RU2404516C2 - Packet transmission acknowledgment in wireless communication system - Google Patents

Abstract

FIELD: information technology. ^ SUBSTANCE: packet transmitted from UE is received; said packet is decoded and it is determined whether the packet was successfully decoded; an ACK signal or a NACK signal is transmitted based on the decoding result. Different transmission powers are allocated for the ACK signal and the NACK signal. Alternatively, the transmission power for the NACK signal selectively has an OFF level. The present invention optimises the transmission powers for downlink ACK/NACK signals in accordance with the required reception quality of each of the ACK/NACK signals, and thus, enables the system to operate efficiently. ^ EFFECT: accurate determination of signal downlink transmission power. ^ 6 cl, 3 dwg

Description

FIELD OF THE INVENTION

The present invention relates to a method for transmitting an ACK / NACK acknowledgment / negative acknowledgment signal, and in particular, for transmitting an ACK / NACK signal from a network receiving packet data transmitted from a user equipment (UE) over an uplink data channel.

State of the art

The 3rd Generation Partnership Project (3GPP) discusses the application of a hybrid automatic repeat request (HARQ) scheme to a channel for high speed uplink packet data. The specified channel is known as an enhanced uplink dedicated channel (E-DCH).

When applying the HARQ system to the uplink, the network (for example, Node B), in response to a packet transmitted from the user equipment (UE), transmits a negative acknowledgment (NACK) signal to the UE when, based on the results obtained after decoding the packet, it is determined that the packet is decoded in error, and the network transmits an acknowledgment signal (ACK) to the UE when it is determined that the packet has been successfully decoded. The ACK / NACK signal is transmitted over the 1-bit ACK / NACK channel.

In response to receiving the NACK signal, the UE retransmits the previously transmitted packet. The Node B combines the decoding information of the retransmitted packet with the decoding information of the previously transmitted packet, using various transmission methods to improve the reception quality of the retransmitted packet. In this case, the ACK / NACK signal is a 1-bit signal that is transmitted in the downlink. No channel coding is provided for the specified ACK / NACK signal to protect it from interference or other adverse transmission factors. For this reason, in order to enable the UE equipment to successfully receive the ACK / NACK signal, it is necessary to use very high transmit power.

In a HARQ system, the NACK signal must have a higher percentage of successful transmission attempts than the ACK signal. When the UE mistakenly receives the ACK signal for the NACK signal, the UE retransmits a packet that has already been received by the Node B. Accordingly, there will be no damage other than retransmitting the same data. However, when the UE erroneously receives the NACK signal as an ACK signal, the UE erroneously determines that the packet data associated with this signal has been successfully transmitted to the Node B, and then transmits the next packet. As a result, an erroneously decoded packet cannot be restored at the physical level of node B. It will still be necessary to recover an erroneous packet at a higher level. As a result, packet transmission delay increases.

In addition, when the UE is in fast transient mode, or in a soft handoff state with many nodes B, the communication over the lines between the UE and each node B can be very unstable. In this case, unrealistically high ACK / NACK transmit power (especially NACK transmit power) may be required to ensure satisfactory ACK / NACK reception quality.

Accordingly, it is necessary to correctly set the transmit power ACK / NACK in the downlink, taking into account all of the above possibilities.

Therefore, for wireless communication systems that use the enhanced dedicated uplink dedicated channel, there is a need for an improved ACK / NACK transmission facility that solves these and related problems.

SUMMARY OF THE INVENTION

Thus, the present invention is directed to methods for transmitting an ACK / NACK signal and determining ACK / NACK in uplink packet transmission, which essentially solve one or more problems associated with the limitations and disadvantages of the prior art.

An object of the present invention is to provide methods for transmitting an ACK / NACK signal and determining ACK / NACK in uplink packet transmission, which are capable of providing efficient ACK / NACK signal transmission and reliable determination of ACK / NACK.

