Transmission of overhead information for reception of multiple data streams

Transmission of additional information for the reception of multiple data streams

This application claims the rights of the following applications and incorporates them by reference in their entirety: "Methods for adding additional information to receive multiple multimedia streams on mobile radio links" filed on October 24, 2003 US Provisional Patent Application No. 60/514,320; US Patent Application No. 10 filed on September 1, 2004 entitled "Method for Adding Additional Information to Receive Multiple Multimedia Streams on Mobile Radio Links" /932,586; and the United States Provisional Patent Application No. 60/559,740 filed on April 5, 2004 entitled "Multitasking and Transmission of Multiple Data Streams in a Wireless Multi-Carrier Communication System".

The present invention generally relates to communication, and more specifically to several methods of transmitting additional information to receive multiple data streams in a communication system.

A base station in a wireless communication system can simultaneously transmit multiple data streams for broadcast, multicast, and unicast services. Broadcast transmission is sent to all wireless devices in a designated coverage area, multicast transmission is sent to a wireless device group, and unicast transmission is sent to a specific wireless device. For example, a base station can broadcast multiple data streams for multimedia (such as television) programs through a land radio link for reception by wireless devices. Generally speaking, a base station can send any number of data streams, the number of data streams can change over time, and each data stream can have a fixed or variable data rate.

A wireless device located in the area covered by the base station may only want to receive one or several specific data streams from the multiple data streams transmitted by the base station. If the base station multiplexes all data streams into one composite data stream before transmission, the wireless device may need to receive the signal sent by the base station, and process the received signal (such as down-conversion, demodulation, and decoding). Obtain the composite data stream sent by the base station, and implement demultiplexing to retrieve one or several specific data streams. This type of processing may not be a problem for receiving units that are to be turned on all the time. However, many wireless devices are portable and powered by internal batteries. Therefore, continuously demodulating and decoding the received signal system to restore only one or several data streams will consume a lot of battery energy, which may greatly shorten the "operation" time of the wireless device.

If multiple data streams are transmitted separately, the base station will also transmit control information on a dedicated control channel to indicate when and where each data will be transmitted. In this case, the wireless device may need to continuously decode the dedicated control channel to obtain the control information of each related data stream, which will drain the battery energy. The wireless device may also need to decode the related data stream and the dedicated control channel at the same time, which will increase the complexity of the wireless device.

Therefore, there is a need in the industry to send additional information so that the relevant individual data stream sent to the wireless device can be effectively received with reduced energy consumption.

This article describes several techniques for transmitting additional information to facilitate the effective reception of separate data streams. A base station can transmit multiple data streams on multiple data channels. In the following description, the data channel is also referred to as a multiplex logic channel (MLC), but it can also be referred to as other terms. Each MLC can carry one or more data streams, and can be transmitted on different frequency sub-bands at different times, etc. The time-frequency position of each MLC can be changed over time. The additional information indicates the time-frequency position of each MLC transmitted. All additional information of MLC can be sent in two parts called "composite" additional information and "embedded" additional information.

In one embodiment, as described below, the composite additional information includes the location information of all MLCs and is periodically sent at the beginning of each super frame with a predetermined duration. The synthesized additional information of each super frame includes the position information of each MLC of that super frame, and the position information indicates the time-frequency position of the MLC to be sent in the super frame. The wireless device can receive the combined additional information of the current super frame, determine the time-frequency location of each related MLC based on the location information of the MLC, and receive each related MLC in the current super frame at the indicated time-frequency location. The regular and conventional transmission of synthetic additional information enables the wireless devices in the system to quickly obtain each relevant MLC, decode each required MLC with the least "operation" time, and quickly switch between MLCs.

The combined additional information can be divided into a wide area part and a regional part. The wide area part may include the location information of all MLCs with a wide coverage area (for example, nationwide). The area part may include the location information of all MLCs with a partial coverage area (for example, a city area). Base stations and wireless devices can perform different processing on these wide areas and areas to achieve strong reception performance.

In one embodiment, the embedded additional information of each MLC in each super frame includes the position information of the other MLC of a future (for example, the next) super frame, and is combined with the payload of the MLC in the current super frame transmission. A wireless device receiving a given MLC can obtain the embedded additional information of that MLC as part of the processing of the MLC in the current super frame. Then, the wireless device can use the information to receive the MLC in the next super frame without having to "wake up" and receive the combined additional information sent in the next super frame.

Various aspects and embodiments of the present invention will be described in further detail below.

The term "exemplary" as used herein means "serving as an example, example, or illustration." In this context, any embodiment or design that is construed as "exemplary" should not necessarily be regarded as better or advantageous than other embodiments or designs.

