Method and system for communicating content on a broadcast services communication system

Method and system for transmitting content on a broadcast service communication system

The present invention relates to broadcast communication, or is known as point-to-multipoint communication in a wired or wireless communication system. More specifically, the present invention relates to a system and method for using an external decoder in this broadcast communication system.

Communication systems have been developed to allow the transmission of information signals from an initial station to an actual destination station. In transmitting the information signal from the start station on a communication channel, the information signal is first converted into a form suitable for efficient transmission on the communication channel. The conversion or modulation of the information signal includes modulating the information signal whose carrier frequency spectrum is limited to the bandwidth of the communication channel according to the result, which will change a carrier parameter. At the destination station, the original information signal is copied from the modulated carrier received on the communication channel. This replication is usually achieved by using a modulation process that is opposite to that used by the start station.

Modulation also facilitates multiple access, that is, the simultaneous transmission and/or reception of several signals on a common communication channel. Multi-access communication systems often include multiple subscriber units, and these subscriber units require intermittent services of a relatively short duration instead of continuously storing common communication channels. Several multiple access technologies are known in the art, such as time division multiple access (TDMA), frequency division multiple access (FDMA), and amplitude modulation multiple access (AM). Another type of multiple access technology is the Code Division Multiple Access (CDMA) spread spectrum system, which complies with "TIA/EIA/IS-95 Mobile Station-Base Station Compatibility Standard for Dual-Mode Wide-Band Spread Spectrum Cellular System" , Hereinafter referred to as IS-95 standard. The use of CDMA technology in the multiple access communication system is in the U.S. Patent No. 4,901,307 under the name "SPREAD SPECTRUM MULTIPLE-ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS", and the U.S. Patent No. 5,103,459 under the name "SYSTEM AND METHOD FOR GENERATING WAVEFORMS IN A CDMA CELLULAR TELEPHONE SYSTEM" discloses that both have been assigned to the assignee of the present invention.

A multiple access communication system can be wireless or wired, and can carry voice and/or data. An example of a communication system that conveys voice and data is a system based on the IS-95 standard. The IS-95 standard specifies the transmission of voice and data on a communication channel. The method for transmitting fixed-size code channel frame data is described in detail in US Patent No. 5,504,773 titled "METHOD AND APPARATUS FOR THE FORMATTING OF DATA FOR TRANSMISSION", which has been assigned to the assignee of the present invention. According to the IS-95 standard, data or voice is divided into 20 millisecond code channel frames, and the data rate is 14.4 Kbps. An additional example of a communication system for transporting audio and data includes a communication system that complies with the "3rd Generation Partnership Project" (3 GPP), and this is included in the document number 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (W-CDMA standard), or "TR-45.5 Physical Layer Standard for cdma2000 Spread Spectrum Systems" (the IS-2000 standard) in a set of documents.

The only example of a data communication system is a high data rate (HDR) communication system that complies with the TIA/ELA/IS-856 industrial standard, hereinafter referred to as the IS-856 standard. This HDR system is based on the communication system disclosed in the patent case No. 08/963,386 named "METHOD AND APPARATUS FOR HIGH RATE PACKET DATA TRANSMISSION" filed on November 3, 1997, which has been assigned to the present invention. The HDR communication system defines a set of data rates ranging from 38.4 kbps to 2.4 Mbps, in which an access point (AP) can transmit data to a user station (access terminal AT). Because AP is similar to a base station, the terms related to the unit and area are the same as the voice system.

In a multiple access communication system, communication among users is conducted via one or more base stations. The first user on a user station communicates with the second user on the second user station by transmitting data to a base station on the reverse link. The base station can receive data and route the data to another base station. The data is transmitted to the second user station on the forward link of the same base station or another base station. The forward link can be regarded as a transmission from a base station to a subscriber station, and the reverse link can be regarded as a transmission from a subscriber station to a base station. Similarly, communication can be performed between the first user on a subscriber station and the second user on the ground line station. A base station receives data from users on the reverse link and routes the data to a second user via a public switched telephone network (PSTN). In many communication systems such as IS-95, W-CDMA, IS-2000, the forward link and the reverse link are configured with separate frequencies.

The above-mentioned wireless communication service is an example of a point-to-point communication service. In contrast, broadcast services can provide point-to-multipoint communication services. The basic model of a broadcasting system is composed of user broadcasting networks served by one or more central stations, and can transmit certain content information, such as news, movies, sports events, and user favorites. The subscriber station of each broadcast network user can supervise a common broadcast forward link signal. Because the central station can determine the content, users usually reply by correspondence. The general usage examples of the broadcasting service communication system are television broadcasting, radio broadcasting, and so on. This communication system is usually an obviously highly special purpose-built communication system. Recently, the forefront of the wireless cellular phone system is to use the existing structure of the point-to-point cellular phone system, which is mainly used for broadcast services. (As used herein, the term "cellular" system encompasses communication systems that use cellular and PCS frequencies).

The information signals exchanged in the terminal of the communication system often constitute a plurality of packets. For the purpose of this description, a packet is a group of bytes configured in a special format, including data (payload) and control components. The control element includes, for example, a header information and a quality metric. Quality metrics include, for example, Cyclic Redundancy Check (CRC), check bits, and other types of metrics known to those who are familiar with this technique. The packet is usually formatted into a message according to a communication channel structure. The message traveling between the starting terminal and the destination terminal with proper modulation is affected by the characteristics of the communication channel, such as signal-to-noise ratio, attenuation, time change, and other such characteristics. This feature will affect the modulated signal in different communication channels. As a result, the consideration of the transmission of the modulated signal on the wireless communication channel needs to be different from the transmission of the modulated signal on a wired communication channel, such as a coaxial cable or an optical cable. In addition to selecting a modulation suitable for a particular communication channel, other methods to protect the information signal have been designed. This method includes, for example, encoding, symbol repetition, interleaving, and other methods known to those familiar with this technique. However, these methods increase the load. Therefore, an engineering compromise must be reached between the reliability of message transmission and the amount of load. Even with the above information protection, the situation of the communication channel will be reduced to the point where the destination station cannot decode (erase) some packets containing the message. In a data-only communication system, the process is to retransmit non-decoded packets using the automatic repeat request (ARQ) reached from the destination to the start station. However, as mentioned above, the subscriber station will not communicate back to the base station. In addition, even if the user allows ARQ communication, this communication may overload the communication system. As a result, other devices for information protection will be desired.

