HK1082991A - Reverse link automatic repeat request - Google Patents

Description

Reverse link automatic repeat request

Technical Field

The present invention relates to wireless communications, and more particularly, to transmitting data in a wireless communication system.

Background

The cdma2000High Rate Packet Data Air Interface Specification (cdma2000High Rate Packet Data Air Interface Specification), more specifically qualcomm cdma 2001 xEV-DO version, published as TIA/EIA/IS-856, IS an Air Interface optimized for High-speed wireless Data delivery to mobile and fixed terminals.

In 1xEV-DO, an Access Terminal (AT) is a data interface with a wireless modem and allowing a user to access a packet data network through a 1xEV-DO network. The AT IS a mobile station similar to that in an IS-41 cellular network.

AN Access Network (AN) is a network device that provides data connectivity between a packet-switched data network (e.g., the internet) and AN AT. As referred to herein, AN may comprise only modem pool transceivers, and (additionally) other network devices, such as modem pool controllers.

The Forward Link (FL) refers to communication from the AN to the AT. Correspondingly, the Reverse Link (RL) refers to communication from the AT to the AN.

Multiple ATs may communicate within a sector covered by a single BTS. The AN is limited by the receive threshold power. The received power is a function of the number of ATs in the sector and the data rate of each AT in the sector. An AT transmitting AT a high data rate transmits signals AT a higher power than an AT transmitting AT a low data rate. When the AN approaches its transmit threshold power, the AN can send a message on the reverse link active channel to all ATs in the sector of the AN to reduce the transmission rate. The reduction in transmission rate results in reduced throughput, and the limit on the receive threshold power may be a limiting factor on the overall data throughput of the AT in the sector.

There is therefore a need for methods and apparatus that increase data throughput in a sector.

Drawings

Fig. 1 illustrates transmission of signals between AN AT and AN;

fig. 2 illustrates a method of data transmission by an AT;

fig. 3 illustrates a method of data transmission with AN; and

fig. 4 illustrates a block diagram of AN AT and AN in a wireless communication system.

Detailed Description

Techniques for FL Transmission are described in a Code Division Multiple Access (CDMA) System conforming to the TIA/EIA/IS-95 Mobile Station-Base Station compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System (IS/EIA/IS-95 Mobile Station-Base Station compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System), where (IS-95) Data packets may be retransmitted on the FL, U.S. patent application Ser. No. 08/963,386, "Method and Apparatus for High Rate packet Data Transmission," filed 11/3/1997, for example, No. 08/963,386, the Data packets may contain a predetermined number of Data units, each identified by a sequence number, when a Mobile Station incorrectly receives one or more Data units, the Mobile Station may send an acknowledgement (NACK) on the RL channel, indicating the sequence number of the lost data unit for retransmission from the base station. The base station receives the NACK message and may retransmit the erroneously received data unit.

In a CDMA system, there is no such acknowledgement or retransmission in the RL for data transmission.

The transmission unit of the physical layer of 1xEV-DO is a physical layer packet. The data is contained in a physical layer packet. In the RL, physical layer packets are contained in frames. The duration of a frame may be 26.66 milliseconds (ms). A frame may contain 16 slots, each slot having a duration of 1.66 ms.

Data is modulated at various data rates on the reverse traffic channel. The data rates may be 9.6 kilobits per second (kbps), 19.2kbps, 38.4kbps, 76.8kbps, and 153.6 kbps. For data rates below 76.8kbps, data may be repeated within one frame. For example, at 9.6kbps, data may be sent in the first two slots of a frame, and the same number may be repeated 7 times in the next 14 slots of a 16-slot frame; at 19.2kbps, data can be sent in the first four slots of the frame, and the same number can be repeated 3 times in the lower 12 slots of a 16-slot frame; at 38.4kbps, data may be sent in the first eight slots of the frame, and the same number may be repeated 1 time in the lower 8 slots of the 16-slot frame. Although the data is not repeated in the frame for the 76.8kbps data rate, redundancy may be provided by encoding, such as Turbo codes, as encoding provides redundancy for data at other data rates.