Additional advantages, objects and features of the invention are set forth in part in the following description, and in part will become apparent to those skilled in the art after analyzing the subsequent material, or they can be learned from the results of the practical implementation of the invention. The objectives and advantages of the invention can be realized and achieved by using the structure shown in detail in the description and claims, as well as in the accompanying drawings.

To solve these problems and achieve other advantages according to the purpose of the invention, a method for confirming reception of data on an uplink in a wireless communication system comprises the steps of transmitting packet data from user equipment to at least one of the networks: a serving network or a non-serving network through a dedicated channel ; receiving a first acknowledgment status indicator from the serving network in response to decoding packet data by the serving network, wherein the first acknowledgment status indicator is transmitted using modulation based on phase shift keying; and receiving a second acknowledgment status indicator from the non-serving network in response to decoding packet data by the non-serving network, the second confirmation status indicator being transmitted using modulation based on amplitude manipulation. Preferably, the dedicated channel is an enhanced uplink dedicated channel.

According to one aspect of the invention, the first confirmation status indicator comprises a confirmation indicator if the packet data is decoded without error, and a negative confirmation indicator if the packet data is decoded with error. The second confirmation status indicator contains a confirmation indicator if the packet data is decoded without error, and no signal is received if the packet data is decoded with error. Preferably, the confirmation indicator comprises a signal with a positive amplitude.

According to another aspect of the invention, phase-shift modulation based modulation comprises on-off phase shift key modulation. In addition, modulation based on amplitude manipulation comprises modulation based on on-off manipulation.

According to another aspect of the invention, the user equipment is in communication with a non-serving network during a soft handoff.

According to another embodiment of the invention, a method for acknowledging reception of uplink data by a network comprises the steps of receiving packet data from user equipment through a dedicated channel; decode packet data; transmitting a first acknowledgment status indicator in response to decoding packet data, the first acknowledgment status indicator being transmitted using phase-shift modulation if the network is a serving network for said user equipment; and transmitting a second acknowledgment status indicator in response to decoding the packet data, the second acknowledgment status indicator being transmitted using modulation based on amplitude manipulation if the network is a non-serving network for said user equipment.

According to another embodiment, a mobile terminal for transmitting data on an uplink in a wireless communication system comprises means for transmitting packet data to at least one of the networks: a serving network or a non-serving network via a dedicated channel; means for receiving a first acknowledgment status indicator from the serving network in response to decoding packet data by the serving network, wherein the first acknowledgment status indicator is transmitted using modulation based on phase shift keying; and means for receiving a second confirmation status indicator from a non-serving network in response to decoding packet data by a non-serving network, the second confirmation status indicator being transmitted using modulation based on amplitude manipulation.

According to a further embodiment, a network, such as a Node B, for acknowledging reception of data on an uplink, comprises means for receiving packet data from user equipment through a dedicated channel; means for decoding packet data; means for transmitting a first acknowledgment status indicator in response to decoding packet data, the first acknowledgment status indicator being transmitted using modulation based on phase shift keying if the network is a serving network for said user equipment; and means for transmitting a second acknowledgment status indicator in response to decoding the packet data, the second acknowledgment status indicator being transmitted using modulation based on amplitude manipulation if the network is a non-serving network for said user equipment.

It should be understood that the previous general description and the following detailed description of the present invention are illustrative and are provided for the purpose of further clarifying the claimed invention.

Brief Description of the Drawings

The accompanying drawings, included to provide an additional understanding of the invention, are an integral part of this invention and illustrate a variant (s) of the invention and together with its description serve to explain the principles of the invention. In the drawings:

1 is a diagram explaining a method for distributing ACK / NACK signal transmit power according to a first embodiment of the present invention;

FIG. 2 is a diagram explaining a method for allocating ACK / NACK signal transmit power according to a second embodiment of the present invention; FIG.

figure 3 - wireless communication system in which the present invention is implemented.

