Method and apparatus for adaptive transmission control in a high data rate communication system

A method and device for adaptive transmission control in a high-speed data rate communication system

The features, objectives and benefits of the present invention will be better understood in the following detailed description in conjunction with the accompanying drawings, where the same reference signs are corresponding throughout the text, in which:

Figure 1 shows an example wireless communication system.

Figure 2 shows an example forward link signal structure.

Figures 3a and 3b show an example sequence of forward link time slot transmission.

4a and 4b show a flowchart of an exemplary method of receiving a multiple time slot packet.

Figure 5 shows a flowchart of an exemplary method for transmitting a multiple time slot packet.

Figure 6 shows an example subscriber station device.

Figure 7 shows an example base station device.

Background of the invention I. Scope of invention

The present invention relates to wireless data communication. More specifically, the present invention relates to an innovative and improved method and device for high-speed packet data transmission in a wireless communication system.

II. Description of related skills

Today's communication systems need to support different applications. Such a communication system is a coded multi-directional proximity (CDMA) system, which complies with the "TIA/EIA-95 Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System" and its subsequent versions, which are referred to as IS hereinafter -95. The CDMA system allows voice and data communication between users on a terrestrial link. The use of CDMA technology in a multi-directional proximity communication system is disclosed in U.S. Patent No. 4,901,307, entitled "SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE ORTERRESTRIAL REPEATERS"), And U.S. Patent No. 5,103,459, titled "System and Method FOR GENERATING WAVEFORMS IN A CDMA CELLULAR TELEPHONE SYSTEM"), which are all authorized to the assignee of the present invention, and are incorporated herein by reference.

In a CDMA system, communication between users is carried out through one or more base stations. In a wireless communication system, the forward link represents that the signal is transmitted from a base station to a subscriber station through the channel, and the reverse link represents that the signal is transmitted from a subscriber station to a base station through the channel, and the first on a subscriber station is The user can communicate with a second user on a second user station. The base station receives data from the first user station and guides the data to a base station serving the second user station. According to the location of the subscriber station, it can be served by a single base station or multiple base stations. In any case, the base station serving the second subscriber station transmits data on the forward link. In addition to communicating with a second subscriber station, a subscriber station can also communicate with a terrestrial Internet by connecting to a serving base station. In wireless communications such as those complying with IS-95, forward link and reverse link signals are transmitted in discrete frequency bands.

The user station communicates with at least one base station during a communication period. The CDMA subscriber station can communicate with multiple base stations simultaneously during soft handover. Soft handover is the process of establishing a link with a new base station before cutting off the link with the previous base station. Soft handover can minimize the probability of call interruption. During the soft handover process, the method and system for communicating with one user station through more than one base station is disclosed in US Patent No. 5,267,261, entitled "Mobile-assisted soft handover in a CDMA cellular telephone system. "Pass", which is hereby quoted as a reference by the assignee of the present invention. Softer handover is the process of communicating on multiple sectors served by the same base station. The processing of softer handover is disclosed in detail in the US Patent No. 5,625,876, which was also filed at the same time, entitled "Method and Apparatus for Handover Between Sections of a Shared Base Station" ("METHOD AND APPARATUS FOR PERFORMINGHANDOFF BETWEEN SECTORS OF A COMMON BASESTATION"), the assignee authorized to the present invention is hereby quoted as a reference.

With the increasing need for wireless data applications, there is an increasing need for highly efficient wireless information communication systems. The IS-95 standard can transmit traffic data and voice data through forward and reverse links. U.S. Patent No. 5,504,773 "METHOD AND APPARATUS FOR THEFORMATTING OF DATA FOR TRANSMISSION" describes in detail a method of transmitting traffic data using a fixed-size coded channel beacon, which is authorized to the assignee of the present invention here Cite as a reference. According to the IS-95 standard, the traffic data or voice data is divided into code channel frame, which is 20ms wide, and the data rate is up to 14.4Kbps.

An obvious difference between voice service and data service is that the former requires strict and fixed delay requirements. Basically, the overall one-way delay of the voice frame must be less than 100ms. Conversely, the data delay can be a variable parameter used to optimize the efficiency of the data communication system. In particular, it can utilize more efficient error correction coding techniques that are significantly longer than those voice services can tolerate. An example of an efficient data encoding method is disclosed in US Patent No. 5,933,462, which is named "Soft Decision Output Decoder Decoding Codes of Convolutional Encoding", which is authorized to the assignee of the present invention and incorporated herein by reference.

Another obvious difference between voice service and data service is that the former requires a fixed and shared service level (GOS) for all users. Basically, for digital systems that provide voice services, this can be translated into a fixed and equal transmission rate for all users, and the maximum allowable value of the error rate of the voice frame. On the contrary, for data services, the GOS can be different for each user, and it can be a parameter that optimally increases the overall efficiency of the data communication system. The GOS of a data communication system is basically defined as the overall delay that occurs in the transmission of a predetermined amount of data, which is hereinafter referred to as a data packet.

Another obvious difference between voice service and data service is that the former requires a reliable communication link. In this exemplary CDMA communication system, it is provided by soft handover. Soft handover can cause redundant transmissions from two or more base stations to improve reliability. However, this additional reliability is not required for data transmission, because the data packet received with errors can be retransmitted. For data services, the transmission energy used to support soft handover can be more effectively used to transmit additional data.

The transmission delay required to transmit a data packet and the average flow rate are two attributes that define the quality and effectiveness of a data transmission system. Transmission delay does not have the same effect on data transmission, as it does for voice communication, but it is an important metric to measure the quality of the data communication system. The average flow rate is a measure of the efficiency of the data transmission capacity of the communication system. In this art, there is a need to provide improved data flow for the communication system, while at the same time providing GOS suitable for wireless packet data services.

Summary of the invention

The present invention is an innovative and improved method and device for high-speed packet data transmission in a CDMA system. An exemplary system for transmitting high-speed digital data in a wireless communication system is disclosed in the jointly filed U.S. Patent Application Serial No. 08/963,386, entitled "Method and Apparatus for Higher Rate Packet Data Transmission" ("METHOD AND APARATUS FOR HIGHER RATEPACKET DATA). TRANSMISSION"), (hereinafter referred to as the '386 application), which is authorized to the assignee of the present invention, and is incorporated herein by reference. The present invention can preferably improve the traffic of a high-data-rate CDMA system, which is based on the successful decoding of the relevant packet data by a target network node such as a wireless subscriber station, so that the data in the slot is not transmitted during transmission. The retransmission of necessary packet data can be minimized.

One aspect of the present invention is to improve the data flow of a high-speed data rate system, such as shown in the '386 application. In one example, a target network node, such as a user station, can send a data rate control (DRC) signal to a source network node, such as a base station on a data rate control (DRC) channel . According to the DRC signal, the base station selects a data rate for transmitting data packets to the subscriber station on the forward link. The information in the DRC signal is based on carrier and interference (C/I) measurements, which is performed by the subscriber station on the previous forward link signal received from the base station. In one example, the subscriber station selects a data rate, which can ensure that the packet error rate (PER) will not exceed a predetermined target PER, and sets the data rate of the DRC signal. Because the characteristics of the forward link channel will change over time, the subscriber station can adjust the DRC signal accordingly.

In an exemplary aspect of the present invention, the base station transmits data to the subscriber station at a data rate specified by the DRC signal newly received from the subscriber station. The base station uses a fixed time forward link slot to transmit data packets to multiple user stations. In an exemplary aspect, the base station only transmits data to one of the plurality of user stations during each forward link time slot.

If the data rate specified by the DRC signal of a target subscriber station is sufficiently small, the base station transmits each data packet in multiple forward link time slots. In an exemplary aspect, a 1024-bit data packet can be transmitted in 16 time slots at a rate of 38,400 bits per second (bps), and the duration of each time slot is 1.67 milliseconds. In this exemplary aspect, the same data packet can be transmitted at 76,800 bps in another 8 time slots. Therefore, several other data rates can be considered in this example, which have a predetermined number of time slots for each data.

In one aspect of the present invention, the forward link signal transmitted in each multiple time slot of a packet may contain all the data in the packet. In other words, the packet data are not separated in the multiple time slots. Instead, the entire data packet is transmitted in every time slot. The lower the data rate represented by the DRC request of the subscriber station, the greater the number of slots in which the packet must be repeated to maintain the target PER. For example, a DRC request with a data rate of 38,400 will require the base station to transmit 1024-bit packets in 16 time slots. Then the base station will transmit the same 1024-bit packet during 16 subsequent time slots. In an exemplary aspect, the base station uses the interleaving technique well known in the art to interleave a preamble into the signal transmitted in the first period of the multiple time slots of a multiple time slot packet. The subscriber station uses the preamble to determine whether the base station has started to transmit a multiple time slot packet addressed to the subscriber station.