The redundancy provided by data repetition and coding within a frame can advantageously be used to reduce the transmission of redundant data by individual ATs. By reducing the amount of redundant data transmitted by individual ATs within a sector, data output is effectively increased for the sector since the data is transmitted in a shorter duration.

For data rates below 153.6kbps, a 16-slot frame may be divided into 16/N groups of slots before transmission by the AT, where N may be 1, 2, 4, or 8. For example, when N equals 2, the AT may send the first half of the frame (8 slots) to the AN and hold the second half of the frame in the queue for possible retransmission of data based on successful decoding of the data of the first half frame received by the AN.

Automatic repeat request (ARQ) refers to a protocol in which a receiver requests a sender to retransmit data. When the first half of the frame is successfully decoded, the AN may send AN acknowledgement message (ACK) to the AT to indicate that the AN successfully decoded the data received in the first half of the frame. When the first half of the frame is not successfully decoded, the AN may send a negative acknowledgement message (NAK) to the AT to indicate that the AN failed to successfully decode the data received in the first half of the frame.

An ACK is a message sent to indicate that some data was received correctly. Generally, if the sender does not receive an ACK message or receives a NAK after a predetermined period of time, the original data is transmitted again.

A NAK is a message sent to indicate that some data was received incorrectly, e.g., the data may have a checksum error. An alternative to sending a NAK is to use only an ACK message, in which case the non-receipt of an ACK after a certain time is considered a NAK. As used herein, NAK refers to the receipt of a NAK message or the non-receipt of an ACK.

The ACK or NAK may be sent on the FL ACK channel. In 1xEV-DO, the FL ACK channel may be introduced into a new MAC subchannel. The existing FL Media Access Control (MAC) channel of 1xEV-DO contains sub-channels called reverse Link Power control (RPC) channels. The RPC channel uses Binary Phase Shift Keying (BPSK) modulation to send RPC bits that request ATs in a sector to increase or decrease their power. The FL ACK channel may use BPSK modulation at a right angle phase to the phase of the RPC channel.

Other techniques may be used to create the FL ACK channel. There are currently 64 MAC subchannels. A portion of these subchannels may be used for the FL ACK channel. In this example, the modulation phase of the FL ACK channel does not have to be orthogonal to the RPC channel.

The ACK byte may be sent from only one serving sector or all sectors in the AT's active set when the AT is in soft handoff.

Fig. 1 illustrates transmission of signals between AN AT102 and AN104 using ARQ. The AT transmits a first set of slots 106 of packet n. In this example, the first set of slots comprises 8 slots. A first set of slots 114 of packet n is received by the AN. Immediately after the AT transmits the first set of slots 106 of packet n, the AT transmits the first set of slots 108 of packet n +1 and the AN receives the first set of slots 116 of packet n + 1.

As shown in fig. 1, AT102 transmits a first set of slots 122 of packet n-1 before transmitting the first set of slots 106 of packet n, and AN104 receives a first set of slots 124 of packet n-1.

The AT receives AN acknowledgement signal ACK or NAK from the AN indicating that the first set of channels 114 of packet n was successfully or unsuccessfully decoded before sending the next set of slots. The acknowledgement signal informs the AT whether to retransmit the data, e.g., by transmitting a second set of slots of packet n that contains redundant data, or transmitting new data, e.g., a first set of slots of packet n + 2.

In this example, the AN sends AN ACK122 to indicate that the first set of slots 114 of packet n has been successfully decoded. The AT receives the ACK indicating that the AT may send the first set of slots 110 for packet n + 2. The AN receives the first set of slots 118 of packet n + 2.