According to the foregoing, a system and a method are required in this technology to facilitate the use of an external decoder in a broadcast communication system.

The specific embodiment disclosed here describes the above-mentioned requirements by providing a method and system for implementing an external decoder. The use of an external decoder can further help reduce power consumption by determining the number of frames that must be received correctly; and when a predetermined number of frames are received correctly, the frame reception will be terminated.

In another aspect of the present invention, the use of an external decoder can further help the improved method of hard handover on a common channel by: receiving a subscriber station frame transmitted on the common channel from a first area; Determine the need for handover; identify at least one area on the user station, where the at least one area belongs to a soft handover group different from the soft handover group including the first area; from a current buffer that must be received correctly A number of frames are determined; when the determined number of frames are received correctly, the reception of the frames is terminated; and the reception of the frames is started from at least one area identified.

In another aspect of the present invention, the use of an external decoder can further help the improved method of hard handover between frequencies by the following: receiving on a subscriber station and receiving a channel service from a region where the reunification begins; on the subscriber station To determine the need for handover; identify a destination system on the subscriber station; determine many frames from the current buffer that must be received correctly; when the determined number of frames are received correctly, terminate the frame reception; tuning The frequency to the destination system; and if at least one area of the destination system is obtained at the subscriber station, a channel service is received from at least one area.

In another aspect of the present invention, the use of an external decoder can further help the use of a common broadcast channel for transmission by: using a transmission message to replace a part of the transmission buffer to verify part of the content; and The content of the transmission buffer is transmitted on the common broadcast channel at any time.

<u style="single">definition</u>

As used herein, "example" means "to be used as an example, instance, or illustration." Any specific embodiments described as "examples" herein do not necessarily constitute the advantages or advantages of other specific embodiments.

The term "point-to-point" communication is used here to refer to communication between two user stations on a dedicated communication channel.

The term "broadcast communication or point-to-multipoint" communication is used here to indicate a communication method in which a plurality of subscriber stations are receiving communication from a source.

The term "packet" is used here to mean a group of bits arranged in a special format, such as data payload and control elements. The control element includes, for example, a header data, a quality metric, and others known to those familiar with the technology. Quality metrics include, for example, a cyclic redundancy check (CRC), a check bit, and others known to those who are familiar with this technique.

The term "access network" is used here to mean that a base station (BS) and one or more base stations are connected as a whole. Access to the network can transmit data packets between heavy user stations. An access network is an additional network that is further connected to the outside of the access network, such as a company corporate network or the Internet, and can transmit data packets between each access terminal and this external network.

The term "base station" is used here to refer to the hardware that the subscriber station communicates with. The cellular area can be regarded as a hardware or a geographic coverage area, which depends on the terminology used in this article. An area is a part of the honeycomb area. Because an area has the attributes of a unit, the description from the honeycomb point of view can be extended to some areas.

The term "user station" used here refers to a piece of hardware that accesses network communications. A user station can be mobile or stationary. A subscriber station can be any data device that communicates via a wireless channel or via a wired line, such as optical fiber or coaxial cable. A user station can be any of many types of devices including (but not limited to) PC cards, compact flashes, external or internal modems, or wireless or wired telephones. A user station that establishes an active routing channel to connect with a base station is in a connection establishment state. A base station that establishes an active routing channel connection with a base station is called an active subscriber station and is in a routing state.

The term "physical channel" as used herein refers to a signal transmission communication path described from the viewpoint of modulation characteristics and coding.

The term "logical channel" used herein refers to a communication path in the protocol layer of a base station or a subscriber station.

The term "communication channel/link" as used herein means a physical channel or a logical channel according to this document.

The term "reverse channel/link" as used herein refers to a communication channel/link through which the subscriber station transmits signals to the base station.

The term "forward channel/link" as used herein refers to a communication channel/link through which a base station transmits a signal to a subscriber station.

The term "soft handoff" as used herein refers to a communication between a subscriber station and two or more areas, where each area belongs to a different unit. Reverse link communications are received by two regions, and forward link communications are carried on the forward links of two or more regions at the same time.

The term "softer handoff" as used herein refers to a communication between a subscriber station and two or more areas, where each area belongs to the same unit. Reverse link communications are received by two regions, and forward link communications are simultaneously carried on one of the forward links of two or more regions.

The term "erased" used here means that a message has not been successfully confirmed.

The term "dedicated channel" used here means that a channel is modulated by special information of a different user station.

The term "common channel" as used herein means that a channel is modulated through an information shared among all subscriber stations.

<u style="single">instruction</u>

As mentioned above, the basic model of a broadcasting system includes a user broadcasting network served by one or more central stations, which can transmit information with a certain content, such as news, movies, sports events, and user favorites. The subscriber station of each broadcast network user can supervise a common broadcast forward link signal. FIG. 1 depicts a conceptual block diagram of a communication system 100, which can implement a high-speed broadcast service (HSBS) according to a specific embodiment of the present invention.

The broadcast content is sent out in a content server (CS) 102. The content server can be located on a delivery network (not shown in the figure) or an external Internet (IP) 104. The content is delivered to a broadcast packet data service node (BPDSN) 106 in the form of packets. The term BPDSN is used because although BPDSN can actually exist in a community or is the same as a general PDSN (not shown in the figure), BPDSN can be logically different from a general PDSN. The BPDSN 106 passes the packet to a packet control function (PCF) 108 according to the destination of the packet. When a base station controller is used for general voice and data services, the PCF is a control entity used to control the functions of the HSBS base station 110. In order to describe the high-level conceptual connection between HSBS and the actual access network, Figure 1 shows that a PCF actually coexists or even the same, but the logic is different from a base station controller (BSC). Those who are familiar with this technique can understand that this is only for illustrative purposes. The BSC/PCF 108 can provide the packet to the base station 114.