In one aspect of the invention, multiple copies of a multiple time slot packet can be transmitted in non-contiguous time slots. For example, a 16-time slot packet can be transmitted in every interval of the time slot in the 31-time slot period. In another aspect of the present invention, a 16 time slot packet can be transmitted in every 5 time slots in a 65 time slot period. In both aspects, the time slot pattern for each rate used to transmit the frame is predetermined. All signals transmitted in the time slot for a single packet are transmitted at the same data rate. In other words, once the transmission of a multiple time slot packet has started at this data rate, other time slots related to the packet are transmitted at the same data rate. The subscriber station accumulates the received data during each relevant time slot so as to successfully decode the packet data and distinguish it from the signal noise.

In one example, the base station will not increase the data rate of a multi-time slot packet once the first time slot of the packet starts to transmit. In order to avoid losing a multiple time slot packet when the forward link channel is degraded, the data rate selected for the multiple time slot packet is very conservative. Generally, if the forward link channel improves during the transmission of a multiple time slot packet, the target subscriber station can successfully decode the packet before all multiple copies of the packet are transmitted by the base station. The longer the period during which the multi-time slot packet is transmitted, the higher the probability that the C/I of the forward link will change and no longer meet the DRC data rate required by the subscriber station. If the subscriber station successfully decodes the packet within the predetermined number of packet copies, and then transmits the remaining copies of the packet, the previous forward link bandwidth is wasted. In addition, if the forward link signal periodically decays during the transmission of a multiple time slot packet, the data accumulated by the packet may be ignored prematurely. For one or two more time slots to transmit the packet can cause successful decoding and avoid the signal transmitted in the previous time slot.

In an exemplary aspect, each packet has a sequence number, and packets that are not successfully received by a user station are retransmitted by a higher protocol layer. However, the subscriber station will ignore the buffered samples from the first transmission of the packet before receiving the first time slot of the packet transmission. For this reason, the subscriber station cannot combine the packet retransmission of the higher protocol layer and the sample buffered by the packet from the first attempt to transmit. For example, suppose that a multiple time slot packet is transmitted at a low rate in 16 time slots. If the packet layer cannot be transmitted in the 16 time slots, the higher protocol layer will retransmit the packet at some point in the future. If the retransmission uses the same data rate as the first attempt, the retransmission consumes an additional 16 time slots, which are based on the data rate used for the retransmission. However, if the subscriber station can request slightly more time slots in the first attempt, the packet can be successfully decoded within, say, 18 time slots. The net savings on this forward link will be 14 time slots.

In one aspect of the present invention, each forward link data rate is set to have a preset number of time slots for each packet. If the user station successfully decodes a multiple time slot packet earlier (before it receives the preset number of time slots), the user station stops transmitting the remaining time slots of the packet. The subscriber station is completed by sending a stop-repeat signal to the base station. When receiving a stop-repeat signal, the base station stops transmitting the packet in the subsequent time slot.

In another aspect of the present invention, if the subscriber station is unable to decode a multiple time slot packet of the signal received from the preset number of time slots, the subscriber station requests the base station to additionally retransmit the packet. The user station is completed by sending a continue-repeat signal to the base station. When receiving a continue-repeat signal, the base station will transmit additional packet copies in one or more subsequent time slots in addition to the preset number of time slots.

Schematic description

The features, objectives and benefits of the present invention will be better understood in the following detailed description in conjunction with the accompanying drawings, where the same reference signs are corresponding throughout the text, in which:

Figure 1 shows an example wireless communication system.

Figure 2 shows an example forward link signal structure.

Figures 3a and 3b show an example sequence of forward link time slot transmission.

4a and 4b show a flowchart of an exemplary method of receiving a multiple time slot packet.

Figure 5 shows a flowchart of an exemplary method for transmitting a multiple time slot packet.

Figure 6 shows an example subscriber station device.

Figure 7 shows an example base station device.

Detailed description of preferred embodiments

Figure 1 shows a first wireless base station 106a, which transmits to a user station in a coverage area 108a, and a second wireless base station 106b, which transmits to a user station in a coverage area 108b of the overlapping coverage area 108a tower. The subscriber station 102a is located in the coverage area 108a, but not in the coverage area 108b. The subscriber station 102b is located within the coverage area 108a and the coverage area 108b at the same time. The base station 108a transmits data to the subscriber station 102a through the communication channel 104a, and transmits data to the subscriber station 102b through the communication channel 104b. The base station 108b transmits data to the subscriber station 102b through the communication channel 104c.

In an exemplary embodiment, each user station 102 generates a signal quality metric based on the signal received by the base station 106. A subscriber station 102b receives forward link signals from a plurality of base stations 106, and identifies the base station (for example, base station 106b) of the received signal with the highest quality metric. The subscriber station 102b generates a data rate prediction, wherein the packet error rate (PER) of the packets received from the selected base station 106b will not exceed a target PER. An exemplary embodiment uses a target PER of approximately 2%.

In an exemplary embodiment, the subscriber station 102b calculates a rate, wherein the "tail end probability" is greater than or equal to the target PER. The tail end probability is the probability that during the packet transmission period, the actual signal quality is less than the signal quality required to successfully decode a packet correctly at a requested rate. The subscriber station 102b then transmits a data rate control (DRC) signal to the selected base station 106b according to the predicted tail probability. In an exemplary embodiment, the tail end probability is calculated using signal quality attributes, such as the carrier-to-interference (C/I) ratio of the previously received signal. Based on the previous signal quality measurement, the subscriber station generates a prediction of the possible signal quality during the time slot used to transmit the next packet.

In an exemplary embodiment, each DRC signal transmitted by a subscriber station 102b is specifically addressed to a selected base station 106b. Then the selected base station 106b is the only base station that will transmit traffic channel data to the subscriber station 102b during the subsequent time slot of the DRC signal. In an exemplary embodiment, the DRC signal represents a requested data rate that transmits forward link data to a specific selected base station of the subscriber station 102b during a specific future time slot. Because the selected base station 106b is the only base station that will serve the subscriber station 102b during the specific future time slot, the selected base station is called a "serving base station". In an exemplary embodiment, the subscriber station 102b can identify the serving base station 106b by using a specific Walsh code for the selected base station 106b to decode the DRC signal. Because the user station 102b uses a different orthogonal Walsh code to encode the DRC signal to each different base station, no base station can decode the DRC signal used in a different base station.

In another embodiment, the DRC signal sets a predetermined data rate, where the base station 106b is used to transmit forward link data to the subscriber station 102b. The specified data rate in the DRC signal can be selected from the predetermined combination of data rates based on the measurement of the previous signal quality metric. The data rate is selected so that at this rate, the predicted tail probability of a packet will be less than or equal to the target tail probability. In an exemplary embodiment, the DRC signal specifies one of 13 possible data rates, although the number of possible data rates will vary. The DRC signal encodes the selected data rate into a 4-bit signal transmitted on a DRC channel. In an exemplary embodiment, the DRC channel is orthogonal to the reverse link data channel. The backlink data and the leading channel system are orthogonally divided by the Walsh function W of 4 ₂⁴ And W ₀⁴ To expand, which is defined in Table 1 below:

<tables><img file="TW511349B_D0001.tif" /></tables>

In an exemplary embodiment, the base station 106b monitors DRC signals from one or more subscriber stations, and transmits forward link data to no more than one target subscriber station during each forward link transmission time slot. The base station 106b selects the target user station (for example, the user station 102b) according to a scheduling program designed to balance the quality of service (QOS) requirements of each user station, and its need is to maximize the traffic of the system. In an exemplary embodiment, the base station 106b transmits data to the target subscriber station 102b, which is only transmitted at the rate represented by the latest DRC signal received from the target subscriber station. This limitation makes it unnecessary for the target subscriber station 102b to perform rate detection on the forward link signal. The subscriber station 120b only needs to determine whether it is the desired target subscriber station during a given time slot.

In another specific embodiment, the base station 106b may transmit forward link packets at a rate different from the rate represented by the DRC signal received from the target subscriber station 102b. In an exemplary embodiment, the base station 106b transmits a data rate signal on the forward link, which is used by the subscriber station to decode the corresponding forward link packet. In another specific embodiment, the base station 106b only transmits the forward link packet, which requires the target user station 102b to perform blind rate determination when decoding the packet.

