WO2010122419A2 - Methods and apparatus for subframe splitting to obtain uplink feedback using relay nodes - Google Patents

Abstract

Systems and methods for enabling the use of certain subframes for communicating uplink messages from a first communications element such as a UE (185,187) attached to a relay node (183), to a second communications element such as a base station or e-Node B (181), via a backhaul communications link between the relay node and the e-Node B are disclosed. A base station or e-Node B (181) may allocate certain subframes within a repeating radio frame of a TDD configuration as either DL or UL subframes for communicating to and from the relay node (183) on a backhaul link. User equipment or UE devices (185, 187) attached to the relay node (183) can then communicate certain status symbols to the e-Node B via the relay node to increase efficient use of the system. Methods for dynamically allocating certain subframes between the relay node (183) and the e-Node B (181) are disclosed.

Description

METHODS AND APPARATUS FOR SUBFRAME SPLITTING TO OBTAIN UPLINK FEEDBACK USING RELAY NODES

TECHNICAL FIELD

The present invention is directed, in general, to communication systems and, more particularly, to a system and method for providing the use of user equipment or mobile transceiver devices in a packet based communication system that includes relaying equipment between at least one user equipment in the system and one other communications element in the system while allowing for efficient use, simple implementation and conservation of system resources.

BACKGROUND As wireless communication systems such as cellular telephone, satellite, and microwave communication systems become widely deployed and continue to attract a growing number of users, there is a pressing need to accommodate a large and variable number of communication subsystems transmitting a growing volume of data with a fixed resource such as a fixed channel bandwidth accommodating a fixed data packet size. Traditional communication system designs employing a fixed resource (e.g., a fixed data rate for each user) have become challenged to provide high, but flexible, data transmission rates in view of the rapidly growing customer base.

The third generation partnership project long term evolution (3GPP LTE) is the name generally used to describe an ongoing effort across the industry to improve the universal mobile telecommunications system (UMTS) for mobile communications. The improvements are being made to cope with continuing new requirements and the growing base of users. Goals of this broadly based project include improving communication efficiency, lowering costs, improving services, making use of new spectrum opportunities, and achieving better integration with other open standards and backwards compatibility with some existing infrastructure that is compliant with earlier standards. The project envisions a packet switched communications environment with support for many voice, data and video services. The 3GPP LTE project is not itself a standard-generating effort, but will result in new recommendations for standards for the UMTS.

The UTRAN includes multiple Radio Network Subsystems (RNSs), each of which contains at least one Radio Network Controller (RNC). However, it should be noted that the RNC may not be present in the actual implemented systems incorporating Long Term Evolution (LTE) of UTRAN (E-UTRAN). LTE may include a centralized or decentralized entity for control information. In UTRAN operation, each RNC may be connected to multiple Node Bs which are the UMTS counterparts to Global System for Mobile Communications (GSM) base stations. In E-UTRAN systems, the e-Node B may be, or is, connected directly to the access gateway (aGW," sometimes referred to as the services gateway "sGW). Each Node B may be in radio contact with multiple UEs (generally, user equipment including mobile transceivers or cellphones, although other devices such as fixed cellular phones, mobile web browsers, laptops, PDAs, MP3 players, gaming devices with transceivers may also be UEs) via the radio Uu interface.

The wireless communication systems as described herein are applicable to, for instance, 3GPP LTE compatible wireless communication systems and of interest is an aspect of developing LTE networks referred to as "evolved UMTS Terrestrial Radio Access Network," or E-UTRAN. In general, E-UTRAN resources are assigned more or less temporarily by the network to one or more UEs by use of allocation tables, or more generally by use of a downlink resource assignment channel or physical downlink control channel (PDCCH). LTE is a packet-based system and, therefore, there may not be a dedicated connection reserved for communication between a UE and the network. Users are generally scheduled on a shared channel every transmission time interval (TTI) by a Node B or an evolved Node B (e-Node B). A Node B or an e-Node B controls the communications between user equipment terminals in a cell served by the Node B or e-Node B. In general, one Node B or e-Node B serves each cell. A Node B may sometimes be referred to as a "base station." Resources needed for data transfer are assigned either as one time assignments or in a persistent/semi-static way. The LTE, also referred to as 3.9G, generally supports a large number of users per cell with quasi-instantaneous access to radio resources in the active state. It is a design requirement that at least 200 users per cell should be supported in the active state for spectrum allocations up to 5 megahertz (MHz), and at least 400 users for a higher spectrum allocation. Further developments in LTE standards continue, and the present application is directed to embodiments that are envisioned as having applicability to these standards such as LTE-A, 3GPP ReI. 9, and other standards being released or in development presently as are known in the art. hi order to facilitate scheduling on the shared channel, the e-Node B transmits a resource allocation to a particular UE in a downlink-shared channel (PDCCH) to the UE. The radio resource allocation information may be related to both uplink and downlink channels. The allocation information may include information about which physical resource blocks (PRBs) in the frequency domain or time domain, or both, are allocated to the scheduled user(s), the modulation and coding schemes to use, what the size of the transport block is, and the like.

