Radio communication systems, such as a wireless data networks (e.g., Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, spread spectrum systems (such as Code Division Multiple Access (CDMA) networks), Time Division Multiple Access (TDMA) networks, etc.), provide users with the convenience of mobility along with a rich set of services and features. This convenience has spawned significant adoption by an ever growing number of consumers as an accepted mode of communication for business and personal uses. To promote greater adoption, the telecommunication industry, from manufacturers to service providers, has agreed at great expense and effort to develop standards for communication protocols that underlie the various services and features. One area of effort involves control signaling, notably acknowledgment signaling in response to successful or failure of data transmission. However, acknowledgement signaling can impose significant overhead if performed inefficiently, thereby reducing network performance.
Therefore, there is a need for an approach for providing efficient acknowledgment signaling.
According to one aspect of an embodiment of the invention, a method comprises determining designating a predetermined number of acknowledgment channels corresponding to transmission channels utilized by a plurality of user equipment. Each of the acknowledgement channels provides signaling to indicate success or failure of a transmission over a respective one of the transmission channels. The method also comprises generating a message to map the acknowledgement channels with the transmission channels.
According to another aspect of an embodiment of the invention, an apparatus comprises a logic configured to designate a predetermined number of acknowledgment channels corresponding to transmission channels utilized by a plurality of user equipment. The logic is further configured to generate a message to map the acknowledgement channels with the transmission channels.
According to another aspect of an embodiment of the invention, a method comprises receiving a message from a network element. The method also comprises the message specifying a mapping of acknowledgment channels to transmission channels. Each of the acknowledgement channels provides signaling to indicate success or failure of a transmission over a respective one of the transmission channels.
According to yet another aspect of an embodiment of the invention, an apparatus comprises a logic configured to receive a message from a network element, the message specifying a mapping of acknowledgment channels to transmission channels. Each of the acknowledgement channels provides signaling to indicate success or failure of a transmission over a respective one of the transmission channels.
Still other aspects, features, and advantages of the invention are readily apparent from the following detailed description, simply by illustrating a number of particular embodiments and implementations, including the best mode contemplated for carrying out the invention. The invention is also capable of other and different embodiments, and its several details can be modified in various obvious respects, all without departing from the spirit and scope of the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
The invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements and in which:
An apparatus, method, and software for providing acknowledgment signaling are disclosed. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It is apparent, however, to one skilled in the art that the embodiments of the invention may be practiced without these specific details or with an equivalent arrangement. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the embodiments of the invention.
Although the embodiments of the invention are discussed with respect to a communication network having a Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) architecture, it is recognized by one of ordinary skill in the art that the embodiments of the inventions have applicability to any type of communication system and equivalent functional capabilities.
The UE 101 includes a transceiver 105 and an antenna system 107 that couples to the transceiver 105 to receive or transmit signals from the base station 103. The antenna system 107 can include one or more antennas (of which only one is shown). Accordingly, the base station 103 can employ one or more antennas 109 for transmitting and receiving electromagnetic signals. As with the UE 101, the base station 103 employs a transceiver 111, which transmits information over a downlink (DL) to the UE 101.
The base station 103, in an exemplary embodiment, uses OFDM (Orthogonal Frequency Divisional Multiplexing) as a downlink (DL) transmission scheme and a single-carrier transmission (e.g., SC-FDMA (Single Carrier-Frequency Division Multiple Access) with cyclic prefix for the uplink (UL) transmission scheme. SC-FDMA can be realized also using DFT-S-OFDM principle, which is detailed in 3GGP TR 25.814, entitled “Physical Layer Aspects for Evolved UTRA,” v.1.5.0, May 2006 (which is incorporated herein by reference in its entirety). SC-FDMA, also referred to as Multi-User-SC-FDMA, allows multiple users to transmit simultaneously on different sub-bands.
In one embodiment, the communication system 100 employs a hybrid automatic repeat request (HARQ) technique to increase the air interference throughput and spectrum efficiency. Acknowledgment/negative acknowledgment (ACK/NACK) signaling is part of HARQ, for connecting a transmitter and a receiver, to enable the fast L1 (Layer 1 or Physical Layer) retransmission. As such, the UE 101 and the base station 103 include acknowledgement signaling logic 1113 and 115 to determine occurrence of transmission errors and to notify the source of the transmission of the errors, according to the HARQ mechanism. In one embodiment, the system 100 addresses the uplink (UL) ACK/NACK in downlink (DL) transmission, particularly for LTE TDD system, and thus, is provided with an efficient, lower-overhead and robust acknowledgement signaling approach.