In a specific embodiment, the base station transmits a preamble in the first time slot of each new forward link packet. The preamble identifies the desired target user station. In an exemplary embodiment, the base station assigns one of a set of 32 possible Walsh codes to each active subscriber station in its cell. In other words, in the same cell at the same time, no two user stations will be assigned the same Walsh code. The preamble of each packet will be overwritten with the Walsh code assigned to the target subscriber station. This Walsh coverage identifies the desired target user station for each packet. In a specific embodiment, only the first of multiple time slots containing a single packet of data is transmitted with a preamble. In an exemplary embodiment, the preamble is interspersed with the forward link packet data.

In an exemplary embodiment, once a target user station establishes its desired data target in a time slot, the user station starts to decode the data in the related time slot. In an exemplary embodiment, the target subscriber station 102b determines the data rate of the data in the forward link slot according to the previous DRC signal transmitted by the target subscriber station 102b. As mentioned above, the target subscriber station 102b can also determine the rate based on a forward link data rate signal or based on blind rate detection.

In an exemplary embodiment, the base station 106b uses a single data rate to transmit a single packet of data. In other words, if a packet is transmitted in 16 time slots, the forward link data rates in those time slots will be equal to each other.

In an exemplary embodiment, the number of forward link time slots used to transmit a packet is changed according to the data rate of the packet. Packets transmitted at a lower rate use a larger number of time slots. An example series of data rates and the number of related forward link time slots is shown in Table 2.

<tables><img file="TW511349B_D0002.tif" /></tables>

<tables><img file="TW511349B_D0003.tif" /></tables>

In an exemplary embodiment, the target subscriber station 102b decodes a preamble transmitted in the first time slot of a multiple time slot packet to identify the beginning of a new packet transmission from the base station 106b. The data rate for the transmission of the new packet can determine the maximum number of time slots that will be used to carry the packet. In the above exemplary embodiment, the subscriber station knows the priority of the time slot after receiving the data in the preamble of the same multiple time slot packet.

The signal received by the target subscriber station 102b in a single time slot includes noise and interference components, as well as the data signal transmitted by the base station 106b. By accumulating samples of a packet on multiple time slots, the target user station 102b has the advantage of a stronger slot-to-slot correlation in the data signal compared to the slot-to-slot correlation of interference and noise components . The samples accumulated on multiple time slots will finally be able to successfully decode the packet. A multiple time slot packet is transmitted on a maximum number of time slots at a fixed data rate. If the noise characteristics of the forward link channel are improved after transmitting the first time slot, the target subscriber station 102b can successfully decode the packet before receiving the maximum number of time slots. Once the target subscriber station 102b successfully decodes the packet, the subsequent forward link time slot containing the decoded packet data is ignored. In an exemplary embodiment, each packet includes a cyclic redundancy calculation (CRC), which allows the target user station to determine when the packet has been successfully decoded.

Another advantage of transmitting a packet on multiple time slots is that the received signal will have a greater time diversity. In a dynamic environment with strong and weak conditions, packets transmitted in a short period of time can easily be lost in a rather decayed change in the signal. However, if the transmission time of a packet is longer than the duration of a strong and weak moment, the signal received outside the period of strong and weak moment may allow the packet to be successfully decoded. The longer the transmission time of a packet, the lower the chance that it will block the entire packet signal when it is strong and weak. However, the longer transmission time also makes it more difficult to correctly predict the signal quality over the entire transmission period. In an exemplary embodiment, the feedback signal allows the system to have the benefit of temporal diversity while least suffering from incorrect predictions of tail-end probability.

In an exemplary embodiment, the target user station 102b accumulates a sample of a packet transmitted within multiple time slots of a multiple time slot packet. After receiving the first time slot sample of the packet, subsequent time slot samples containing the data of the same packet will be accumulated in a packet accumulation buffer. If the CRC of the content of the packet accumulation buffer indicates that an error-free packet has been received, the target user station 102b declares that the packet has been successfully decoded. In an exemplary embodiment, the target user station 120b transmits a stop-repeated signal to the base station 106b, which means that the packet is successfully decoded. Upon receiving the stop-repeat signal from the target subscriber station 102b, the base station 106b suspends the transmission of the forward link packet. If the time slot used to transmit the packet is less than the maximum number of time slots, the stop-repeat signal causes the base station 106b to use less than the maximum number of time slots to transmit the packet. For example, if the base station 106b receives a stop-repeated signal after transmitting only 8 time slots in a 16-time slot packet, the base station 106b will no longer transmit the data time slot containing the packet.

It is necessary to avoid transmitting the stop-repeat signal, which will not cause the change of the behavior of the base station 106b. For this reason, in an exemplary embodiment, the target subscriber station 102b only transmits the stop-repeated signal when the number of time slots that it receives including a multiple time slot packet data is less than the maximum number.

Figure 2 shows the forward link signal structure transmitted by each base station in an exemplary high-speed data rate system. The forward link signal is divided into time slots of fixed duration. In an exemplary embodiment, the length of each time slot is 1.67 milliseconds long. Each time slot 202 is divided into two half-time slots 204. In an exemplary embodiment, each time slot is 2048 segments long, which corresponds to a time slot duration of 1.67 milliseconds. In an exemplary embodiment, each pilot burst 208 is 96 segments long and is centered on the midpoint of its related half-time slot 204. A reverse link power control (RPC) signal 206 is transmitted to either side of the pilot burst in every two half-time slots 204b. In an exemplary embodiment, the RPC signal is transmitted before or after 64 segments of the second pilot burst 208b of each time slot 202, and is used to adjust the reverse link transmitted by each subscriber station. The power of the signal. In an exemplary embodiment, the forward link traffic channel data is transmitted in the remaining part of the first half-time slot 210 and the remaining part of the second half-time slot 212.

In an exemplary embodiment, the pilot glitch signal is continuously transmitted on an orthogonal code channel, which is similar to the IS-95 system. In an exemplary embodiment, the pilot burst signal uses a Walsh code W ₀ To expand (which is equivalent to no Walsh coverage). In an exemplary embodiment, the pilot glitch signal is used by the subscriber station for initial recognition, phase recovery, timing recovery, and wireless combination. In an exemplary embodiment, the pilot glitch signal can also be used by the user station to perform C/I measurement.

Figure 3a shows an exemplary configuration diagram of slot transmission in the forward link. In an exemplary embodiment, a base station transmits a first time slot data 302a of a multiple time slot packet. The sampling of the first time slot data 302a is accumulated in a packet accumulation buffer in the user station. After receiving the first time slot data of a packet, the subscriber station decodes the preamble from the first time slot to identify the packet addressed to the subscriber station. If the preamble cannot be successfully decoded, the subscriber station searches for a preamble in the next time slot 308.

When it is determined that the first time slot 302a contains the packet data addressed to the user station, the user station attempts to decode the received packet data from the data stored in the packet accumulation buffer. In an exemplary embodiment, the data rate of the packet is based on a DRC signal previously transmitted by the subscriber station and specifically addressed to the serving base station.

In an exemplary embodiment, each attempt to decode a packet from the contents of the packet accumulation buffer will occupy an additional number of time slots, as shown by the decoding period 312a. Although three time slots are shown, the decoding period 312a will change. At the end of the decoding period 312a, the subscriber station checks the cyclic redundancy check value (CRC) of the received forward link packet. If the CRC indicates that there is no error in the reception of the packet, the target subscriber station transmits a stop-repeat signal to the serving base station during the next time slot 304. When the base station successfully decodes the stop-repeated signal, it will not transmit the same packet repeatedly.

In an exemplary embodiment, a subscriber station can receive multiple packets in staggered time slots. For example, the time slot 302a may include the first time slot of a first multiple time slot packet of the subscriber station. In addition, during the decoding period 312a and the next time slot 304, the subscriber station can receive additional packets of data. For example, during the three time slots of the shown decoding period 312a, the subscriber station can receive the third time slot data of a second multiple time slot packet, and the 16th time slot of a second multiple time slot packet Data, and the first and only time slot data of a third packet. In addition, the subscriber station can receive the time slot data of a fourth packet during the following time slot 304. The user station stores the data of each independent packet in a separate packet accumulation buffer. In an exemplary embodiment, each multi-time slot packet is transmitted in a forward link time slot separated by 5 time slots, and a user station has 5 packet accumulation buffers to decode a maximum of 5 packets at a time. In an exemplary embodiment, the 5 packets need not be transmitted by the same serving base station. For example, a first serving base station can transmit the first two multiple time slot packets, and the time slot used is the same as that of the three multiple time slot packets transmitted by a second serving base station. staggered.