The methods described in this article for transmitting additional information can be used in: wireless communication systems and wired communication systems, time division multiplexing (TDM) systems, frequency division multiplexing (FDM) systems and code division multiplexing (CDM) systems, single input Single output (SISO) system and multiple input multiple output (MIMO) system, single carrier system and multi-carrier system, etc. Multi-carrier can be provided by Orthogonal Frequency Division Multiplexing (OFDM) or some other multi-carrier modulation technique or some other construction. OFDM effectively divides the entire system bandwidth into multiple (N) orthogonal sub-bands. These sub-bands are also called tones, carriers, subcarriers, bins, and channels. Regarding OFDM, each sub-frequency band is related to a corresponding subcarrier that can be used for data modulation. The methods described herein can also be used for broadcast, multicast, and unicast services. For clarity, these methods are described below for an exemplary wireless multi-carrier broadcasting system.

FIG. 1 shows a wireless multi-carrier broadcasting system 100. The system 100 includes a plurality of base stations 110 distributed throughout the system. A base station is usually a fixed station, and can also be called an access point, a transmitter, or some other terminology. The wireless device 120 is throughout the area covered by the system. The wireless device can be a fixed device or a mobile device, and can also be called a user terminal, a mobile station, a user equipment, or some other terminology. The wireless device may also be a portable unit such as a cellular phone, a handheld device, a wireless module, and a personal digital assistant (PDA).

Each base station can transmit wide-area content, regional content, or a combination of the two. Wide-area content is content that is sent within a large coverage area (for example, nationwide), while regional content is content that is sent within a smaller coverage area (for example, city). Adjacent base stations can send the same or different content. Each base station can also send multiple data streams of wide-area content and/or regional content to wireless devices within its coverage area. These data streams can carry multimedia content such as video, audio, telex video, data, and video/audio clips. These data streams can be sent on the data channel or MLC.

In a specific embodiment described in detail below, each MLC can carry up to three data streams, for example: one signal data stream and up to two packet/service data data streams. Each multimedia program can be sent as one or more data streams, such as different data streams for different multimedia content, such as video, audio, and data. One or more data streams of each multimedia program can be sent on one or more MLCs. For example, one MLC can carry two data streams of a given program, one is the data stream of real-time content, and the other is the data stream of video clips that are played together with the real-time content at a specified time. As another example, two MLCs can carry three data streams for a single multimedia (such as TV) program, that is, one MLC can carry one data stream for video and another data stream for data. And a second MLC can carry a data stream for audio. Transmission of the video and audio parts of the program on an independent MLC enables wireless devices to independently receive video and audio. Generally speaking, each MLC can carry any number of data streams, and each multimedia program can be sent in any number of data streams and on any number of MLCs.

FIG. 2 shows an exemplary super frame structure that can be used in the system 100. The data is transmitted in units of super frame 210. Each super frame spans a predetermined duration. The predetermined duration can be selected based on various factors, such as: statistical multiplexing required by the data stream, time diversity required by the data stream, data stream acquisition time, and wireless device buffering Request etc. The size of the super frame with a length of about one second can provide a better balance among the above-mentioned various factors. However, super frames of other lengths can also be used. Super frame can also be called frame, time slot or some other terminology.

For the embodiment shown in FIG. 2, each super frame includes a TDM pilot field 212, an additional information field 214, and four frames 216a-216d of equal size. Wireless devices can use TDM pilot signals for synchronization (such as frame detection, frequency error estimation, timing acquisition, etc.) and can be used for channel estimation. The additional information indicates the specific location of each data channel in the super frame, and can be sent as described below. These data streams are multiplexed and sent in four frames.

Figure 2 shows a specific super frame structure. Generally speaking, a super frame can span any duration, can include any number and type of fields, and can have any number of frames. The system can also use other frame structures for transmission.

In one embodiment, the protocol stack of the system includes a plurality of upper layers located on a data stream layer, the data stream layer is located on a media access control (MAC) layer, and the media access control layer is located on a physical layer. These upper layers control the transmission of multimedia content, access to such content, and so on. The data stream layer provides a combination of the upper layer packets to the data stream on a MLC-by-MLC basis. The MAC layer multiplexes the packets of different data streams related to each MLC. The physical layer provides a mechanism for transmitting multiple data streams via a communication channel.

Figure 3 shows an embodiment of the packet format used by the data stream layer, the MAC layer and the physical layer. Figure 3 also shows the processing of one MLC in a super frame. MLC can carry up to three data streams, which are labeled as data streams 0, 1, and 2. Data stream 0 can be used to send MLC signals, and data streams 1 and 2 can be used to send different multimedia contents (such as video, audio, data broadcast, and multicast, etc.). This signal can be used for many items, such as the decryption key used to decrypt other data streams sent on the MLC (a wireless device can obtain a subscription key once a service is activated, and the wireless device with the correct subscription key is sufficient. Decrypt the decryption key). Other types of signals can also be sent on data stream 0. For example, data stream 0 can carry a presentation record that defines the characteristics of the media carried by the MLC, the position of the same MLC in the next super frame, text components/or media, and so on. Generally speaking, each data stream can carry more than one media type. Of course, it is more convenient to carry only a single media type in each data stream. For each super frame, the data stream layer provides a data stream layer packet for each data stream sent on the MLC in that frame. For clarity, the following description assumes that three data streams are sent on the MLC.