Best Mode for Carrying Out the Invention

Turning now to the details of preferred embodiments of the present invention, examples of which are shown in the accompanying drawings. Wherever possible, the same reference numbers in all drawings are used to refer to the same or similar parts.

According to the latest requirement for improved uplinks in wireless mobile communication systems, there is a need for a system for high speed uplink packets from a mobile terminal (also known as user equipment) to node B. Dedicated channel for enhanced uplink (E-DCH) ) was created with this in mind.

The user equipment transmits at high speed a packet to the Node B via the E-DCH. The Node B decodes the received packet and determines based on the decoding result whether the packet reception was successful or unsuccessful. Based on the result of this determination, node B transmits a physical layer acknowledgment / negative acknowledgment (ACK / NACK) signal. Thus, a high speed automatic repeat request (ARQ) operation is implemented.

In some systems, the required reception quality of the ACK and NACK signals may differ from each other. Accordingly, when the ACK and NACK signals are transmitted through the ACK / NACK channel, it may be necessary to set the transmit power for the ACK signal and the transmit power for the NACK signal at different levels.

In some cases, it may be effective to detect only ACK signals using a threshold. In this case, the transmit power for NACK signals is set to OFF (intermittent transmission (intermittent transmission) (DTX)). In other words, the NACK signal is not transmitted. Therefore, according to the present invention, the ACK / NACK signal transmit power parameters are determined to enable the setting of different transmit power levels for the ACK and NACK signals transmitted from the Node B, and to allow the transmission of NACK signals intermittently. This method is also known as modulation based on on-off manipulation or amplitude manipulation. Alternatively, the transmit power levels of the ACK and NACK signals may differ from each other. In the general case, more serious problems may arise when there is an error in the NACK signal compared to the case when the error is in the ACK signal. For this reason, a higher transmit power is required to transmit the NACK signal. If the ACK and NACK signals are transmitted using the same transmit power, the NACK signal is transmitted with an insufficient transmit power level, and the ACK signal is transmitted with an excessive transmit power level. This can cause a number of problems.

Accordingly, if the transmit power levels for transmitting the ACK signal and transmitting the NACK signal are set different, then it is possible to provide more efficient transmission of the ACK and NACK signals.

1 is a diagram illustrating an ACK / NACK signal transmit power distribution method according to a first embodiment of the present invention. Referring to FIG. 1, where ACK and NACK signals, respectively, different transmit power levels are used, which makes it possible to transmit ACK and NACK signals using on-off phase shift keying (BPSK). Preferably, BPSK-based modulation for transmitting the ACK / NACK signal is used in the absence of a handover (for example, the UE is in communication with only one serving Node B). For the purpose of explaining the present invention, node B may also be called a network.

Preferably, the UE can determine the reception of the ACK signal when the signal transmitted through the downlink ACK / NACK and received by the UE has a positive (+) voltage level, and the reception of the NACK signal when the received signal has a negative (-) level voltage, as shown in figure 1.

According to a first embodiment of the present invention, transmit power of dedicated downlink channels for UEs of different users can be set using offset values for transmit power of dedicated physical channels for transmitting data (DPDCH) on a downlink. Accordingly, the transmit powers for the downlink ACK / NACK signals can be set using offset values for the transmit power of the downlink DPDCHs.

Preferably, the transmit powers of the ACK and NACK signals can be set at different levels (e.g., phase shifted) by determining the transmit power levels for the ACK and NACK signals between the radio network controller (RNC) and the Node B, respectively. For example, assuming that the “PO _ACK ” parameter represents the power offset for the downlink DPDCH when transmitting the ACK signal, and the “PO _NACK ” parameter represents the power offset for the downlink DPDCH when transmitting the NACK signal, you can control the transmission powers for ACK and NACK signals, so that they have different levels, by sending the specified parameters from the RNC to node B. For example, when the NACK signal requires intermittent transmission (DTX), this is achieved by setting the “PO _NACK ” parameter to “0 "(" PO _NACK "= 0) .

