METHOD FOR DETECTING RADIO LINK FAILURE FOR TRANSMISSION OVER ENHANCED DEDICATED CHANNEL IN A CELL_FACH STATE
A method and apparatus are used for detecting a radio link (RL) failure and a post verification process. A quality of a downlink fractional dedicated physical channel (F-DPCH) is monitored once a transmission on an enhanced dedicated channel (E-DCH) has begun. It is determined whether the quality of the downlink F-DPCH is below a predefined threshold. If the quality is below the predefined threshold, then an occurrence of an RL failure is declared and a transmission over the E-DCH in a cell forward access channel (CELL_FACH) state is terminated. In a case of the post verification failure, E-DCH resources are released.
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This application is a continuation of U.S. patent application Ser. No. 12/259,691 filed on Oct. 28, 2008, which claims the benefit of U.S. provisional application No. 60/983,406 filed on Oct. 29, 2007, and 61/047,909 filed on Apr. 25, 2008, the contents of which are incorporated by reference as if fully set forth herein.
FIELD OF INVENTIONThis application is related to wireless communications.
BACKGROUNDAs part of ongoing evolution of the Wideband Code Division Multiple Access (WCDMA) standard in Release 8 of the Third Generation Partnership Project (3GPP) standard, a new work item was established to incorporate an enhanced dedicated channel (E-DCH) for wireless transmit receive units (WTRUs) in a CELL_FACH state.
In the CELL_DCH state, a dedicated physical channel is allocated to the WTRU in the UL and the downlink (DL). The WTRU is known on a cell level according to its current active set. The WTRU may use dedicated transport channels, shared transport channels, or a combination of these transport channels.
A WTRU is in the CELL_FACH state if it has been assigned to use the common channels (e.g., forward access channel (FACH), random access channel (RACH)). In the CELL_FACH state, no dedicated physical channel is allocated to the WTRU, and the WTRU continuously monitors a forward access channel (FACH) (e.g., carried over the secondary common control physical channel (S-CCPCH)) or a high speed downlink shared channel (HS-DSCH) in the DL. The WTRU is assigned a default common or shared transport channel in the UL (e.g., random access channel (RACH)) that it may use anytime according to the access procedure for that transport channel. The position of the WTRU is known by the UTRAN on a cell level according to the cell where the WTRU last performed a cell update.
In the CELL_PCH state, no dedicated physical channel is allocated to the WTRU. The WTRU selects a PCH, and uses discontinuous reception for monitoring the selected PCH via an associated page indicator channel (PICH). No UL activity is possible. The position of the WTRU is known by the UTRAN on a cell level according to the cell where the WTRU last performed a cell update in the CELL_FACH state.
In the URA_PCH state, no dedicated channel is allocated to the WTRU. The WTRU selects a PCH, and uses discontinuous reception for monitoring the selected PCH via an associated PICH. No UL activity is possible. The location of the WTRU is known on a UTRAN registration area level according to the URA assigned to the WTRU during the last URA update in the CELL_FACH state.
The RACH transport mechanism is based on a slotted-Aloha approach with an acquisition indication. Before transmitting a message, a WTRU acquires the channel by transmitting a short preamble that is made up of a randomly selected signature sequence in a randomly selected access slot. The WTRU then listens and waits for an acquisition indication from a Node-B on the acquisition indication channel (AICH). The indication includes a specific AICH signature sequence mapped one-to-one to the preamble signature sequence chosen by the WTRU. If a positive acquisition indication is received, the WTRU has effectively acquired the channel, and may transmit its message. The resources that the WTRU may use in the RACH systems are predetermined by the choice of the preamble signature sequence.
CELL_FACH may be used to increase the data rate for CELL_FACH WTRUs in a new enhanced RACH (E-RACH). The WTRU may transmit via the E-DCH for a longer duration than is possible using the Release 99 RACH (i.e., 10 ms or 20 ms durations).
