Patent Publication Number: US-2021195556-A1

Title: Method and apparatus for receiving broadcast information in an ofdm communication system

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. patent application Ser. No. 16/864,882, filed May 1, 2020, which is a continuation of U.S. patent application Ser. No. 15/724,228, filed Oct. 3, 2017, which is a continuation of U.S. patent application Ser. No. 14/596,109, filed on Jan. 13, 2015, which issued as U.S. Pat. No. 9,780,959 on Oct. 3, 2017 which is a continuation of U.S. patent application Ser. No. 13/712,848, filed Dec. 12, 2012, which issued as U.S. Pat. No. 8,934,394, on Jan. 13, 2015 which is a divisional of Ser. No. 13/422,829, filed Mar. 16, 2012, which issued as U.S. Pat. No. 8,457,081, on Jun. 4, 2013 which is a continuation of U.S. patent application Ser. No. 11/571,469, filed Oct. 9, 2008, which issued as U.S. Pat. No. 8,155,098, on Apr. 10, 2012, which is a National Stage application of PCT/US06/22376, filed Jun. 6, 2006, which claims priority from U.S. Patent Application No. 60/688,937, filed on Jun. 9, 2005, which are incorporated by reference as if fully set forth. 
    
    
     FIELD OF THE INVENTION 
     The disclosed embodiments relate, in general, to wireless communication and, in particular, to methods and apparatus for power efficient signal broadcasting and communication. 
     BACKGROUND 
     As a wireless service to mobile users, the transmission of multimedia is becoming as important as voice connectivity. It is forecasted that multimedia applications will include interactive data services such as gaming and internet access as well as on-demand video and audio services. 
     Digital video and audio broadcasting and multicasting are one class of wireless services. Some applications such as news-casting, sports-casting, and other types of multimedia entertainment require no or minimum interaction. The most efficient way to deliver these types of mass multimedia contents is broadcasting. Given these broadband wireless applications, the platform for the next generation wireless communications should deliver interactive data and broadcasting services at the same time. The design of such a platform with mixed applications must be well balanced, optimizing quality of service, efficiency, power consumption by mobile stations, etc. 
     A mobile station in continuous reception of a video broadcasting stream consumes significant amount of power, which becomes even a bigger challenge if the mobile station is running on battery. Furthermore, when data application traffic shares the same air link resource with the video streams, a video burst that utilizes the entire air link resource will cause a long delay for other applications such as for Transmission Control Protocol (TCP). This can become a major problem if some control data transmissions require swift responses, such as power control, hybrid automatic retransmission request (HARQ) feedback and channel quality information (CQI) measurement reports. The exclusive use of a resource for video broadcasting blocks these control messages and causes system performance problems. 
     SUMMARY 
     A method for receiving broadcast information in an orthogonal frequency division multiplex (OFDM) communication system may comprise receiving, by a mobile station, a periodically broadcast scheduling message from a base station which indicates for each type of a plurality of types of broadcast information included in broadcast information, a pattern of frames to monitor for the type of broadcast information and indicates a length of time to monitor. The mobile station may monitor for information corresponding to at least one of the plurality of types of broadcast information, based on the periodically broadcast scheduling message. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates examples of a system architecture of a cellular wireless system. 
         FIG. 2  illustrates an example of sub-carriers and sub-channels. 
         FIG. 3  illustrates an example of time and frequency resources. 
         FIG. 4  illustrates three different types of video frames. 
         FIG. 5  illustrates video bursts along with a scheduling message pointing to their positions. 
         FIG. 6  illustrates different video burst patterns for a single video stream. 
         FIG. 7  illustrates different video-burst distributions for multiple video streams. 
         FIG. 8  illustrates an example of how a video burst and its video frame configuration change as the number of video streams increases. 
         FIG. 9  illustrates an example of FEC (Forward Error Correction) coding configurations with multiple video frames within a video burst. 
         FIG. 10  illustrates how AVBs (auxiliary video bursts) are used with their original video bursts. 
         FIG. 11  illustrates using an RF tuner to receive both video and data in a multiple frequency band system. 
         FIG. 12  illustrates a receiver with a single RF tuner in a multiple frequency band system. 
         FIG. 13  illustrates a mobile station receiver in a broadcasting and communication system. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Methods and apparatus are disclosed herein for resource configuration in a cellular broadcasting and communication network of base stations and mobile stations. In this network a video stream can be transmitted from a base station to a mobile station as bursts of video and data frames are configured in a particular sequential manner. Special scheduling signals are designed to efficiently announce video burst information to the subscribing mobile stations, allowing the mobile stations to turn on their transceiver circuitry only when video bursts arrive. In a video burst, the available data resources, in addition to video resources, are used to transmit data application packets and/or special control information to the subscribing mobile stations. Methods and processes are also disclosed for a mobile station to use a single RF tuner within a system with multiple frequency bands. 
     The disclosed multiple access technology can be of any special format such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or Multi-Carrier Code Division Multiple Access (MC-CDMA). Without loss of generality, OFDMA is employed as an example to illustrate the present invention. The system can also be either time division duplex (TDD) or frequency division duplex (FDD). 
     The following description provides specific details for a thorough understanding of the various embodiments and for the enablement of one skilled in the art. However, one skilled in the art will understand that the invention may be practiced without such details. In some instances, well-known structures and functions have not been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments. 