The lowest level of communication in the e-UTRAN system, Level 1, is implemented by the Physical Layer (PHY) in the UE and in the e-Node B and the PHY performs the physical transport of the packets between them over the air interface using radio frequency signals. In order to ensure a transmitted packet was received, an automatic retransmit request (ARQ) and a hybrid automatic retransmit request (HARQ) approach are provided. Thus, whenever the UE receives packets through one of several downlink channels, including command channels and shared channels, the UE performs a communications error check on the received packets, typically a Cyclic Redundancy Check (CRC), and in a later subframe following the reception of the packets, transmits a response on the uplink to the e-Node B or base station. The response is either an Acknowledgement (ACK) or a Negative Acknowledgement (NACK) message. If the response is a NACK, the e-Node B automatically retransmits the packets in a later subframe on the downlink or DL. In the same manner, any UL transmission from the UE to the e-Node B is responded to, later in time, by a NACK/ ACK message on the DL channel to complete the HARQ. In this manner, the packet communications system remains robust with a low latency time and fast turnaround time.

As presently proposed, uplink HARQ messages are synchronous. The synchronous HARQ follows a downlink transmission from an eNB to a UE by a predetermined number of subframes. The use of the synchronous HARQ therefore places timing requirements on the following subframes, as an uplink HARQ message must be able to be transmitted within certain time constraints.

The e-UTRAN project requires backwards compatibility support as well. To provide this support, any changes to the interface timing should also be compatible with devices that do not implement the improvements. For example, currently, so called "Release 8.0" devices are being contemplated. If these devices are produced, any changes to the e-UTRAN timing specifications in future releases or standards must be implemented in such a manner so that these earlier devices will still operate correctly in the system, even though later devices may have additional features. This ensures backwards compatibility for the devices already in use. Presently, an additional device called a relay node (RN) is considered for these networks, for example, in systems designed to conform to the standards known to those skilled in the art as "LTE-A" or "LTE Advanced". A relay node may be (as one non-limiting example) a fixed relay station used to address poor reception due to radio frequency "shadowing" or interference in an urban environment, or to increase signal strength in rural areas to overcome reflection or multipath problems in office buildings or other environments. In some contemplated schemes, an existing e-Node B station may act as a relay node to another Node B station, or in some schemes currently being considered as potential advances in the standards, user equipment such as a cellphone or PDA may also sometimes act as a relay station between user equipment and a Node B station. The use of relay nodes is expected to greatly improve the resource efficiency and performance of these systems by improving signal strength between the user equipment and the base station that would otherwise require frequent retransmissions of packets improperly received, and increase the bit error rate (BER) obtained.

In this discussion, for simplicity of the discussion only and not to limit the invention or the embodiments claimed in any appended claims, the examples used will be described in the context of the use of a fixed relay station as the RN. However, the embodiments provided and the principles of operation detailed for these embodiments have applicability to other relay node RN types, including base stations acting as relay nodes, and user equipment acting as relay nodes. In general, any communications element relaying the packet based radio signals between devices over an air interface is an appropriate relay node where the embodiments and principles of operation may be advantageously applied.