ACK/NACK signaling requires sufficient robustness to avoid neither retransmitting successfully received data packet nor transmitting new data packet before successful receipt the on-the-air old data packet. On the other hand, due to fast L1 retransmission, the frequency of ACK/NACK transmission to the designated receiver is very high (e.g., up to 1000 Hz), thus, transmission efficiency of ACK/NACK is desired to minimize the signaling overhead. The system 100, according to one embodiment, utilizes an acknowledgement signaling scheme that provides transmission efficiency, as detailed in
On the receiver side (as shown in
The UE 101 obtains position of UL AN channels, per step 223. If the system 100 provides an implicit allocation for the AN channels (as determined in step 225), then, per step 227, the system 100 determines the AN channel based on the UL subframe. However, if the system 100 does not provide for implicit allocation, a signaling message is transmitted for conveying the position of the UL AN channels within the downlink, as in step 229.
In the context of a TDD system, the UE 101 can learn of its UL ACK/NACK bit(s) in the DL by a predefined implicit resource allocation or through use of minimal signaling overhead. Because there can be multiple UL and DL subframes in one TDD frame or one duplex space, and multiple scheduled UE in one UL subframe, the implicit allocation can be viewed in two parts. First, the time position of the ACK/NACK corresponding to the data transmission in the ith UL subframe; and second, multiplexing of ACK/NACKs for different UEs that transmitted UL data in the ith UL subframe.
A predefined mapping can be designated to indicate on which DL subframe to transmit the ACK for the data in the ith UL subframes. In an exemplary embodiment, the AN channels are mapped on a one-to-one (unique) basis to different UL subframes. Thus, as long as the UE 101 knows which UL subframe it is transmitting UL data packet (the UE 101 should know already before it gets ready to receive the ACK/NACK), the UE 101 will know uniquely which AN channel it should listen for. When UE 101 is transmitting data in multiple UL subframe, the UE 101 will then listen for multiple AN channels for its ACK/NACK bits.
To appreciate the above processes, it is instructive to examine other mechanisms for acknowledgment signaling.
As seen in
Also, other conventional approaches, in the case of TDD, can result in time-domain ambiguity when transmitting UL ACK/NACK in the DL subframe.
By contrast, the processes of
Each UL AN channel 503 can transmit UL ACK/NACK bits for the scheduled UE 101 in previous known subframe (TTI) by, for instance, various reliable and efficient known methods. Additionally, the timing requirement can be specified such that the needed processing time defines the smallest/shortest duration until an ACK/NACK can be transmitted. In the LTE example, this smallest/shortest duration can be a value (e.g., 1 ms) that satisfies the processing time and fits into numerology (for instance, ˜400 μs is acceptable for decoding the longest Turbo code block). As shown, it is observed that AN-3 can be mapped only into DL subframe-2, but not DL subframe-1 because processing time is insufficient.
Furthermore, the ACK-NACK in the same DL subframe can multiplexed using various standard techniques (e.g., frequency division multiplexing, code division multiplexing, or a hybrid scheme), and the UE 101 can determine the exact position within one AN channel by indexing the UE 101 within an AN channel. It is contemplated that other techniques can be employed as well. Under these approaches, a base station (e.g., base station 103), in subframe k, informs a terminal (e.g., UE-n) of the UL radio resources assignment using x-th L1/L2 control channel; and in subframe k+t, the base station transits UL AN to the UE-n using the x-th radio resources in AN channel (x-th sub-carrier set or x-th code).
The above acknowledgement signaling approach provides an efficient and robust technique that minimizes the required bits for UL ACK/NACK transmission in DL down to the least, i.e., 1 bit per user equipment. Also, the approach is flexible and consistent to support a variety of downlink/uplink configuration scenarios in a TDD system, and an UL AN channel structure for other non-dynamic scheduled user equipment. Further, the approach provides the flexibility of maintaining UL AN channel position in the TDD system, i.e. not necessarily to have UL AN channel in each of DL subframe or have only one UL AN channel in each of DL subframe. This may leave more room for a UL scheduler and UL transmission, and may potentially benefit the round trip delay in the TDD system.
The MME (Mobile Management Entity)/Serving Gateways 601 are connected to the eNBs in a full or partial mesh configuration using tunneling over a packet transport network (e.g., Internet Protocol (IP) network) 603. Exemplary functions of the MME/Serving GW 601 include distribution of paging messages to the eNBs, IP header compression, termination of U-plane packets for paging reasons, and switching of U-plane for support of UE mobility. Since the GWs 601 serve as a gateway to external networks, e.g., the Internet or private networks 603, the GWs 601 include an Access, Authorization and Accounting system (AAA) 605 to securely determine the identity and privileges of a user and to track each user's activities. Namely, the MME Serving Gateway 601 is the key control-node for the LTE access-network and is responsible for idle mode UE tracking and paging procedure including retransmissions. Also, the MME 601 is involved in the bearer activation/deactivation process and is responsible for selecting the SGW (Serving Gateway) for a UE at the initial attach and at time of intra-LTE handover involving Core Network (CN) node relocation.