After each time slot before the maximum number of time slots in a multi-time slot packet, the subscriber station attempts to decode the packet by using the data accumulated in the corresponding packet accumulation buffer. In an exemplary embodiment, the process of decoding the contents of the packet accumulation buffer occupies several time slots, as shown by the decoding period 312a. If at the end of the decoding period 312a, the packet has been successfully decoded, the subscriber station transmits a stop-repeat signal to the serving base station. The stop-repeat signal is transmitted during the time slot 304 immediately after the decoding period 312a. After transmitting a stop-repeat signal, the subscriber station searches for subsequent packets starting in the time slot 302b.

If the packet is not successfully decoded by the received signal of the first time slot 302a, the serving base station transmits the packet data in a second time slot 302b. If the serving base station never receives a stop-repeat signal, the serving base station will continuously transmit the packet in every fifth time slot. The serving base station stops transmitting the packet after the maximum number of time slots for the transmission data rate has been reached. At the same time, the target subscriber station accumulates the data received during different time slots of a multiple time slot packet into a packet accumulation buffer. For example, after receiving the first data of a packet in a first time slot 302a, the data is accumulated in a previously empty packet accumulation buffer. When the next set of data of the same packet is received during the time slot 302b, the received data is accumulated in the same packet accumulation buffer and the data from the first time slot 302a. The data of the same packet is sent again in the time slot 302c, and the data is accumulated in the packet accumulation buffer again, as well as the data from the previous time slots 302a and 302b.

After each time slot is associated with the multiple time slot packet 302, the subscriber station attempts to decode the packet from the contents of the packet accumulation buffer. If the subscriber station successfully decodes the packet after a decoding period 312, the subscriber station transmits a stop-repeat signal during the time slot after the decoding period 312, in which the packet is decoded. In an exemplary embodiment, when the packet is decoded after receiving the maximum number of time slots of the packet, there is a special case of this rule. The stop-repeat signal is not transmitted after receiving the maximum number of time slots for a packet, regardless of whether the packet is successfully decoded.

In an exemplary embodiment, a base station uses multiple time slot packets to transmit at a low data rate. In order for the base station to use the full forward link capability to a subscriber station using a low data rate, the base station must transmit 5 multiple time slot packets at a time. In another specific embodiment, the packet accumulation buffer of the subscriber station may be less than the number of time slots in the decoding period 312a and the following time slots 304. This will reduce the number of simultaneous packets that the user station can receive, but can save memory in the user station.

If the base station does not receive a stop-repeated signal in the time slot 304, the base station transmits the packet in the time slot 302b immediately following the time slot 304. The inability of the base station to decode a stop-repeat signal may indicate that the subscriber station cannot transmit a stop-repeat signal or that the stop-repeat signal is lost due to a communication error. In the latter, the base station can use more time slots than required for the subscriber station to successfully decode the packet to transmit the packet. For example, if the base station transmits a 16-time slot packet, which is successfully decoded by the subscriber station after the first time slot, the target subscriber station will transmit a stop-repeat signal to the base station. If the base station does not successfully decode the stop-repeated signal, the base station will transmit the remaining 15 time slots of the packet, resulting in unnecessary waste of forward link bandwidth.

There are several methods that can be considered to minimize the probability of a stop-repeat signal being lost due to communication errors. In an exemplary embodiment, a user station uses a Walsh code channel to transmit the stop-repeated signal instead of transmitting the DRC signal. In an exemplary embodiment, 11 data rates will be encoded into the 4-bit signal on the DRC channel. The number of data rates will be less than the 16 possible 4-bit DRC code words, leaving some code words for other uses. In an exemplary embodiment, the stop-repeat signal is transmitted with one of the unused DRC code words. In an exemplary embodiment, the stop-repeat signal is transmitted through the preamble/DRC channel, which uses greater power than the preamble and DRC signals to improve the decoding reliability of the stop-repeat signal.

In another specific embodiment, the preamble signal and the DRC signal are transmitted at the same time as the stop-repeat bit. The stop-repeat bit is transmitted using an orthogonal Walsh function different from the reverse link data signal and the preamble and DRC signals. In an exemplary embodiment, the reverse link data, the preamble/DRC channel, and the stop-repeat signal are respectively determined by the Walsh function W of 4 ₂⁴ , W ₀⁴ And W ₃⁴ To expand orthogonally, as defined in Table 1 above.

Fig. 3b shows a pattern diagram of a forward link time slot transmission according to another specific embodiment. The subscriber station monitors the signal quality of the pilot burst data, and uses the signal quality information to predict whether the attached data in the time slot can be decoded correctly. For example, the subscriber station monitors the quality of the pilot glitch signal in a first time slot 322a of a multiple time slot packet to determine whether the packet can be successfully decoded. If the subscriber station decides that the packet may be successfully decoded, the subscriber station transmits a stop-repeated signal in the next time slot 324a. In an exemplary embodiment, the stop-repeat signal may be transmitted before the packet is completely decoded.

In an exemplary embodiment, the subscriber station accumulates the data received in the first time slot 322a into a packet accumulation buffer, and attempts to decode a packet preamble from the signal. According to the preamble, the subscriber station recognizes the time slot 322a when the first time slot of a multiple time slot packet is addressed to the subscriber station. In an exemplary embodiment, the subscriber station analyzes the quality of the pilot burst data received in the time slot 322a. The pilot burst quality information is then used to predict whether the packet data in the slot 322a can be successfully decoded.

In an exemplary embodiment, the pilot burst signal quality information from the subsequent time slots of the same packet is combined to form a new prediction whether the packet can be reliably decoded. For example, a subscriber station may receive a first transmission of a multiple time slot packet in a first time slot 322a. If the subscriber station does not transmit a stop-repeated signal in the time slot 324a, the serving base station will transmit the second transmission of the multiple time slot packet in the time slot 322b. The subscriber station will combine the signal quality information generated by the pilot glitch in the first time slot 322a and the signal quality information generated by the pilot glitch in the second time slot 322b. This process can continue to the third time slot of the multiple time slot packet 322c, and continues until the serving base station has transmitted the maximum number of time slots of the multiple time slot packet. After receiving each new time slot of a multiple time slot packet, the subscriber station uses the accumulated pilot glitch signal quality information to generate a new prediction as to whether the packet can be successfully decoded. If it determines that the packet can be successfully decoded, the base station transmits a stop-repeated signal to the serving base station in the closest reverse link time slot. After transmitting the stop-repeat signal, the subscriber station starts to search for the beginning of a new time slot in the subsequent forward link time slot.

In an exemplary embodiment, a multiple time slot packet is transmitted in every other time slot. In order to accumulate multiple time slot packets in each forward link time slot, a user station only needs two independent packet accumulation buffers. It requires a smaller number of packet accumulation buffers because it reduces the cost of constructing the subscriber station.

In an exemplary embodiment, the target user station uses the second half-time slot of a first time slot 322a to evaluate the pilot highlight received during the first half-time slot of the first time slot 322a. The signal quality of the wave. In an exemplary embodiment, it must have time to decide whether to transmit a stop-repeated signal during the next time slot 324a. A stop-repeating signal transmitted in the time slot 324a will be based on the pilot glitch signal quality information from the pilot glitch in the first half-time slot, but not in the second half of the time slot 322a. Leading burst in the time slot. If the stop-repeat signal is not transmitted in the time slot 324a, the signal quality information from the three pilot burst periods can be analyzed in the second half-time slot of the time slot 322b to determine whether it is in the time slot During 324b, a stop-repeat signal is transmitted. The pilot glitch period analyzed during the second half-time slot of the time slot 322b may include the pilot glitch received during the time slot 322a and the pilot glitch from the first half-time slot of the time slot 322b. Oscilloscope. Similarly, pilot glitch data from 5 pilot glitches can be analyzed during time slot 322c, which has two additional pilots analyzed in each subsequent time slot for the same multiple time slot packet Burst. In another specific embodiment using a faster processor, the pilot burst of each new time slot will be used to determine whether to transmit a stop-repeated signal in a subsequent time slot.

