Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J3/00—Time-division multiplex systems
  • H04J3/16—Time-division multiplex systems in which the time allocation to individual channels within a transmission cycle is variable, e.g. to accommodate varying complexity of signals, to vary number of channels transmitted
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
  • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
  • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
  • H04L1/1812—Hybrid protocols; Hybrid automatic repeat request [HARQ]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
  • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
  • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
  • H04L1/1867—Arrangements specially adapted for the transmitter end
  • H04L1/1887—Scheduling and prioritising arrangements
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W28/00—Network traffic management; Network resource management
  • H04W28/02—Traffic management, e.g. flow control or congestion control
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W80/00—Wireless network protocols or protocol adaptations to wireless operation
  • H04W80/02—Data link layer protocols

Definitions

• the invention is related to the 3 rd Generation Partnership Project (3GPP) radio access network (RAN) standards, high speed uplink packet access (HSUPA) and high speed downlink packet access (HSDPA), and 3GPP Core Network and Speech Codecs and, more particularly, to a system and methods for slow medium access control entity (MAC-e) for autonomous transmission during HSUPA, an for service specific transmission time control in HUSPA.
• 3GPP 3rd Generation Partnership Project
• RAN radio access network
• HSUPA high speed uplink packet access
• HSDPA high speed downlink packet access
• MAC-e slow medium access control entity
• the Third Generation Partnership Project (3 GPP) Technical Specification (TS) 25.309, "Frequency Division Duplex (FDD) Enhanced Uplink; Overall description; Stage 2 TS” has established that some level of enhanced dedicated channel (E-DCH) minimum set support is required to provide backward system compatibility.
• E-DCH enhanced dedicated channel
• a minimum set autonomous transmission of data packets can occur in an uplink signal without prior allocation of resources by a base station (i.e., Node B) scheduler.
• the minimum set defines a set of transport formats (TFs) for which a valid scheduling grant is not required in order for packets to be transmitted, hi normal conditions, the Node B allocates a share of an uplink resource to the UE via a scheduling grant. Only after this allocation of resources occurs is it possible for the UE to transmit packets in the uplink signal.
• the defined minimum set always guarantees a minimum bit rate, which is typically used for signaling purposes.
• the possibility for non- scheduled UEs to autonomously transmit a set of TFs has implications on Node B processing resources, because Node Bs must be continuously ready to process transmissions made from all such UEs, irrespective of the number of UEs that actually perform an autonomous transmission.
• the ability of the Node Bs to optimize the use of available Node B processing resources via scheduling becomes limited. Consequently, the complexity of the Node B for processing a given number of TFs may become increased.
• the potential for a number of UEs to perform unscheduled autonomous transmissions may require the reservation of a "Rise over Thermal" (RoT) margin for these UEs.
• the worst case combined data rate in the cell due to autonomous transmission is n * 45 kb/sec for a fixed total number of retransmissions of 4.
• an assumption is made that the 45 kb/sec rate is achieved by transmitting at 180 kb/sec four times, at a reduced power level.
• the required RoT margin may become significant, which would then degrade the performance of the scheduled transmissions.
• the RiO41069 specification "Signaling Radio Bearer (SRB) Mapping, E-
• DCH Minimum Set and Node B Complexity Issues developed by Motorola, Inc., includes proposed solutions to the foregoing problems, such as restricting the scenarios in which the minimum set applies to cases where, for example, there is no dedicated physical data channel (DPDCH).
• DPDCH dedicated physical data channel
• TDM Automatic Transmission with Time Division Multiplex
• E-DCH enhanced dedicated channels
• a grant is required, i.e., a non-scheduled grant is required for non-scheduled medium access control dedicated (MAC-d) flows and a serving grant is required for a scheduled transmission.
• MAC-d medium access control dedicated
• the Node B controls when the UE is allowed to transmit packets and the maximum enhanced dedicated physical data channel (E- DPDCH) to dedicated physical control channel (DPCCH) power ratio that the UE is allowed to use for scheduled data in the following transmission.