The MAC layer forms a MAC capsule for the MLC of each super frame in which the MLC is transmitted. The MAC capsule includes a MAC capsule header and a MAC capsule payload. The MAC packet header carries embedded additional information for the MLC, and the embedded additional information can be used to receive the MLC in a future super frame (for example, the next super frame). The MAC capsule payload is the data stream carried by the MLC and the data stream layer packet to be sent in the current super packet. The MAC layer forms N for the MAC packet header and data stream 0 packets₀One MAC layer packet (or MAC packet for short), forming N for 1 packet of data stream₁MAC packets and form N for data stream 2 packets₂MAC packets, if all three data stream packets are in the sending state, then N₀<img file="TW200529596A_D0001.tif" />1, N₁<img file="TW200529596A_D0002.tif" />1 and N₂<img file="TW200529596A_D0003.tif" />1. To facilitate independent reception of these data streams, each data stream layer packet is sent in an integer number of MAC packets, and the length of each data stream layer packet is included in the additional information. The MAC layer also (N₀+N₁+N₂) MAC packets implement block coding and form N_PParity check MAC packets, where N_P<img file="TW200529596A_D0004.tif" />0 and depends on whether block coding is enabled, if enabled, select block coding mode for MLC. For each super frame in which MLC is transmitted, the MAC layer provides a (N₀+N₁+N₂+N_P) The encoded MAC capsule of the data and parity check MAC packet.

The physical layer receives the encoded MAC packet and processes (such as encoding, interleaving, and symbol mapping) each MAC packet to generate a corresponding physical layer (PL) packet. In one embodiment, the MAC packet has a fixed size (approximately 1 kilobyte), the PL packet of the MLC has an equal size, and the size of the PL packet is determined by the coding rate and modulation scheme used for the MLC. One-to-one mapping between MAC packets and PL packets simplifies the processing between the base station and the wireless device.

Data can be transmitted in various forms in the system 100. In one embodiment, M time slots are formed in each symbol period, and these M time slots are mapped to M sets of disjoint or non-overlapping sub-bands, where M<img file="TW200529596A_D0005.tif" />. In order to obtain frequency diversity, the sub-bands in each group can be evenly allocated to a total of N sub-bands in the system. Thus, the sub-bands in each group are interleaved with the sub-bands of each group in the other M-1 groups. Therefore, each frequency band group can be called an "interlace". Each time slot can be mapped to different interlaces in different symbol periods (for example, based on a predetermined mapping scheme) to improve frequency diversity and obtain other benefits. For the sake of clarity, the following description is for the data transmission in the time slot, and not the mapping from the time slot to the interleaving.

For a given super frame structure, a fixed number of time slots are available for transmission in each super frame. Certain available time slots can be used to transmit an FDM pilot signal for wireless devices to use for channel estimation and other purposes. As described below, certain time slots can also be allocated to the control channel used to transmit MLC signals. Then, the remaining time slots are available for allocation to these MLCs.

A fixed or variable number of time slots in each MLC can be allocated in each super frame according to the effective load of the MLC, the available time slots in the super frame, and other factors. 0 time slots are allocated to each "non-active" MLC (ie, MLC that is not transmitted in a predetermined super frame). At least one time slot is allocated to each "active" MLC (ie MLC transmitted in a predetermined super frame). In addition, based on an assignment scheme to assign a specific time slot to each active MLC in the super frame, the assignment scheme aims to: (1) fill all the active MLC time slots as effectively as possible, (2) shorten The transmission time of each MLC reduces the amount of signal required to indicate the time slot assigned to each MLC. Various schemes can be used to assign time slots to the MLC. Generally speaking, there is a balance between time diversity and power saving. The system can provide flexibility to allow power consumption to be prioritized over time diversity for different MLCs, and vice versa. For example, some MLCs can be optimized for time diversity, while other MLCs can be optimized for power consumption. An MLC containing many Turbo code blocks can inherently obtain more time diversity, while an MLC with a lower data rate can benefit from the additional time diversity.

Figure 4 shows an example time slot assignment scheme for assigning time slots to the MLC using a "sine line" or "zigzag" pattern. For this scheme, a frame is divided into one or more "strips", and each segment spans at least one slot index and further spans several consecutive (for example, all) symbol periods in the frame . Each active MLC is mapped to a segment and is assigned a time slot in that segment. A vertical zigzag pattern can be used to assign the time slots in each segment to the MLCs mapped to that segment in a specific order. The zigzag pattern selects time slots from the lowest time slot index of the segment to the highest time slot index of the segment starting from the first symbol period of the segment one symbol period at a time.

FIG. 4 also shows that the time slot is assigned to a predetermined MLC x for a frame 216. Assign time slots to MLC x in the following order: a specified symbol period index (Start Offset) starts from the beginning time slot index (start time slot) and proceeds to the highest time slot index (max time slot) ), and then start from a lowest time slot index (minimum time slot) in the next symbol period index and proceed to the highest time slot index, and so on, until the number of time slots allocated to MLC x is reached. For the example shown in Figure 4, MLC x is assigned to 16 time slots. The assignment starts at time slot index 4 within symbol period index 3 and zigzags between the lowest time slot index 2 and the highest time slot index 5. And ends at slot index 3 within symbol period index 7.