The AT receives AN acknowledgement signal ACK or NAK from the AN indicating that the first set of channels 114 of packet n +1 was successfully or unsuccessfully decoded before sending the next set of slots 112. In this example, the AN sends a NAK. Upon receipt of the NAK, the AT retransmits the data by transmitting the second set of slots 120 of packet n +1 containing redundant data. The AN receives the second set of slots 120 of packet n + 1. The AN may combine the data contained in the first set of slots 116 of packet n +1 with the data contained in the second set of slots 120 of packet n +1 and attempt to decode the data contained in the combined set of slots. With the additional redundant data, the likelihood of successfully decoding the data increases.

Those skilled in the art will appreciate that when the AN successfully decodes the data contained in the first set of slots, the data throughput of the system is increased by not transmitting redundant data, i.e., the second set of slots. In this two-set 8-slot example, the data throughput can potentially be doubled.

Fig. 2 illustrates a method for data transmission with an AT. AT step 202, the AT sends a first set of slots of a first packet to the AN. AT step 204, the AT sends a first set of slots of a second packet to the AN. Those skilled in the art will appreciate that when the packets are divided into more than two groups, e.g., four slot groups of four slots each, additional transmissions of the first group of packets may be performed before proceeding to step 206.

AT step 206, the AT determines whether the AT receives AN ACK or NAK from the AN. In this example, AN ACK indicates that the AN successfully decoded the first set of slots of the first packet and a NAK indicates that the AN unsuccessfully decoded the first set of slots of the first packet.

Upon receiving the ACK, the AT sends the first set of slots of the third packet AT step 210. Upon receiving the NAK, the AT transmits a second set of slots of the first packet AT step 208.

The example above is for a packet divided into two groups of eight slots. Those skilled in the art will appreciate that a packet may be divided into more than two equal parts.

For example, if the packet is divided into four slot groups of four slots each, the AT may transmit the first set of slots of the first packet AT step 202, and then the AT may transmit the first set of slots of the second packet AT step 204. When the AT receives the ACK AT step 206, corresponding to the AN successfully decoding the first set of slots of the first packet, the AT may send the first set of slots of the third packet AT step 210. When the AT receives a NAK, corresponding to the AN not successfully decoding the first set of slots of the first packet, AT step 206, the AT may send a second set of slots of the first packet, AT step 208.

In addition, when the AT receives the ACK, corresponding to the AN (not shown) successfully decoding the first set of slots of the second packet, the AT can transmit (a) the first set of slots of the fourth packet if the first set of slots of the first packet were also successfully decoded or (b) the first set of slots of the third packet if the first set of slots of the first packet were not successfully decoded.

When the AT receives a NAK, corresponding to a failure of the AN (not shown) to successfully decode the first set of slots of the second packet, the AT may transmit the second set of slots of the second packet.

This process may similarly continue for other groups of slots.

Further, the AT may sequentially transmit the first set of slots of the first packet AT step 202, the first set of slots of the second packet, the first set of slots of the third packet (not shown), and the first set of slots of the fourth packet (not shown) AT step 204. The AN may receive the first three sets of slots before sending the acknowledgement signal for the first set of slots of the first packet. When the AT receives the ACK AT step 206, corresponding to the AN successfully decoding the first set of slots of the first packet, the AT may send the first set of slots of the fifth packet AT step 210. When the AT receives a NAK, corresponding to the AN not successfully decoding the first set of slots of the first packet, AT step 206, the AT may send a second set of slots of the first packet, AT step 208.

In addition, when the AT receives the ACK, the AT may transmit a first set of slots of a sixth packet (not shown) corresponding to the AN successfully decoding the first set of slots of the second packet. When the AT receives a NAK, corresponding to the AN failing to successfully decode the first set of slots of the second packet, the AT may transmit the second set of slots of the second packet (not shown).

This process may similarly continue for other groups of slots.

Further, those skilled in the art will appreciate that other combinations of transmitting a slot by the AT and transmitting AN acknowledgement signal by the AN may be made and are within the scope of the appended claims.

Fig. 3 illustrates a method for data transmission with AN, corresponding to the method for data transmission by the AT shown in fig. 2.