• E- DPDCH maximum enhanced dedicated physical data channel
• DPCCH dedicated physical control channel
• each non-scheduled grant is applicable for the specific set of HARQ processes indicated by radio resource control (RRC), where the RRC can also restrict the set of HARQ processes for which scheduled grants are applicable.
• RRC radio resource control
• the data mapped on non-scheduled MAC-d flows is transmitted as soon as possible by the possible HARQ process restrictions and the possible available power restrictions, with the rate defined by the non-scheduled grant.
• the Universal Telecommunication Radio Access Network is limited in its ability to control the uplink (UL) transmission interval on an E-DCH.
• the UTRAN can select the TTI to be either 2 ms or 10 ms, when 2 ms TTI is supported by the UE.
• the UTRAN can define the permitted processes for scheduled MAC-d flows and non-scheduled MAC-d flows.
• BTS base transceiver station
• the transmission of a low bit rate service over E-DCH introduces the requirement for large control overhead due to several control channels in the uplink (UL) and the downlink (DL), and because the amount of control bits per TTI is the same for all packet sizes.
• an acknowledge/non-acknowledge (ACK/NACK) is transmitted in the DL and the enhanced transport format combination indicator (E- TFCI), in a robust secure network (RSN), and a ⁇ appy bit' is transmitted in the UL. It is possible to reduce the control overhead by transmitting more packets in the same transport block but less often. However, the payload in the TB and the TTI would be increased.
• the UTRAN could increase the transmission interval for specific services (e.g. voice over Internet protocol (VoIP)) in the UTRAN in order to increase transmission capacity.
• VoIP voice over Internet protocol
• the UTRAN should take into account the characteristics of the service, e.g. an assumed or known bit rate, delay requirement, possibly known service data unit (SDU) arrival rates, etc, when defining the transmission interval. For example, according to rules set forth in chapter 5.1.1.
• the present invention relates to enhancing the uplink discrete channel (E-DCH) for packet data traffic during Third Generation Partnership Project (3GPP) High Speed Uplink Packet Access (HSUPA), the 3FPP TR 25.808, specification "frequency division duplex (FDD) Enhanced Uplink; Physical Layer Aspects” and during the 3GPP TS 25.309, “Frequency Division Duplex (FDD) Enhanced Uplink; Overall description; Stage 2".
• E-DCH uplink discrete channel
• HSUPA High Speed Uplink Packet Access
• a control parameter that is independent from an air interface transmission time interval (TTI), hybrid automatic repeat request (HARQ) processes or enhanced dedicated transport channel (E-DCH) scheduling is used.
• TTI air interface transmission time interval
• HARQ hybrid automatic repeat request
• E-DCH enhanced dedicated transport channel
• This control defines the minimum time interval between subsequent new transmissions. The control has no impact on retransmissions, which are performed normally.
• MAC-e PDU For every MAC-e PDU, a check is made to determine whether the transmission is autonomous. If the transmission is not autonomous, a check is continually performed until an autonomous transmission occurs. That is, a continuous loop is performed. If an autonomous transmission is detected, then the exchange rate between the MAC-e and the physical layer (layer one) is slowed down, i.e.
• the exchange rate is decelerated, hi accordance with the present invention, the slow down of the exchange rate between the MAC-e and the physical layer occurs when the MAC-e layer, i.e., the sub-layer of Layer Two sends a MAC-e PDU to the Layer One (i.e., the physical layer).
• the MAC-e PDU is sent to the physical layer every n*TTI, instead of once every transmission time interval (TTI).
• the rate at which the MAC-e sends power distribution units (PDUs) to the physical layer for the transport format (TF(s)) belonging to a minimum set is decelerated so as to reduce the impact of the minimum set over a "Rise over Thermal" (RoT).
• the minimum set defines a set of transport formats (TFs) for which a valid scheduling grant is not required in order for packets to be transmitted.
• a Node B i.e., a base station
• n is selected as a multiple of the number of HARQ processes.
• different HARQ processes can be used based on a different value of n.
• the value of n may be selected by specification, signaled to UEs (i.e., a common value is signaled to the UEs) or UE dependant (i.e., a specific value that is signaled to a specific UE).