     The terminology used in the description presented below is intended to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific embodiments of the invention. Certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this Detailed Description section. 
     Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” Words using the singular or plural number in this Detailed Description section also include the plural or singular number respectively. Additionally, the words “herein,” “above,” “below” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. When the claims use the word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list and any combination of the items in the list. 
     In order to minimize the power consumption of a mobile station, it is desirable to deliver video broadcasting data within a short period of time and fill up a video buffer of the mobile station (MS) so that it can be played back later. This only requires the radio frequency (RF) and the base-band transceivers of the mobile station to be powered up during the same short period. The rest of the time the transceiver can be shut down; minimizing the power consumption. Implementing such scheme, in a system with other types of data application, requires harmonizing various applications and optimizing the results. 
     In one embodiment, to reduce the power consumption of a receiving mobile station, a video stream is transmitted from a base station (BS) as bursts of video and data frames configured in a particular sequential manner. A mobile station can turn off its transmitting and receiving circuits during the periods between the video bursts. In a video burst, the available data resources, in addition to video resources, are used to transmit data application packets and/or special control information. Special scheduling signals are designed to efficiently announce video burst information to the subscribing mobile stations. 
     A video broadcasting application is used as an example to illustrate some aspects of the invention. More generally, the disclosed methods and apparatus can be applied to other applications that use broadcasting or multicasting and benefit from buffering data and playing it back to save power. Examples are music/audio broadcasting and multicasting-based data downloading. On the other hand, “data application” refers to other applications with non-broadcasting/multicasting nature, such as web access, voice over IP, and FTP. 
     Throughout the following specification, examples of a single frequency network (SFN) are used to illustrate the applications of video broadcasting; however, employing a SFN is not a requirement. 
     Cellular Broadcasting and Communication Systems 
       FIG. 1  depicts a typical wireless network  100 , where there are a plurality of base stations (BS&#39;s)  101  each of which provides coverage to its designated area, normally called a cell  102 . If a cell  102  is divided into sectors, from system engineering point of view each sector itself can be considered to be a cell. Therefore, the terms “cell” and “sector” are interchangeable in this context. 
     There is at least one control server  104  in a wireless network  100  for controlling one or multiple BS&#39;s  101 . The control server  104  is connected to the BS&#39;s  101  via the backbone network  106 , which can be either a wired network or a wireless network. The backbone network  106  can also be either a circuit switched network or a packet switched network. The backbone network  106  may connect to other servers in the system, such as a number of content servers  108 , a number of network management servers  112 , and/or a number of authentication/authorization/accounting (AAA) servers  110 . 
     A BS  101  serves as a focal point to wirelessly distribute information to and collect information from its MS&#39;s  114 , which are the communication interface between the users and the wireless network  100 . The transmission from a BS  101  to an MS  114  is called a downlink and the transmission from an MS  114  to a BS  101  is called an uplink. The term “MS” also can represent a user terminal in a fixed wireless system or a portable device with a wireless communication interface. 
     In wireless applications such as digital video broadcasting, the SFN technology is used to alleviate the problem of interference between BS&#39;s  101 . Using OFDM, BS&#39;s  101  simultaneously transmit the same broadcasting content while employing the same time/frequency resource. A receiver can then combine the received signals from different BS&#39;s  101  to boost its SNR (signal to noise ratio). 
     In the backbone network  106 , the control server  104  coordinates the synchronized video broadcasting. When video stream packets are distributed from the control server  104  to the BS&#39;s  101 , additional synchronization information is appended to the packets by a device called Distribution Adapter (DA). The video packet distribution network is built on top of the backbone network  106  via tunneling technologies. 
     For a video broadcasting packet, the BS  101  forwards the packet to a Receiving Adapter (RA), which extracts the synchronization information, and broadcasts the video simultaneously with other BS&#39;s  101 . 
     Data application packets are transmitted to the BS  101  directly, without encapsulation, using tunneling protocols. The BS  101  separates data application packets from video broadcasting packets by their destination addresses and other properties. Data application packets bypass RA and are transmitted to MS&#39;s  114  according to a scheduling by each individual BS  101 . 
     Video Frames 
     The physical media resource (e.g., radio or cable) in a multi-carrier communication system can be divided in both the frequency and time domains. This canonical division provides a high flexibility and fine granularity for resource sharing. The building-blocks of multi-carrier signals in the frequency domain are sub-carriers, a fixed number of which are within a particular spectral band or channel. 
       FIG. 2  depicts three types of sub-carriers, as follow:
         1. Data sub-carriers  200 , which carry information data;   2. Pilot sub-carriers, whose phases and amplitudes are predetermined and are made known to all receivers, and which are used for assisting system functions such as estimation of system parameters; and   3. Silent sub-carriers, which have no energy and are used as guard bands and DC carriers.       