At step 302, the AN receives a first set of slots of a first packet. At step 304, the AN receives a first set of slots of a second packet. At step 306, the AN attempts to decode a first set of slots of the first packet. Although the attempt to decode 306 is shown after receiving the first set of slots of the second packet, the AN may attempt to decode the first set of slots of the first packet before or after receiving the first set of slots of the second packet, or at the same time as receiving the first set of slots of the second packet.

At step 308, the AN determines whether the first set of slots of the first packet was successfully decoded. When the AN successfully decodes the first set of slots of the first packet, the AN sends AN ACK to the AT step 310 and receives the first set of slots of the third packet AT step 312. When the AN fails to successfully decode the first set of slots of the first packet, the AN sends a NAK to the AT step 314, receives the second set of slots of the first packet AT step 316, and attempts to decode a combination of the first set of slots of the first packet and the second set of slots of the first packet AT step 318.

The above example is for a packet divided into two groups of 8 slots. Those skilled in the art will appreciate that a packet may be divided into more than two equal parts, as depicted in fig. 2.

The timing of sending the ACK or NAK may be independent of the number of received groups of slots. The AN may send AN ACK or NAK AT some time after decoding the corresponding received slot group or groups and before the AT needs AN acknowledgement signal to determine to send the particular slot group AT step 206, e.g., AT step 308. The timing of sending the ACK or NAK may be independent of the crossing of the groups of slots.

Fig. 4 illustrates a block diagram of AN AT102 and AN104 in a wireless communication system. The AT and the AN may employ conventional hardware and software techniques. Both the AT and the AN may each include a logic and processing unit 402 or 404, respectively, including a radio frequency unit 406 and 408, respectively, for performing the functions described above. For example, those skilled in the art will appreciate that the radio unit may send and receive signals between the AN and the AT, and that the logic and processing unit may perform logic operations and signal processing.

Although the above description is made with specific reference to a 1xEV-DO communication system, reverse link automatic repeat request may also be used in other CDMA systems.

The previous description of the preferred embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (25)

1. A method of automatically repeat requesting a reverse link of a high rate packet data code division multiple access wireless communication system, the method comprising:

transmitting, by an access terminal, a first set of slots of a first packet to an access network;

transmitting, by the access terminal, a first set of slots of a second packet to the access network;

determining, by the access terminal, whether it receives an ACK or NAK from the access network corresponding to the first set of slots of the first packet, successful or unsuccessful, respectively, and

upon receiving the ACK, the first set of slots of the third packet is transmitted by the access terminal.

2. The method of claim 1, further comprising:

a second set of slots of the first packet is transmitted by the access terminal upon receiving the NAK.

3. The method of claim 1, further comprising:

receiving, by an access network, a first set of slots of a first packet;

the access network attempting to decode a first set of slots of a received first packet;

determining, by the access network, whether a first set of slots of the received first packet was successfully decoded; and

the access network sends an ACK to the access terminal when the access network successfully decodes the first set of slots of the received first packet.

4. The method of claim 3, further comprising:

a NAK is sent by the access network to the access terminal when the access network fails to successfully decode the first set of slots of the received first packet.

5. A method of automatically repeat requesting a reverse link of a high rate packet data code division multiple access wireless communication system, the method comprising:

transmitting, by an access terminal, a first set of slots of a first packet to an access network;

determining, by the access terminal, whether it receives an ACK or NAK from the access network; and

a second set of slots of the first packet is transmitted by the access terminal when a NAK is received.

6. The method of claim 5, further comprising:

receiving, by an access network, a first set of slots of a first packet;

the access network attempting to decode a first set of slots of a first packet;

determining, by the access network, whether a first set of slots of the received first packet was successfully decoded; and

the access network sends an ACK to the access terminal when the access network successfully decodes the first set of slots of the received first packet.

7. The method of claim 6, further comprising:

a NAK is sent by the access network to the access terminal when the access network fails to successfully decode the first set of slots of the received first packet.