• a new control parameter is implemented in either a packet data protocol (PDP) context/radio access bearer (RAB) layer or in the MAC layer.
• PDP packet data protocol
• RAB radio access bearer
• a new PDP context/ quality of signal (QoS) parameter is used.
• the new parameter is a "service data unit (SDU) inter-arrival rate" that establishes the minimum required time interval between consecutive SDUs that are transmitted on a specific RAB.
• the parameter is signaled in different interfaces than the existing PDP context/RAB QoS parameters.
• the application does not deliver SDUs to the MAC layer at a higher rate than the rate specified by the parameter. If the data source produces several packets within this time interval, the packets are grouped into a single SDU. Grouping the packets in the MAC layer provides the ability to obtain the benefits associated with optimizing the packet header overhead, such as more efficiently sharing the uplink power resource between packet data users.
• the new parameter is a "virtual TTI" that defines the minimum time interval between subsequent new transmissions for a MAC-d flow. A first transmission would be permitted only once, during the virtual TTI.
• the virtual TTI could be signaled to the UE by the radio network controller (RNC). The UE could then implement the virtual TTI in the MAC-d layer.
• RNC radio network controller
• FIG. 1 is an exemplary block diagram of a wireless communication system in which the method of the invention is implemented
• FIG. 2 is an exemplary flow chart illustrating the steps of the method of the invention in accordance with an embodiment of the invention
• FIGS. 3 and 4 are exemplary timing diagrams associated with the introduction of a packet data protocol (PDP) context/ radio access bearer (RAB)
• PDP packet data protocol
• RAB radio access bearer
• QoS Quality of Signal
• FIGS. 5 and 6 are exemplary timing diagrams associated with the introduction of a new medium access control (MAC) parameter can be introduced in the medium access control dedicated (MAC-d) layer in accordance with an embodiment of the invention for a 10 ms and 2 ms transmission time interval , respectively; and
• MAC medium access control
• FIG. 7 is an exemplary timing diagram associated with the embodiment of FIG. 5 in accordance with an alternative embodiment of the invention.
• the present invention relates to a system and methods for slow medium access control entity (MAC-e) for autonomous transmission in HSUPA, along with service specific transmission time control, m accordance with the invention, a control parameter that is independent from the air interface transmission time interval (TTI), hybrid automatic repeat request (HARQ) processes or enhanced dedicated transport channel (E-DCH) scheduling is used.
• TTI air interface transmission time interval
• HARQ hybrid automatic repeat request
• E-DCH enhanced dedicated transport channel
• FIG. 1 shows an exemplary network operator 2 having, for example, a mobile switching center (MSC) 3 for connecting to a telecommunications network, such as the Public Switched Telephone Network (PSTN), at least one base station controller (BSC) 4, and a plurality of base transceiver stations (BTS) 5 that transmit in a forward or downlink direction both physical and logical channels to the mobile stations 10 in accordance with a predetermined air interface standard.
• PSTN Public Switched Telephone Network
• BSC base station controller
• BTS base transceiver stations
• the BTSs 5 define cells, which can be different sizes, different frequencies and so forth.
• the air interface standard may conform to a Time Division Multiple Access (TDMA) air interface, and the network may be a Universal Mobile Telecommunications System (UMTS) network or other type of network.
• TDMA Time Division Multiple Access
• UMTS Universal Mobile Telecommunications System
• CDMA Code Division Multiple Access
• the network operator 2 can include a Message Service Center (MSCT) 6 that receives and forwards messages for the MS 10, such as Short Message Service (SMS) messages, or any wireless messaging technique including e-mail and Supplementary Data Services.
• SMS Short Message Service
• enhancements to SMS can be used, such as one under development and known as Multimedia Messaging Service
• MMS multimedia messaging
• image messages video messages, audio messages, text messages, executables and the like, and combinations thereof, can be transferred between a network and a mobile station.
• the mobile station (MS) 10 typically includes a micro-control unit (MCU) 12 having an output coupled to an input of a display 14 and an input coupled to an output of a keyboard or keypad 16.
• the MS 10 may be considered a handheld radiotelephone, such as a cellular, mobile telephone or a personal digital assistant (PDA), and may have a microphone and a speaker (not shown) for conducting voice communications.
