Patent Application
20070070942
The present invention relates generally to establishing channels between a mobile station and radio access network and, in particular, creating a semi-active state as a part of channel establishment.
Wireless communications networks use numerous different protocols, such as Code Division Multiple Access (CDMA), Global System for Mobile Communications (GSM), Universal Mobile Telecommunication System (UMTS), Push-to-Talk (PTT) and Push-to-Talk over Cellular (PoC) and others, to effectuate communication between users of mobile stations and other communication devices. In these systems, the communication link from the radio access network (RAN) to the mobile station is typically called the forward link or the downlink. Similarly, the communication link from the mobile station to RAN is typically called the reverse link or uplink. CDMA and other wireless network protocols use medium access control identifiers (MAC IDs) as a part of a means to identify a channel to the mobile station on the forward link. On the reverse link, the mobile stations transmissions are differentiated from one another by scrambling codes. Once a MAC ID and a scrambling code have been identified and exchanged, a dedicated channel is established between the mobile station and the base transceiver stations (BTSs) of the wireless network. With a dedicated channel established, data can be sent directly between the mobile station and the BTS such that when the MAC ID is assigned an active channel is established in which data flows.
One reason to establish a dedicated channel is that certain messaging or user data is too large to fit on shared or common channels. To transfer this data therefore requires establishment of such a dedicated channel. One of the drawbacks of establishing a dedicated channel is that the establishment of the dedicated channel itself can add significant delay. In dispatch communications, such as PTT and PoC, this additional delay can degrade the user experience while using the system.
Known methods of reducing the delay in setting up communication channels comes at the expense of RF capacity and battery life. Such methods speculatively place a user on a channel or use longer RF inactivity timers. RF capacity is reduced because dedicated channels are used before they are needed or longer than they are needed. In addition, prematurely using channels or extending the timer uses valuable battery life that could otherwise be used when data is actually being transmitted between the mobile station and the RAN.
In a typical wireless communication system, a large fraction of the resources dedicated to a given cell is not utilized or is otherwise underutilized. It has been estimated that approximately 70% of calls occur in cells or other sectors that have unused RF resources. It is possible, therefore, to leverage those unused RF resources to reduce the mobile initiated setup delay caused by the current call up routines of CDMA by over 400 msecs while simultaneously not degrading battery life.
It is known in High Rate Packet Data system and IS2000 traffic channel set up procedures to adjust the setup procedures to reduce delay times. In such systems, it is known for the controller to provide for multiple types of modes during the communication channel setup process. These modes can include an active mode, radio environment report (RER) mode and a dormant mode. The active mode permits active data transmission between the mobile station and the RAN, typically on dedicated channels. The RER mode is a mobility tracking mode where the mobile station reports significant changes in its radio environment to the network, typically on common channels. In this mode, the dedicated resources associated with the mobile station, such as the MAC ID, may be released and the mobile station's reverse pilot channel may operate in a reduced mode.
In contrast, a control-hold mode operates as an interim position between the active and dormant mode where the power control or dedicated pilot signaling is sent at a low rate in order to decrease the resource costs associated with a call. In this mode, the link is less effective at actually carrying bearer traffic thereby providing additional latency when data must be exchanged. Thus, resources remain allocated but the average reverse link power is reduced. In other words, the channel still operates but at a reduced capacity. Because the channel is still operating, battery life is compromised.
In view of the foregoing, it is desired to create a method and apparatus that establishes a communication channel that uses underutilized network resources but does not compromise battery life and the like. Such a solution can use the concept of multiple modes to establish a communication channel.
The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of method steps and apparatus components related to the use of a semi-active state during the establishment of a channel between a mobile station and a radio access network. Accordingly, the apparatus components and method steps have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.
In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.
It will be appreciated that embodiments of the invention described herein may be comprised of one or more conventional processors and unique stored program instructions that control the one or more processors to implement, in conjunction with certain non-processor circuits, some, most, or all of the functions for the use of a semi-active state during the establishment of a channel between a mobile station and a radio access network as described herein. The non-processor circuits may include, but are not limited to, a radio receiver, a radio transmitter, signal drivers, clock circuits, power source circuits, and user input devices. As such, these functions may be interpreted as steps of a method to perform the use of a semi-active state during the establishment of a channel between a mobile station and a radio access network. Alternatively, some or all functions could be implemented by a state machine that has no stored program instructions, or in one or more application specific integrated circuits (ASICs), in which each function or some combinations of certain of the functions are implemented as custom logic. Of course, a combination of the two approaches could be used. Thus, methods and means for these functions have been described herein. Further, it is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and ICs with minimal experimentation.
A system and method that creates a semi-active state during the establishment of a channel between a mobiles station and a wireless network, such as a RAN, is described. The approach described reduces the delay time in the request for a channel, the establishment of the channel and the sending of data over the channel. The use of the semi-active state also leverages resources within the wireless network that are otherwise not used without degrading the battery life of the mobile station. Such wireless networks include, but are not limited to, Code Division Multiple Access (CDMA), Global System for Mobile Communications (GSM), Universal Mobile Telecommunication System (UMTS), Push-to-Talk (PTT), Push-to-Talk over Cellular (PoC), wireless local area networks (WLANs) and networks that follow 802.xx standards, such as 802.16.