8. A method of automatically repeat requesting a reverse link of a high rate packet data code division multiple access wireless communication system, the method comprising:

receiving, by an access network, a first set of slots of a first packet from an access terminal;

the access network attempting to decode a first set of slots of a first packet;

determining, by the access network, whether a first set of slots of the received first packet was successfully decoded; and

the access network sends an ACK to the access terminal when the access network successfully decodes the first set of slots of the received first packet.

9. The method of claim 8, further comprising:

a NAK is sent by the access network to the access terminal when the access network fails to successfully decode the first set of slots of the received first packet.

10. The method of claim 9, further comprising:

receiving, by the access network, a second set of slots of the first packet from the access terminal;

an attempt is made by the access network to decode a combination of the first set of slots of the received first packet and the second set of slots of the received first packet.

11. The method of claim 8, wherein the ACK is transmitted by the access network on a forward link ACK channel that is binary phase shift keyed, wherein the ACK is transmitted on a phase that is orthogonal to a phase of the reverse link, and wherein the power control bit is transmitted on a reverse link power control channel.

12. A method of automatically repeat requesting a reverse link of a high rate packet data code division multiple access wireless communication system, the method comprising:

transmitting, by an access terminal, a first set of slots of a first packet to an access network;

receiving, by an access network, a first set of slots of a first packet;

the access network attempting to decode a first set of slots of a first packet;

determining, by the access network, whether a first set of slots of the received first packet was successfully decoded; and

when the access network fails to successfully decode the first set of slots of the received first packet,

a NAK is sent by the access network to the access terminal,

determining, by the access terminal, whether it received a NAK from the access network, and

when a NAK is received by the access terminal,

transmitting, by the access terminal, a second set of slots of the first packet;

receiving, by the access network, a second set of slots of the first packet from the access terminal;

an attempt is made by the access network to decode a combination of the first set of slots of the received first packet and the second set of slots of the received first packet.

13. The method of claim 12, further comprising:

transmitting, by the access terminal, a first set of slots of a second packet;

wherein when the access network successfully decodes the first set of slots of the received first packet,

an ACK is sent by the access network to the access terminal,

determining, by the access terminal, whether it received an ACK from the access network, an

When the access terminal receives the ACK, it,

the first set of slots of the third packet is transmitted by the access terminal.

14. The method of claim 12, wherein the ACK is transmitted by the access network on a forward link ACK channel that is binary phase shift keyed, wherein the NAK is transmitted on a phase that is orthogonal to a phase of the reverse link, and wherein the power control bit is transmitted on a reverse link power control channel.

15. An access terminal for a high rate packet data code division multiple access wireless communication system, the access terminal comprising:

a radio frequency unit configured to:

a first set of slots of a first packet is transmitted,

a first set of slots for transmitting a second packet, an

Receiving ACK or NAK;

a logic and processing unit configured to:

determining whether an ACK or NAK is received;

wherein the radio frequency unit is further configured to:

when the ACK is received, a first set of slots of a third packet is sent, an

A second set of slots of the first packet is transmitted when a NAK is received.

16. An access network for a high rate packet data code division multiple access wireless communication system, the access network comprising:

a radio frequency unit configured to:

receiving a first set of slots of a first packet; and

a logic and processing unit configured to:

attempting to decode a first set of slots of a received first packet; and

determining whether a first set of slots of a received first packet was successfully decoded,

wherein the radio frequency unit is further configured to:

sending an ACK when the logic and processing unit successfully decodes a first set of slots of a received first packet, an

The NAK is sent when the logic and processing unit fails to successfully decode the first set of slots of the received first packet.

17. The access network of claim 16, wherein

The radio frequency unit is further configured to

Receiving a second set of slots of the first packet;

the logic and processing unit is further configured to

An attempt is made to decode a combination of the received first set of slots of the first packet and the second set of slots of the first packet.

18. The access network of claim 16, wherein the radio frequency unit is further configured to:

transmitting reverse link control bits on a reverse link power control channel modulated by binary phase shift keying; and

an ACK or NAK is sent on a binary phase shift keying modulated forward link ACK channel, where the ACK or NAK is sent with a phase that is orthogonal to a phase of a reverse link power control channel.