Preferably, the specified parameters are also sent to the user equipment UEs to enable each UE to select the desired parameter based on the detection of the BKSP and the threshold detection for the ACK and NACK signals received by the UE, and to select a suitable threshold value in case of detection of a threshold.

For UEs that are in handover mode, preferred in soft handoff mode, you can enable transmit power control for the NACK signal so that it always has a DTX level. That is, for a UE that is in a handover mode, a downlink ACK / NACK transmit power distribution can be provided so that the transmit power for the ACK signal is set above a predetermined threshold value using the “PO _NACK ” parameter, that is, provide the power offset for the downlink DPDCH when transmitting the ACK signal, and the transmit power for the NACK signal was set to “0” (off). Preferably, a “PO _NACK ” parameter is also sent to the UE to allow the UE to select an appropriate threshold for receiving ACK / NACK signals.

2 is a diagram illustrating an ACK / NACK signal transmission power allocation method according to another embodiment of the present invention.

If the condition of the downlink ACK / NACK channel through which the Node B transmits the ACK / NACK signal worsens, the transmit power for the ACK / NACK signal may not be sufficient. Accordingly, in ensuring successful transmission of the NACK signal and successful transmission of the ACK signal, preference should be given to the NACK signal.

To give preference to the successful transmission of the NACK signal, the distribution of signal transmission power can be performed according to the method shown in FIG. That is, using the transmit power of a given level, provided that the transmit power for the NACK signal is OFF (DTX), only the ACK signal can be transmitted.

Transmitting an ACK signal using a predetermined amplitude and intermittently transmitting a NACK signal are known as amplitude modulation modulation. Preferably, the UE can detect the ACK signal using a threshold. That is, the UE determines that an ACK signal is received when the signal transmitted through the downlink ACK / NACK and received by the UE has a voltage level exceeding a predetermined threshold value, and determines that the NACK signal is received when the received signal has a level voltage not exceeding a predetermined threshold value.

If the threshold value for determining ACK / NACK is set high enough on the equipment side of the UE, it is possible to provide the desired probability of successful transmission of NACK signals even when the transmit power of the ACK signal is insufficient.

The following describes a method for efficiently setting transmission powers for ACK / NACK signals according to a second embodiment of the present invention.

In a second embodiment, amplitude modulation based modulation is applied, preferably during soft handoff. In other words, the UE is in communication with one serving cell, as well as at least one non-serving cell.

In a second embodiment, the RNC informs the Node B whether the transmit power for the NACK signal should be OFF (DTX), taking into account whether the corresponding UE is in soft handoff, and other conditions associated with the transmission of ACK signals and NACK. For example, the physical layers of node B can transmit a NACK signal using the transmit power of the NACK signal set to “0” (for example, using a signal called “NAC_PW_OFF”) when the parameter received from the upper level is 1 and using power transmitting the NACK signal determined by the RNC when the received parameter is 0. Preferably, information about the transmit power levels for the ACK / NACK signals is sent from the RNC to node B.

When in the above example, the transmit power of the NACK signal has a level other than “0”, then to set the transmit powers for the ACK and NACK signals, you can use a single parameter for the transmit power level determined by the RNC so that they have the same level for easy implementation the above transmission power setting. The indicated parameter may be “PO _{ACK / NACK} ”, which is an offset value for the transmit power of the downlink DPDCH for transmitting ACK / NACK signals. Preferably, the “PO _{ACK / NACK} ” parameter is also necessarily sent to the UE to allow the UE to select a suitable threshold value for receiving ACK / NACK signals.

The transmit powers for the ACK and NACK signals can be set independently using two independent parameters, respectively, to enable Node B to use the power more efficiently. The transmit power for the ACK signal is preferably set using a power offset for the downlink DPDCH when transmitting the ACK signal, namely “PO _ACK ”, while the transmit power for the NACK signal can be set using the power offset for the downlink DPDCH when transmitting a NACK signal, such as “PO _NACK ”. In this case, the “PO _ACK ” value must also be sent to the UE to allow the UE to select a suitable threshold value for receiving ACK / NACK signals.

