Systems and methods for multiplexing control data for multiple data channels onto a single control channel

Systems and methods for communicating control data for multiple data channels using a single control channel. In one embodiment, a method is implemented in a WCDMA communications system. This method includes combining data rate information for a first data channel and data rate information for a second data channel in a mobile station, encoding the combined data rate information and transmitting the encoded combined data rate information from the mobile station to a base station via a single control channel. This method further includes receiving the encoded combined data rate information in the base station, decoding the encoded combined data rate information to produce the combined data rate information, and extracting the data rate information for the first and second data channels and decoding the first and second data channels using this information.

REFERENCE TO CO-PENDING APPLICATIONS FOR PATENT

“Systems and Method for Multiplexing Control Information Onto a Physical Data Channel” having Ser. No. US 2005/0163071 A1, filed concurrently herewith, assigned to the assignee hereof, and expressly incorporated by reference herein; and

“Systems and Method for Communication Control Data Using Multiple Slot Formats” having Ser. No. US 2005/0163065 A1, filed concurrently herewith, assigned to the assignee hereof, and expressly incorporated by reference herein.

FIELD OF INVENTION

The present invention relates generally to communication systems and more particularly to systems and methods for providing control information for multiple data channels by combining the control information and transmitting the combined information on a single control channel.

BACKGROUND OF THE INVENTION

A wireless telecommunications system may be used to enable information to be communicated between a mobile device and a base station, between a mobile device and an information server, between mobile devices, and so on. The information communicated between the various devices may include audio (e.g., voice) information, high speed data, control information and various other types of data.

One exemplary telecommunications system includes a base station controller, one or more base stations and one or more mobile stations. Each of the base stations is coupled to the base station controller by a network that is normally referred to as the backhaul network. The backhaul network typically comprises physical communication links between the base station controller and the base stations. Each of the mobile stations is coupled to one of the base stations. The communication links between the mobile stations and the base stations comprise wireless links.

The wireless communication link between each mobile station and the base station with which it communicates includes a set of channels for communicating data from the base station to the mobile station, as well as a set of channels for communicating data from the mobile station to the base station. The first set of channels (from base station to mobile station) are referred to as the forward link. The second set of channels (from mobile station to base station) are referred to as the reverse link.

The channels of both the forward link and reverse link are configured to carry various types of information. For example, some of the channels carry data, while others carry control information. In one embodiment, the reverse link includes a primary dedicated data channel and a corresponding dedicated control channel. The control channel is configured to carry information necessary to decode the primary dedicated data channel, such as an indication of the data rate at which data is transmitted on the data channel.

It may be desirable to add another data channel to this system. Just as with the primary dedicated data channel, it will be necessary to transmit control information for the additional data channel in order to enable the base station to decode the data that is transmitted on the additional data channel. Conventionally this control information would be transmitted on an additional control channel corresponding to the additional data channel. This solution, however, is disadvantageous in that it requires the use of resources (e.g., additional processing, additional spreading codes, etc.) to support the additional control channel. It would therefore be desirable to provide improved systems and methods for communicating the necessary control information for the additional data channel.

SUMMARY

Embodiments disclosed herein address the above stated needs by using a single control channel to transmit control information for multiple data channels. One embodiment comprises a method implemented in a W-CDMA communications system. This method includes combining data rate information for a first data channel and data rate information for a second data channel in a mobile station, encoding the combined data rate information and transmitting the encoded combined data rate information from the mobile station to a base station via a single control channel. This method further includes receiving the encoded combined data rate information in the base station, decoding the encoded combined data rate information to produce the combined data rate information, and extracting the data rate information for the first and second data channels and decoding the first and second data channels using this information.

An alternative embodiment comprises a method implemented in a mobile station for a wireless communication system. This method includes combining data rate information for a first data channel and data rate information for a second data channel in a mobile station, encoding the combined data rate information and transmitting the encoded combined data rate information from the mobile station to a base station via a single control channel.

Another alternative embodiment comprises a method implemented in a base station for a wireless communication system. This method includes receiving the encoded combined data rate information in the base station, decoding the encoded combined data rate information to produce the combined data rate information, and extracting the data rate information for the first and second data channels and decoding the first and second data channels using this information.