The communication system 100 allows a high-speed broadcast service (HSBS) by introducing a forward broadcast shared channel (F-BSCH) 112 with a high data rate, and this can be received by many subscriber stations 114. The term "forward broadcast shared channel" as used herein refers to a single forward link physical channel that can carry broadcast routes. A single F-BSCH can carry one or more HSBS channels, and these HSBS channels are multiplexed in a single F-BSCH in a TDM manner. The term "HSBS channel" used here means that a single logical HSBS broadcast conversation is defined by the broadcast content of the conversation. Each conversation is defined by broadcast content that changes over time; for example, 7 am-news, 8 am-weather, 9 am-movie, etc. Figure 2 describes the concept of the actual and logical channels of HSBS.

As shown in Figure 2, an HSBS is provided on two F-BSCHs 202, each of which is transmitted on a separate frequency fx and fy. For example, in the above-mentioned cdma2000 communication system, this physical channel includes, for example, a forward supplemental channel (F-SCH), a forwarding broadcast control channel (F-BCCH), a forward common control channel (F-CCCH), and other common channels. A combination of exclusive channels and channels. The use of the common and exclusive channels for information broadcasting is disclosed in the US Patent No. 60/279,970 filed on March 28, 200, entitled "METHOD AND APPARATUS FOR GROUP CALLS USING DEDICATED AND COMMON CHANNELS IN WIRELESS NETWORKS" and assigned to this The transferee of the invention. Those who are familiar with this technique can understand that other communication systems use channels that perform similar functions. Therefore, the description can be applied to other communication systems. F-BSCHs 202 carry broadcast routes and include one or more broadcast conversations. F-BSCHs 202b can carry one HSBS channel 204c; two HSBS channels 204a, 204b are multiplexed in F-BCCH 202a. The content of an HSBS channel is formatted into a packet containing a payload 206 and a header 208.

Those who are familiar with this technique can confirm that the HSBS broadcast service described in Figure 2 is just an illustration. Therefore, in a specific area, the HSBS broadcast service can be used in several ways according to the features supported by a particular communication system implementation. Implementation features include, for example, the number of HSBS conversations supported, the number of frequency allocations, the number of broadcast physical channels supported, and other implementation features known to those familiar with the technology. Therefore, for example, more than two frequencies and F-BSCHs can be arranged in one area. In addition, more than two HSBS channels can be multiplexed to one F-BSCH. In addition, a single HSBS channel can be multiplexed on more than one broadcast channel in an area, serving users on these frequencies on different frequencies.

As mentioned above, communication systems often transmit information in frames or boxes, and these are protected by encoding unfavorable conditions that affect a communication channel. Examples of this system include cdma2000, WCDMA, and UMTS. As shown in FIG. 3, the transmission information bit stream 302 starting at a higher layer is provided to an (internal) encoder 304 on a physical layer. The encoder can accept block bits of length S. This S-bit block typically includes some loads, for example, the tail element of the internal encoder, a cyclic redundancy check (CRC), to assist the internal decoder to determine the success or failure of the internal decoder at the receiving end, and to be familiar with it. Other load information known to this technician. The encoder then encodes the S bits using a selection code resulting in a coded block of length P=S+R, where R represents the number of redundant bits. Those who are familiar with this technique can understand that although the specific embodiments are described from the perspective of a layered model, this is for illustrative purposes, and the logic blocks, modules, circuits, and algorithm steps can be described with electronic Implementation of hardware, computer software, or a combination of both. Therefore, for example, the internal encoder 304 and a general purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic Any combination of devices, discontinuous gates or transistor logic, discontinuous hardware components, or designed to perform the functions described herein are implemented or executed together. The general purpose processor can be a microprocessor, or the processor can be any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, such as a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors with the same DSP core, or any other combination of such constructions.

According to a specific embodiment of the present invention, as shown in FIG. 4, the transmission information bit stream 402 is first encoded by an external encoder 406, and the encoded stream is then provided to the internal encoder at the physical layer 408 (not shown in the figure). ). The transmission information bit stream 402 starting at a higher layer is provided to a transmission buffer 404. The transfer buffer is described in detail in Figure 5. Please refer to FIG. 5, the bits fill up the regular portion 504 of the transmit buffer 404 (FIG. 4) column by column from left to right. The regular portion 504 includes k rows 508 of length L. In a specific embodiment, as shown in FIG. 5, the length L of the buffer corresponds to the length of a radio frame without loading (for example, CRC can help the end bit of the internal decoder and internal encoder). Please refer to Fig. 4, as long as the regular part 504 (Fig. 5) is filled, the external block encoder 406 will start to perform bit column coding in the regular part 504 (Fig. 5) to generate check bits (Nk) additional columns 510 (Figure 5). This column operation is performed column by column in the binary external code, that is, m=1. For non-binary code, that is, m&gt;1, and each m adjacent column of the row is processed with m-bit symbols. The m-bit symbols along the top k columns are read by an external encoder to generate nk m-bit symbols corresponding to the lower nk columns that fill these columns.

In another specific embodiment, the length L of the buffer is equal to the number of bits conveyed by the inner encoding frame divided by m, the size of the outer encoder code. In this specific embodiment, the first m columns from the TX buffer are transmitted in the first inner coded frame, and the second m columns of bits are transmitted in the second inner coded frame until the entire buffer is transmitted. Please refer to Figure 4 again. As long as the regular part 504 (Figure 5) is filled, the external block encoder 406 will start to execute the bit field encoding in the regular part 564 (Figure 5) to generate a check bit M(nk) extra columns 510 of yuan (Figure 5). This column operation is performed column by column in the binary external code, that is, m=1. For non-binary codes, that is, m&gt;1, and each m column of a column forms an m-bit symbol. The k symbols in the km column from the top of the column are read by an external encoder to generate (nk)m bit symbols corresponding to the lower m(nk) column to fill this column.