     The data sub-carriers can be arranged in a particular manner into groups called sub-channels to support both scalability and multiple access. The pilot sub-carriers are also distributed over the entire channel in a predetermined manner. The sub-carriers forming one sub-channel are not necessarily adjacent to each other. 
     The building-blocks of multi-carrier signals in the time domain are time slots to support multiple access. The resource division in both the frequency and time domains is depicted in  FIG. 3 , where the radio resource is divided into small units in both the frequency and time domains: sub-channels and time slots. The basic structure of a multi-carrier signal in the time domain is made up of time slots. A time slot may contain one or multiple OFDM symbols. A “frame,” typically of a fixed length (e.g., 5 ms), may contain one or multiple slots. 
     In a broadcasting and communication system with a frame structure, the video broadcasting application and the data application use different air link resources. If SFN is used for the video broadcasting application, its reserved resource in a frame is called SFN video resource. A frame containing a video resource is called a video frame; otherwise, it is called a data frame. 
       FIG. 4 , while only illustrating the downlink, shows three different types of video frames. The first type contains both video and data resources. They are separated in the time domain using different OFDM symbols. In the second type frame, the video resource and the data resource are using different sub-carriers. The third type contains only the video resource. 
     A video broadcasting “stream” is defined as a stream for a particular video broadcasting program. For example, one stream carries CNN news channel program, the other carries video broadcasting information from FOX. 
     Each video stream is associated with a bit rate, which can be either fixed or variable. In order to support a certain bit rate, the number of video frames per second is derived based on the calculations of the video resource capacity. As an example, a system with an 8-MHz wireless channel and a 5-ms frame is used herein to illustrate the disclosed embodiments. It is further assumed that the system is sampling at 10 MHz and using 1024-point FFT. This example of a system&#39;s effective bandwidth is comprised of 600 OFDM sub-carriers. Each symbol in the system lasts about 100 ns; therefore, it has a total of 50 symbols within each frame. 
     In one embodiment, a frame is used either entirely or partially for video broadcasting. For example, the entire frame (all 50 symbols) is used for video broadcasting with 16QAM modulation and 1/2-rate coding, resulting in a frame capacity of 2×600×50=60K bits. With N video frames per second, the video stream bit rate is 60N Kbps. If a video stream requires 240 Kbps throughput, a burst of 4 video frames every second is enough. In contrast, if only a part of the frame, for Example Six Symbols, is Used as Video Resource, with the Same 16-QAM and 1/4 Rate coding, the video capacity per frame is 2×600×6=7.2K bits, in which case the transmission of a 144-Kbps video stream requires 20 frames per second. 
     Video Burst 
     A video burst is defined as a sequence of frames within a short period of time. For one video stream, the duration between the two consecutive video bursts is relatively longer than the length of the video burst itself. To reduce the power consumption of a receiving MS  114 , a video stream can be transmitted from the BS  101  as video bursts configured in a particular sequential manner with both video and data frames. The temporal location and the configuration of a video burst are announced by a special message carrying the scheduling signal, wherein the special message is broadcasted periodically. 
       FIG. 5  illustrates the relationship of video bursts  502  with the scheduling message  500 . The video burst takes about 50 ms, with a gap of 950 ms between two video bursts. The scheduling signal indicates the location of the video bursts as well as other control information. The format of the scheduling signal and its transmission mechanism is discussed below. 
       FIG. 6  illustrates three examples of “video burst patterns” for a single video stream, where video burst patterns are the interleaving video and data frames within a video burst. Different video burst patterns may be used, depending on the nature of the data applications. In the first pattern, a video burst has five consecutive video frames. In the second pattern the video burst has three video frames and, to mitigate the latency impact on the data applications, there is a data frame between the first and the second video frame and another data frame between the second and the third video frame. In this pattern the maximum latency between two neighboring data frames is only 5 ms, and the entire video burst lasts 5×5=25 ms. In the third depicted pattern the video burst has 4 video frames with a data frame between the second and the third video frame. With this pattern, the maximum delay between two neighboring data frames is 10 ms. The total video burst lasts 25 ms. 
     Transmitting a video stream by video bursts can reduce the power consumption of the receiving MS&#39;s  114 . With such arrangement, each MS  114  can turn on its RF and base-band circuit to receive a video burst and shut them down subsequently to save power for a relatively long period, until the arrival of a next burst. The video burst pattern and its schedule is announced to all the receiving MS&#39;s  114  using scheduling signal. The video burst pattern for a video stream can be reconfigured over time. The pattern change is also announced to all the receiving MS&#39;s  114  through the scheduling signal. 
     Within a video burst, the data frames and the data resource of the video frames are called “available data resource.” In one embodiment, the system can use the available data resource in a video burst to perform security key update, establishing network connection, paging, location update, resynchronization, or power control for the subscribing MS&#39;s  114 . 
     In another embodiment, an MS  114  measures the receiving signal quality and collects statistics of the received video stream, such as the packet error rate. The BS  101  allocates a resource from the available data resource of the video burst for an MS  114  to report its CQI measurement and other statistics of the received video stream. When necessary, the MS  114  may be required to report which video stream it receives. 
     In yet another embodiment, since the receiving circuit in an MS  114  is turned on during its video burst, the BS  101  can notify the MS  114  about its newly arrived data application packets, using the available data resource in the burst. The MS  114  can also send uplink data packets to the BS  101  during the burst. 
     If there are only a small number of data application packets for downlink and uplink, the BS  101  and MS  114  can complete the transmission of data packets during a video burst. However, if the number of data packets exceeds the capacity of the available data resource in a video burst, the BS  101  and the MS  114  can coordinate to extend the power-on period to continue the data exchange. 
     Multiple Video Streams 
       FIG. 7  depicts an embodiment wherein multiple video streams are transmitted with their own video bursts. The bursts associated with different video streams are evenly distributed, next to each other or overlapping/interleaving with each other. In the first example, Video burst  1  and Video burst  2  are evenly distributed over time. In the second example, Video burst  1  and Video burst  2  are next to each other. In the third example, Video burst  1  and Video burst  2  are overlapped and interleaved with each other. 
     In some systems, the number of supported video streams can change over time, which affects the video burst pattern and its distribution in the time domain. The video broadcasting resource in a system can be increased by:
         1. increasing the number of video frames, while keeping the video burst pattern unchanged;   2. changing the video burst pattern so it contains less data frames; and/or   3. increasing the video resource in each video frame, which also affects the video burst pattern.       

