises:

the first wireless terminal is operated to perform timing control signaling operations.

3. The method of claim 1, further comprising:

operating a first wireless terminal to transition from a first state to a second state, the transition comprising reducing a rate of power control signaling performed by the first wireless terminal.

4. The method of claim 3, wherein the step of reducing the rate of power control signaling when transitioning from one of said first and second states to said third state comprises ceasing to perform power control signaling.

5. The method of claim 4, further comprising: ceasing to perform timing control signaling upon transitioning from the first state to the third state.

6. The method of claim 3, wherein reducing the power control signaling operation rate comprises:

performing a transmission power control update operation at a time interval greater than a transmission power control update operation performed in the first state.

7. The method of claim 6, wherein transitioning from the second state to the third state comprises:

the first wireless terminal is operated to stop performing the transmission power control update operation.

8. The method of claim 2, wherein the timing control update operation is performed in said first state but not in said third state, said method further comprising the steps of:

operating a first wireless terminal to transition from said third state to one of said first and said second states, the step of transitioning to one of said first and second states comprising: resuming transmission timing control update operations.

9. The method of claim 8, wherein operating the first wireless terminal to transition from the third state to one of the first state and the second state comprises: the first wireless terminal is operated to resume transmission power control signaling operations.

10. The method of claim 9, wherein resuming transmission timing control update operations comprises:

a request is transmitted to the base station for allocation of communication resources required to perform transmission timing control signaling.

11. The method of claim 10, wherein transmitting a request for communication resources required to perform transmission timing control signaling comprises:

the request is transmitted using a shared communication channel segment.

12. The method of claim 11, further comprising:

operating a first wireless terminal to transition from the second state to the first state, the step of transitioning from the second state to the first state comprising: a request is transmitted that requires dedicated communication resources that can be used to transmit data to be communicated to the base station.

13. The method of claim 12, wherein operating the first wireless terminal to transmit a request for dedicated communication resources available for transmitting data comprises: the resource request is transmitted to the base station using a dedicated resource request uplink allocated to the first wireless terminal.

14. The method of claim 1, wherein said control communications resource is a control signaling bandwidth for communicating control signals between said base station and a plurality of wireless terminals served by said base station.

15. The method of claim 14, wherein the first state is an on state, the second state is a hold state, and the third state is a sleep state, the method further comprising:

in at least a portion of the on state, the first wireless terminal is operated to transmit and receive data as part of a communication session with another terminal.

16. The method of claim 15, further comprising:

in at least a portion of the holding state, the first wireless terminal is operated to receive data from another terminal, and no data is transmitted at any time while operating in the holding state.

17. The method of claim 16, wherein operating the first wireless terminal in the dormant state comprises: the first wireless terminal is controlled so that data corresponding to a communication session is neither transmitted from nor received by the first wireless terminal in any portion of the dormant state.

18. The method of claim 1, wherein the first state is an on state, the second state is a hold state, and the third state is a sleep state, the method further comprising:

operating a second wireless terminal in each of the on state, the hold state, and the sleep state at different times;

wherein operating the second wireless terminal in the on state comprises: communicating control information between the second wireless terminal and the base station using a fourth amount of control communication bandwidth; and

wherein operating the second wireless terminal in the hold state comprises: communicating control information between the second wireless terminal and the base station using a fifth number of control communication bandwidths, wherein the fifth number of control communication bandwidths is less than the fourth number.

19. The method of claim 18, further comprising:

operating the second wireless terminal to transmit and receive data as part of a communication session with another terminal for at least a portion of the time the second wireless terminal is operated in the on state.

20. The method of claim 19, further comprising:

operating the second wireless terminal to receive data from another terminal for at least a portion of the time the second wireless terminal is operated in the holding state, no data being transmitted at any time while the second wireless terminal is operated in the holding state.