Another alternative embodiment comprises a mobile station including a transceiver subsystem and a processing subsystem coupled to the transceiver subsystem, where the processing subsystem is configured to combine data rate information for a first data channel and data rate information for a second data channel, encode the combined data rate information, and transmit the encoded combined data rate information via a single control channel.

Another alternative embodiment comprises a base station including a transceiver subsystem and a processing subsystem coupled to the transceiver subsystem, where the processing subsystem is configured to receive encoded combined data rate information via a single control channel, decode the encoded combined data rate information to produce combined data rate information and extract data rate information for a first data channel and data rate information for a second data channel from the combined data rate information.

Another alternative embodiment comprises a wireless communication system including a mobile station and a base station. The mobile station is configured to combine data rate information for a first data channel and data rate information for a second data channel, encode the combined data rate information, and transmit the encoded combined data rate information via a single control channel. The base station is configured to receive the encoded combined data rate information via the single control channel, decode the encoded combined data rate information to produce the combined data rate information, and extract the data rate information for the first data channel and the data rate information for the second data channel from the combined data rate information.

Numerous additional alternative embodiments are also possible.

While the invention is subject to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and the accompanying detailed description. It should be understood, however, that the drawings and detailed description are not intended to limit the invention to the particular embodiments which are described.

DETAILED DESCRIPTION

As described herein, various embodiments of the invention comprise systems and methods for communicating control data for multiple data channels using a single control channel. In one embodiment, a method is implemented in a W-CDMA communications system. This method includes combining data rate information for a first data channel and data rate information for a second data channel in a mobile station, encoding the combined data rate information and transmitting the encoded combined data rate information from the mobile station to a base station via a single control channel. This method further includes receiving the encoded combined data rate information in the base station, decoding the encoded combined data rate information to produce the combined data rate information, and extracting the data rate information for the first and second data channels and decoding the first and second data channels using this information.

One embodiment of the invention is implemented in a wireless telecommunications system that is designed in accordance with a W-CDMA (wideband code division multiple access) standard. It will therefore be helpful to describe the basic structure and operation of such a system in order to aid in the understanding of the invention. It should be noted that, while the following description focuses primarily upon a system that follows this standard, alternative embodiments may be implemented in systems that follow other standards as well.

Referring toFIG. 1, a diagram illustrating the structure of a wireless telecommunications system in accordance with one embodiment is shown. System100includes a base station controller110, a base station120that is coupled to base station controller110through a backhaul network130, and a mobile station140. System100may include additional base stations and mobile stations which, for purposes of clarity, are not shown in the figure.

The terminology used to refer to the components of the system may differ from one embodiment to another. For example, base station controller110may be referred to as a radio network controller (RNC), base station120may be referred to as a “Node-B,” and mobile station140may be referred to as user equipment (UE). Because the various embodiments of the invention may be implemented in different types of wireless communication systems (e.g., systems designed according to different standards or different releases of the same standard,) references to the different components of the systems should be interpreted broadly, and references to particular components using terminology applicable to a particular type of system should not be construed to imply that the embodiments of the invention are limited to that particular type of system.

It should also be noted that, while the description herein of this and other embodiments focuses on a system in which a mobile station may move with respect to a base station, other embodiments may be implemented in systems that enable wireless communication between alternative types of devices. It is not necessary that one of the devices be a “base station,” nor is it necessary that the other of the devices be “mobile.” References herein to mobile stations and base stations should therefore be construed to include any wireless transceiver devices that are in communication with each other.

While, in practice, the specific designs of base station120and mobile station140may vary significantly, each serves as a wireless transceiver for communicating over the forward and reverse links. Base station120and mobile station140therefore have the same general structure. This structure is illustrated inFIG. 2.

Referring toFIG. 2, a functional block diagram illustrating the basic structural components of a wireless transceiver system in accordance with one embodiment is shown. As depicted in this figure, the system comprises a transmit subsystem222and a receive subsystem224, each of which is coupled to an antenna226. Transmit subsystem222and receive subsystem224may be collectively referred to as a transceiver subsystem. Transmit subsystem222and receive subsystem224access the forward and/or reverse link through antenna226.