Because the ARQ and HARQ symbols in the LTE 3GPP system have to be transmitted in an uplink message from a UE attached to a relay node (RN-UE) to the hosting base station (eNB), some timing constraints are placed on the relay node. Presently, the standards and proposed working solutions consider a relay node that has a single frequency and is time multiplexed between receiving and transmitting signals. That is, while the relay node is transmitting a

"backhaul uplink" message to the eNB, it cannot simultaneously receive messages, including ACK/NACK messages, from the RN-UE corresponding to an earlier downlink message on the link between the relay node RN and the UE, the "access link". However, the system timing constraints for the HARQ features require that the ACK/NACK from the UE to the eNB are transmitted within certain time parameters for the HARQ scheme in the communications standards to operate correctly. Further, the UE attached to a relay node should operate exactly as if it were attached directly to the eNB which, as is presently being described; the RN-UE (UE attached to a relay node RN) is not required to change any signaling to operate through a relay node. As an additional constraint in present systems complying with the current Release 8.0 standard, for example, TDD subframes may not be split, further restricting the ability to transmit an ACK/NACK from the UE to the base station in a time efficient manner.

A continuing need thus exists for a system, signaling methods and circuitry to implement support for communication protocols to enable efficient system resource usage in a packet based communications system with radio frequency signals transmitted and received over an air interface where a relay node is used between an e-Node B device and one or more UEs.

SUMMARY OF THE INVENTION

These and other problems are generally solved or circumvented, and technical advantages are generally achieved, by advantageous embodiments of the present invention which include an apparatus and methods according to an embodiment for providing a relay node and novel signaling schemes for the relay node, an e-Node B in communications with the relay node, and one or more UEs attached to the relay node, while also supporting the efficient allocation of subframes within a TDD communication system to provide efficient use of downlink (DL) and uplink (UL) resources, and to provide efficient support of the HARQ transmissions from the UE to the relay node. According to an illustrative embodiment, an apparatus is provided that may communicate

TDD radio frames to and from a UE and to and from an eNB which communicate messages over a relay node. Packets are downloaded from the eNB to the UE using defined signaling protocols, including radio frequency signals that are coded for transmission and decoded by the receiver. The messages include information such as a cyclic redundancy check (CRC) so the receiver can determine whether the symbols were received correctly. A hybrid asynchronous retransmission request (HARQ) scheme is used whereby following receipt of messages over a downlink communications resource, the receiver can either request retransmission, or acknowledge receipt, by transmitting an ACK/NACK message on an uplink channel within a certain time period. An efficient method of obtaining the HARQ ACK/NACK message from the UE by a relay node at the subframe of backhauling transmission from the relay node to the eNB is provided, wherein certain defined message subframes are split between the presently defined use of communicating a physical uplink control channel (PUCCH) and an uplink backhaul transmission from the relay node to the eNB.

According to another illustrative embodiment, in a system having an eNB communicating with one or more UEs attached to a relay node RN over an access link, the RN may allocate in a scheduling message an uplink resource UL physical uplink shared control channel (PUSCH) transmission. The PUSCH includes several UE fields such as channel quality indicia (CQI), certain precoding matrix identifiers (PMI), and may include the ACK/NACK for a previously received downlink message. By receiving only part of the information that includes the ACK/NACK, and splitting the subframe usage, the RN may use the remaining resources in the subframe to perform an uplink backhaul transmission to the eNB, and may obtain HARQ ACK/NACK from UEs attached to the RN at the subframe of backhaul transmission.

According to another illustrative embodiment, in a system having an eNB communicating with one or more UEs attached to a relay node RN over an access link, the RN may allocate in a scheduling message transmitted to an attached UE an uplink resource UL physical uplink shared control channel (PUSCH) transmission, or an uplink resource UL physical control channel (PUCCH). The RN may make a determination of which of these uplink resource allocations to transmit based on, inter alia, the signal conditions and channel quality at the RN-UE. If the RN- UE has good signaling conditions, the PUCCH approach described above may be used. For RN- UEs with poor channel quality or signaling conditions, the PUSCH uplink resource may be used. In either approach, the RN uses part of a subframe to perform a backhaul transmission to the eNB, therefore obtaining HARQ ACK/NACK from UEs attached to the RN at the subframe of the backhaul transmission.