In at least one embodiment of the present invention, the channel is established between the mobile station and the wireless network or RAN by pre-assigning the mobile station a resource or other type of channel identifier without utilizing the resource to send data between the mobile station and the RAN. A MAC ID or reverse scrambling code can be used as the resource to identify the communication channel. By identifying the channel while not sending data, the semi-active state is established and the channel is ready for data transmission at the appropriate time. The semi-active state is a quasi sleeping state where the communication channel between the mobile station and the RAN is known and ready for use but some network resources previously utilized in the active mode are not utilized so that running capacity and battery life are not compromised.
On the forward link, the mobile station monitors the MAC ID for the transmission of data that is sent from the RAN to the mobile station. The mobile station is sent information and packets labeled by the MAC ID to differentiate information and packets sent to other mobile stations communicating with the RAN. Once the channel has been fully activated, the forward link sends power control information indicating whether the mobile station should power up or power down on the reverse link. In some cases, the mobile station receives from the RAN on the forward link acknowledgment/negative acknowledgments indicated whether or not the mobile's transmission was correctly received.
On the reverse link, the reverse scrambling code identifies the channel and is monitored by a reverse link dedicated channel element modem at the base transceiver sites of the RAN. The scrambling code for a given mobile station is typically assigned to a mobile station, either permanently or temporarily. When temporarily assigned, this is typically done through communication between the mobile station and the base station. The present invention does not impact the means for establishing or exchanging the scrambling code. On the reverse link, the mobile transmits the reverse pilot channel and the reverse data rate control using the scrambling code. The reverse pilot channel is a known signal used to assist in receiving any other channels transmitted by the mobile station and is used by the base station to determine power control for the mobile station transmissions. The data rate control channel carries channel quality information. In the past, a modem was only allocated to a mobile station when the mobile station was actually on the dedicated channel and actually transmitting on the reverse link. In accordance with the principles of the present invention, however, the modem is dedicated to monitor the reverse link before the mobile station begins transmitting on the dedicated channel.
As will be appreciated by those of skill in the art, in the active state voice and non-voice data can be sent over the channel between the mobile station and the RAN. Such communication can be both on the forward link and the reverse link. When the data transmission is detected on the reverse link, data rate control and power and pilot data are sent to convert the channel from the semi-active state to the active state. In at least one embodiment, the channel becomes active when the transmitted data rate control and power data reaches a given threshold, where such threshold is a maximum power rate. In an alternate embodiment, the channel becomes active when the RAN sends data at a wake-up interval for the assigned resource.
In one embodiment of the present invention, the mobile station initiates the establishment of the channel when the mobile station has data to send to the RAN on the reverse link using the reverse scrambling code. The network has pre-established the semi-active channel with the mobile unit, identifying and exchanging the MAC ID and the reverse scrambling code for the channel. The mobile station initiates the use of the semi-active channel when there is data to be sent to the RAN, such as when a call is being made. The RAN is monitoring the reverse scrambling code, which can be monitored by the reverse dedicated channel element at the RAN, to determine if the mobile station is sending data. The RAN monitors the power level received on the reverse dedicated power/pilot data or the reverse data rate control channels. When a threshold value is reached, the network begins transmitting to the mobile over the MAC ID including sending power control bits to the mobile. In one embodiment, a threshold number of power down messages is used to indicate that the RAN has detected the mobile station's initiation of using the channel. Thereby, the channel is effectively moved from the semi-active state to an active state so that data is transmitted between the mobile station and the RAN.
In another embodiment of the present invention, establishment of the channel by utilization of the semi-active channel is initiated from the RAN to the mobile station. Data transfer between the RAN and the mobile station can occur at given intervals. One such interval is the wake-up interval and that is when the mobile station will “wake-up” and listen to see if the RAN is establishing an active channel. At the wake-up interval the RAN sends the mobile station a packet using the MAC ID to indicate that the semi-active channel will be utilized and data will be sent. The mobile station will begin to send reverse data rate control and reverse dedicated pilot and power data. The RAN then monitors the power received on the reverse link and on the reverse dedicated power/pilot data or reverse data rate control channels.
Turning to
The system 100 may operate according to any number of protocols, including but not limited to CDMA and UMTS. For instance, messages may be exchanged between the system elements according to the Session Initiation Protocol (SIP). However, it will be understood that other protocols or SIP-compliant protocols may be used in addition or in place of the SIP protocol.
The BTSs 106, 108 are connected to the BSC 112. The BSC 112 is responsible for controlling operation of the BTSs 106, 108 and for routing communication between the BTSs 106, 108 and the other network elements, such as the Packet Control Function (PCF) 114. Further, the BSC 112 is responsible for identifying calls where the semi-active state is being utilized or can be utilized. It will be realized, however, that although these functions are described herein as being implemented at the BSC 112, the function can be alternatively be implemented at other elements within the infrastructure, including but not limited to the BTSs 106, 108 or the PCF 114.