Transmit subsystem222and receive subsystem224are also coupled to processor228, which is configured to control transmit and receive subsystems222and224. Memory230is coupled to processor228to provide working space and local storage for the processor. Processor228and memory230may be collectively referred to as a processing subsystem. A data source232is coupled to processor228to provide data for transmission by the system. Data source232may, for example, comprise a microphone or an input from a network device. The data is processed by processor228and then forwarded to transmit subsystem222, which transmits the data via antenna226. Data received by receive subsystem224through antenna226is forwarded to processor228for processing and then to data output234for presentation to a user. Data output234may comprise such devices as a speaker, a visual display, or an output to a network device.

Persons of skill in the art of the invention will appreciate that the structure depicted inFIG. 2is illustrative and that other embodiments may use alternative configurations. For example, processor228, which may be a general-purpose microprocessor, a digital signal processor (DSP) or a special-purpose processor, may perform some or all of the functions of other components of the transceiver, or any other processing required by the transceiver. The scope of the claims set forth below are therefore not limited to the particular configurations described herein.

Mobile station140typically is not stationary (although, in some instances, it may be.) Mobile station140is instead likely to move with respect to base station120. The changing position of mobile station140typically causes the channel conditions for the wireless link between mobile station140and base station120to vary. The channel conditions may also be affected by other factors, such as atmospheric conditions, movement of other objects between mobile station140and base station120, interference from other transmitters, and so on.

Because of the changes in the channel conditions for the wireless communication link, there may be changes in the data rate at which mobile station140transmits data to base station120. These changes in the data rates used by mobile station140to transmit the data are necessary to provide a high enough signal-to-noise ratio, SNR, (or signal-to-interference-and-noise ratio, SINR,) that base station120will receive the data with an acceptable error rate. The better the channel conditions, the higher the data rate that can be used by the mobile station. The worse the channel conditions, the lower the data rate that must be used by the mobile station.

The data rate and corresponding data format for one or more channels may, in some embodiments, be referred to as a transport format (TF) or transport format combination (TFC). For purposes of clarity, individual transport formats as well as transport format combinations may be referred to below simply as data rates.

In one embodiment, the mobile station of the wireless telecommunications system is configured to transmit information to the base station on three channels. The first of these channels is a dedicated data channel. This data channel may carry various types of data, including such high priority data as voice data, streaming video or the like, and lower priority data, the delivery of which is not delay-sensitive. This dedicated data channel may be referred to herein as the primary data channel. The second of the channels is a control channel. The control channel carries control information that is needed by the base station in order to properly decode the data transmitted on the primary data channel. This control information may, for example, include pilot channel information, power control information and data rate information. These different types of information may also be characterized as different logical channels within the physical control channel.

The primary data channel and the control channel are found in conventional WCDMA systems. Typically, for each frame that is transmitted on the primary data channel, there is a corresponding frame that is transmitted on the control channel. The information contained in the frame of the control channel is received by the base station, decoded, and then used to decode the information in the data channel frame. The control channel frame may be transmitted synchronously with the corresponding data channel frame, or it may be transmitted prior to transmission of the corresponding data channel frame.

In the present embodiment, in addition to the primary data channel and the control channel, a third channel (an enhanced dedicated data channel) is transmitted from the mobile station to the base station. The enhanced data channel is used in this embodiment to transmit data for high-speed, non-delay-sensitive services. In alternative embodiments, other types of data may be transmitted. While it is necessary to transmit control information for the enhanced data channel to the base station so that the base station can decode the data received via the enhanced data channel, this control information is not transmitted in a control channel that is separate from the control channel described above. Instead, the control information for the enhanced data channel is combined with the control information for the primary data channel, and the combined control information is transmitted from the mobile station to the base station on the one control channel. The manner in which this is accomplished is described in detail below.

In the present embodiment, all three of the channels (the primary dedicated data channel, the dedicated control channel and the enhanced dedicated data channel) use the same frame format. This format is illustrated inFIG. 3.FIG. 3shows two frames,300and310. As shown in this figure, each frame spans ten milliseconds. Each frame is further broken down into 15 slots.