In a specific embodiment, the external encoder includes a regular Reed-Solomon (RS). The content of the transmission buffer 404 is then provided to a physical layer 408. On the physical layer 408, individual frames are encoded by an internal encoder (not shown in the figure), resulting in encoded frames. The structure of the internal decoder may be, for example, the structure of FIG. 3. When the total number of internal code erasures exceeds the external code modification capability, the regular columns and check columns of the buffer can be interleaved during transmission to reduce the chance of a large number of regular columns being erased. The frame can be further processed according to a selected modulation method. In a specific embodiment, the processing is performed according to the IS-2000 standard. The processed frame is then transmitted on a communication channel 410.

The transmitted frame is received at the destination station and provided to a physical layer 412. On the physical layer 412, individual frames are demodulated and provided to an internal decoder (not shown in the figure). In a specific embodiment, the internal decoder can decode each component, and if it decodes successfully, it can output a correct decoded frame; or, if it fails to decode, it declares erasure. The success or failure of decoding must be determined with high accuracy. In a specific embodiment, this can be achieved by including a long (for example, 16-bit) cyclic redundancy check (CRC) in the frame after the outer encoding and before the inner encoding. However, those familiar with this technique can confirm the frame quality indicator can be used by other organizations. The included CRC obtained from the decoded frame is compared with a CRC calculated from the bits of the decoded frame, and if the two CRCs are the same, the decoding is declared successful. Further processing at the physical layer can be performed according to the result of the decision of the internal decoder.

The correctly decoded frame is provided to the appropriate row of a receive buffer 414. If all the regular k frames are correctly decoded by the internal decoder, the regular frames from the regular part 414(1) of the receiving buffer 414 will be passed to the upper layer (not shown in the figure) for no external decoding Further processing.

If the internal decoder cannot decode the frame, the decoder will declare the erasure and provide an indication that the frame is missing to an external block decoder 416. The processing will continue until many check bit frames are correctly received, and when there are regular frames that are erased, they are passed to the check bit portion 414(2) of a receiving buffer 414. The receiver will stop receiving any remaining frames, and the external decoder (not shown in the figure) will start to restore the erased regular frames. The restored regular frame is passed to the upper layer.

If the total number of correctly received frames in the receiving buffer 414 is less than k, according to a specific embodiment, since there is no guarantee that the decoding will succeed, the external decoder will not start. The confirmation of the correct reception of the regular frame and the missing bits will be passed to the higher layer together. In another specific embodiment, the receiver uses decoded bits from an internal decoder (as indicated by a failed CRC check to indicate unreliability) to restore regular bits. According to a specific embodiment, the receiver decodes the unreliable bits from the internal decoder and finds the most likely codeword. In another specific embodiment, the receiver uses the signal quality measurement of the erased frame in the buffer to select the erroneously received frame, and the erroneously received frame has a high signal-to-noise ratio to form a k-row A sub-buffer. The receiver then performs a bit change (every time a column changes the bit value of 0 to 1 and vice versa), and checks whether the bit change causes a codeword. In a specific embodiment, the bit change is performed on the least reliable bits first, and continues on these bits in the order of increasing reliability of the bits. For example, the bit reliability of a signal noise-to-interference ratio during the frame period is determined based on internal decoding metrics, such as Yamamoto metric, re-encoded symbol error rate, re-encoded energy metric, and known to those who are familiar with this technique. Other measures, or a combination of measures. If a codeword is not found, the bit change will continue for all remaining columns of all unreliable columns. If a codeword is not found, the bit change will continue with the increasing number of bit changes (that is, each time it changes 2 bits, then 3 bits, until the maximum number of bits), until one The code word is found or all combinations are exhausted. In another specific embodiment, the CRC from the unreliable column is used to check whether the entire decoding in this case is successful. Only if the CRCs from all the columns match, the frame will be passed to the higher layer; otherwise, the bits from the reliable column will be passed to the higher layer.

To improve the reliability of decoding, in another specific embodiment, demodulation and internal decoding are performed in more than k correctly received frames in a buffer. According to still another specific embodiment, demodulation and internal decoding are performed on all frames of the buffer. In two specific embodiments, the outer decoding is performed on the k (or km) column with the highest quality. Quality can be determined based on internal decoding metrics, for example, a signal noise to interference ratio during the frame, similar to Yamamoto metrics, re-encoded symbol error rate, re-encoded energy metric, and others known to those who are familiar with this technique Measures, or combinations of measures. The quality measurement of quality evaluation is used in US Patent No. 5,751,725 under the name "METHOD AND APPARATUS FOR DETERMINING THE RATE OF RECEIVED DATA IN A VARIABLE RATE COMMUNICATIONS SYSTEM" and US Patent No. 5,774,496 under the name "METHOD AND APPARATUS FOR DETERMINING DATA RATE OF TRANSMITTED VARIABLE" "RATE DATA IN A COMMUNICATIONS RECEIVER" is disclosed in detail, and both have been assigned to the assignee of the present invention.

<u style="single">Battery power saving</u>

An important requirement of a user station is low battery power consumption. The above coding method can ensure that the correctly received frame smaller than n is sufficient to decode the regular information of each transmission buffer. As a result, it is not necessary for the subscriber station to receive all n frames to decode the transmitted information. If the user station decides, for example, the amount of redundancy from the frame encoding rate, the user station can determine the many frames that must be received correctly, that is, the internal decoder declares the correct decoding for the external decoder to decode correctly. The user station can determine the encoding rate through several methods known to those who are familiar with this technique. Therefore, for example, there may be only a fixed coding rate. If more than one coding rate is used, the user station can use a blindly-acting coding rate decision, or the possible data rate can be provided to the user station through the start station. In addition, information about the amount of redundancy can be provided to the user station.