The PCF 114 is connected to the RAN 104 and the Packet Data Server Node (PDSN) 116. The PCF is responsible for maintaining the connection between the mobile station 102 and the PDSN 116 as the connection between the mobile station 102 and the RAN 104 moves among the various modes and states as discussed above.
The PDSN 116 is connected to the PCF 114 and the Internet 118. The PDSN 116 routes packets between the Internet 118 and the mobile station 102 via the PCF 114, and performs other functions such as accounting and security.
Communication between the RAN 104 and the mobile station 102 is accomplished through channels. There are two classes of channels: dedicated channels and common channels. These channels are as described earlier in this specification.
When a dedicated channel 122 is established using the wireless communication network shown in
When the mobile station 102 and RAN 104 communicate when no dedicated channel 122 is established, they do so using common channels 130. The common channels include a forward control channel 132 and a reverse access channel 134. The forward control channel 132 is used by the RAN 104 to send messages to the mobile station 102 when no dedicated channel is established, such as the case when various control messages are sent from the RAN 104 to the mobile station 102. The reverse access channel 134 is used by the mobile station 102 to send messages to the RAN 104 when no dedicated channel is established, such as the case when various control messages are sent from the mobile station 102 to the RAN 104.
Turning now to
Turning now to
When the packet arrives at the PDSN 414 it relays that packet to the PCF 412. Because the PCF 412 is operating in dormant mode, it will request that the RAN 404 return the mobile station 402 to the active mode. One such way the RAN 404 can return the mobile station 402 to the active mode is to follow the routine as described in
As stated, the semi-active state is created by allocating a MAC ID, reverse scrambling code or other identification resource to a communication channel between the mobile station 502 and the RAN 504. With the identification resource allocated to the channel, there is no need to maintain the channel by sending data over the channel that will adversely affect the mobile station 402, e.g. draw on battery life, or affect the RF for the mobile station 502 or other mobile stations within the network. The MAC ID is assigned to a channel by the traffic channel assignment (TCA) message. A scrambling code can be used to identify the reverse link channel. It will be appreciated by those of ordinary skill, that other known features can be used to identify the channel while maintaining the semi-active status of the channel by not sending data between the mobile station and the RAN.
In an alternate embodiment, the RAN 504 can send data on the forward link that is detected by the mobile station 502 at a predetermined data rate. When the mobile station detects the designated data rate over the semi-active channel, the channel is converted to an active channel as described. Without having to send the connection request messages, the TCA messages and the various acknowledgements described in relation to
In an alternate embodiment of the present invention, at least one resource is allocated for use by a communication channel between the mobile station 502 and the RAN 504. This resource is preassigned to the channel so that either the mobile station 502 or the RAN 504 can utilize the allocated resource to refer to the channel. As the resource is preassigned, voice and non-voice data is not being sent between the mobile station 502 and the RAN 504, but when such data is detected or it is otherwise determined that data is being sent between the network elements, the channel is ready to transmit the data. The determination that data is to be transmitted can be achieved by monitoring network resources such as MAC IDs, reverse scrambling codes etc. When the monitoring activities indicate data transmission, the preassigned resource indicates the communication channel between the mobile station 502 and the RAN 504 that will be activated and over which the data will be transmitted. The transition between having a preassigned resource to designate the channel over which no data is transmitted and an active channel is described above. As will be appreciated, data transmission can be initiated from either the mobile station 502 or RAN 504 using the preassigned resource to designate the channel.
For a preassigned resource of the channel or the semi-active channel, an overhead channel can be used to transmit data between the mobile station and the RAN. As a part of the transition to utilize the communication channel to transmit data, such as converting the semi-active channel to an active channel, the overhead information is transmitted over the overhead channel. Such overhead information include RDRC data, increasing power up messages, power down messages and threshold messages to indicate to indicate that data will be properly transmitted over the communication channel.
A resource can be preassigned or a semi-active channel can be formed at any time depending on given resources. In some cases, particularly in areas where network resource are not fully utilized, a resource can be preassigned and a semi-active channel established whenever a mobile station 502 is in the area of a RAN 504. As the mobile station 502 moves within a wireless communication network, different semi-active channels can be established as a part of the soft hand off process between cells. In areas where the network resources are more fully utilized, not all mobile stations can be preassigned a resource because there are not enough the limited resources for all the mobile stations. Thus, criteria such as expiration of the mobile station's inactivity timer, accessing a phone book, opening a phone, dialing a number etc. will cause the mobile station 504 to request the preassignment of the resource. From the RAN's perspective similar criteria can be used to create the semi-active channel. Alternatively, the semi-active state is particularly appropriate for the subset of mobile stations that are most likely to send or receive a call shortly. The subset of users may be identified as users that had very recently made a call as a call may have been dropped. Additionally, the network may specifically select the subset of users or mobile stations with lower mobility or less than a threshold amount of handoffs because users which are mobile generate more load. When a mobile station is in the semi-active state, or switches from one BTS or sector to another, some messaging is exchanged over the common channel so the network can assign a new MAC ID in its new BTS. Thus, a highly mobile semi-active user uses more resources than stationary semi-active user.
In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.
| Number | Date | Country | |
|---|---|---|---|
| 60721286 | Sep 2005 | US |