A more detailed description of the LTE interface is provided in 3GPP TR 25.813, entitled “E-UTRA and E-UTRAN: Radio Interface Protocol Aspects,” which is incorporated herein by reference in its entirety.
In
The basic architecture of the system 602 contains following network elements. As seen in
The MME 608, as a key control node, is responsible for managing mobility UE 101 identifies and security parameters and paging procedure including retransmissions. The MME 608 is involved in the bearer activation/deactivation process and is also responsible for choosing Serving Gateway 610 for the UE. MME 608 functions include Non Access Stratum (NAS) signaling and related security. MME 608 checks the authorization of the UE 101 to camp on the service provider's Public Land Mobile Network (PLMN) and enforces UE roaming restrictions. The MME 608 also provides the control plane function for mobility between LTE and 2G/3G access networks with the S3 interface terminating at the MME 608 from the SGSN (Serving GPRS Support Node) 614. The principles of PLMN selection in E-UTRA are based on the 3GPP PLMN selection principles. Cell selection can be required on transition from MME_DETACHED to EMM-IDLE or EMM-CONNECTED. The cell selection can be achieved when the UE NAS identifies a selected PLMN and equivalent PLMNs. The UE 101 searches the E-UTRA frequency bands and for each carrier frequency identifies the strongest cell. The UE 101 also reads cell system information broadcast to identify its PLMNs. Further, the UE 101 seeks to identify a suitable cell; if it is not able to identify a suitable cell, it seeks to identify an acceptable cell. When a suitable cell is found or if only an acceptable cell is found, the UE 101 camps on that cell and commences the cell reselection procedure. Cell selection identifies the cell that the UE 101 should camp on.
The SGSN 614 is responsible for the delivery of data packets from and to the mobile stations within its geographical service area. Its tasks include packet routing and transfer, mobility management, logical link management, and authentication and charging functions. The S6a interface enables transfer of subscription and authentication data for authenticating/authorizing user access to the evolved system (AAA interface) between MME 608 and HSS (Home Subscriber Server) 616. The S10 interface between MMEs 608 provides MME relocation and MME 608 to MME 608 information transfer. The Serving Gateway 610 is the node that terminates the interface towards the E-UTRAN 612 via S1-U.
The S1-U interface provides a per bearer user plane tunneling between the E-UTRAN 612 and Serving Gateway 610. It contains support for path switching during handover between eNBs 612. The S4 interface provides the user plane with related control and mobility support between SGSN 614 and the 3GPP Anchor function of Serving Gateway 610.
The S12 is an interface between UTRAN 606 and Serving Gateway 610. Packet Data Network (PDN) Gateway 618 provides connectivity to the UE 101 to external packet data networks by being the point of exit and entry of traffic for the UE 101. The PDN Gateway 618 performs policy enforcement, packet filtering for each user, charging support, lawful interception and packet screening. Another role of the PDN Gateway 618 is to act as the anchor for mobility between 3GPP and non-3GPP technologies such as WiMax and 3GPP2 (CDMA 1X and EvDO (Evolution Data Only)).
The S7 interface provides transfer of QoS policy and charging rules from PCRF (Policy and Charging Role Function) 620 to Policy and Charging Enforcement Function (PCEF) in the PDN Gateway 618. The SGi interface is the interface between the PDN Gateway and the operator's IP services including packet data network 622. Packet data network 622 may be an operator external public or private packet data network or an intra operator packet data network, e.g., for provision of IMS (IP Multimedia Subsystem) services. Rx+ is the interface between the PCRF and the packet data network 622.
As seen in
The eNB 103 communicates with the aGW 601 (Access Gateway) via an S1 interface. The aGW 601 includes a User Plane 601a and a Control plane 601b. The control plane 601b provides the following components: SAE (System Architecture Evolution) Bearer Control 635 and MM (Mobile Management) Entity 637. The user plane 601b includes a PDCP (Packet Data Convergence Protocol) 639 and a user plane functions 641. It is noted that the functionality of the aGW 601 can also be provided by a combination of a serving gateway (SGW) and a packet data network (PDN) GW. The aGW 601 can also interface with a packet network, such as the Internet 643.