As mentioned above, the control channel is used in this embodiment to transmit control information including pilot data, power control data and data rate information. Referring toFIG. 4, a diagram illustrating the structure of this information within each slot is shown.FIG. 4depicts a single slot400. Contained within slot400is pilot data410, power control data420and data rate information430. Slot400consists of ten data bits. Six of these ten bits are used to convey pilot data410, while two bits are used as power control data420and two bits are used for data rate information430. The data rate information is shown in the figure as the TFCI, or transport format combination indicator.

While TFCI information430comprises only two bits of each slot, more than two bits are available to communicate the TFCI value for each frame. This is because the selected transport formats used by the mobile station to transmit data on the primary and enhanced data channels are updated on a frame by frame basis. In other words, while each data channel can select a different transport format for each succeeding frame, the transport format remains unchanged during the frame. Thus, all of the 30 TFCI bits in the frame (two bits times fifteen slots,) rather than only the two TFCI bits in a single slot, are available to communicate the selected TFCI value.

While 30 of the bits transmitted in a frame are dedicated to transmitting TFCI information from the mobile station to the base station, less than 30 bits of actual transport format information are communicated. This is because the transport format information is encoded before being transmitted. The encoding process, which is intended to increase the reliability with which the data is communicated, increases the number of bits that need to be transmitted. This process will be described briefly below.

Referring toFIG. 5, a flow diagram illustrating the process through which data rate information is encoded in accordance with one embodiment is shown. In this figure, data rate information (TFCI) is encoded (block510.) In this case, the encoder implements a ⅓ encoding scheme. The encoding consists of covering the original data rate information with spreading codes in a manner which is well known to persons of skill in the field of WCDMA communications. The encoding of the original data rate information, which consists of ten data bits, results in 32 bits of encoded rate information data. Because the control data format described above in connection withFIG. 4makes available only 30 bits for data rate information, some form of rate matching must be performed (block520.) In one embodiment, the rate matching function may simply consist of “puncturing” the encoded data, or dropping the last two bits.

Thus, 30 bits of encoded data rate information are generated from the ten bits of the original data rate information. These 30 bits of encoded data rate information can then be transmitted from the mobile station to the base station by transmitting the first two bits in the first slot of the frame, the next two bits in the second slot of the frame, and so on, until all 30 bits have been transmitted.

In a conventional system, all ten bits of the original data rate information are available for use in conveying the data rate used by the primary dedicated data channel. Typically, however, ten bits are not required to identify the data rate for the primary data channel. It is normally the case that there are a relatively small number of possible data rates for this data channel. For instance, there may only be four, eight, or 16 possible data rates from which the actual data rate for the primary dedicated channel may be selected. If there are only four possible data rates, only two bits are necessary to identify which of the four (22) possible data rates has been selected. Similarly, if there are only eight (23) or 16 (24) possible data rates, only three or four bits, respectively, are necessary to identify the selected rate. Consequently, in these examples, six to eight bits of the ten bits that are available to convey data rate information are unused.

In the present embodiment, the bits that are not used to identify the data rate for the primary data channel are instead used to identify the data rate of the enhanced data channel. In the above example in which four bits are used to convey the data rate of the primary data channel, six of the ten bits are available for use in identifying the data rate of the enhanced data channel. These six bits can serve to identify which data rate is selected from among 64 (26) possible rates.

In the present embodiment, a mobile station therefore selects appropriate data rates for the primary and enhanced data channels, combines data rate indicators corresponding to these values in the ten available bits, and then processes the ten bits in the same manner as if these bits contained only the data rate information for the primary data channel. When a frame of control data is received by the base station, this information is decoded and the data rate information corresponding to each of the primary and enhanced data channels is extracted and used in the decoding of the corresponding data channels.

The methodology employed in the present embodiment is illustrated inFIG. 6.FIG. 6is a flow diagram illustrating the process of communicating control information for two data channels over a single control channel. The method depicted in the figure includes a first portion on the left side of the figure and a second portion on the right side of the figure. The first portion corresponds generally to the portion of the method that is performed by a mobile station. The second portion corresponds generally to the portion of the method that is performed by a base station. It should be noted that, in addition to the entire method depicted in the figure, the first and second portions of the method may, in themselves, be considered alternative embodiments.