Transmission over E-DCH requires dedicated radio control channels to be established. In pre-Release 8 systems, when moving from the CELL_FACH state to the CELL_DCH state, a synchronization procedure is executed whereby the transmit power of the Node-B and the WTRU are set to the appropriate level. This synchronization procedure A, defined in the 3GPP standards, is designed to accommodate long connection time. The procedure consists of two phases. During the first phase, only in-sync primitives may be reported from the physical layer to the Layer 3 (L3) of the WTRU. An in-sync primitive is reported if the quality of the DL radio link (RL) (i.e., fractional dedicated physical channel (F-DPCH) or dedicated physical control channel (DPCCH)) during the previous 40 ms is above a predefined threshold. Primitives are reported every 10 ms frames. The physical channel is considered established when N312 consecutive in-sync are reported in a duration period of T312, where both N312 and T312 may be configured by the UTRAN. When the physical channel is established, the WTRU may start an UL transmission. Phase 2 begins 160 ms after the physical channel is established, at which point both in-sync and out-of-sync primitives may be reported to the L3 of the WTRU.
In the case of an E-DCH transmission in the CELL_FACH state, another synchronization procedure (e.g., synchronization procedure AA) which makes use of the post-verification period is provided. The post-verification period is a 40 ms time period wherein the DL signal quality is confirmed. During the post-verification procedure, the WTRU may transmit data on the UL immediately. While transmitting, the WTRU monitors the quality of the transmission power control (TPC) field of the F-DPCH. If after the first 40 ms the quality of the TPC field of the F-DPCH is better than a threshold Qin, then the post-verification is successful, otherwise it has failed.
When the post-verification period fails for a WTRU in or moving to CELL_DCH state, the WTRU's behavior of the synchronization procedure is defined in the 3GPP standard. However, the WTRU's behavior is not defined for the proposed synchronization procedure for the WTRU when it is operating in the CELL_FACH state.
Current specifications for the RL establishment and power control are defined for dedicated RL resources that are reserved for long periods of time to a particular WTRU. However, they are not well suited for situations where the WTRU occupies the channel for short periods of time, (e.g., for burst traffic), followed by a release of the radio resources.
In the current 3GPP standard, RL failure is only triggered when the WTRU is in the CELL_DCH state. The WTRU's behavior after the RL failure includes transitioning to the CELL_FACH state, performing cell reselection and initiating a cell update procedure. However, procedures are desired for triggering an RL failure for a WTRU that is in the CELL_FACH state.
SUMMARYA method and apparatus are used for detecting an RL failure and a post verification process. A quality of a downlink F-DPCH is monitored once a transmission on an E-DCH has begun. It is determined whether the quality of the downlink F-DPCH is below a predefined threshold. If the quality is below the predefined threshold, then an occurrence of an RL failure is indicated and a transmission over the E-DCH in the CELL_FACH state is terminated. In a case of the post verification failure, E-DCH resources are released.
A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein:
When referred to hereafter, the terminology “wireless transmit/receive unit (WTRU)” includes but is not limited to a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a computer, or any other type of user device capable of operating in a wireless environment. When referred to hereafter, the terminology “base station” includes but is not limited to a Node-B, a site controller, an access point (AP), or any other type of interfacing device capable of operating in a wireless environment.
When referred to hereafter, the term E-DCH may be used to indicate transmission over the E-DCH following a contention based access in the CELL_FACH state, the CELL_PCH state, the URA_PCH state, or IDLE mode. The term E-DCH in CELL_FACH state may indicate E-DCH in CELL_PCH state, URA_PCH state, and/or IDLE mode. The methods disclosed herein are also applicable to any other improvement to the existing contention based access (i.e., RACH) where the WTRU occupies the channel for longer durations.
In addition to the components that may be found in a typical WTRU, the WTRU 210 includes a processor 215, a receiver 216, a transmitter 217, and an antenna 218. The processor 215 is configured to perform a method for detecting the occurrence of an RL failure when a WTRU transmits over the E-DCH in the CELL_FACH state. The receiver 216 and the transmitter 217 are in communication with the processor 215. The antenna 218 is in communication with both the receiver 216 and the transmitter 217 to facilitate the transmission and reception of wireless data.