       FIG. 8  shows a number of system configuration transitions to increase video capacity. First, the data frames between video bursts in the configuration  800  are displaced by new video bursts in the configuration  802 . Next, the data frames within the video bursts in configuration  802  are removed to reallocate resource to new video bursts in configuration  804 . Finally, the video resource within the video frame increases from 7.2 Kbits in configuration  804  to 10.8 Kbits in configuration  806 . 
     In one embodiment, in order to meet the video throughput demand as the number of video streams increases, the system replaces data frames with video frames to form video bursts. The video bursts for different video streams are still transmitted sequentially, possibly with some data frames in between. 
     In another embodiment, the video burst pattern for a particular video stream is configured in accordance with the overall video throughput demand. As the number of video streams increases, a video bursts pattern is changed into more video centric (i.e., the burst contains fewer data frames). On the other hand, as the number of video streams decreases, a video bursts pattern is changed into less video centric. 
     In yet another embodiment, the video resource in each video frame is adjusted to meet the video throughput demand. In a video frame, the video resource is augmented by displacing the data resource, either in the time domain or the frequency domain. In a TDD system, the uplink period in the video frame is also reduced if necessary, thereby increasing the downlink video/data resource. 
     Video Burst Scheduling Signal 
     In some embodiments the video burst schedule is announced to the subscribing MS&#39;s  114 . In one embodiment, the video burst schedule is broadcasted periodically at a fixed time and frequency, either in a video frame or in a data frame. An MS  114  that loses the synchronization to the video burst can resynchronize to the burst sequence by decoding the scheduling information. If the video burst schedule changes, all the MS&#39;s  114  are to be notified at the earliest possible opportunity. 
     In another embodiment, the scheduling signal is transmitted in special resource regions. For example, a special message carrying the scheduling signal appears once every 10 seconds in the first data frame. Alternatively, the scheduling signal is transmitted using the first symbol of the video resource in the first video frame of a video burst. 
     In yet anther embodiment, a frame (sequence) number, which is known to all the control servers is used to represent a synchronized network time by being associated with a common time reference such as the GPS. Such a time reference is also critical to SFN operation. A modular number, instead of the absolute sequence number may be used to reduce the overhead of indicating the frame number. 
     The video burst scheduling signal may include the following control information for each video stream:
         1. the frame number where each video burst starts;   2. the length of each video burst;   3. the pattern of each video burst;   4. the video resource region in each video frame of each video burst; and/or   5. the coding and modulation scheme for each video burst.       