• the MS 10 could also be contained within a card or module that is connected during use to another device.
• the MS 10 could be contained within a PCMCIA or similar type of card or module that is installed during use within a portable data processor, such as a laptop or notebook computer, or even a computer that is wearable by the user.
• the MCU 12 is assumed to include or be coupled to some type of a memory 13, including a read-only memory (ROM) for storing an operating program, as well as a random access memory (RAM) for temporarily storing required data, scratchpad memory, received data packets and data packets prepared for transmission, etc.
• ROM read-only memory
• RAM random access memory
• the memory 13 is assumed to store the various parameters that are used by the MS 10 for performing cell reselection.
• a separate, removable SIM can be also be provided, the SIM storing, for example, a preferred Public Land Mobile Network (PLMN) list and other subscriber-related information.
• PLMN Public Land Mobile Network
• the ROM is assumed, for the purposes of this invention, to store a program enabling the MCU 12 to execute the software routines required to operate in accordance with the presently preferred embodiments of the present invention.
• the MS 10 also contains a wireless section that includes a digital signal processor (DSP) 18, or equivalent high speed processor, as well as a wireless transceiver comprised of a transmitter 20 and a receiver 22, both of which are coupled to an antenna 24 for communication with the network operator 2.
• DSP digital signal processor
• the receiver 22 is used for making signal measurements used in the cell reselection process.
• packet schedulers are located in the Radio Network Controller (RNC) (not shown).
• RNC Radio Network Controller
• RRC Radio Resource
• UE user equipment
• the packet scheduler is limited in its ability to adapt to instantaneous traffic changes.
• the packet scheduler must conservatively allocate uplink power to take into account the influence from inactive users during a subsequent scheduling period.
• E-DCH enhanced dedicated channel
• the present invention utilizes the Node B (i.e., the base station) to handle the allocation of uplink resources, i.e.
• the UE selects a transport channel combination (TFC) that is optimal for the amount of data to be transmitted in the radio link control (RLC) buffer of the UE in order to transmit data.
• TFC transport channel combination
• RLC radio link control
• the selection of the TFC is subject to constraints on the maximum transmission power of the UE and the maximum allowed TFC.
• the UE can request a higher bit rate, and the Node B will then decide whether to grant additional resources.
• the Node B may adjust the resources allocated to all UEs based on the current cell load.
• FIG. 2 is an illustration of the steps associated with the method of the present invention.
• a check is made to determine whether the transmission is autonomous, as indicated in step 200. If the transmission is not autonomous, a check is continually performed until an autonomous transmission occurs, that is the method continues in a loop. If an autonomous transmission is detected, then the exchange rate between the MAC-e and the physical layer (layer one) is slowed down, i.e. the exchange rate is decelerated, as indicated in step 210.
• the slow down of the exchange rate between the MAC-e and the physical layer occurs when the MAC-e layer, i.e., the sub-layer of Layer Two as described in the 3GPP IS 25.
• FDD frequency division duplex
• Stage 2 sends a MAC-e PDU to the layer one (i.e., the physical layer), as indicated in step 220.
• the MAC-e PDU is sent to the physical layer every «*TTI, instead of once every transmission time interval (TTI), as indicated in step 230.
• the rate at which the MAC-e sends power distribution units (PDUs) to the physical layer for the transport format (TF(s)) belonging to a minimum set is decelerated so as to reduce the impact of the minimum set over a "Rise over Thermal" (RoT).
• the minimum set defines a set of transport formats (TFs) for which a valid scheduling grant is not required in order for packets to be transmitted.
• the Node B allocates a share of an uplink resource to the UE via a scheduling grant. From the perspective of layer one, the method of the invention is transparent, i.e., it appears that packets are only sent occasionally (e.g. once in a while).
• HARQ hybrid automatic repeat request
• n may be selected by specification, signaled to UEs (i.e., a common value is signaled to the UEs) or UE dependant (i.e., a specific value that is signaled to a specific UE).
• the method of the invention is advantageously simpler than conventional methods for performing scheduling grants for scheduled transmissions.