In an exemplary embodiment, the time to analyze the quality of the pilot glitch signal will be less than the actual time to decode the contents of the packet. For this reason, the subscriber station can transmit the stop-repeat signal in the time slot 324a after the time slot 322a containing the packet data. One disadvantage of this method is that incorrect predictions waste bandwidth. For example, the subscriber station can predict whether a packet can be successfully decoded according to the quality of the pilot glitch signal. The subscriber station transmits a stop-repeated signal to the serving base station according to the prediction. After receiving the stop-repeat signal, the base station will not transmit the packet data in any other time slots. If the prediction becomes incorrect and the packet cannot be successfully decoded, all the forward link time slots used by the packet will be wasted.

In a specific embodiment, the signal quality information of multiple pilot glitches can be accumulated for analysis, and a decoding prediction metric is generated. In an exemplary embodiment, all pilot glitches except in the last half-time slot will be analyzed to generate the decoded prediction metric. In an exemplary embodiment, each forward link time slot system is divided into two half-time slots. Each half-time slot has a pilot burst, which is transmitted at the center of the half-time slot. The pilot glitch information generates the decoded prediction metric by adding the C/I value generated on each pilot glitch. Then the decoding prediction metric is greater than or equal to the decoding prediction threshold, and the subscriber station transmits a stop-repeat signal to the serving base station.

Either an unnecessarily high or an unnecessarily low decoder prediction threshold can lead to system inefficiency. For example, if the decoder predicts that the threshold is too low, the subscriber station will incorrectly predict that a packet can be successfully decoded. After transmitting a stop-repeat signal, the subscriber station will not be able to decode packets from data received in the previous time slot. The data received in the previous time slot will be lost. On the other hand, if the decoder predicts that the threshold is too high, the subscriber station will incorrectly predict that a packet cannot successfully decode the data received in the previous time slot. Because the subscriber station will not be able to send a stop-repeat signal, it will receive an extra time slot data that it does not need. The bandwidth used to transmit unnecessary time slots will be wasted. In an exemplary embodiment, the decoder prediction threshold can be selected to balance the cost of incorrect predictions in two directions. In addition, the decoder predicts that the threshold can be modified in time to compensate for a changing signal transmission environment.

In another exemplary embodiment, the serving base station transmits a multiple time slot packet in each interval time slot, and the subscriber station performs complete decoding before transmitting the stop-repeat signal. For example, if the decoding period is two time slots in length, the signal received in the first time slot 322a will not be decoded until the end of the time slot 322b. When the subscriber station decodes the first time slot 322a of the packet, the next time slot 322b of the packet will have been received. After the first time slot 322a has been decoded, the subscriber station accumulates the data of the same packet received in the next time slot 322b into the same packet accumulation buffer. If the subscriber station correctly decodes the packet from the signal received in the first time slot 322a, the subscriber station transmits a stop-repeated signal during the next time slot 324b. In this result, the bandwidth used to transmit the copy of the packet in the second time slot 322b will be wasted. If the packet can be correctly decoded after receiving and accumulating the data of the fourth time slot 322d of the packet, the subscriber station transmits a stop-repeated signal during the time slot 324e after the decoding period. In an exemplary embodiment, multiple time-slot packets are transmitted in every interval of the time slot, and the subscriber station performs complete decoding after each packet time slot, and most of the one-time slot data will be wasted.

In an exemplary embodiment, the subscriber station does not transmit a stop-repeat signal after the maximum number of time slots of a packet have been received. Even the user station successfully decodes a multi-time slot packet after accumulating the data in the second to last time slot of the packet. For the subscriber station, it is not necessary to consume the reverse link bandwidth to tell the serving base station that when the serving base station will stop at that time, it will stop repeating the packet.

In other specific embodiments, the subscriber station combines the above two technologies. The user station executes the pilot burst signal analysis, and if the decoding prediction metric is greater than or equal to the decoding prediction threshold, the user station transmits a stop-repeated signal to the serving base station. When analyzing the quality of the received pilot burst signal in parallel, the subscriber station performs a complete decoding of the received time slot data.

In an exemplary embodiment, multiple time-slot packets are transmitted in the time-slot of each interval, and the decoding period is two time-slots. The subscriber station receives the first time slot of a multiple time slot packet in the time slot 322a, and stores the received data in a packet accumulation buffer. The subscriber station analyzes the quality of the preamble signal received in the time slot 322a, and generates a decoding prediction metric. If the decoding prediction metric is greater than or equal to the decoding prediction threshold, the subscriber station transmits a stop-repeated signal in the time slot 324a. If the decoding prediction metric is less than the decoding prediction threshold, the subscriber station will not transmit a stop-repeated signal in the time slot 324a. The subscriber station also starts to decode the contents of the packet accumulation buffer. If the packet can be successfully decoded by the contents of the packet accumulation buffer, the subscriber station transmits a stop-repeat signal in the slot 324b immediately after the decoding period. The subscriber station analyzes the pilot burst data received in the time slots 322a and 322b to determine whether to send a stop-repeated signal in the time slot 324b. The pilot glitch analysis continues in each time slot until the maximum number of time slots of the packet has been received, or until the subscriber station transmits a stop-repeat signal. Similarly, the subscriber station accumulates the signals received during the time slots 322a and 322b to determine whether to transmit a stop-repeated signal in the time slot 324c. Each subsequent data time slot is accumulated in the packet accumulation buffer, and the data is decoded. If the packet can be successfully decoded from the contents of the packet accumulation buffer before the maximum number of time slots of the packet, the subscriber station transmits a stop-repeat signal. When the subscriber station transmits a stop-repeat signal, regardless of whether it is based on the quality of the pilot burst signal or successfully decoded, the subscriber station starts to search for a new frame in the next forward link time slot.

Sometimes, a packet cannot be successfully decoded even after repeating the time slot in the maximum number of time slots related to the transmission data rate of the packet. In some cases, the packet becomes decodable after the frame is retransmitted in one or two additional time slots. For example, if a 16 time slot packet cannot be successfully decoded by the content of the packet accumulation buffer after 16 time slots, perhaps accumulating the packet data in the 17th time slot will only be enough to make the packet Become decodable. If this is true, the 17th time slot will be worth expanding to avoid wasting the first 16 time slots that have been contributed to the packet. In another specific embodiment, the subscriber station may request a packet to be repeated for a limited number of time slots after the maximum time slot has been transmitted. For example, after receiving the last of the 16 time slots of a multi-time slot packet, the user may request additional repeated transmission of the packet from the serving base station.

In an exemplary embodiment, the subscriber station transmits a continue-repeated signal to the serving base station, thereby requesting to retransmit a packet of data in a display time slot. In an exemplary embodiment, the subscriber station can transmit at most n/2 repeated transmissions of n time-slot packets in an increment of one time-slot. For example, after receiving the last time slot of a 16 time slot packet in the time slot 322p, the subscriber station may request at most 8 additional repetitions of the packet after the time slot 322p. If the subscriber station cannot decode the data packet received in the time slot 322p, the subscriber station transmits a continue-repeated signal in the next time slot 324p. Upon receiving the continue-repeat signal transmitted during the time slot 324p, the serving base station retransmits the packet in the 17th time slot 322q. This process will continue until the subscriber station has requested and received the packet in the entire 24 time slots, and still cannot decode the packet.

In an exemplary embodiment, the base station only retransmits the packet in a time slot after receiving a continue-repeat signal. For example, in order to receive the 17th retransmission of a packet in time slot 322q, the subscriber station must transmit a continue-repeated signal in time slot 324p. In order to receive the 18th retransmission of a packet in time slot 322r, the subscriber station must transmit another continue-repeat signal in time slot 324q. In an exemplary embodiment, the subscriber station may request the continuation of a packet-the number of repetitions is half of the maximum number of time slots of the multiple time slot packet. For example, the subscriber station can transmit up to 8 continuation-repetition signals for a 16-time slot packet.

Even when a user station receives all the time slots of a multiple time slot packet and cannot decode the packet correctly, the user station does not have to transmit a continue-repeated signal. Based on the signal quality of the entire transmission period, the subscriber station can estimate the probability so that the packet is successfully decoded even after receiving several continuous-repetitive retransmissions. For example, the subscriber station can use the quality information generated by the pilot burst signal received from the serving base station to generate the estimate. In another specific embodiment, the subscriber station decides whether to transmit a continue-repeated signal after the last time slot of a multiple time slot packet based on this estimate. If the subscriber station predicts that the packet will probably not be decoded even after receiving the highest number of allowable continuation-repetition retransmissions, then the subscriber station will not transmit a continuation-repetition signal.