     In one embodiment, some scheduling information is reduced or omitted or is broadcasted less frequently when it is already known, implied, inferred, or redundant. For example, if the video bursts of a video stream are broadcasted periodically and regularly and the video burst pattern remains unchanged, the scheduling signal is sent out infrequently, for example, once every 10 seconds. This greatly reduces the overhead of scheduling signals. 
     In another embodiment, to save the air link resource, the schedule information is compressed using a certain technique or be represented via a certain format. In particular, a finite set of video-burst patterns is predefined in the system. The mapping between the video burst patterns and their corresponding pattern indices is broadcasted in a message to all the MS&#39;s  114 . The pattern index is used to indicate the pattern for each video burst. The mapping is implemented, for example, as in the table shown below: 
     
       
         
           
               
               
             
               
                   
               
               
                 Pattern Index 
                 Pattern Format 
               
               
                   
               
             
            
               
                 0 
                 VDVDVDV 
               
               
                 1 
                 VVDVV 
               
               
                   
               
            
           
         
       
     
     Alternatively, the video burst pattern is expressed in the video burst scheduling signal using bitmap format. A bit of “1” stands for video frame and a bit of “0” stands for data frame or vice versa. 
     In yet another embodiment, a number of video streams are supported in the system. The mapping between the stream index and its associated video burst scheduling information is implemented, for example, as in the table shown below: 
     
       
         
           
               
               
             
               
                   
               
               
                 Stream Index 
                 Associated Scheduling Information 
               
               
                   
               
             
            
               
                 1 
                 Start frame number: 20 
               
               
                   
                 Length of the video burst: 7 
               
               
                   
                 Video burst pattern bitmap: 0 × 55 (01010101B) 
               
               
                   
                 Start symbol No. for video resource: 2 
               
               
                   
                 Number of symbols for video resource: 8 
               
               
                   
                 MCS index for the video resource: 2 (QPSK ½ coding) 
               
               
                 2 
                 Start frame number: 40 
               
               
                   
                 Length of the video burst: 5 
               
               
                   
                 Video burst pattern bitmap: 0 × 15 (00010101B) 
               
               
                   
                 Start symbol No. for video resource: 0 
               
               
                   
                 Number of symbols for video resource: 6 
               
               
                   
                 MCS index for the video resource: 4 (16QAM ½ coding) 
               
               
                 . . . 
                 . . . 
               