• the present invention is transparent to Layer One, and provides a minimum impact on Layer Two.
• the method of the invention is implemented as a new control parameter in either a packet data protocol (PDP) context/radio access bearer (RAB) layer or in the MAC layer.
• PDP packet data protocol
• RAB radio access bearer
• a new PDP context/ quality of signal (QoS) parameter is used.
• the new parameter is a "service data unit (SDU) inter-arrival rate" that establishes the minimum required time interval between consecutive SDUs that are transmitted on a specific RAB.
• the parameter is signaled in different interfaces than the existing PDP context/RAB QoS parameters.
• the application does not deliver SDUs to the MAC layer at a higher rate than the rate specified by the parameter. If the data source produces several packets within this time interval, the packets are grouped into a single SDU. Grouping the packets in the MAC layer provides the ability to obtain the benefits associated with optimizing the packet header overhead, such as more efficiently sharing the uplink power resource between packet data users.
• FIGS. 3 and 4 are exemplary timing diagrams associated with the introduction of a packet data protocol (PDP) context/ radio access bearer (RAB) Quality of Signal (QoS) parameter in the PDP context/RAB layer in accordance with an embodiment of the invention for a 10 ms and 2 ms air interface transmission time interval (TTI), respectively.
• PDP packet data protocol
• RAB radio access bearer
• QoS Quality of Signal
• 2 VoIP packets (i.e., 1 RLC SDU) are transmitted every 40 ms.
• a single VoIP packet is transmitted from the source every 20 ms. That is, the data source produces several (i.e. two) data packets within the 40 ms SDU inter-arrival rate that are grouped into the single SDU.
• RLC SDUs #1 and #2 both containing 2 VoIP packets.
• the SDU inter-arrival rate of 40 ms ensures that the subsequent new RLC SDU #2 (B) will be transmitted after a delay of at least 40 ms after the RLC SDU #1 (A), and that the 2 VoIP packets produced by the source during the 40 ms period are grouped into single RLC SDU #2 (B). Due to retransmission (C) of the RLC SDU #1 (A), the delay for the first generated packet in the RLC SDU #1 (A) is 70 ms and the delay for the packet in the RLC SDU #1 (A) that is subsequently generated 20 ms later is 50 ms, i.e., both packets in the single RLC SDU are retransmitted.
• a packet refers to a VoIP packet from the source (e.g., voice codec) and the numbers with the boxes (A, B) refers to RLC SDU numbers. As shown in FIG.
• the delay for the first generated packet in the RLC SDU #1 (A) is 70 ms and the delay for the VoIP packet in the RLC SDU #1 (A) that is subsequently generated 20 ms later is 50 ms, i.e., both packets in the single RLC SDU are retransmitted 3 times.
• the preferred transmission interval would be an optimization for radio access network purposes and depends on, for example, the transport channel that is used. Consequently, the PDP context/RAB QoS parameter may not be the best place in which to define the transmission interval. Alternatively, it is possible to introduce a new MAC parameter in the MAC-d layer.
• the new parameter is a "virtual TTI" that defines the minimum time interval between subsequent new transmissions for a MAC-d flow.
• a first transmission would be permitted only once, during the virtual TTI.
• the virtual TTI could be signaled to the UE by the radio network controller (RNC). The UE could then implement the virtual TTI in the MAC-d layer.
• RNC radio network controller
• VoIP packets are transmitted every 20 ms.
• a 40 ms virtual TTI in MAC-d 2 VoIP packets are transmitted in the same air interface TTI every 40 ms.
• a single packet is transmitted from the source every 20 ms and each RLC SDU contains one VoIP packet. That is, RLC SDUs, each containing a single VoIP packet, are delivered from the application to MAC every 20 ms.
• packets #1 (A) and packets #2 (B) are delivered to MAC layer in their own separate RLC SDUs with a 20 ms time difference, and grouped at MAC-d layer for transmittal in the same single 10 ms air interface TTI.
• the subsequent new packets #3 and #4 are grouped together in MAC-d for transmittal in the same 10 ms air interface TTI, because the 40 ms virtual TTI prevents this transmission before 40 ms after the start of the previous transmission has elapsed.