As shown inFIG. 6, the method begins with selection of data rate information for the first, primary dedicated data channel (block605,) as well as selection of data rate information for the second, enhanced dedicated data channel (block610.) The data rate selection for each of the data channels may be performed in any suitable manner, such as those methods that are known in the wireless telecommunications art. When a data rate for each channel has been selected, a corresponding data rate indicator is also selected. As noted above, if a data rate is selected from among 2npossible data rates, the selected rate can be represented by an n-bit value.

The data rate information (e.g., data rate indicators) for the two data channels is then combined (block615.) In one embodiment, the two data rate indicators are combined simply by appending one to the other. Thus, if the data rate indicator for the first data channel consists of a four-bit value and the data rate indicator for the second data channel consists of a six-bit value, the first four of the ten data rate bits may contain the first data rate indicator, while the last six of the ten data rate bits may contain the second data rate indicator. In alternative embodiments, the data rate indicators for the two data channels may be combined (multiplexed) in a different manner.

After the data rate information for the two data channels is combined, the combined information is encoded (block620.) In one embodiment, the ten bits of combined data rate information are encoded in the same manner that the ten bits of data rate information for the primary data channel is conventionally encoded. In the embodiment described above, the encoding consists of covering the data bits with spreading codes (e.g., using a ⅓ encoding scheme) and then rate matching (e.g., puncturing) the data to generate the number of bits (e.g., 30) that can be transmitted in the control frame.

The encoded data rate information is then transmitted in a frame on the control channel (block625.) In the embodiment described above, this consists of transmitting two bits of the encoded data rate information in each slot of the control frame. Thus, the first two bits of the encoded data rate information are transmitted in slot0, the next two bits are transmitted in slot1, and so on.

After the frame of control data is transmitted by the mobile station, it is communicated to and received by the base station via the dedicated control channel (block630.) The received frame of control information is then decoded (block635.) In one embodiment, the decoding of the control information is performed in the same manner as if only control data for the first data channel were included. In other embodiments, the decoding of the control information may be performed in other ways.

When the control data has been decoded, the ten bits of control information are available to the base station. The base station therefore extracts the data rate information for each of the first and second data channels (block640.) If the mobile station combined to the data rate indicators by simply appending one to the other, the base station extracts the indicators by parsing the ten bits into the respective data rate indicators for the first and second data channels. If the mobile station multiplexed the data rate indicators in a more complex manner, a corresponding demultiplexing method is used by the base station to extract the indicators.

After the data rate indicators for the first and second data channels have been extracted from the control information, the base station uses these data rate indicators to determine the data rates at which the first and second data channels are transmitted and then the codes the first data channel and the second data channel using the respective data rate information (blocks645,650.)

It should be noted that numerous variations may be made in the embodiments described above without departing from the scope of the invention as detailed in the claims below. For instance, while the foregoing embodiments involve the combining of data rate information for two data channels on a single control channel, it may be possible in other embodiments to combine the data rate information for more than two data channels. It may also be possible to combine the data rate information for n data channels in m control channels, where n is greater than m. In another embodiment, information other than data rate information (e.g., frame formatting information) for the different data channels may be combined on one or more control channels.

In another variation, the bits that are available for transmitting data rate information may be allocated to the different data channels in a different manner than described above. For example, rather than allocating four bits to one channel and six bits to another, the allocation may be two/eight bits, three/seven bits, five/five bits, etc. It is also possible to use alternative frame and/or slot formats that make more or less than ten bits available for transmitting data rate information. The allocation of the bits between the different data rate indicators may be varied from time to time using higher layer signaling.

Although not discussed in detail above, it should be noted that the functionality described above may be implemented in the mobile stations and base stations described above by providing suitable programs that are executed in the respective processing subsystems of these devices. These program instructions are typically embodied in a storage medium that is readable by the respective processing subsystems. Exemplary storage media may include RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage media known in the art. Such a storage medium embodying program instructions for implementing the functionality described above comprises an alternative embodiment of the invention.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and method steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. It should also be noted that the illustrative components, blocks, modules, circuits, and steps may be reordered or otherwise reconfigured in alternative embodiments. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.