               
                 10  
                 Start frame number: 180 
               
               
                   
                 Length of the video burst: 7 
               
               
                   
                 Video burst pattern bitmap: 0 × 55 (101010101B) 
               
               
                   
                 Start symbol No. for video resource: 1 
               
               
                   
                 Number of symbols for video resource: 12 
               
               
                   
                 MCS index for the video resource: 2 (QPSK ½ coding) 
               
               
                   
               
            
           
         
       
     
     In addition, an application layer message announces the content of the video stream associated with its index, as shown in the following table. Some of the content information, such as the channel and program names, can be used in a video program menu for the user. When a user selects a channel from the menu, the corresponding stream index signals the MS  114  to find the corresponding scheduling information for the video stream. 
     
       
         
           
               
               
               
             
               
                   
               
               
                 Stream Index 
                 Channel Name 
                 Program Name 
               
               
                   
               
             
            
               
                 1 
                 FOX 
                 The Simpsons 
               
               
                 2 
                 CNN 
                 News Update 
               
               
                 . . . 
                 . . . 
                 . . . 
               
               
                 10  
                 ESPN 
                 Sports Update 
               
               
                   
               
            
           
         
       
     
     Forward Error Correction for Video Burst 
     In one embodiment, the FEC (Forward Error Correction) coding block comprises information bits from multiple consecutive video frames within a video burst. Coding across video frames can increase time diversity and therefore improve the performance over fading channels. 
       FIG. 9  illustrates the FEC coding configurations with multiple video frames within a video burst. A coding block in Video burst  1  may consist of bits from two neighboring video frames and a coding block in Video burst  2  may comprise bits concatenated across three neighboring frames. 
     Auxiliary Video Burst 
     When additional transmission capacity in either the time or the frequency domain is available, auxiliary video bursts (AVBs) may be used to deliver additional information to enhance video broadcast signals. 
     In one embodiment, an AVB is transmitted in a redundant form of the original video burst. An AVB can be a simple replica of a video burst itself and when an MS  114  receives the auxiliary video burst, it combines it with its original, using the Chase combining technique, to decode the video signals. An AVB can also carry incremental redundancy information of a video burst. In such a case, the MS  114  fuses the incremental redundancy information to the original video burst, using a predetermined algorithm, to decode the video signals. An MS  114  can elect to receive the video information in the AVB if an error has been detected in the original video burst. The announcement of the scheduling information should include additional information regarding the retransmission. 
     In another embodiment, an AVB is used to transmit additional video information to improve the video quality. An AVB can be transmitted by the individual BS  101  using multicasting. The BS  101  stores the additional video broadcasting information locally and, if the situation permits (e.g., light local traffic or additional bandwidth available), transmits them as the auxiliary video bursts. The BS  101  is responsible for announcing the scheduling information. 
       FIG. 10  shows an example of the use of AVBs. The MS  114  receiver will jointly decode V 1  and V 1 ′ using an incremental redundancy algorithm. In the case where V 2 ′ is a repetition of V 2 , the MS  114  receiver uses, for example, the Chase combining algorithm to decode. 
     Designs for a System with Multiple Frequency Bands 
     In one embodiment frequency-switch methods and processes are used in a system with multiple frequency bands such that only one RF tuner is needed in the receiving MS  114 . A single RF tuner implies that the receiver, regardless of its number of branches, operates in one single RF frequency. For example, some MS&#39;s  114  may have multiple branches in their receivers to implement a type of multiple antenna technology, such as diversity combining or multiple-input-multiple-output (MIMO) techniques, but they are referred to as one-RF-tuner receivers. 
     In another embodiment, when an MS  114  is to switch from a video stream in one frequency band to another video stream in a different frequency band, it triggers the inter-frequency handoff process. Triggering the inter-frequency handoff process hands off the data application associated with the original video stream to be in the switched frequency band. 
     In yet another embodiment, the data application continues to use the same frequency band when the video stream is switched to another frequency band. The BS  101  scheduler tracks the video frame for each MS  114  and makes resource allocation to avoid simultaneous delivery of the video stream in the video frequency band and other application data in a different data frequency band. The controller in the MS  114  receiver will switch from its data frequency band to video frequency band when its video frame arrives. 
