A Universal Mobile Telecommunications System (UMTS) is a third generation mobile communications system that evolved from the European Global System for Mobile communications (GSM) that aims to provide an improved mobile communications service based upon a GSM core network and W-CDMA (Wideband Code Division Multiple Access) wireless connection technology.
FIG. 1 illustrates an exemplary basic structure of a UMTS network (100). The UMTS is roughly divided into a terminal 100 (e.g., mobile station, User Equipment, etc.), a UMTS Terrestrial Radio Access Network (UTRAN) 120, and a core network (CN) 130. The UTRAN 120 consists of one or more radio network sub-systems (RNS: 121, 122). Each RNS consists of one radio network controllers (RNC: 123, 124) and one or more base stations (e.g., Node-Bs: 125, 126) that are managed by the RNC. One or more cells exist for each Node-B.
The RNC (123, 124) handles the assigning and managing of radio resources, and operates as an access point with respect to the core network 130. The Node-Bs (125, 126), thus operate as access points of the UTRAN 120 for the terminal 100. Also, the RNC (123, 124) allocates and manages radio resources and operates as an access point with the core network 130.
Between various network structure elements, there exists an interface that allows data to be exchanged for communication therebetween.
FIG. 2 illustrates a radio interface protocol architecture (structure) between the terminal 100 and the UTRAN 120 that is based upon a 3GPP wireless access network technology. Here, the radio access interface protocol has horizontal layers including a physical layer, a data link layer, and a network layer, and has vertical planes including a user plane for transmitting data information and a control plane for transmitting control signals. The user plane is a region to which traffic information of a user (such as voice data, IP (Internet Protocol) packets and the like) are transmitted. The control plane is a region to which control information (such as the interface of the network, maintenance and management of calls, and the like) is transmitted.
Also in FIG. 2, the protocol layers can be divided into a first layer (L1), a second layer (L2), and a third layer (L3) based upon the three lower layers of an open system interconnection (OSI) scheme that is a well-known in the art of wireless (mobile) communication systems.
The first layer (L1) is a physical layer (PHY) that provides information transfer service to upper layers by using various radio transmission techniques. The first layer (L1) is connected to a medium access control (MAC) layer that is located thereabove via a transport channel through which data travels between the MAC layer and the physical layer. Also, between the different physical layers (namely, between the respective physical layers of the transmitting side and the receiving side), data is transferred via a physical channel.
The medium access control (MAC) layer handles the mapping between the logical channels and the transport channels, and provides a re-allocation service of the MAC parameter for allocation and re-allocation of radio (wireless) resources.
The MAC layer of the second layer (L2) is connected to an upper layer called a radio link control (RLC) layer through a logical channel, and various logical channels are provided according to the type of transmitted information. Namely, the MAC layer provides services to an upper layer (the RLC layer) via a logical channel. The RLC layer of the second layer (L2) can support reliable data transmissions, and can perform a segmentation and concatenation function on a plurality of RLC service data units (RLC SDUs) delivered from an upper layer.
A packet data convergence protocol (PDCP) layer is located at an upper layer from the RLC layer, allowing data to be transmitted effectively via a radio interface with a relatively small bandwidth through a network protocol.
The radio resource control (RRC) layer located at the lowest portion of the third layer (L3) is only defined in the control plane, and controls the transport channels and the physical channels in relation to the configuration, the re-configuration, and the releasing of the radio bearers (RBs).
The radio bearer service refers to a service that the second layer (L2) provides for data transmission between the terminal (UE) 110 and the UTRAN 120 in order to guarantee a predetermined quality of service by the UE and the UTRAN. And in general, the radio bearer (RB) establishment refers to regulating the protocol layers and the channel characteristics of the channels required for providing a specific service, as well as respectively setting substantial parameters and operation methods.
Among the RBs, the particular RB used between the UE and the UTRAN for exchanging RRC messages or NAS messages is called a SRB (Signaling Radio Bearer). When an SRB is established between a particular UE and the UTRAN, a RRC connection exists between the UE and the UTRAN. A UE having a RRC connection is said to be in RRC connected mode, and a UE without a RRC connection is said to be in idle mode. When a UE is in RRC connected mode, the RNC determines the cell in which the UE is located (i.e., the RNC determines the UE location in units of cells), and manages that UE.
The MAC layer of the second layer provides a service to an upper layer of a radio link control (RLC) layer through a logical channel. The MAC layer is sub-divided into several types of sub-layers such as a MAC-d sub-layer and a MAC-e sub-layer according to the type of transport channel that is managed.
A related art structure of a dedicated channel (DCH) and an enhanced dedicated channel (E-DCH) is illustrated in FIG. 3. As shown, the DCH 14 and the E-DCH 16 are dedicated transport channels used by one mobile terminal. In particular, the E-DCH 16 is used to transmit data to the UTRAN 120 at a high speed compared to the DCH 14. In order to transmit data at a high speed, various techniques may be employed for the E-DCH 16 such as a HARQ (Hybrid ARQ), an AMC (Adaptive Modulation and Coding), and a Node B controlled scheduling, and the like.
For the E-DCH 16, the Node B 125 or Node B 126 transmits downlink control information to a mobile UE 110 to control the E-DCH transmission of the mobile UE 110. The downlink control information may include response information (ACK/NACK) for the HARQ, channel quality information (CQI) for the AMC, E-DCH transmission rate information, E-DCH transmission start time and transmission time period information, and a transport block size information for the Node B controlled scheduling, or the like.