• the packets #1 (A) and #2 (B) are retransmitted (C and D).
• the packet #1 (A) is transmitted from the source 20 ms earlier than packet #2 (B), but is not allowed to be transmitted before the 40 ms virtual TTI has elapsed after the start of the previous packet first transmission.
• the delay for the packet #1 (A) with one retransmission (C) is 70 ms and the delay for the packet #2 (B) with one retransmission (D) is 50 ms.
• a packet refers to a VoIP packet from the source (e.g., voice codec) and the numbers with the boxes (A, B, C, D) refers to both packet and RLC SDU numbers.
• packets #1 (A) and #2 (B) are transmitted in the same 2 ms air interface TTI and are retransmitted 3 times.
• the delay for packet #1 (A) is 70 ms and the delay for packet #2 (B) is 50 ms.
• the first transmission for the packet #1 (A) is allowed only 40 ms later than the previous packet first transmission and is thus, delayed an additional 20 ms in comparison to packet #2 (B) that can be transmitted without additional delay.
• the packets #3 (C) and #4 (D) are transmitted at the 40 ms virtual TTI later than the first transmission of the packets #1 (A) and #2 (B).
• Defining the parameter in the MAC layer advantageously supports the elimination of the dependency on the radio access network, as compared to the case where the transmission interval is defined in the PDP context/RAB parameter. If several radio bearers (RB) are multiplexed into the same transport channel, it should be possible to separately define a "virtual TTI" for each RB.
• the RNC uses the parameters delivered by the serving general packet radio service (GPRS) support node (SGSN) to identify the specific services.
• GPRS general packet radio service
• SGSN serving general packet radio service support node
• the control i.e., the calculated delay
• the QoS values such as "source statistics descriptor” (SSD), "traffic class”, and "transfer delay” can be used to calculate the delay.
• SSD source statistics descriptor
• traffic class traffic class
• transfer delay can be used to calculate the delay.
• the virtual TTI is determined to be 40 ms.
• the load in the radio access network can be included as another criterion for determining the most optimal virtual TTI length.
• the lower the load level the shorter the virtual TTI that is used.
• the present invention is not to be limited to the examples based on the QoS and the like, i.e., the general approach regarding RNC algorithms in 3GPP. It is to be appreciated that other specific implementations are possible, which are based on specific RNC algorithms as required be each specific implementation.
• the invention is implemented in a high speed downlink shared transport channel (HS-DSCH).
• HS-DSCH high speed downlink shared transport channel
• the RAB attribute 'SDU inter-arrival rate' in the DL would permit the UTRAN to optimize its DL resources.
• the UTRAN is permitted to determine whether to use a 'virtual TTI' in the DL in the MAC layer.
• the advantage of signaling the 'virtual TTI' to the UE in the DL is that the UE can switch the receiver off during the inter-arrival period, even though it is possible to provide this functionality in the DL without signaling it to the UE.
• an alternative periodicity parameter T can be used to define the HS-SCCH decoding period instead of the HS-DSCH decoding period.
• the radio network controller (RNC) and base station (i.e., Node B), as defined in the current 3GPP specified network are exemplary. Therefore, the present invention is not to be limited to such a device. Rather, the present invention may be implemented in other packet switched (PS) networks, e.g., in an evolved 3GPP network depending on their frame structure and flexibility of the structure.
• PS packet switched
• the UE decides whether to use a 40 ms virtual TTI when it detects that the underlying RAN network is HSUPA. i.e., signalling of the parameters (i.e., the transmission interval) is not performed by the network, but is implemented internally in the UE.
• the UE may decide to use the 40 ms virtual TTI when it detects that the underlying RAN network is HSUPA.
• the virtual TTI is signalled by the network, and used on the MAC level as describe above.
• the information pertaining to the virtual TTI is conveyed to a unit that controls the packetization of packets from the data source into SDUs, for example, packetization of speech frames (in real-time transport protocol (RTP) payload).
• RTP real-time transport protocol
• one 20 ms speech frame is placed into one user datagram protocol/real-time transport protocol/Internet protocol (UDP/RTP/IP) packet.