In an alternative embodiment, as shown in
In the system of
The eNB interfaces via the S1 to the Serving Gateway 645, which includes a Mobility Anchoring function 647, and to a Packet Gateway (P-GW) 649, which provides an UE IP address allocation function 657 and Packet Filtering function 659. According to this architecture, the MME (Mobility Management Entity) 661 provides SAE (System Architecture Evolution) Bearer Control 651, Idle State Mobility Handling 653, NAS (Non-Access Stratum) Security 655.
One of ordinary skill in the art would recognize that the processes for acknowledgement signaling may be implemented via software, hardware (e.g., general processor, Digital Signal Processing (DSP) chip, an Application Specific Integrated Circuit (ASIC), Field Programmable Gate Arrays (FPGAs), etc.), firmware, or a combination thereof. Such exemplary hardware for performing the described functions is detailed below with respect to
The computing system 700 may be coupled via the bus 701 to a display 711, such as a liquid crystal display, or active matrix display, for displaying information to a user. An input device 713, such as a keyboard including alphanumeric and other keys, may be coupled to the bus 701 for communicating information and command selections to the processor 703. The input device 713 can include a cursor control, such as a mouse, a trackball, or cursor direction keys, for communicating direction information and command selections to the processor 703 and for controlling cursor movement on the display 711.
According to various embodiments of the invention, the processes described herein can be provided by the computing system 700 in response to the processor 703 executing an arrangement of instructions contained in main memory 705. Such instructions can be read into main memory 705 from another computer-readable medium, such as the storage device 709. Execution of the arrangement of instructions contained in main memory 705 causes the processor 703 to perform the process steps described herein. One or more processors in a multi-processing arrangement may also be employed to execute the instructions contained in main memory 705. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement the embodiment of the invention. In another example, reconfigurable hardware such as Field Programmable Gate Arrays (FPGAs) can be used, in which the functionality and connection topology of its logic gates are customizable at run-time, typically by programming memory look up tables. Thus, embodiments of the invention are not limited to any specific combination of hardware circuitry and software.
The computing system 700 also includes at least one communication interface 715 coupled to bus 701. The communication interface 715 provides a two-way data communication coupling to a network link (not shown). The communication interface 715 sends and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information. Further, the communication interface 715 can include peripheral interface devices, such as a Universal Serial Bus (USB) interface, a PCMCIA (Personal Computer Memory Card International Association) interface, etc.
The processor 703 may execute the transmitted code while being received and/or store the code in the storage device 709, or other non-volatile storage for later execution. In this manner, the computing system 700 may obtain application code in the form of a carrier wave.
The term “computer-readable medium” as used herein refers to any medium that participates in providing instructions to the processor 703 for execution. Such a medium may take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks, such as the storage device 709. Volatile media include dynamic memory, such as main memory 705. Transmission media include coaxial cables, copper wire and fiber optics, including the wires that comprise the bus 701. Transmission media can also take the form of acoustic, optical, or electromagnetic waves, such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, CDRW, DVD, any other optical medium, punch cards, paper tape, optical mark sheets, any other physical medium with patterns of holes or other optically recognizable indicia, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave, or any other medium from which a computer can read.
Various forms of computer-readable media may be involved in providing instructions to a processor for execution. For example, the instructions for carrying out at least part of the invention may initially be borne on a magnetic disk of a remote computer. In such a scenario, the remote computer loads the instructions into main memory and sends the instructions over a telephone line using a modem or via a wireless link. A modem of a local system receives the data on the telephone line and uses an infrared transmitter to convert the data to an infrared signal and transmit the infrared signal to a portable computing device, such as a personal digital assistant (PDA) or a laptop. An infrared detector on the portable computing device receives the information and instructions borne by the infrared signal and places the data on a bus. The bus conveys the data to main memory, from which a processor retrieves and executes the instructions. The instructions received by main memory can optionally be stored on storage device either before or after execution by processor.
While the invention has been described in connection with a number of embodiments and implementations, the invention is not so limited but covers various obvious modifications and equivalent arrangements, which fall within the purview of the appended claims. Although features of the invention are expressed in certain combinations among the claims, it is contemplated that these features can be arranged in any combination and order.
This application claims the benefit of the earlier filing date under 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No. 60/888,230 filed Feb. 5, 2007, entitled “Method and Apparatus for Providing Acknowledgement Signaling,” the entirety of which is incorporated by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/IB08/00251 | 2/5/2008 | WO | 00 | 8/5/2009 |
Number | Date | Country | |
---|---|---|---|
60888230 | Feb 2007 | US |