19. A Code Division Multiple Access (CDMA) wireless communication system for a reverse link for automatic repeat request high rate packet data, the CDMA wireless communication system comprising:

an access terminal, comprising:

a first radio frequency unit configured to

A first set of slots of a first packet is transmitted,

a first set of slots for transmitting a second packet, an

Receiving ACK or NAK; and

a first logic and processing unit configured to

Determining whether an ACK or NAK is received;

wherein the first radio frequency unit is further configured to

When the ACK is received, a first set of slots of a third packet is sent, an

Transmitting a second set of slots of the first packet when a NAK is received; and

an access network, comprising:

a second radio frequency unit configured to,

receiving a first set of slots of a first packet; and

a second logic and processing unit configured to,

attempting to decode a first set of slots of a received first packet, an

Determining whether a first set of slots of the received first packet was successfully decoded,

wherein the second radio frequency unit is further configured to,

sending an ACK when the logic and processing unit successfully decodes a first set of slots of a received first packet, an

The NAK is sent when the logic and processing unit fails to successfully decode the first set of slots of the received first packet.

20. The CDMA wireless communication system of claim 19, wherein:

the second radio frequency unit is further configured to

Receiving a second set of slots of the first packet;

the second logic and processing unit is further configured to

An attempt is made to decode a combination of the received first set of slots of the first packet and the second set of slots of the first packet.

21. The CDMA wireless communication system of claim 19, wherein the second radio unit is further configured to send an ACK or NAK on a binary phase shift keying modulated forward link ACK channel, wherein the ACK or NAK is sent with a phase that is orthogonal to a phase of a reverse link power control channel.

22. An apparatus for automatically repeat requesting a reverse link of a high rate packet data code division multiple access wireless communication system, the apparatus comprising:

means for transmitting, by the access terminal, a first set of slots of a first packet to the access network;

means for transmitting, by the access terminal, the first set of slots of the second packet to the access network;

means for determining by the access terminal whether it receives an ACK or NAK to the access network corresponding to the first set of slots of the first packet being successfully or unsuccessfully decoded, respectively, and

means for transmitting, by the access terminal, the first set of slots of the third packet when the ACK is received.

23. An apparatus for automatically repeat requesting a reverse link of a high rate packet data code division multiple access wireless communication system, the apparatus comprising:

means for transmitting, by the access terminal, a first set of slots of a first packet to the access network;

means for determining, by the access terminal, whether it receives an ACK or NAK from the access network; and

means for transmitting, by the access terminal, a second set of slots of the first packet when the NAK is received.

24. An apparatus for automatically repeat requesting a reverse link of a high rate packet data code division multiple access wireless communication system, the apparatus comprising:

means for receiving, by an access network, a first set of slots of a first packet from an access terminal;

means for the access network to attempt to decode a first set of slots of a first packet;

means for determining, by the access network, whether a first set of slots of the received first packet was successfully decoded; and

means for the access network to send an ACK to the access terminal when the access network successfully decodes the first set of slots of the received first packet.

25. An apparatus for automatically repeat requesting a reverse link of a high rate packet data code division multiple access wireless communication system, the apparatus comprising:

means for transmitting, by the access terminal, a first set of slots of a first packet to the access network;

means for receiving, by an access network, a first set of slots of a first packet;

means for the access network to attempt to decode a first set of slots of a first packet;

means for determining, by the access network, whether a first set of slots of the received first packet was successfully decoded; and

means for when the access network fails to successfully decode the first set of slots of the received first packet,

means for sending a NAK by the access network to the access terminal,

means for determining by the access terminal whether it received a NAK from the access network, an

Means for when an access terminal receives a NAK, comprising

Means for transmitting, by the access terminal, a second set of slots of the first packet;

means for receiving, by the access network, a second set of slots of the first packet from the access terminal;

means for attempting, by the access network, to decode a combination of the first set of slots of the received first packet and the second set of slots of the received first packet.