In addition to the components that may be found in a typical base station, the Node-B 220 includes a processor 225, a receiver 226, a transmitter 227, and an antenna 228. The processor 225 is configured to perform a method for detecting the occurrence of an RL failure when a WTRU transmits over the E-DCH in the CELL_FACH state. The receiver 226 and the transmitter 227 are in communication with the processor 225. The antenna 228 is in communication with both the receiver 226 and the transmitter 227 to facilitate the transmission and reception of wireless data.
Alternatively, the WTRU 210 may perform the cell update procedure indicating a cell reselection, an RL failure, or a new action indicating a failure during the E-DCH in the CELL_FACH state. Optionally, the WTRU 210 may be configured to indicate transmission failure to higher layers.
Releasing the E-DCH resources or terminating the E-DCH access in the CELL_FACH state or idle mode may comprise of the following. The PHY layer may report to the MAC that the PHY layer procedure has failed and ended, at which point the MAC layer stops transmitting the data to the physical layer. The E-DCH reception (E-DCH Access Grant Channel (E-AGCH), E-DCH Hybrid Automatic Repeat Request (HARQ) Indicator Channel (E-HICH), E-DCH Relative Grant Channel (E-RGCH)) and the transmission (E-DPCCH, E-DCH Dedicated Physical Data Channel (E-DPDCH)) procedures are stopped. The MAC-i/is entity is reset. Resetting the MAC-i/is entity includes flushing HARQ processes, setting transmission sequence number (TSN) to initial value and discarding any remaining segments in the segmentation buffer. Alternatively, the WTRU 210 may flush the HARQ processes only or flushes the HARQ processes and resets the TSN values instead of performing a full MAC-i/is reset. Optionally, the WTRU 210 may clear the E-DCH radio network temporary identity (E-RNTI), HS-DSCH RNTI (H-RNTI), or cell RNTI (C-RNTI).
Alternatively, when the RL failure has occurred, the WTRU 210 may flush the HARQ processes; reset the TSN; and perform the cell update procedure with an action indicating cell reselection, RL failure, or any action indicating a failure during the E-DCH in the CELL_FACH state.
Alternatively, the WTRU 210 may reattempt the transmission via the E-DCH up to predefined K times, and then trigger a cell reselection procedure.
Alternatively, if the WTRU 210 had attempted the transmission using a shortened transmission time interval (TTI) value (e.g., 2 ms), the WTRU 210 may reattempt transmission via the E-DCH using a larger TTI value (e.g., 10 ms).
Alternatively, if the WTRU 210 had attempted the transmission via the E-DCH using a large TTI value (e.g., 10 ms), the WTRU 210 may attempt transmission over the RACH.
Alternatively, the quality of the associated DL DPCCH may be monitored. If the quality of the DPCCH is below a predefined threshold for N frames, it is determined that an RL failure has occurred, where N is a predefined number of consecutive frames.
The L1 may also be configured to report to the L3 declaring the RL failure, if the quality of the F-DPCH or the DPCCH is below a predefined threshold, QF-DPCH, for the N out of M consecutive frames.
Alternatively, the WTRU 210 may be configured to monitor the quality of a common pilot channel (CPICH). If the quality of the CPICH or any other DL control channel is below a predefined threshold for the N frames, the WTRU's 210 L1 reports RL failure to the L3 of the WTRU 210.
Alternatively, the WTRU 210 may be configured to monitor the reception of a positive acknowledgment (ACK) or a negative acknowledgment (NACK) from the Node-B 220 for its UL transmissions. If the WTRU 210 receives K NACKs within a window of predefined successive UL transmission L, wherein K and L are preconfigured or signaled to the WTRU 210, the L1 at the WTRU 210 reports to L3 at the WTRU 210 indicating that an RL failure has occurred.