As long as the subscriber station has accumulated the internal decoder to correctly decode the determined number of frames into the receiving buffer 414 (the regular part 414(1) and the check bit part 414(2)), the subscriber station can end the additional frames The reception and internal decoding. Therefore, a battery power saving can be achieved. Because the subscriber station knows the many frames in the transmission buffer 404 and the number of frames it receives, the subscriber station can determine when the subscriber station needs to start receiving and internal decoding of frames containing new system information.

Because HSBS can provide traditional communication system services such as voice, short message system, data, and other services that are familiar with the technology, when working in HSBS, the subscriber station needs to be able to receive this traditional service. Therefore, the subscriber station needs to be able to receive sent messages. The broadcasting service letter is disclosed in detail in the patent case No. 09/933,978 named "METHOD AND SYSTEM FOR SIGNALING IN BROADCAST COMMUNICATION SYSTEM" filed on August 20, 2001, which has been assigned to the present invention. Sending actions include, for example, receiving paging messages, responding to paging messages, including load messages received by the system structure, searching for neighboring systems on the same or different frequencies, and sending other messages known to those familiar with this technology. As mentioned above, after accumulating enough frames in the buffer, the subscriber station will terminate the receiving operation, so that the sending information may be missed.

As a result, in a specific embodiment, the signaling action that the subscriber station must perform to receive the broadcast channel is performed at the most likely time when the subscriber station is receiving the broadcast channel. The most likely time for the subscriber station to receive the broadcast channel is usually when a regular column of the buffer is transmitted in the atmosphere. Or, a user station is responsible for receiving the broadcast channel at a predefined time. Therefore, before the user station takes over the time during which the broadcast channel is received, the user station must make sure that the user station will not terminate frame reception.

<u style="single">Hard handoff on a common broadcast forward link</u>

To improve the forward link efficiency of co-broadcasting, the overlapping coverage areas of soft and softer handovers in different areas are desired. During the soft handover process, the method and system for providing communication with a user via more than one base station was applied for patent number 09/933,607 on August 20, 2001 under the name "METHOD AND SYSTEM FOR A HANDOFF IN A BROADCAST" COMMUNICATION SYSTEM" discloses that it has been assigned to the assignee of the present invention.

Although the soft and softer handover method described because the subscriber station will not experience the discontinuity of the transmission of information is desired, this method cannot always be used in a broadcast communication system. A user station can transmit only the soft group synchronously; as a result, the user station can only perform a soft handover and a softer handover between base stations belonging to the same soft handover (SHO) group. As used here, the SHO group means a group of all base stations to broadcast the forward link together with simultaneous transmission. Figure 6 depicts two SHOs, one containing BS₁, BS₂, And BS₃, The other contains BS₄, BS₅, BS₆, And BS₇. As a result, if the subscriber station crosses the boundary of a coverage area of SHO group 1 602 to a coverage area of SHO group 2 604, a hard handover is required.

The use of the above coding method will increase the subscriber station not experiencing interruption in transmitting information, or reduce the discontinuity if interruption occurs.

Figure 7 depicts asynchronous transmission between SHO group 1 602 and SHO group 2 604 (from Figure 6), where the delay of the transmission from the SHO group 2 604 base station is related to the transmission from the SHO group 1 602 base station. The subscriber station (not shown in the figure) is supervising the transmission from the SHO group 1 602 base station. The subscriber station can determine the hard handover representation for a different SHO group. For example, when the quality metric of the received transmission drops below a critical value, the handover will be indicated. The user station then decides whether a soft handover is possible. According to a specific embodiment, the subscriber station can determine the structure of the neighbor area according to the value of an HSBS neighbor structure indicator (NGHBR_CONFIG_HSBS) transmitted by the current base station. This method is described in detail in the "METHOD AND SYSTEM FOR A HANDOFF IN A BROADCAST COMMUNICATION SYSTEM" named "METHOD AND SYSTEM FOR A HANDOFF IN A BROADCAST COMMUNICATION SYSTEM" cited in the patent application No. 09/933,607 dated August 20, 2001, which has been assigned to the assignee of the present invention. When the user station has accumulated good enough frames in the buffer 1 702(1) for decoding, the user station can continue to accumulate the frames of the buffer 1 702(1) until time t₁until. This includes packet P₀ 704(2), P₁(It is in the part P of buffer 0 702(0)_1-1704(4) and part P in buffer 1 702(1)_1-2 706 (2) transmission), and P₂ 706(4). The symbol P represents a regular part of a buffer; the symbol R represents a redundant part. User station is at time t₂Start the hard handover and obtain a base station transmission of SHO group 2 604. Interval Δt=t₂-t₁It depends on the type of handover performed by the user station, such as hard handover between frequencies, same frequency handover, user station and base station design, and other standards known to those familiar with this technology. The different methods of performing delivery are discussed in the above cited patent application No. 09/933,607 dated August 20, 2001, titled "METHOD AND SYSTEM FOR A HANDOFF IN A BROADCAST COMMUNICATION SYSTEM", which has been assigned to the assignee of the present invention. people. So, at time t₂, The subscriber station can start to receive the frame 712 sent by a station in SHO group 2 604. Because of the encoding modification capability according to a specific embodiment of the present invention, the received frame is sufficient to correctly decode the packet P of the buffer 1 716(4)₂ 716(2), P₃ 716(4). The user station can discard any copied packets. Those who are familiar with this technique can confirm the principle of the above application, where the base station transmission from SHO group 1 602 is related to the base station transmission from SHO group 2 604.