21. The method of claim 20, wherein operating the second wireless terminal in the dormant state comprises: controlling the second wireless terminal to neither transmit data corresponding to a communication session from the second wireless terminal nor receive the data by the second wireless terminal during any portion of time that the second wireless terminal is operating in the dormant state.

22. The method of claim 19, wherein said step of treating,

wherein the data to be communicated as part of a communication session comprises IP packets, wherein at least some of the IP packets comprise voice data; and

wherein the second wireless terminal transmits the IP packet to the base station using an orthogonal frequency division multiplexing signal.

23. The method of claim 1, wherein operating the first wireless terminal in the second state comprises: transmitting a control signal initiating a state change using a dedicated uplink communication resource, wherein transmission of the state change control signal is contention free due to the use of the dedicated communication resource.

24. The method of claim 23, wherein operating the first wireless terminal in the second state further comprises:

communicating a transition message of a state change via a shared downlink communication resource, wherein a plurality of wireless terminals monitor the shared downlink communication resource for state transition control messages.

25. The method of claim 24, wherein the first state is an on state, the second state is a hold state, and the third state is a sleep state, in the hold state the first wireless terminal performing power control signaling at a lower rate than in the on state, and in the sleep state the first wireless terminal not performing power control signaling.

26. The method of claim 25, wherein said first wireless terminal does not perform timing control signaling in said dormant state.

27. The process of claim 1, wherein the first step is carried out,

wherein the first state is an on state, the second state is a hold state, and the third state is a sleep state,

wherein the first wireless terminal has dedicated contention-free uplink and downlink resource request communication resources that can be used in the on-state;

wherein the first wireless terminal has a dedicated contention-free uplink resource request communication resource that can be used in the holding state and also has a contention-signaling based shared downlink resource request communication resource that can be used in the holding state; and

wherein in the dormant state the first wireless terminal has neither a dedicated contention-free uplink resource request communication resource nor a dedicated contention-free downlink resource request communication resource.

28. The method of claim 1, wherein the state transition is performed as a function of a quality of service level provided to said first wireless terminal.

29. The method of claim 1, wherein the state transition is performed as a function of user activity.

30. The method of claim 1, wherein the transition from said one of said first and second states is performed as a function of user data activity.

31. The process of claim 1, wherein the first step is carried out,

wherein operating the first wireless terminal in the third state comprises: using a first set of communication resources;

wherein operating the first wireless terminal in the second state comprises: using the first set of communication resources and the second set of communication resources used in the third state; and

wherein operating the first wireless terminal in the first state comprises: a third set of communication resources is used in addition to the first and second sets of communication resources.

32. The method of claim 31, wherein each of said first, second and third communication resources comprises a communication channel segment used by said first wireless terminal.

33. The method of claim 1, wherein operating the first wireless terminal in the first state and the second state comprises:

communicating a timing control signal between the base station and the first wireless terminal.

34. The method of claim 33, wherein timing control signals are communicated between said base station and said first wireless terminal in said first state at least as fast as the rate at which timing control signals are communicated between said base station and said first wireless terminal in said second state.

35. The method of claim 33, wherein a rate at which timing control signals are communicated in said first state does not exceed a rate at which power control signals are communicated in said first state.

36. The method of claim 35, wherein a rate at which timing control signals are communicated in said second state does not exceed a rate at which power control signals are communicated in said second state.

37. The method of claim 1, wherein operating the first wireless terminal in the second state comprises:

in addition to timing control and power control signaling, downlink signaling is received using a communication channel whose data is monitored by a plurality of wireless terminals.

38. The method of claim 37, wherein the shared communication resource is a communication channel, and wherein the downlink signal includes text information transmitted to the plurality of wireless terminals.

39. The method of claim 1, wherein operating the first wireless terminal in the third state comprises: the common uplink signaling resource is used to transmit a signal for initiating a state change.

40. The method of claim 39, wherein using the common uplink signaling resource to transmit the signal for initiating the state change comprises: the contention-based signaling is performed as part of a process of transitioning from the third state to one of the first and second states.