Figure 3 shows a wireless communication system that implements the present invention. As shown here, the mobile terminal, or user equipment (UE) 2, is connected to the core network (CN) 4 through the UMTS terrestrial radio access network (UTRAN) 6. The UTRAN 6 configures, supports, and manages the radio access channel to provide communication between the UE 2 and core network.

UTRAN 6 includes many radio network subsystems (RNS) 8, each of which contains one radio network controller (RNC) 10 for multiple base stations or nodes B 12. The RNC 10 connected to this base station 12 is an RNC control controller for distribution and management of shared resources provided for a number of UE 2 operating in one cell. In one node, there is one or more cells. The RNC 10 control controller manages the traffic load, monitors the cell congestion and organizes the receipt of new radio links. Each Node B 12 may receive an uplink signal from UE 2 equipment and may transmit downlink signals to UE 2. Each Node B 12 serves as an access point enabling UE 2 equipment to connect to UTRAN 6, while how the RNC 10 serves as an access point for connecting the respective nodes B to the core network 4.

From the above description, it is obvious that the present invention can optimize the transmit power for downlink ACK / NACK signals in accordance with the desired reception quality of each of the ACK / NACK signals and, therefore, allows the system to operate efficiently.

It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention covers these modifications and variations provided that they come within the scope of the appended claims and their equivalents.

Industrial applicability

The present invention can be used in a broadband wireless access system.

Claims (6)

1. A method for confirming reception of data on the uplink in a user equipment (UE) in a wireless communication system, the method comprising transmitting packet data to a serving node B and at least one non-serving node B through a dedicated channel; receiving a first acknowledgment status indicator from the serving node B in response to decoding packet data by the serving node B, the first acknowledgment status indicator being a positive value if the packet data is decoded without error, and the first acknowledgment status indicator is a negative value if the packet data is decoded with a mistake; and receiving a second confirmation state indicator from at least one non-serving node B in response to decoding packet data by a non-contracting node B, the second confirmation state indicator being a positive value if the packet data is decoded without error, and the second confirmation state indicator is zero if packet data decoded in error. 2. The method of claim 1, wherein the dedicated channel is an enhanced uplink dedicated channel. 3. A method of confirming the reception of uplink data through a network in a wireless communication system, which consists in receiving packet data from user equipment through a dedicated channel; decode packet data; transmitting the first acknowledgment status indicator in response to decoding the packet data from the serving node B to the user equipment, the first acknowledgment status indicator being a positive value if the packet data is decoded without error, and the first acknowledgment status indicator is a negative value if the packet data is decoded with an error ; and transmitting a second confirmation status indicator in response to decoding the packet data from non-serving node B to the user equipment, the second confirmation status indicator being a positive value if the packet data is decoded without error and the second confirmation status indicator is zero if the packet data is decoded with error . 4. The method of claim 3, wherein the dedicated channel is an enhanced uplink dedicated channel. 5. A mobile terminal for uplink communication in a wireless communication system, comprising: means for transmitting packet data to a serving node B and at least one non-serving node B through a dedicated channel; means for receiving a first confirmation status indicator from the serving node B in response to decoding packet data by the serving node B, the first confirmation status indicator being a positive value if the packet data is decoded without error and the first confirmation status indicator is a negative value if the packet data decoded in error; and means for receiving a second confirmation status indicator from a non-serving node B in response to decoding packet data by a non-contracting node B, wherein the second confirmation status indicator is a positive value if the packet data is decoded without error and the second confirmation status indicator is zero if the packet data decoded in error. 6. The mobile terminal of claim 5, wherein the dedicated channel is an enhanced uplink dedicated channel.

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