Alternatively, the WTRU 210 may be configured to monitor success of hybrid automatic retransmit request (HARQ) processes. If R HARQ processes fail within a window of J new HARQ process, the WTRU 210 may be configured to declare an RL failure, where R and J are parameters that may be preconfigured or signaled to the WTRU 210.
The WTRU 210 maybe configured to receive S successive TPC up commands over the F-DPCH or the DPCCH, where S is preconfigured or signaled to the WTRU 210. If the WTRU 210 is unable to further increase its transmission power because the maximum power has been reached, the WTRU 210 may declare an RL failure.
Alternatively, RL failure may be declared when the WTRU 210 transmits the S successive TPC up commands over the UL DPCCH to request that the Node-B 220 increase its DL transmission power, without observing an increase in received power on the DL control channels.
In a limited UL transmission, the WTRU 210 may be configured to use the E-DCH to ping the Node-B 220 and the WTRU 210 verifies the Node-B 220 in either AICH or F-DPCH, then the WTRU 210 reports an RL failure. The ping transmission is setup so that the ping transmission occurs when there have been no UL transmission in over a period Tping.
Alternatively, if the WTRU 210 does not receive signal from the Node-B 220 on designated slots over M period, then the WTRU 210 reports RL failure.
Alternatively, the WTRU 210 may be configured to monitor the RL quality while it is not transmitting via the E-DCH in the CELL_FACH state. Specifically, the WTRU 210 in the CELL_FACH state, the CELL_PCH state, or the URA_PCH state may continuously monitor the quality of any other DL control channel (e.g., CPICH). If the quality of an observed DL control channel falls below a predefined threshold for a predefined time, the WTRU's 210 L1 may signal the WTRU's 210 L3 indicating that an RL failure has occurred.
Alternatively, the Node-B 220 may be configured to monitor the E-DCH for feedback from the WTRU 210 over a predetermined window period, P 910. If the quality of associate control channels (e.g., UL DPCCH, UL E-DPCCH, or UL HS-DPCCH) is below a predetermined threshold for a predefined time 915, the Node-B 220 declares an RL failure.
Alternatively, the Node-B 220 may monitor the transmission of an ACK or NACK feedback signals for the associated UL transmissions. When the Node-B 220 transmits KNACKS within a window of predetermined successive UL transmissions, L, the Node-B 220 may declare an RL failure.
Alternatively, the Node-B 220 may monitor success of HARQ processes. The Node-B 220 is configured to monitor the HARQ processes, and if R HARQ processes fail within a window of a predefined number of new HARQ process attempts, J, the Node-B 220 may declare an RL failure.
Alternatively, the Node-B 220 may be configured to transmit S successive TPC up commands over the F-DPCH or the DPCCH (i.e., indication from Node-B 220 to increase its power) to the WTRU 210 using the E-DCH in the CELL_FACH state. If the Node-B 220 transmits the commands without observing an increase in received power from the WTRU 210 to which the commands are sent, the Node-B 220 may declare an RL failure.
Alternatively, the Node-B 220 may be configured to receive the STPC up commands over the UL DPCCH, F-DPCH or DPCCH (i.e., indication from the WTRU 210 to increase its power), and if the Node-B 220 is unable to further increase its transmission power, the Node-B 220 may declare an RL failure.
Alternatively, the Node-B 220 is configured to indicate to the WTRU 210 to release the E-DCH resources via a high speed shared control channel (HS-SCCH) order. The Node-B 220 may transmit and the HS-SCCH order may be a command transmitted via the HS-SCCH control channel.
Alternatively, new or existing L3 RRC messages may be used to indicate to the WTRU 210 that it may stop transmission via the E-DCH in the CELL_FACH state. Alternatively, the Node-B 220 may be configured to not respond to any UL transmission over a timeout period. Alternatively, the Node-B 220 may be configured to transmit K successive NACKs over the E-DCH HARQ indicator channel (E-HICH) to the WTRU 210.