41. The method of claim 1, wherein the method further comprises: operating a base station comprised in the same cell as the first wireless terminal, wherein the base station allocates at least some downlink communications resources for communicating data from the base station to the first wireless terminal in the second state, the downlink communications resources for communicating data being different from control communications resources for controlling wireless terminal signalling activity.

42. The method of claim 1, wherein the method further comprises operating a base station comprised in the same cell as the first wireless terminal so as not to allocate dedicated uplink data communication resources to the first wireless terminal in the second state, wherein the uplink data communication resources are different from timing control and power control communication resources.

43. The method of claim 1, wherein the method further comprises operating a base station comprised in the same cell as the first wireless terminal to control state transitions to provide different levels of quality of service for different terminals in the cell.

44. A method for operating at least a first wireless terminal, the method comprising:

controlling the first wireless terminal to operate in each of at least three different operating states at different times, the three different operating states including an on state, a hold state, and a sleep state;

wherein operating the first wireless terminal in the on state comprises: communicating power control information at a first rate between the first wireless terminal and a base station;

wherein no power control information is communicated between the base station and the first wireless terminal when the first wireless terminal is operated in a sleep state;

wherein operating the first wireless terminal in the hold state comprises: communicating power control information between the first wireless terminal and a base station at a rate lower than the first rate and using a dedicated uplink communications resource to communicate information to the base station, the base station using the dedicated uplink communications resource in addition to power control signalling and timing control signalling communications resources in the holding state; and

in response to a change, a transition from one of the three states to another of the three states is user activity.

45. The method of claim 44, wherein said information transmitted using said dedicated uplink communications resource in said hold state includes a signal for initiating a state transition, said signal being transmitted without contention due to transmission of said signal using at least one uplink communications resource segment dedicated to said first wireless terminal.

46. A method for a base station in a communication system, the base station controlling allocation of control signaling resources and data transmission resources to a plurality of nodes served by the base station, the method comprising:

controlling a first subset of the plurality of nodes to operate in an on state in which nodes in the first subset are allocated data communications resources for communicating data and a first level of control signalling resources for performing control signalling,

controlling a second subset of the plurality of nodes to operate in a holding state, wherein nodes in the second subset are allocated a second level of control signaling resources for performing control signaling in the holding state, the second level of control signaling being less than the first level of control signaling; and

controlling a third subset of the plurality of nodes to operate in a dormant state in which relatively less control signaling resources are allocated to nodes in the third subset than to the first or second subsets;

wherein the base station allocates relatively more power control signalling resources for nodes in the on state than for nodes in a holding state; the base station allocates relatively more power control signalling resources for nodes in the holding state than for nodes in the dormant state.

47. The method of claim 46, wherein said system includes said plurality of nodes, a first subset of nodes performing transmission timing control signaling operations while in said on state.

48. The method of claim 47, wherein the second subset of nodes, when in said hold state, perform transmit timing control signaling operations and reduced rate transmit power control signaling operations.

49. The method of claim 47, wherein the second subset of nodes cease transmission power control update operations upon transitioning from the on state to the hold state.

50. The method of claim 47, wherein a third subset of said nodes cease transmitting timing control signals upon transitioning from said holding state to said dormant state.

51. The method of claim 46, wherein the communication system further comprises the plurality of nodes, the third subset of nodes comprising more communication devices than the second subset of nodes.

52. The method of claim 51, wherein the second subset of nodes includes more nodes than the first subset of nodes.

53. The method of claim 52, wherein the third subset of nodes do not perform transmission power control signaling operations.

54. The method of claim 53, wherein the second subset of nodes do not perform transmission power control signaling operations.

55. The method of claim 53, wherein the second subset of nodes perform power control signaling operations at a rate that is lower than a rate at which nodes in the first subset perform transmit power control signaling operations.