<u style="single">Hard handover between frequencies</u>

If the subscriber station travels outside the boundary of the currently communicating communication system, it can maintain the communication link by forwarding the call to an adjacent system (if any exists). Adjacent systems can use any wireless technology, such as CDMA, NAMPS, AMPS, TDMA, or FDMA. If the adjacent system uses CDMA as the current system on the same frequency, the soft handover of the system will be executed. In the case where the soft handover between systems cannot be used, the communication link will be transmitted via a hard handover, in which the current connection will be interrupted before a new connection is reached. Examples of typical hard handover situations include: (1) a subscriber station is moving from an area served by a CDMA system to an area served by a system using another technology; and (2) a call is using a different frequency band ( Hard handover between frequencies) for transmission between two CDMA systems.

Hard handover between frequencies can also occur between base stations of the same CDMA system. For example, a high-demand area in a downtown area requires more frequencies than surrounding suburban areas. It is not a cost-effective configuration of all available frequencies of the system. When the user travels to a non-crowded area, the call that only starts on the configured frequency in the high-congestion area must be handed over. Another example is microwave or other service operations operating on system boundary frequencies. When users travel to areas suffering from interference from other services, their calls need to be handed over to different frequencies.

An attempt to perform a hard delivery with a higher probability of success is disclosed in US Patent No. 5,999,816 titled "METHOD AND APPAPATUS FOR PERFORMING MOBILE ASSISTED HARD HANDOFF BETWEEN COMMUNICATION SYSTEMS", which has been assigned to the assignee of the present invention. In Patent No. 5,999,816, the subscriber station temporarily tunes to the frequency of the hard handover destination system and searches for available pilot signals on this frequency, including relevant base stations in the active group. If the search is successful and at least one of the related base stations can meet the criteria included in the active group, the user station can obtain the base station. In the case of an unsuccessful attempt at hard handover, the user station can use the start system to assist future handover attempts with efficiency information and return to the original system. Or, as no handover attempt is successfully reached, the subscriber station may search for the destination system. After the search is completed, the user station can return to the original frequency to restart the current communication. When tuned to another frequency, any data frame generated by the subscriber station or transmitted by the base station will be destroyed. Typically, the base station can only provide a part of the possible offset that the subscriber station searches. Even so, the duration of the handover attempt or search is so long that it potentially destroys many data frames.

As a result, an improved method for performing hard handover with a higher probability of success is in US Patent No. 6,134,440 titled "METHOD AND APPARATUS FOR PERFORMING MOBILE STATION ASSISTED HARD HANDOFF USING OFF LINE SEARCHING" and has been assigned to the assignee of the present invention. In U.S. Patent No. 6,134,440, after searching for a pilot signal in another frequency band, the user station can tune to another frequency and sample the input data to combine these The samples are stored in memory. During the period when the user station is tuned to another frequency, all data sent to the user station on the forward link will be lost. Similarly, any reverse link data sent through the user station will be on the other frequency. Therefore, the reverse link data will not be received at the initial base station. When enough samples are stored, the subscriber station will return to the initial frequency. At this time, the forward link data will be received by the subscriber station again Receive, and the reverse link data can be successfully transmitted to the starting base station. After returning to the starting frequency, the searcher at the subscriber station can then use it to search for the pilot signal offset and use the storage collected from another frequency Data. According to the present invention, due to the relatively short period of time required to sample and store information on another frequency, the active communication link will not be interrupted. The active communication link will not be affected by subsequent offline searches. Because at another frequency Up-sampling data requires less time than real-time search for pilot signals, and because the communication link will be destroyed by the hard handover process when the subscriber station is tuned to another frequency, the forward and reverse on the system is started. The link interruption can be reduced. In fact, if the sampling time is quite small, the error modification code used in the current communication system can avoid all errors caused by sampling another frequency.

The search methods disclosed in the aforementioned two applications can be improved by using the aforementioned encoding method. Because the subscriber station does not need to accumulate all n frames from the transmitter buffer 404, for restoring all regular information, as long as the subscriber station accumulates the determined number of frames correctly decoded by the internal decoder into the receiving buffer of Fig. 4 414 (the regular part 414(1) and the check bit part 414(2)), the subscriber station can end the reception of the extra frame. Because the subscriber station knows the many frames in the transmission buffer 404 and the number of frames it receives, the subscriber station can determine when it needs to start receiving and internal decoding of frames containing new system information. According to the concepts disclosed in U.S. Patent Nos. 5,999,816 and 6,134,440, the subscriber station then uses the time between the end of additional frame reception and the restart of frame reception and internal decoding to perform handover/search.

As a result, as long as the subscriber station accumulates a determined number of frames correctly decoded by the internal decoder, and when the subscriber station needs to start receiving and internal decoding, the subscriber station can end the reception of additional frames. The subscriber station then tunes to the frequency of the destination system. The information belonging to the destination system can be obtained, for example, from the starting system. If the subscriber station tunes to the destination system to perform the handover, the subscriber station can try to obtain at least one area of the destination system. If the acquisition of at least one area of the destination system is like, for example, the measurement of the minimum pilot signal strength through at least one area of the destination system, the handover can be considered as successful, and the subscriber station can remain in the destination system and start Receive a service from the acquired area on a channel. Otherwise, the subscriber station can start receiving and storing signals on the frequency of the destination system. The user station can perform storage at the required time or until the time when the user station needs to return to the starting system area. The subscriber station can then receive the frame at the same time and analyze the stored signal to identify the area in the destination system for handover. The subscriber station may then repeat the described method or hand over the area identified by the analysis.

Those familiar with this technique can confirm that as long as the encoding-decoding of the present invention can be used by a special channel, the specific embodiment of the present invention is also suitable for hard handover on a common broadcast channel and handover on a routing channel.

<u style="single">Paging</u>

As shown in Figure 6, all user stations in a SHO group are supervising the common broadcast forward link and are engaged in communication with other user stations; or supervising a paging channel. The paging channel that the subscriber station is supervising is known as the communication system. The paging channel is assigned to the user to supervise the paging channel according to the method used by the current communication system (for example, IS-2000, WCDMA, UMTS), and to engage in communication with other user stations. In addition, the user's paging channel is designated according to the method disclosed in the patent application Nos. 09/933,607 and 09/933,978 on August 20, 2001 under the name "METHOD AND SYSTEM FOR SIGNALING IN BROADCAST COMMUNICATION SYSTEM". This patent has been assigned to this The transferee of invention. As a result, any user can be paged.