Although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements. The methods or flow charts provided herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs).
Suitable processors include, by way of example, a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a state machine.
A processor in association with software may be used to implement a radio frequency transceiver for use in a wireless transmit receive unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a videophone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, a Bluetooth® module, a frequency modulated (FM) radio unit, a liquid crystal display (LCD) display unit, an organic light-emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB) module.
Claims
1-26. (canceled)
27. A wireless transmit receive unit (WTRU), the WTRU comprising:
- a processor configured to:
- determine a quality of a downlink channel when operating in a cell forward access channel (CELL_FACH) state;
- determine that a RL failure has occurred based on the quality of the downlink channel being below a predefined threshold over a predetermined period of time;
- release an enhanced dedicated channel (E-DCH) resource; and
- reset a medium access control (MAC) entity.
28. The WTRU of claim 27, wherein the downlink channel comprises a fractional dedicated physical channel (F-DPCH).
29. The WTRU of claim 27, wherein the downlink channel comprises an E-DCH physical control channel (DPCCH).
30. The WTRU of claim 27, wherein the E-DCH comprises an E-DCH dedicated physical control channel (E-DPCCH).
31. The WTRU of claim 27, wherein the E-DCH comprises an E-DCH dedicated physical data channel (E-DPDCH).
32. The WTRU of claim 27, wherein a physical layer indicates to a MAC layer that the RL failure has occurred and the MAC layer stops sending data to the physical layer.
33. The WTRU of claim 27, wherein the processor is configured to stop a transmission associated with an enhanced dedicated channel (E-DCH).
34. The WTRU of claim 33, wherein the processor is further configured to, after stopping the transmission associated with the enhanced dedicated channel (E-DCH):
- wait a predefined amount of time,
- start a backoff timer; and
- wait for the backoff timer to expire prior to initiating another RACH access.
35. The WTRU of claim 34, wherein the processor is further configured to terminate the backoff timer and perform a cell reselection procedure upon the cell reselection being met.
36. A method implemented in a wireless transmit receive unit (WTRU) for detecting a radio link (RL) failure in cell forward access channel (CELL_FACH) state, the method comprising:
- determining a quality of a downlink channel when operating in in cell forward access channel (CELL_FACH) state;
- determining that a RL failure has occurred based on the quality of the downlink channel being below a predefined threshold over a predetermined period of time;
- releasing an enhanced dedicated channel (E-DCH) resource; and
- resetting a medium access control (MAC) entity.
37. The method of claim 36, wherein the downlink channel comprises a fractional dedicated physical channel (F-DPCH).
38. The method of claim 36, wherein the downlink channel comprises an E-DCH physical control channel (DPCCH).
39. The method of claim 36, wherein the E-DCH comprises an E-DCH dedicated physical control channel (E-DPCCH).
40. The method of claim 36, wherein the E-DCH comprises an E-DCH dedicated physical data channel (E-DPDCH).
41. The method of claim 36, wherein a physical layer indicates to a MAC layer that the RL failure has occurred and the MAC layer stops sending data to the physical layer.
42. The method of claim 36, further comprising stopping a transmission associated with an enhanced dedicated channel (E-DCH).
43. The method of claim 36, further comprising, after stopping the transmission associated with the enhanced dedicated channel (E-DCH):
- waiting a predefined amount of time;
- starting a backoff timer, and
- waiting for the backoff timer to expire prior to initiating another RACH access.
44. The method of claim 43, further comprising terminating the backoff timer and performing a cell reselection procedure upon the cell reselection being met.
Type: Application
Filed: Aug 2, 2017
Publication Date: Nov 16, 2017
Applicant: InterDigital Patent Holdings, Inc (Wilmington, DE)
Inventors: Christopher R. Cave (Dollard-des-Ormeaux), In H. Kim (Norristown, PA), Benoit Pelletier (Roxboro), Paul Marinier (Brossard), Diana Pani (Montreal)
Application Number: 15/666,639