In another embodiment, the first continue-repeated signal causes the serving base station to transmit multiple retransmissions of the packet. The number of multiple retransmissions of the packet is based on the highest number of time slots for the multiple time slot packet. For example, the first continuation-repeat signal is received by a serving base station in time slot 324p after the 16th time slot 322p of a 16 time slot packet is transmitted, which may cause the serving base station to retransmit an additional Of the 8 time slots of the packet. The subscriber station can send a stop-repeat signal to cause the serving base station to send 8 retransmissions less than the packet. Professionals in the art will understand that the number of extra time slots can be any part of the maximum number.

In a specific embodiment, the stop-repeat signal and the continue-repeat signal are transmitted using a spare DRC codeword on the DRC channel. For example, if the first 11 code words of the 4-bit DRC channel signal are used to request each of the 11 data rates, then the 12th DRC code word is used to transmit stop-repeat and continue- heavy complex signal. The base station distinguishes between stop-repeated signals and continue-repeated signals according to the receiving time. For example, if the base station receives the 12th DRC code word from the target user station before the last time slot of a multiple time slot pair packet, the base station will regard it as a stop-repeated signal . If the base station receives the twelfth DRC code word from the target subscriber station immediately after the last time slot of a multi-time slot packet, the base station will regard it as a continuation-repeat signal. As described above, the subscriber station can transmit the stop-repeat signal and continue-repeat signal with a power greater than the power requested by the preamble signal or the DRC rate. This is to improve the reliability of the stop-repeat signal and continue-repeat signal at the base station.

In another specific embodiment, stop-repeat and continue-repeat are transmitted using different spare DRC codewords on the DRC channel. For example, the first 11 code words of the 4-bit DRC channel signal can be used to request 11 data rates. One of the remaining 5 DRC code words can be used to transmit a stop-continue signal, and a different one of the remaining 4 DRC code words can be used to transmit a continue-repeat signal.

The stop-repeat and continue-repeat signals occupy the reverse link bandwidth, and therefore affect the reverse link capability. For this reason, the transmission of stop-repeat and continue-repeat signals can be preferably minimized in this system. Because each base station transmits to no more than one target subscriber station at a time, no more than one subscriber station in each cell can transmit a stop-repeat or a continue-repeat signal. At the same time, a subscriber station does not transmit a stop-repeat and continue-repeat signal to a base station unless it will change the behavior of the base station. For example, a subscriber station does not transmit a stop-repeated signal after the last time slot of a multi-slotted packet, because the base station will stop transmitting the packet even if it does not receive the stop-repeated signal. Similarly, when the base station will continuously transmit a copy of a packet when the base station does not receive the continue-repeat signal, it will not transmit a continue-repeat signal.

In another specific embodiment, the continue-repeat signal is transmitted using the negative number of the Walsh function of 4 used to transmit the stop-repeat symbol. In an exemplary embodiment, the backlink data uses the Walsh function W of 4 as defined in Table 1 above ₂⁴ Come to unfold. The preamble/DRC channel uses the Walsh function W of 4 as defined in Table 1 above ₀⁴ Come to unfold. In an exemplary embodiment, one +1 uses the Walsh function W of 4 as defined in Table 1 above ₃⁴ Let's unfold a stop-repeat signal. A value (-1) is the Walsh function W using 4 ₃⁴ (As defined in Table 1 above), it represents a continuation-repetition signal. If a stop-repeat signal and a continue-repeat signal are not transmitted, there will be no power in the Walsh function W of 4 ₃⁴ The distinguished orthogonal channels are transmitted as defined in Table 1 above.

In an exemplary embodiment, the time slots of a multiple time slot packet are separated by a fixed interval. For example, in Figure 3a, the different time slots of a multiple time slot packet are shown in every 5 time slots. In Fig. 3b, the different time slots of a multiple time slot packet are shown in each of the spaced time slots. At very low data rates, the probability that a packet can be successfully decoded in the first several time slots is usually very small. However, separating the time slots used to transmit a multiple time slot packet will also extend the time it takes to completely transmit the packet. There is a need to minimize the overall time required to transmit a multi-time slot packet. In another specific embodiment, the serving base station continuously transmits the first time slot of a multiple time slot packet. For example, the serving base station may continuously transmit the first 8 time slots of a 16 time slot packet, and then transmit the remaining time slots during the 5 time slot period. In an exemplary embodiment, the serving base station continuously transmits the first n/2 time slots of an n time slot packet, and transmits the remaining time slots at fixed intervals. In other specific embodiments, other types of time slots for multiple time slot packets may also be considered.

Figures 4A-4B are an exemplary flow chart of a method for a subscriber station to use stop-repeat to decode a forward link packet. In step 402, the subscriber station measures the C/I ratio of the forward link signal from each base station in the active combination of the subscriber station. According to the measured C/I information, an example user station can transmit a DRC signal to a serving base station on a reverse link DRC channel. As described above, an exemplary subscriber station transmits a DRC signal in step 404 to designate one of a predetermined rate combination for transmitting forward link data to the subscriber station. In an exemplary embodiment, the DRC signal is transmitted in step 404 based on the measurement of the C/I ratio performed during multiple forward link time slots.

In step 404, during a forward link time slot after transmitting the DRC signal, the subscriber station reads the received forward link signal to a buffer in step 406. In an exemplary embodiment, the buffer is a packet accumulation buffer as described above. The subscriber station then attempts to decode a preamble from the contents of the buffer in step 408. In an exemplary embodiment, the serving base station inserts a preamble into the first time slot of a packet transmission, and only the desired target subscriber station can decode it.

If the preamble is not decoded in step 408, then in step 410, the subscriber station requests a new packet again, and step 402 starts. In an exemplary embodiment, the packet data transmission rate must be equal to the required data transmission rate in the DRC signal transmitted in step 404. In an alternative embodiment, the data transmission rate is encoded in the packet preamble and extracted in step 408. If the preamble decoded in step 408 indicates that the slot contains packet data to be transmitted to the user station during the forward link, then in step 412, the user station analyzes the contents of the buffer.

In an exemplary embodiment, in step 412, the subscriber station attempts to decode the received packet completely from the contents of the buffer. In another specific embodiment as described above, in step 412, the subscriber station analyzes the received signal quality of the pilot glitch signal received during the time slot related to the packet data in the buffer.

After analyzing the contents of the buffer in step 412, it is determined in step 414 whether the serving base station will transmit any more data of the packet. In an exemplary embodiment, the maximum number of time slots used to transmit a forward link packet is based on the data rate used to transmit the packet. In an exemplary embodiment, the serving base station uses no more than the maximum number of forward link time slots based on the data rate to transmit a multi-time slot packet. In step 414, the subscriber station determines whether the maximum number of time slots has been used in the packet. If the maximum number of forward link time slots are available for the packet, then the subscriber station proceeds to step 440 to determine whether to send a continue-repeat message.

The processing performed at step 440 is preferably similar or equal to the processing performed at step 416. If in step 440, the user station determines that the packet has been successfully decoded, or it may be successfully decoded according to the quality of the pilot glitch, then the user station returns to step 402 to request the next packet. Otherwise, the subscriber station proceeds to step 442. In step 442, the subscriber station decides whether to transmit a new continuation-repeat signal to request retransmission of the packet based on the number of continuation-repeat signals previously transmitted for the packet.

If in step 442, the subscriber station has not transmitted the highest allowable number of continuation-repeat signals to the serving base station of the packet, then the subscriber station proceeds to step 444 to transmit a continuation-repeat signal. The maximum allowable number of continuation-repetition signals can vary with the data rate and the number of slots in the multiple time slot packet. In an exemplary embodiment, a maximum of n/2 additional time slots can be requested for a packet of n time slots. The continue-repeat signal can be transmitted using any of the above-mentioned techniques.

After transmitting the continue-repeat message in step 444, the subscriber station accumulates the next data of the packet to the packet accumulation buffer in step 446. Then, the subscriber station decodes the content of the packet accumulation buffer in step 448 again.

In another specific embodiment, the subscriber station transmits the maximum value of a continuation-repetition message for each packet, while decoding a predetermined number of time slots retransmitted by the serving base station. In step 444, after transmitting a continuation-repeat signal of a packet, the subscriber station no longer transmits the continuation-repeat signal of the packet. For example, in step 444, after transmitting a continuation-repeat signal of a packet, the subscriber station accumulates the next data slot of the packet to the buffer in step 446, and decodes the buffer in step 448Contents. Contents. If the packet can be successfully decoded in step 442, the subscriber station proceeds to step 402. If in step 442, the packet has been successfully decoded, but the base station has not yet transmitted all retransmissions regarding the continue-repeated signal, the base station proceeds from step 440 to step 418 and transmits a stop-repeated signal .