According to a specific embodiment, the common broadcast channel is used to page subscriber stations that supervise the forward link of the common broadcast. As described with reference to FIG. 4, the HSBS channel constituting the packet is multiplexed on the F-BSCH. Therefore, a subscriber station receiving an HSBS channel can distinguish packets carrying message signals, such as paging messages from packets carrying HSBS channel content. According to a specific embodiment, a certain value of BSR_ID such as '000' can be reserved to indicate whether the content of a packet or some packets carries out signaling (paging) information. The disadvantage of this method is that because the contents of packets or some packets are synchronized in a SHO group, all subscriber stations in the SHO group can receive the same paging information. Because the payload of each packet is limited, several packets can carry paging information to page all users in the SHO group. This can cause undesirable HSBS channel content delays in some applications.

As a result, according to another specific embodiment, the contents of a packet or some packets of an HSBS channel transmitted through the area of a SHO group are not synchronized at predetermined periodic intervals. As a result, the contents of a packet or some packets may be different in each area, and therefore, it is allowed to upload call user stations on a per-area basis. Because the periodic interval is pre-defined, the user station knows that the packet or some packets are sent in the interval sending message.

Please refer to FIG. 5 again. According to a specific embodiment, a number of predetermined rows in the check bit portion 506 of the transmission buffer 502 can be replaced by paging information. When a user station encounters a packet that the user station knows to carry paging information, the user station can interpret the predetermined row as sending information. Because the predetermined rows in the check bit portion 506 can be replaced, the information bit will not be protected and will be erased. However, because the paging information is carried in some packets, the base station can increase the capacity during the packet transmission of the sending information and HSBS content to compensate for the loss of protection due to encoding.

Alternatively, the external encoder can encode the information string using a packet redundancy that carries HSBS content and paging information that is less redundant than a packet that carries HSBS content information. Therefore, the (nk) row less than the check bit portion 506 of the transmission buffer 502 is filled with check bit information. The unused rows of check bits can be used for paging information. Although the protection of packets carrying HSBS content and paging information is less than the protection of packets carrying HSBS content information, the design of the encoding rate can be met under normal channel conditions. In addition, the base station can increase the capacity during the packet transmission period for the transmission of signaling information and HSBS signals to compensate for the loss of protection due to less coding.

According to another embodiment, no predefined interval is required for the transmission of paging information. The packet that carries HSBS content information is encoded with another rate, and a packet that carries paging information is encoded with another rate. The user station can try to decode a received packet according to a first rate hypothesis. If the decoding is successful, the packet can be processed according to the relationship between the rate assumption and the packet content. If the decoding is unsuccessful, the user station can try to decode the received packet according to a second rate hypothesis. If the decoding is successful, the packet can be processed according to the relationship between the rate assumption and the packet content. Otherwise, it can be declared erased.

<u style="single">Handover of broadcast system transmission content</u>

When the transfer content is buffered, the handover will occur. FIG. 8 is a timing chart describing a subscriber station unit handover from a base station A 801 to a base station B 803 when receiving broadcast content buffers from the base station A and the base station B. In this example, the content is an introduction and weather forecast for San Diego and Chicago. The same message content is contained in the frames F1 to F4, 802(1) to 802(4), and 804(1) to 804(4) of the transmission buffers 806 and 808. For ease of explanation, the check bits or redundant parts of the transmit buffer are not displayed.

When the content transmitted through base station A and base station B are at different times, the subscriber unit will experience copy content and content cut.

For example, in the system for communicating content on a broadcast channel shown in FIG. 8, the first base station 801 includes a first transmission buffer 806 configured to store a first plurality of internal codes; and an external coded signal containing the content Blocks 802(1) to 802(4). The first group of inner and outer coded frames F1 802(1) of the first plurality of inner coded and outer coded frames contains the first part of content, such as "Welcome to the display". The first base station 801 is configured on the broadcast channel to transmit the first plurality of inner coded and outer coded frames.

A second base station 803 includes a second transmission buffer 808 constructed to store a second plurality of inner coded and outer coded frames 804(1) to 804(4) containing the same content. The second plurality of inner coded and outer coded frames is the second group of inner coded and outer coded frames 804(1) and 804(2) including the second part of the interior, such as "Welcome to Display" and "San Diego" The weather forecast is ". The second base station 803 is configured to transmit a second plurality of inner coded and outer coded frames on the broadcast channel.

The frames in the transmission buffers 806 and 808 are internally coded and externally coded in the same manner. However, the transmission delay of the content in the transmission buffer 808 is related to the content in the transmission buffer 806.

When the content is transmitted by two base stations 801 and 803 on the broadcast channel, a user station can perform handover from the first base station 801 to the second base station 803. In this example, the subscriber station can receive the first set of internal and external coded frames F1 802(1) transmitted from the first base station A; moreover, after the handover, it can receive the second set of frames from the second base station B Set the internal and external code frames F1 804(1) and F2 804(2).

The user station can also be handed back to base station A. In this example, after handing over back to the base station, the subscriber station can receive frame F4 802(4) from the base station.

Figure 9 depicts the receive buffer of a subscriber station. The subscriber station stores the received frame in the receiving buffer 910. The left side of Fig. 9 shows the content of the receive buffer in the order in which the subscriber station receives the frame. The right side of FIG. 9 shows the contents of the receiving buffer after the copied frame is removed from the receiving buffer, and the clipped frame is regarded as erasure recognition. As a result of the handover, the continuous frame of the content is not received, and the transmission time of the same broadcast content between the units is not aligned, which can be regarded as a "cut" frame.