     In yet another embodiment, when inter-frequency handoff for data application is required, the data application is switched to another frequency channel but the video stream continues transmitting in the original frequency band. The BS  101  scheduler tracks the video frame for each MS and makes resource allocation to avoid simultaneous delivery of the video stream in the video frequency band and other application data in a different data frequency band. The controller in the MS  114  receiver will switch from its data frequency band to video frequency band when its video frame arrives. 
     In still another embodiment, the system dedicates multiple frequency bands for the video broadcasting application and multiple frequency bands for other applications such as data. In this case an interleaving video frame pattern, called mixed video burst pattern, is used. The mixed video burst pattern will have video frames of different streams interleaved with each other, such as V 1 -V 2 -V 1 -V 2 -V 1 -V 2 . With this configuration, the controller in the MS  114  receiver will switch from its data frequency band to video frequency band when its video burst arrives. The BS  101  scheduler tracks the video frame for each MS  114  and makes resource allocation to avoid simultaneous delivery of the video stream in the video frequency band and other application data in the data frequency band. 
       FIG. 11  shows two examples of using one RF tuner to receive both video and data in a multiple frequency band system. In the first example, both the video and date applications are in a same frequency band. When switching to another video frequency band is requested, the MS  114  triggers the inter-frequency handoff process. In the second example, the video and data transmissions are carried out in different frequency bands. The controller in the receiver handles the switching between different frequency bands. The arrows in  FIG. 11  indicate how the controller should switch between the frequency bands. 
       FIG. 12  illustrates a receiver with a single RF tuner in a multiple frequency band system. The receiver stores, in its memory  1204 , the synthesizer information and the previous channel information for both video frequency band and data frequency band. Based on scheduling information, a controller  1206  determines the switch point between these two frequency band configurations. Once the controller switches to the video frequency band configuration, it applies the control information to the mixer  1200  and the base-band processor  1202 . 
     Receiving Operation 
     In a typical scenario, a user subscribes to a video broadcasting program, which corresponds to a particular video stream. The content provider and the network service provider will authenticate the request and admit the access by assigning to the MS  114  the key information as well as the video burst scheduling information. 
     In one embodiment, an MS  114  turns on its receiving and transmitting circuit(s) during its subscribed video bursts and turns off its circuit(s) during the periods in between video bursts. The received video burst is decoded and stored in a video buffer and is later played back on the display. 
     In another embodiment, an MS  114  with a single RF tuner operates within a multiple-frequency-band system and its controller switches and synchronizes to the data frequency band or the video frequency band when a data frame or a video frame arrives, respectively. 
       FIG. 13  illustrates an MS  114  receiver in a broadcasting and communication system. After the RF transceiver  1300  and base-band  1302  processing, the packets belonging to video broadcasting application are first stored in a video buffer  1310  and, after video decoding  1312 , are played back on the video display  1314 . Other data application packets are processed along a separate path by the data processing unit  1304 . A control unit  1308  controls the RF transceiver  1300 , base-band processor  1302 , and the operation of the video processing units  1306 . 
     The above detailed description of the embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed above or to the particular field of usage mentioned in this disclosure. While specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. Also, the teachings of the invention provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments. 
     All of the above patents and applications and other references, including any that may be listed in accompanying filing papers, are incorporated herein by reference. Aspects of the invention can be modified, if necessary, to employ the systems, functions, and concepts of the various references described above to provide yet further embodiments of the invention. 
     Changes can be made to the invention in light of the above “Detailed Description.” While the above description details certain embodiments of the invention and describes the best mode contemplated, no matter how detailed the above appears in text, the invention can be practiced in many ways. Therefore, implementation details may vary considerably while still being encompassed by the invention disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the invention should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the invention with which that terminology is associated. 
     In general, the terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification, unless the above Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the invention encompasses not only the disclosed embodiments, but also all equivalent ways of practicing or implementing the invention under the claims. 
     While certain aspects of the invention are presented below in certain claim forms, the inventors contemplate the various aspects of the invention in any number of claim forms. Accordingly, the inventors reserve the right to add additional claims after filing the application to pursue such additional claim forms for other aspects of the invention.