An example time slot assignment scheme is described above. Other schemes can also be used to assign time slots to the MLC in other forms. For example, a time slot can be assigned to each MLC in a rectangular pattern on a two-dimensional (2-D) plane of the time slot versus symbol period, as shown in FIG. 4. Rectangular patterns can be assigned to the current MLC so that these patterns can be filled in the frame as effectively as possible.

The time slots of each active MLC assigned to each super frame can be transmitted in the location information sent to the MLC. The parameters used to describe the time slots assigned to each active MLC usually depend on the scheme used to assign the time slots. For example, if a rectangular pattern is assigned to each active MLC, the pattern can be described by two corners, such as the time slot index and symbol period index in the lower left corner of the pattern and the time slot index and symbol period index in the upper right corner of the pattern No. If a zigzag pattern is used to assign a time slot to each active MLC, the time slot assigned to the MLC can be described by the starting time slot, the minimum time slot, the maximum time slot, and the number of time slots allocated to the MLC. As shown in Figure 4.

Figure 5 shows an embodiment of a system parameter message for carrying the location information of the MLC. Generally speaking, the location information of each MLC includes all parameters used to describe the time-frequency location of the MLC, such as a specific time slot assigned to the MLC. For the embodiment shown in FIG. 5, the system parameter message includes a message header and one or more location records. The message header can carry messages such as: (1) the system time of the start of the current super frame, (2) the network identifier, (3) the system time of the start of the super frame before the message, (2) the network identifier , (3) the source of the message, (4) the protocol version supported by the system, (5) the transmission parameters of the control channel (this will be explained below), (6) the first location record sent immediately after the header in the message MLC, (7) The number of location records being sent in the message (N_rec)Wait. Generally speaking, the message header can contain any relevant information about the wireless devices.

The message is sent after the message header in the form of a location record for each MLC N_recN of MLC_recLocation records, where N_rec<img file="TW200529596A_D0006.tif" />1. In one embodiment, each location record has a fixed length or a size of L bits, and N is sent in consecutive order based on the identifiers of the MLCs._recLocation records. For example, if the first location record corresponds to MLC x, the second location record corresponds to MLC x+1, the third location record corresponds to MLC x+2, and so on, the last location record corresponds to MLC x+N_rec-1. This enables the wireless device to quickly find and retrieve the location record of each related MLC.

For the embodiment shown in FIG. 5, each location record includes an MLC presence bit. If the associated MLC is sent in the current super frame, the MLC presence bit (Present bit) is set to '1', otherwise , Set the MLC presence bit to '0'. If the MLC existence bit is set to '1', the position record carries a start offset field, a time slot information field, and a data stream length field. The start offset field indicates the first or start symbol period index of the time slot assigned to the MLC. The time slot information field contains time slot information, which transmits all the parameters used to describe the assigned time slots (for example, the minimum time slot, the start time slot, and the maximum time slot). The data stream length field carries the length of each data stream layer packet carried by MLC in the current super frame (for example, N of the three data stream layer packets in Figure 3)₀, N₁And N₂). The number of time slots allocated to the MLC can be determined based on the length of the data stream used for the MLC and transmission parameters (such as coding rate and modulation scheme). If the MLC presence bit is set to '0', the position record carries the next super frame offset field and a reserved field. The next super frame offset field indicates that a super frame under the MLC can be sent. If this field is set to '0', MLC can be sent in any future super frame. If the field is set to a non-zero value, the value represents the minimum number of super frames since the MLC can continue the next super frame. For example, if the offset field of the next super frame is set to 4, MLC will be sent only after at least 5 super frames from the current super frame. The wireless device can start looking for the next appearance of MLC from the future super frame. Table 1 summarizes the various location record fields of an MLC.

<tables><img file="TW200529596A_D0007.tif" /></tables>

Time slot information can be encoded to reduce the number of bits required to transmit the information. The following will describe an example coding scheme of one-time slot information. This coding scheme is suitable for the time slot assignment using the zigzag pattern shown in FIG. 4, and further assumes that the lowest time slot index of any MLC is 1 and the highest time slot index is 7. Time slot index 0 can be used for FDM pilot signals, control channels, etc. Based on the above assumptions, the relationship between the lowest time slot index (minimum time slot), start time slot index (start time slot) and highest time slot index (maximum time slot) of MLC is as follows: 1<img file="TW200529596A_D0008.tif" />Minimum slot<img file="TW200529596A_D0009.tif" />Slot at the beginning<img file="TW200529596A_D0010.tif" />Maximum time slot<img file="TW200529596A_D0011.tif" />7 Equation (1)

The or difference between the starting time slot index and the lowest time slot index and the between the highest time slot index and the starting time slot index are calculated as follows: start = starting time slot-minimum time slot, and equation (2) max = maximum time Slot-start time slot equation (3) The time slot information of each MLC can be represented by a time slot information code value (time slot information code), and the time slot information code value is based on that MLC's minimum time slot, start, The biggest to determine.