According to the content of the receiving buffer on the left, after the first handover of base station B 803, the subscriber station can receive duplicate frames P1 907(1) and 907(2), and after the second handover of base station A 801 , The clipped frame F3 is not received.

The time realignment of the two transmissions of the same content and external encoding can alleviate the problem of copying and clipping frames. Even if a new unit is transferred when the buffer of broadcast content is delivered, the user of the subscriber station will experience seamless service without content loss.

The subscriber station can receive the transmission of the first plurality of inner and outer coded frames F1 802(1) to 802(4) and the second plurality of inner and outer coded frames F1 804(1) to F4 804(2) Time alignment representation. From the time-aligned representation, the user station can determine the clipping frame of the content and the copy frame of the content.

The indication of time alignment may be the first frame F1 804(1) transmission start indication of the frame transmitted from the base station B 803 on the broadcast channel. In a WCDMA system, the indication may be, for example, the number of system frames transmitted from base station B on a broadcast control channel. In a cdma2000 system, the indication may be, for example, the system time of the second base station B transmitted from the second base station B on the broadcast control channel.

Knowing the time alignment of the transmission, the subscriber station can decide to display the duplicate frames of F1 907(1) and F1 907(2) in the receiving buffer 910 on the left side of FIG. 9.

The user station can determine whether the copied frame F1 907(1), 907(2) has been internally decoded correctly. When any one of the duplicate frames has been correctly internally decoded, the subscriber station can select one of the duplicate frames F1 907(1) or F1 907(2) correctly internally decoded for external decoding. When the frame that is not copied is correctly internally decoded, the user station can treat the frame as an erased frame. The erased frame can be modified by using external decoding.

The receiving buffer on the right shown in FIG. 9 describes the situation where at least one of the frames F1 907(1) and 907(2) is correctly decoded, and one of the frames F1 907(1) is selected for external decoding. With the absence of the second frame F1, the frame F2 907(3) displayed in the right representation of the receive buffer is currently corrected to the receive buffer 910 such as the frame F2 907(2).

Knowing the time alignment of the transmission, the subscriber station can also decide to cut the frame. The user station regards the clipped frame as the erased frame.

On the right side of the receiving buffer shown in FIG. 9, it is described that the clipped frame F3 907(3) is regarded as the erased frame in the correct position of the receiving buffer 910. To modify the clipped frame F3 907(3), the subscriber station can externally decode the received first set of internal coded and external coded frames F1 907(1), and receive the second set of internal coded and external coded frames F2 907( 2) With F4 907(4). For ease of description, the check bits and redundant parts of the receiving buffer are not shown in the figure.

Those who are familiar with this technique can understand that although the flowchart is drawn in an understandable sequential order, some steps can be implemented in parallel in actual implementation. In addition, unless otherwise specified, the method steps can be interchanged without departing from the scope of the present invention.

Those who are familiar with this technique can understand that information and signals can be expressed using a variety of different techniques. The above-mentioned references such as data, instructions, commands, information, signals, bits, symbols, and chips can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination.

Those who are familiar with this technology can further understand that the various illustrative logic blocks, modules, circuits, and algorithm steps described in the specific embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination. In order to clearly describe the interchangeability of hardware and software, components, blocks, modules, circuits, and steps of various descriptions are usually described from their functional point of view. Whether this function is hardware or software depends on the special application and design of the overall system. Those who are familiar with this technique can implement the description function of each special application in different ways, but this implementation decision does not deviate from the scope of the present invention.

Various descriptions of the specific embodiments of the logic blocks, modules, and circuits are disclosed here. General purpose processors, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), and a programmable gate array (FPGA) or other programmable logic devices, discontinuous gate or transistor logic, discontinuous hardware components, or any combination of the functions described herein are implemented or executed. The general purpose processor may be a microprocessor, or the processor may be any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, such as a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors and a DSP core, or any other combination of such structures.

The methods or algorithm steps described in the specific embodiments disclosed herein can be directly implemented in hardware or a software module executed by a processor, or a combination of both. A software module can be stored in random access memory, flash memory, ROM memory, EPROM memory, EEPROM memory, scratchpad, hard disk, removable disk, CD-ROM, or in technology Any other form of storage media known in. A storage medium is coupled to the processor, and the processor can read instructions from the storage medium and write information to the storage medium. Alternatively, the storage medium may be integrated into the processor. The processor and storage medium can be in ASIC. ASIC can be in the user terminal. Alternatively, the processor and the storage medium can be discontinuous components in the user terminal.

The previous description of the disclosed specific embodiments is provided to allow those skilled in the art to make or use the present invention. Various modifications of these specific embodiments are obvious to those skilled in the art, and the general principles defined herein can be applied to other specific embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the specific embodiments shown here, but conforms to the broad scope of the principles and novel features disclosed herein.

The disclosed part of this patent document contains a copyright protection statement. The copyright owner has no objection to the fax reproduction of any part of the patent document or patent disclosure as if it appeared in the patent file or record of the Patent and Trademark Office, but all copyrights are reserved.

<p>102Content Server</p><p>104External Internet</p><p>106Broadcast Packet Data Service Node</p><p>108Packet control function</p><p>110HSBS base station</p><p>112High-speed broadcasting service</p><p>114Base station</p><p>204HSBS channel</p><p>206Payload</p><p>208Header</p><p>302Transmitting information bit stream</p><p>304Encoder</p>

Fig. 1 depicts a conceptual block diagram of a high-speed broadcast service communication system; Fig. 2 depicts a conceptual diagram of HSBS's physical and logical channels; Fig. 3 depicts a prior art encoding; Fig. 4 depicts physical layer processing according to a specific embodiment of the present invention; Figure 5 describes a transmission buffer; Figure 6 describes the concept of a soft handover group in a broadcast communication system; Figure 7 describes a sequence diagram of hard handover; Figure 8 describes when a user station receives broadcast content from two cells A handover timing diagram; and Figure 9 depicts a receiving buffer of a subscriber station.