If the packet is not successfully decoded in step 442, the subscriber station determines in step 444 whether it has received all retransmissions of the packet with respect to the continue-repeat signal. If in step 444, the base station is expected to send more retransmissions of the packet in response to the previously transmitted continue-repeat signal, the subscriber station proceeds from step 444 to step 446. Please note that in this other specific embodiment, after transmitting the first continue-repeat message, the subscriber station skips step 442. The subscriber station continues to decode the transmitted retransmission in response to the continue-repeat message until the maximum number of retransmissions has been received or the packet has been successfully decoded.

If in step 414, the maximum number of time slots has not been used for the packet, the subscriber station evaluates whether the packet has been decoded in step 416. In an exemplary embodiment, the complete decoding of the buffer content is performed in step 412, and the user station evaluates whether the packet is successfully decoded in step 416. If the packet is not successfully decoded, the subscriber station will wait until the next forward link time slot for the packet, and accumulate the received data into the buffer in step 420.

In another specific embodiment, the signal quality of the received pilot burst data is analyzed in step 412, and the subscriber station predicts in step 416 whether the packet is most likely to be successfully decoded. This prediction is based on the signal quality of the received pilot burst information. If the user station predicts that the packet cannot be successfully decoded, the user station waits for the next forward link time slot for the packet in step 420, and accumulates the received data into the buffer.

In step 412, the user station can perform complete decoding, or can perform prediction of successful decoding, or both can be performed simultaneously. If, in step 416, the subscriber station determines that the packet has been successfully decoded or can be successfully decoded, the subscriber station transmits a stop-repeat signal to the serving base station in step 418. The stop-transmit signal can be transmitted using any of the above-mentioned techniques. After transmitting a stop-repeat signal in step 418, the subscriber station returns to step 402 and requests the next packet.

Figures 4A-4B show the process of receiving a single packet. As mentioned above, a subscriber station can receive more than one multiple time slot packet at a time. For example, two multiple time slot packets can be received in staggered time slots. In an exemplary embodiment, a user station may use the processing shown in FIGS. 4A-4B to use a different packet accumulation buffer for each packet that potentially has several multiple time slots. For example, steps 412 and 420 are performed on a first buffer related to a first multiple time slot packet, and steps 412 and 420 are performed on a second buffer related to a second multiple time slot packet Come up and execute.

Fig. 5 is an exemplary flow chart of a method used by a base station to transmit a forward link packet to a subscriber station. In an exemplary embodiment, the base station receives DRC signals from a plurality of user stations in step 502. In step 504, the base station selects a target user station to select a target user station in the next forward link time slot. The serving base station then transmits the data of the first time slot of the packet to the target subscriber station in step 506.

In an exemplary embodiment, a preamble is transmitted in the first time slot for a new packet. The preamble can be used to initiate the identification of the desired target subscriber station during decoding. The data rate of the packet transmission is based on the DRC signal received from the subscriber station in step 502. If the data rate is low, the data packet (called a multiple time slot packet) is sent in multiple forward link time slots. In a specific embodiment, only the first time slot of the multiple time slot packet is transmitted with the preamble. The preamble can also be transmitted in each forward link slot.

After transmitting the first data slot of a packet of data in step 506, the base station decodes the signal received from the target subscriber station in step 508. In step 510, the base station determines whether a stop-repeated signal has been received by the target subscriber station. If a stop-repeated signal is received in step 510, the base station will proceed to step 502 to select a new target subscriber station for the next new time slot. If a stop-repeated signal number is not received in step 510 (there may be a transmission, but it does not have to be successfully decoded), the base station proceeds to step 512. In step 512, the base station compares the number of time slots that have been used to transmit the packet with the number of time slots related to the data rate of the packet. In an exemplary embodiment, each data rate has some time slots, which are called SLOTS_PER_PACKET, and the base station will use it for a packet without receiving intermediate packet feedback from the target user station. In an exemplary embodiment, the value of SLOTS_PER_PACKET for the high-speed data rate is 1. In an exemplary embodiment, the packet transmitted at the lowest data rate is transmitted in a maximum of 16 forward link time slots, so the value of SLOTS_PER_PACKET is 16. The base station and the user station use the same combination of SLOTS_PER_PACKET values for each forward link data rate.

If in step 512, the base station has transmitted the packet in a slot less than SLOTS_PER_PACKET, then the base station transmits the packet data in an additional forward link time slot in step 514. In step 514, after transmitting the packet data in another time slot, the base station proceeds to step 508 again to decode the reverse link signal received from the target subscriber station.

If in step 512, the base station has already transmitted the packet in the slot of SLOTS_PER_PACKET, then the base station proceeds to step 516. In step 516, the base station determines whether the target subscriber station has requested that the packet can be retransmitted in the forward link time slot when the maximum number of time slots related to the data rate of the packet is exceeded. The base station then determines in step 516 whether a continuation-repetition signal can be decoded by the target subscriber station. If in step 516, a continuation-repeat message is received from the target subscriber station and successfully decoded at the base station, the base station determines in step 518 whether the maximum number of repetitions has been transmitted for the packet. In an exemplary embodiment, each data rate has an associated highest number of continuation-repeat requests, which can be set to exceed the SLOTS_PER_PACKET. In an exemplary embodiment, the number of each data rate is called MAX_CONTINUE_REPEATS.

In an exemplary embodiment, MAX_CONTINUE_REPEATS is equal to SLOTS_PER_PACKET divided by 2, and it is carried down as needed. In step 518, the base station compares the number of received continuation-repeat signals of the packet with the MAX_CONTINUE_REPEATS value of the packet. If the number of received continuation-repeat signals of the packet is greater than or equal to MAX_CONTINUE_REPEATS, the base station proceeds from step 518 to step 502. Otherwise, the base station transmits data in an additional time slot in step 520. Then the base station decodes the reverse link signal received from the target subscriber station in the next time slot in step 522. After decoding the signal received from the target subscriber station in step 522, the base station proceeds to step 516 described above.

Figure 5 shows the process of transmitting a single packet. As mentioned above, a subscriber station can receive more than one multiple time slot packet at a time. For example, two multiple time slot packets can be received in alternate time slots. A single base station can transmit more than one multiple time slot packets in alternate forward link time slots, whether for a single target user station or for multiple user stations. In an exemplary embodiment, a base station uses the process shown in FIG. 5 to transmit each possibly several multiple time slot packets, and each packet may be transmitted at a different data rate.

In an exemplary embodiment, in step 520, the base station repeatedly transmits the packet to a target subscriber station in a single forward link time slot. In another specific embodiment, after receiving the first continue-repeat message, the base station will repeatedly transmit the MAX_CONTINUE_REPEATS times of the packet data, unless the base station receives a stop-repeat from the target subscriber station Signal.

In an exemplary embodiment, the base station transmits a multi-time-slot packet under control, which is performed between a fixed number of time-slots separated by time-slots. For example, the base station transmits the preamble in step 506, and then transmits the next data time slot after 5 time slots in step 514. In addition, the different time slots used to transmit the multiple time slot packet in step 514 are separated by an average interval of 5 time slots. In step 510, after each time slot of the packet is transmitted in step 506 or 514, the base station checks whether it receives a stop-repeated signal from the target subscriber station. In another specific embodiment, the base station transmits the first several time slots of a multiple time slot packet in a continuous forward link time slot. For example, the base station transmits the first 8 time slots of a 16-time slot packet in consecutive time slots. After that, the base station transmits the subsequent time slots of the packet at an interval of 5 time slots. If the base station decodes a stop-repeated message from the target subscriber station in step 510, the base station will stop transmitting the packet regardless of how many time slots have been transmitted.

Figure 6 shows a block diagram of an example subscriber station device. The forward link signal is received, down converted, and sampled at the front end 602, and the resulting sample stream is provided to the demodulator 604. The demodulator 604 demodulates the received signal, and provides the demodulated samples to a packet accumulation buffer (referred to as a buffer only) 606. Although the example system shows three buffers 606, a subscriber station may have a larger or smaller number of packet accumulation buffers. Although the decoded signal can be provided to each buffer 606, there is only one buffer, such as buffer 606a, which can accumulate the samples in any special time slot. The control processor 616 provides a control signal to each buffer 606, which controls when the buffer 606 accumulates data from the demodulator 604. The control processor 616 controls the buffer 606 so that the buffer 606a performs sample accumulation corresponding to the entire forward link time slot. For example, in an exemplary embodiment, the subscriber station receives two multiple time slot packets in alternate time slots at a time. The control processor 616 instructs the buffer 606a to accumulate samples of the even-numbered time slot, and instructs the buffer 606b to accumulate the samples of the odd-numbered time slot.