Table 2 shows the example mapping of minimum time slot, start and max to time slot information coding.

<tables><img file="TW200529596A_D0012.tif" /></tables>

If the maximum time slot index is 7, the parameter minimum time slot, start time slot, and maximum time slot can each be sent using 3 bits, and each MLC time slot information can use 9 bits of these three parameters Meta transfer. The time slot information encoding can be transmitted using 7 bits of the 84 possible encoding values shown in Table 2. Therefore, the above coding scheme reduces the number of bits required to transmit time slot information for each MLC.

The data stream layer packet length can also be encoded to reduce the number of bits required to transmit the information. An exemplary coding scheme for the packet length of the data stream layer is described below. The coding scheme is based on the packet format shown in Figure 3, and further assumes (1) up to three data stream layer packets can be sent in any MLC in a super frame, and (2) these three data stream layers Packets have small, medium, and large sizes.

For the embodiment shown in FIG. 5, the data stream length field includes a data stream mode sub-field, a length format sub-field, a small data stream length sub-field, a data stream length sub-field, and a large data Stream length subfield. If the data stream mode sub-field is set to '0', it means that two data stream layer packets are sent in the MLC; if the data stream mode sub-field is set to '1', it means that three data are sent in the MLC Stream layer packet. The length format subfield indicates the size of the data stream layer packet of up to three data streams sent on the MLC. Table 3 shows example definitions of the length format sub-fields of different data layer packet sizes of the three data streams.

<tables><img file="TW200529596A_D0013.tif" /></tables>

For the embodiment shown in Table 3, one data stream carried by MLC is designated as the "large" data stream, one data stream is designated as the "medium" data stream, and the third data stream (if sent) is designated as " Small" data stream. Data stream layer packets of large, medium and small data streams can carry up to N_large, N_mediumAnd N_smallMAC packets. The large data stream length sub-field indicates the length of the data stream layer packet of the large data stream sent on the MLC, and contains B_largeBits, where B_large=log₂(N_large). The middle data stream length subfield indicates the length of the data stream layer packet of the middle data stream sent on the MLC, and contains B_mediumBits, where B_medium=log₂(N_medium). The small data stream length subfield indicates the length of the data stream layer packet of the small data stream sent on the MLC, and contains B_smallBits, where B_small=log₂(N_small)。

Figure 5 shows a situation where three data streams are sent on the MLC and three sub-fields are used to indicate the data stream layer packet length of the three data streams. If only two data streams are sent on the MLC, then the B of the small data stream_smallOne bit can be used for medium data stream or large data stream (not shown in Figure 5).

If each data stream sent in the MLC can carry up to 1024 MAC packets in each super frame, a 10-bit data stream length subfield can be used for each data stream. In this case, 30 bits can be used to transmit the data stream layer packet length of the three data streams carried in the MLC. However, if the three data streams have different lengths and if the large, medium, and small data streams can carry up to 1024, 256, and 2 MAC packets respectively, then B_large=10, B_medium= 8 and B_small=1 bit can be used for three data streams. If one bit is used for the data stream mode subfield and three bits are used for the length format subfield, a total of 23 bits can be used to transmit the data stream layer packet length of the three data streams carried by the MLC . Therefore, the above coding scheme can reduce the number of bits required to transmit the length of the data stream of each MLC.

A specific coding scheme for time slot information and a specific coding scheme for data stream length have been described above. Other coding schemes can also be used for, for example, different time slot assignment schemes, different packet formats, etc. Different coding schemes can save different numbers of bits. In either case, for most MLCs, the bit savings achieved by encoding is very significant. Since the additional information is sent regularly and the additional bits are relatively expensive, it is desirable to minimize the number of additional bits as much as possible to achieve greater efficiency.

Figure 6 shows an embodiment of transmitting synthesized and embedded additional information in a way that promotes efficient reception of data streams. The combined additional information is sent at the beginning of each super frame in TDM mode, and it includes all MLC location information. For example, one system parameter message may include the location information of all MLCs carrying wide area content, and another system parameter message may include the location information of all MLCs carrying area content. The system parameter information of each coverage type (wide area or area) includes the location record of each MLC carrying the content of that coverage type. If the MLC is currently used, each location record in each system parameter message contains the location information of the related MLC of the current super frame (such as start offset, time slot information, and data stream length).

For each active MLC, a coded MAC capsule is transmitted in the current super frame. In one embodiment, the coded MAC capsule is divided into four equal parts, and each part is further processed and transmitted on a time slot assigned to the MLC in a frame. Transmission of coded MAC capsules on four frames can provide time diversity and robust reception performance in a slow time-varying decay channel. For each MLC, as shown in FIG. 6, the four frames that can be used in the super frame can be assigned at the same time slot, and the time slot assignment is transmitted in the location record of the other MLC.