Meanwhile, the UE 110 transmits uplink control information to the Node B 12. The uplink control information may include E-DCH transmission rate request information, UE buffer status information, and UE power status information for the Node B controlled scheduling, or the like. The uplink control information and the downlink control information for the E-DCH 16 are transmitted through a physical control channel such as an E-DPCCH (Enhanced Dedicated Physical Control Channel).
For the E-DCH 16, a MAC-d flow 18 is defined between the MAC-d sublayer 24 and the MAC-e sublayer 26. In this case, a dedicated logical channel is mapped to a MAC-d flow, the MAC-d flow is mapped to the E-DCH 16, a transport channel, and the E-DCH 16 is mapped to an E-DPDCH (Enhanced Dedicated Physical Data Channel) 20, a physical channel. Also, the dedicated logical channel can be directly mapped to the DCH 14, also a transport channel, and the DCH 14 is mapped to the DPDCH (Dedicated Physical Data Channel) 22.
The MAC-d sub-layer 24, as shown in FIG. 3, manages the DCH 14, the dedicated transport channel of a specific terminal. The MAC-e sub-layer 26 manages the E-DCH 16, the transport channel used for transmitting high-speed uplink data.
A MAC-d sub-layer of a transmitting side generates a MAC-d PDU (Protocol Data Unit) from a MAC-d SDU (Service Data Unit) received from an upper layer, namely, the RLC layer. Alternatively, a MAC-d sub-layer of a receiving side restores the MAC-d SDU from the MAC-d PDU received from a lower layer and delivers it to an upper layer. The MAC-d sub-layer may transmit the MAC-d PDU to the MAC-e sub-layer through a MAC-d flow, or transmit the MAC-d PDU to a physical layer through the DCH. The MAC-d sub-layer of the receiving side then restores the MAC-d SDU by using a MAC-d header included in the MAC-d PDU and then transfers the MAC-d SDU to the upper layer.
The MAC-e sub-layer of the transmitting side generates a MAC-e PDU from the MAC-d PDU, generated from the MAC-e SDU, received from the MAC-d sub-layer. Alternatively, the MAC-e sub-layer of the receiving side restores the MAC-e SDU from the MAC-e PDU received from the physical layer, and transfers it to an upper layer. In this case, the MAC-e sub-layer transmits the MAC-e PDU to the physical layer through the E-DCH. The MAC-e sub-layer of the receiving side then restores the MAC-e SDU by using a MAC-e header included in the MAC-e PDU and then transfers it to the upper layer.
A protocol model for a related art E-DCH is illustrated in FIG. 4. As shown, the MAC-e sub-layer supporting the E-DCH exists at a lower position of the MAC-d sub-layer of the UTRAN 120 and the terminal (UE) 110. The MAC-e sub-layer 30 of the UTRAN 120 is positioned in the Node B. The MAC-e sub-layer 32 exists in each terminal 28. Comparatively, the MAC-d sub-layer 34 of the UTRAN 120 is positioned in an SRNC for managing a corresponding terminal 28. Each terminal 28 includes a MAC-d sub-layer 36.
The QoS of ongoing flows mapped on E-DCH for a UE is maintained by the serving Node B and by the UE. In addition to these mechanisms, guaranteed bit rate services for MAC-d flows/logical channels (FFS) are also supported through non-scheduled transmission. A flow using non-scheduled transmission is defined by the SRNC and provided in the UE and in the Node B. The UE can transmit data belonging to such flow without first receiving any scheduling grant.
To the UE, the following QoS-related information may be provided from the SRNC to enable QoS-based E-TFC selection, multiplexing of logical channels in MAC-e PDUs, and HARQ operation:                Logical channel priority for each logical channel (as in Rel-5);        Mapping between logical channel(s) and MAC-d flow(s) (as in Rel-5);                    Allowed MAC-d flow combinations in one MAC-e PDU;            HARQ profile per MAC-d flow. One HARQ profile consists of a power offset attribute and a maximum number of transmissions attribute. The power offset attribute is used in E-TFC selection to regulate the BLER operating point for the transmission. The maximum number of transmissions attribute is used in the HARQ operation to regulate maximal latency and residual BLER of MAC-d flows.                        
To the Node B, the following QoS-related parameters are provided by the SRNC to enable scheduling and resource reservation:                Power offset or E-TFC (FFS) that corresponds to the guaranteed bit rate (only for MAC-d flows/logical channels that carry guaranteed bit rate services). For scheduled transmission, it is used to allocate grants to UEs. For non-scheduled transmission, it is used for the Node B to reserve sufficient amount of resources. The need for additional mechanisms to optimize the Node-B hardware is FFS (e.g. the UE may tell the Node-B ahead that an non-scheduled transmission is coming);        
UE takes into account following principles:                The E-TFC selection is based on logical channel priorities like in the Release '99, i.e. the UE shall maximise the transmission of higher priority data;        The UE shall respect the allowed combinations of MAC-d flows in the same MAC-e PDU;        The power offset of E-DPDCH(s) relative to DPCCH associated to a MAC-e PDU including MAC-d PDUs coming from one or several MAC-d flows is set as follows;        The UE selects the power offset of the HARQ profile associated to the MAC-d flows with the highest priority logical channel in the MAC-e PDU;        
Upon considering the various issues described above in view of FIGS. 1 through 4, the present inventors recognized that improvements to the High Speed Uplink Packet Access (HSUPA) scheme would be highly desirable.