• UDP/RTP/IP user datagram protocol/real-time transport protocol/Internet protocol
• the virtual TTI is known to have a length of 40 ms, it is possible to insert two 20 ms frames into one UDP/RTP/IP packet and thus, reduce the UDP/RTP/IP protocol overhead and processing load in UE and the network.
• a single speech packet per radio link control (RLC) service data unit (SDU) or UDP/RTP/IP packet potentially provides a greater level of flexibility than embodiments of the invention in which several speech packets are combined into one RTP/UDP/IP packet.
• RLC radio link control
• SDU service data unit
• UDP/RTP/IP packet potentially provides a greater level of flexibility than embodiments of the invention in which several speech packets are combined into one RTP/UDP/IP packet.
• each speech packet in separate RLC SDUs permits the sending of only one speech packet per air interface TTI of 2 ms or 10 ms. This would be the case if, e.g., the transmission of higher priority packets from another radio link control (RLC) buffer, such as the signalling radio bearer (SRB), prohibits the transmittal of large transport block (TB) that contains several speech packets.
• RLC radio link control
• SRB signalling radio bearer
• the size of the RLC SDU is more regular and predictable if only one speech frame is included into one RLC SDU.
• the UE power limitations in bad radio conditions such as the UE running out of transmission power, are taken into account so that it then becomes possible to send a single speech packet per air interface TTI of 2 ms or 10 ms.
• the MAC-d would check the RLC buffer of the UE once per virtual TTI, i.e., at the same interval as a normal TTI as defined in the 3GPP IS 25. 309 specification. As a result, packets received during the virtual TTI would be buffered at the RLC level.
• the MAC is permitted to check the RLC buffer more frequently in certain special cases, such as when it is not possible to clear the RLC buffer due to power limitations, the transmission of higher priority packets from other RLC buffer (e.g. SRB) or if there are bigger RLC SDUs (e.g., non-compressed headers or real time control protocol (RTCP) packets) that cannot be transmitted within one air interface TTI.
• RLC SDUs e.g., non-compressed headers or real time control protocol (RTCP) packets
• RTCP real time control protocol
• a single transmission for packets #1 (C) and #2 (F) and #3 (D) and #4 (E) is shown. However, it is not possible to transmit subsequent new packets #3 (D) and #4 (E) during a single TTI. As a result, these packets are grouped together and transmitted in separate TTIs. Examples of the operation of the UE MAC under such conditions are as follows: (i) if the MAC is able to empty the RLC buffer during this air interface TTI, then the MAC will check the RLC buffer at the next predetermined subsequent time interval after the virtual TTI; (ii) if the MAC is not able to empty the buffer, then the MAC will also check the RLC buffer for the next air interface TTI.
• the implementation of the present contemplated embodiment is permitted based on the configuration of the network, e.g., the network is configured to restrict the transmissions only to instances of times that are established by the virtual TTI or the network is configured to permit the above previously described operations.
• the transmission can be limited by controlling HARQ processes only up to every 16 ms, and in case of a 10 ms TTI up to 40 ms. It is also possible to control the TTI of scheduled transmissions by scheduling. However, this introduces large control overhead, i.e., two scheduled grants per single transmission occur.
• the present invention advantageously conserves control overhead. Specifically, the downlink E-DCH HARQ Indicator Channel (HICH) (i.e., the HARQ ACK/NAK is sent on E-HICH) overhead can be reduced because ACK/NAKs are needed less frequently. Also, the E-DCH dedicated physical control channel (E-DPCCH) overhead is reduced. In addition, a further savings in overhead is possible if the uplink dedicated physical control channel (UL DPCCH) gating is introduced. In this case, the DPCCH is not transmitted continuously but only when other UL channels are transmitted.
• HICH E-DCH HARQ Indicator Channel
• E-DPCCH E-DCH dedicated physical control channel
• UL DPCCH uplink dedicated physical control channel
• Another advantage of the present invention is that battery power of the UE is conserved, since the UE needs to transmit and receive less often when a virtual TTI is used.

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• Mobile Radio Communication Systems (AREA)

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• 2005
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