In one embodiment, if the MLC will be transmitted in that super frame, the MAC packet header of the MAC capsule of each MLC x includes the location information of the MLC x of that super frame. For the embodiment shown in FIG. 6, the MAC packet header includes an MLC ID field and a consecutive next SF field. The MLC ID field contains the ID of MLC x. If MLC x will be transmitted in the next super frame, set the next consecutive SF field to '1', otherwise, set the next consecutive SF field to '0'. If MLC x is transmitted in the next super frame, the MAC packet header further includes a next SF start offset field, a next SF time slot information field, and a next SF data stream length field. These fields The positions respectively carry the same type of information as the start offset, time slot information, and data stream length fields in the location record. However, the start offset field, the time slot information field, and the data stream length field in the location record carry the "current" additional information of the MLC x of the current super frame. The next SF start offset field, the next SF time slot information field, and the next SF data stream length field in the MAC packet header all carry the "future" additional information of the MLC x of the next super frame. In one embodiment, if MLC x is not transmitted in the next super frame, the MAC packet header further includes a super frame offset field and a reserved field (not shown in Figure 6), these fields are respectively in the location record Carry the same type of information as the offset field of the next super frame and a predetermined field. In another embodiment, if MLC x is not transmitted in the next super frame, the MAC packet header carries the position information of MLC x in the super frame below MLC x (for example, the next SF start offset field, the next time slot information fields SF and SF data stream the next length of the field).

As shown in Figure 6, a wireless device that has just been turned on or has just switched to a new MLC can receive the combined additional information sent at the beginning of each super frame, and can determine that the current super frame will send the new MLC. Location. Then, the wireless device can receive the MAC capsule of the new MLC at the location indicated by the location record of the MLC. The wireless device can obtain the embedded additional information of the MLC of the next super frame from the MAC packet header. Then, the wireless device can use the embedded additional information to receive the MLC in the next frame without having to process the synthesized additional information sent at the beginning of the next super frame. If MLC is continuously transmitted in each super frame (this is a common situation of multimedia programs), the wireless device may only need to receive the combined additional information once. Thereafter, the wireless device can obtain the embedded additional information of the MLC of each future super frame from the MAC packet header. As a result, the wireless device can be "turned on" in a short time and can save more battery power. The MLC ID is used to ensure that the MAC capsule of the correct MLC is processed, for example, in case the MLC is decoded incorrectly.

FIG. 7 shows a process 700 for transmitting additional information of multiple data channels or MLC. Determine the location information of each MLC of the current super frame (for example, block 712). The location information of each MLC indicates the time-frequency location of the MLC, and may have the format shown in FIG. 5 or some other format. The location information of each MLC of a future (e.g., next) super frame is also determined (e.g., block 714). The synthetic additional information of the current super frame is formed by the position information of all MLCs of the current super frame (block 716), and is transmitted at the beginning of the current super frame in a TDM manner (block 718). The location information of each MLC of the future super frame is transmitted together with the payload of the MLC in the current super frame (block 720).

For the above embodiment, the additional information is sent in two parts. The combined additional information is periodically sent at the beginning of each super frame (which is relatively infrequent, such as once per second), and carries the time slot assignment of all MLCs sent in that super frame. A wireless device may use synthetic additional information in the following situations: if the wireless device requests content for the first time (for example, after booting); if a related MLC in the previous super frame is incorrectly coded; if the wireless device is receiving a new MLC; if the wireless device will receive from a current MLC, switch to a new MLC, etc.

A wireless device can use the embedded additional information to determine when to wake up in the next super frame. If the wireless device has successfully decoded a related MLC in the current super frame, it does not need to wake up to receive the combined additional information sent in the next super frame. This shortens the startup time of the wireless device to receive the data stream. Therefore, the embedded additional information is a high-power-efficient way to provide the location where the MLC is sent in the next super frame. The wireless device can obtain the embedded additional information as part of the MLC processing. If each MLC carries embedded additional information for itself and not for other MLCs as described above, the embedded additional information only needs to indicate the single location of the MLC in the next super frame. The embedded additional information is protected by the same error correction code used for the payload of the MLC, which ensures robust reception of the embedded additional information.

The duration of the super frame can be selected so that the synthesis and embedding of additional information consumes a relatively small percentage of the total system capacity, while still allowing rapid changes between data channels. Splitting the synthetic additional information into several wide area parts and several regional parts also provides several benefits. The additional data bits of the wide area portion can be sent in a way to obtain the benefits of using OFDM in a single frequency network (SFN). For example, the wireless device can receive and combine additional data bits from multiple base stations to obtain greater reception reliability. The transmission method of additional data bits in the area part can be different from the transmission method of the additional data bits in the wide area part, such as using a different OFDM pilot structure, a lower coding rate, and a lower-level modulation scheme Etc. to improve the reception of bits at the boundary of the partially covered area. Generally speaking, the wide area and regional parts can be processed using the same or different coding and modulation schemes, and they can have the same or different formats and lengths. The processing and transmission of additional information can make it as robust as traffic data.