After the samples have accumulated a forward link time slot, the control processor 616 instructs the buffer for accumulating data for the time slot, such as the buffer 606a, to provide the accumulated samples to the decoder 610. The decoder 610 then attempts to decode the accumulated sampled data received from the buffer 606a. Before the first time slot data of a new packet is received into a buffer 606, the buffer is cleared. Clearing the buffer before receiving the new packet data can prevent the remaining accumulated samples from the previous packet from interfering with the decoded samples of the new packet. The decoder 610 readjusts and reorders the buffer 612 by providing successfully decoded packets.

In an exemplary embodiment, the first time slot for a new packet is transmitted with a preamble. The preamble can be interspersed into the data of the first time slot data and decoded by the demodulated samples in the preamble detector 632. Interleaving is a well-known technique in the art to transmit an additional signal in a forward error correction coded symbol stream. The preamble detector 632 receives the demodulated samples from the decoder 610 and decodes the received demodulated sample preamble, which can provide the decoded preamble information to the control processor 616. Although shown as a separate component from the control processor 616, the preamble detector 632 can be added to the control processor 616, combining preamble detection, decoding, and control processing in a single processor.

The data information is provided by the demodulator 604 to the carrier-to-interference ratio (C/I) processor 614. In an exemplary embodiment, the C/I processor 614 analyzes the received signal quality of pilot burst signals received from one or more base stations. In an exemplary embodiment, the C/I processor 614 uses the pilot burst information to predict the maximum data rate of a packet transmitted by a serving base station, which can be successfully decoded by the subscriber station. According to this prediction, the C/I processor 614 sends an information signal to the control processor 616. Although shown as components independent of the control processor 616, the C/I processor 614 can be added to the control processor 616, and the C/I calculation and control processing are performed by a single processor. The control processor 616 transmits the rate information to the DRC decoder 620 to be encoded into a DRC code word. The signal generated by the DRC encoder 620 is expanded using the Walsh expander 622b. In an exemplary embodiment, the signal generated by the DRC encoder 620 uses the Walsh function W of 4 in the Walsh expander 622b ₀⁴ Come to unfold. The output signal of the Walsh expander 622b is then subjected to gain control in the gain block 624b. The gain applied to the gain block 624b can be controlled by the control processor 616.

In an exemplary embodiment, the control processor 616 can also determine when a stop-repeated signal will continue-repeated signal must be transmitted. The control processor 616 transmits a first signal to the feedback signal generator 618, which can cause the feedback signal generator 618 to generate a continuous-repeat signal. The signal generated by the feedback signal generator 618 can use the Walsh function W of 4 in the Walsh expander 622a. ₃⁴ Come to unfold. The output signal of the Walsh expander 622a is then subjected to gain control in the gain block 624a. The gain applied to the gain block 624a is controlled by the control processor 616.

In an exemplary embodiment, the gain control signal from the gain block 624 is summed in the summing block 626 before being provided to the multiplexer (MUX) 628. The MUX628 can multiplex the output signal of the totalizer 626 with a leading channel signal. In an exemplary embodiment, the output signal of the gain block 624 is a part of a medium access control (MAC) channel, which is interspersed by the MUX 628 to the continuous preamble channel signal. The output signal of MUX628 is provided as an in-phase component of a signal to complicate the virtual noise (PN) expander 630. In an exemplary embodiment, the quadrature phase component of the signal carries the reverse link packet data transmitted by the subscriber station. Then the output of the complex PN expander 630 is up-converted, amplified, and transmitted by the subscriber station.

In an exemplary embodiment, the control processor 616 transmits forward link rate information to the decoder 610, and controls the buffer 606 according to the DRC signal previously transmitted through the DRC encoder 620. In an exemplary embodiment, a serving base station can only use the rate requested in the DRC signal of the subscriber station to transmit packets to the subscriber station. Allowing the subscriber station to indicate the forward link data rate may make blind rate detection at the subscriber station unnecessary. In another specific embodiment, the base station may use data rates other than those specified in the DRC signal of the subscriber station to transmit packets. In this other specific embodiment, the decoder 610 performs blind rate detection.

In an exemplary embodiment, the demodulator 604 may perform functions such as PN inverse unwrapping, Walsh inverse unwrapping, and de-interlacing of the data signal received from the front end 602. The deinterleaving performed by the demodulator 604 can use any interleaving technique, such as block interleaving and bit-reversal interleaving. In an exemplary embodiment, the decoder 610 performs forward error correction (FEC) decoding of the data signal received from the buffer 606. The decoder 610 can use any of several forward error correction coding techniques, including boost coding, convolution coding, block coding, or other coding forms including soft decision coding. In an exemplary embodiment, the control processor 616 may be a general-purpose microprocessor, digital signal processor (DSP), programmable logic device, application-specific integrated circuit (ASIC), or any other The device that controls the functions of the processor 616. In an exemplary embodiment, the C/I processor 614 may be a general-purpose microprocessor, a digital signal processor (DSP), a programmable logic device, an application-specific integrated circuit (ASIC), or any other capable of executing The C/I processor 614 described here functions as a device.

Figure 7 shows a block diagram of an exemplary base station device. In an exemplary embodiment, the data packet is received from a base station controller (not shown) via a base station controller (BSC) interface 702. Each packet received from the base station controller may include an address for identifying the target user station. The packet is stored in the data queue 704 until it is transmitted or discarded. The scheduler 708 selects the target user station for each forward link time slot, receives the corresponding forward link packet from the data queue 704, and provides the data to the modulator (MOD) 706. The modulator 706 modulates the packet data received from the scheduler 708 and provides the modulated signal to the radio frequency (RF) unit 710. The RF unit 710 up-converts and amplifies the modulated signal, and transmits the up-converted signal via the antenna 712. Although only one antenna 712 is shown, the RF unit 710 can transmit and receive signals via multiple antennas.

In an exemplary embodiment, the base station receives the reverse link signal via the antenna 712, which is down-converted in the RF unit 710. The RF unit 710 provides this down conversion, and the sampled signal is sent to the demodulator 716. The demodulated packet is provided by the demodulator 716 to the control processor 714, which can direct the data packet to the base station controller (BSC) interface 702. In an exemplary embodiment, the BSC interface 702 then transmits the reverse link packet to a base station controller (not shown) via a backhaul interface (not shown).

The demodulator 716 also decodes the stop-repeat and continue-repeat signals, and provides those signals to the control processor 714. The control processor 714 transmits stop-repeat and continue-repeat information to the scheduler 708. When receiving a stop-repeat signal, or when no more copies of a packet are sent, the scheduler 708 clears the data of the packet from the data queue 704. The space in the data queue can then be used for subsequent packets. Upon receiving a continue-repeat signal, the scheduler 708 retransmits the data of the related packet from the data queue 704 in a subsequent forward link time slot.

In an exemplary embodiment, the modulator 706 performs functions such as forward error correction (FEC) encoding, interleaving, Walsh expansion, and PN expansion of the data received from the scheduler 708. In an exemplary embodiment, the demodulator 716 performs functions such as PN inverse expansion, Walsh inverse expansion, deinterleaving, and forward error correction (FEC) decoding of the data signal received from the RF unit 710. The interleaving and de-interleaving performed by the modulator 706 and the demodulator 716 can use any interleaving technique, such as block interleaving and bit-reversal interleaving. The modulator 706 and the demodulator 716 can use any forward error correction technology, including boost coding, convolution coding, block coding, or other coding forms including soft decision coding. In an exemplary embodiment, the scheduler 708 can be a general-purpose microprocessor, a digital signal processor (DSP), a programmable logic device, an application-specific integrated circuit (ASIC), or any other The described algorithm device.

The previous description of the preferred embodiments is provided to enable any professional in the art to make or use the present invention. Different modifications to these specific embodiments can be immediately understood by professionals in the art, and the basic principles defined here can be applied to other specific embodiments without using the skills of the present invention. Therefore, the present invention is not limited to the specific embodiments shown here, but is based on the broadest scope of the principles and innovative features disclosed herein.