The location information of each MLC is sent only once to allow wireless devices to receive the MLC. All MLC location information can be sent in the synthetic additional information at the beginning of each super frame. The location information of each active MLC can also be sent with the payload of the MLC in a redundant manner to improve the efficiency of receiving MLC. However, the redundant location information is optional information and can be omitted (that is, not transmitted).

Additional information of the data channel can also be sent in other ways. For example, the data stream length can be included in the MAC packet header instead of included in the location record. If more than one super frame is scheduled for MLC in advance, the location record and/or MAC packet header may also include the location information of a super frame farther than the next super frame. The MAC capsule header may include a bit indicating whether the position information of the next super frame is the same as the position information of the current super frame. If they are the same, the position information of the MAC capsule header can be omitted.

The additional information indicates the location of each MLC to be transmitted. A control channel can be used to carry other related information about MLC. For example, the control channel can carry the coding rate and modulation scheme for the MLC, the block coding for the MLC, and the media type sent on each data stream carried by the MLC for each MLC. , Combined with upper layer entities on each data stream carried by the MLC, etc. The control channel can be transmitted in a manner previously known to the wireless device, whereby the wireless device can receive the control without requiring other signals.

FIG. 8 shows a block diagram of a base station 110x. The base station 110x is one of the base stations in the system 100. At the base station 110x, the transmission (TX) data processor 810 receives multiple (T) data streams from the data source 808 (denoted as {d₁} To {d_r}), where T<img file="TW200529596A_D0014.tif" />1. Each data stream can carry a data stream layer packet for each super frame of the data stream to be sent (for example, as shown in FIG. 3). The TX data processor 810 also receives the embedded additional data of each MLC, and appends the additional data to the correct data stream layer packet to be sent on the MLC (for example, as shown in FIG. 3). The data processor 810 processes each data stream according to a "mode" for that data stream to generate a corresponding data symbol stream. The mode of each data stream can indicate: for example, the encoding speed, modulation scheme, etc. used for the data stream. The TX data processor 810 provides a T data symbol stream (denoted as (s) to a symbol multiplexer (Mux)/channelizer (Channelizer) 820₁} To {s_T}). As used herein, the data symbol is the modulation symbol of the packet/service data, the additional symbol is the modulation symbol of the additional data, and the pilot symbol is the modulation symbol of the pilot signal (this is the information previously known by the base station and the wireless device) , The protection symbol is a zero value symbol, and the modulation symbol is a complex value of a point in the signal horoscope used for modulation schemes (such as M-PSK, M-QAM, etc.).

TX data processor 810 also receives at the beginning of each super frame (marked as {d₀}) Synthesized additional data sent from the controller 840. The TX data processor 810 processes the synthesized additional data according to the mode used by the additional data, and provides the channelizer 820 with an additional symbol data stream (marked as {S₀}). The synthesized additional data can be divided into a wide area part and a regional part (as shown in FIG. 6) and processed separately (for example) based on the same mode or different modes. The mode used to synthesize the additional data is usually related to a lower coding rate and level modulation scheme than those used for the data stream to ensure the time and/or frequency selectivity of synthesizing the additional data in the terrestrial radio channel. Robust reception.

The channelizer 820 T multiplexes the data symbols in the data symbol stream to their assigned time slots. The channelizer 820 also provides pilot symbols on the time slots used for pilot signal transmission and protection symbols on the sub-bands not used for transmission. The channelizer 820 further shows the pilot symbols and additional symbols in the multiplexed pilot field and additional fields at the beginning of each super frame as shown in FIG. 2. The channelizer 820 provides a composite symbol stream (marked as {s_c}). An OFDM modulator 830 performs OFDM modulation on the composite symbol stream and provides an OFDM symbol stream to the transmitter unit (TMTR) 832. The transmitter unit 832 adjusts (for example, converts into analog, filters, amplifies, and frequency up-regulates) the OFDM symbol stream, and generates a deconverted symbol for the antenna 834 to transmit.

The controller 840 directs the operation of the base station 110x. The memory unit 842 provides storage for the program codes and data used by the controller 840. The controller 840 and/or the scheduler 844 allocates and assigns time slots to the active MLC.

FIG. 9 shows a block diagram of a wireless device 120x, which is one of the wireless devices in the system 100. The antenna 912 receives the modulated signal sent by the base station 110x, and provides the received signal to the receiver unit (RCVR) 914. The receiver unit 914 adjusts, digitizes, and processes the received signal, and provides a sample data stream to the OFDM demodulator 916. The OFDM demodulator 916 performs demodulation on the sampled data stream to obtain the received pilot symbols and the received data and additional symbols. The controller 940 obtains an estimate of the channel response of the radio link between the wireless device 120x and the base station 110x based on the received pilot symbols. The OFDM demodulator 916 further uses the channel response estimate to perform coherent detection (such as equalization or matching filtering) on the received data symbols and additional symbols, and send it to a symbol demultiplexer (Demux)/dechannelizer ( dechannelizer) 920 provides "detected" data symbols and additional symbols, which are estimated values of the transmitted data symbols and additional symbols, respectively.

The controller 940 obtains an indication that the wireless device receives one or more MLCs (for example, user selection). Then, the controller 940 determines the time slot assignment of each selected MLC based on any of the following conditions: (1) the synthesized additional information sent at the beginning of the current super frame; or (2) the previous super frame of the MLC The embedded additional information sent in the header of the received MAC capsule. Thereafter, the controller 940 provides a control symbol to the dechannelizer 920. The de-channelizer 920 demultiplexes the detected data and additional symbols in each symbol period based on the control symbol, and provides one or more detected data symbol streams and/or one to the RX data processor 930 The stream of additional symbols that have been detected. The RX data processor 930 processes the detected additional symbol stream (for example, symbol demapping, deinterleaving, and decoding) according to the mode used for the synthesized additional data, and provides the decoded additional data to the controller 940. The RX data processor 930 also processes the detected data symbol stream for each related MLC according to the mode used for each data stream. Generally speaking, the processing of the wireless device 120x is a supplement to the processing of the base station 110x.

The controller 940 also directs the operation of the wireless device 120x. The memory unit 942 provides storage for program codes and data used by the controller 940.

The techniques described herein for transmitting additional information can be constructed by various means. For example, these technologies can be built in hardware, software, or a combination thereof. For the hardware construction scheme, the processing unit located in a base station can be constructed in the following hardware: one or more application-specific integrated circuits (ASIC), digital signal processor (DSP), digital signal processing device (DSPD), Programmable logic device (PLD), field programmable gate array (FPGA), processor, controller, microcontroller, microprocessor, other electronic devices designed to perform the functions described herein, or a combination thereof . The processing unit located in a wireless device can also be constructed in one or more application-specific integrated circuits (ASIC), digital signal processors (DSP), and so on.

For software construction solutions, modules (such as programs, functions, etc.) that perform the functions described herein can be used to construct the functions described herein. The software code may be stored in a memory unit (for example, the memory unit 842 and/or 942) and executed by a processor (for example, the controller 840 and/or 940). The memory unit can be built inside the processor or outside the processor.

The above description of the disclosed embodiments is provided for the purpose of enabling anyone familiar with the art to make or use the present invention. Those who are familiar with the technology can easily obtain various modifications to these embodiments, and the general principles defined herein can also be applied to other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments shown in this text, but to give it the broadest scope consistent with the principles and novel features disclosed in this text.

<p>110aBase station</p><p>110bBase station</p><p>110cBase station</p><p>110dBase station</p><p>110eBase station</p><p>110fBase station</p><p>110gBase station</p><p>120aWireless device</p><p>120bWireless device</p><p>120cWireless device</p><p>120eWireless device</p><p>120fWireless device</p><p>120gWireless device</p><p>120hWireless device</p><p>120iWireless device</p><p>120jWireless device</p><p>120kWireless device</p><p>120lWireless device</p><p>120mWireless device</p><p>120nWireless device</p><p>120oWireless device</p><p>210Super Frame</p><p>212TDM pilot field</p><p>214Additional information field</p><p>216aFrame 1</p><p>216bFrame 2</p><p>216cFrame 3</p><p>216dFrame 4</p><p>700The process of transmitting additional information of multiple data channels or MLC</p><p>712Determine the location information of each MLC in the current super frame</p><p>714Determine the location information of each MLC of the next super frame</p><p>716Form additional information from the location information of all MLCs in the current super frame</p><p>718Transmit synthetic additional information at the beginning of the current super frame in a TDM mode</p><p>720For each MLC, the position information of the next super frame is transmitted together with the payload of the MLC</p><p>808Data source</p><p>810TX Data Processor</p><p>820Symbol Multiplexer/Channelizer</p><p>830OFDM Modulator</p><p>832Transmitter unit</p><p>834Transmitter Unit</p><p>840controller</p><p>842Memory</p><p>844Scheduler</p><p>912antenna</p><p>914receiver unit</p><p>916OFDM demodulator</p><p>920De-channelizer</p><p>930RX Data Processor</p><p>932Data Slot</p><p>940controller</p>

Reading the above detailed description in conjunction with these drawings will make it easier to understand the features and properties of the present invention. In all the drawings, the same reference signs have the same meaning. Among them: Figure 1 shows a wireless multi-carrier broadcast System; Fig. 2 shows an example super frame structure; Fig. 3 shows an example packet processing of an MLC; Fig. 4 shows the use of a "Z" pattern to assign time slots to an MLC; Fig. 5 shows an example for carrying multiple Example messages of the location information of an MLC; Figure 6 shows the transmission of synthesized and embedded additional information; Figure 7 shows the process of transmitting additional information; Figure 8 shows a block diagram of a base station; and Figure 9 shows a block diagram of a wireless device .