According to another illustrative embodiment, an apparatus is provided for a relay node in a time division duplexed (TDD) packet switched radio frequency communications system to switch, during a subframe message, from receiving mode where the RN is receiving signals from an attached UE, to a transmitting mode where the RN is transmitting signals to an eNB over a backhaul link during a defined communications message where the UE operates in an uplink communication without being aware of the switch by the RN. According to another illustrative embodiment, an apparatus is provided for a relay node in a time division duplexed (TDD) packet switched radio frequency communications system to switch, during a subframe message, from receiving mode where the RN is receiving signals from an attached UE over an access link, to a transmitting mode where the RN is transmitting signals to an eNB over an uplink backhaul link during a defined communications message where the UE transmits a defined subframe uplink message in two slots of the subframe.

According to another illustrative embodiment, a method is provided for a relay node in a time division duplexed (TDD) packet switched radio frequency communications system to provide, during a resource allocation download to an attached UE device, additional resource blocks for the UE to use in transmitting a physical uplink shared channel (PUSCH) message to maintain certain desired performance levels to the scheduled UEs. The resource granting to the UE by the relay node RN is provided by higher level signaling as a higher MCS offset for ACK/NACK transmissions, or for more physical resource blocks (PRBs) dynamically scheduled by the RN for the PUSCH channel, and the higher level signaling is allocated using messages defined in present LTE standards. In yet another embodiment, a method embodiment is provided for splitting subframes in an eNB attached by the relay node in a time division duplexed (TDD) packet switched radio frequency communications system to provide, during a resource allocation download to the RN for use in communicating uplink messages on the backhaul link, dynamic slot schedules for different RNs attached to the eNB in different frequency subchannel slots. In this manner, multiple RNs are allocated resources in a frequency division multiplexed (FDM) and also in a time division multiplexed (TDM) manner, so that physical resource blocks are efficiently utilized for backhaul communications.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order for the detailed description of the invention that follows to be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present invention. It should also be realized by those skilled in the ait that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in claims that may be presented.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which: Figure 1 illustrates a system level diagram of a radio frequency interface communication system including a wireless communication system;

Figure 2 illustrates a system level diagram of a radio frequency interface communication system including a wireless communication system incorporating a relay node;

Figure 3 illustrates a block diagram of an embodiment of a wireless communication device and a network element;

Figure 4 illustrates the physical layer and higher layer protocols used in exemplary communication systems;

Figure 5 illustrates the type 2 transport radio frame used in the e-UTRAN system to physically communicate packets to and from, for example, an e-Node B device using TDD; Figure 6 depicts the TDD frame configurations available in e-UTRAN for TDD radio frames;

Figure 7 depicts in a signal block diagram, timing of radio frames with a relay node between an eNB and a UE;

Figure 8 depicts backhaul symbols in the radio frames of Figure 7; Figure 9 depicts backhaul symbols in the radio frames of Figure 8;

Figure 10 depicts the relay transmissions for a relay node in FDD configuration;

Figure 11 illustrates the radio frames used in a system with an eNB communicating through a relay node in a TDD configuration;

Figure 12 illustrates an exemplary embodiment method where a subframe is split into two portions;

Figure 13 illustrates in a signaling block diagram another configuration where ACK/NACK symbols are present;

Figure 14 illustrates an example of a method embodiment providing a subframe split of the signals in Figure 13; Figure 15 illustrates an example of another method embodiment providing another subframe split of the signals in Figure 13; Figure 16 illustrates an example of a subframe split on a signaling block with additional control signal allocation;

Figure 17 illustrates simulation results of ACK/NACK signals in two different system configurations; Figure 18 depicts the use of another method embodiment for a relay node with different protocols for splitting subframes for different UEs;

Figure 19 illustrates another timing aspect of the use of relay nodes in a communications system; and

Figure 20 illustrates the use of another method embodiment where the backhaul transmissions to an eNB are allocated across frequency and time division multiplexed signals.

DETAILED DESCRIPTION

The illustrative embodiments are described as non-limiting examples, in the context of an application in an E-UTRAN system configured with one or more relay node RNs between base stations eNBs and user equipment UEs, typically communications using time division duplexed (TDD) signaling. However, the embodiments and the invention are not limited to this particular example application. The use of the embodiments in other communications systems to provide implicit rales for determining and configuring the splitting of subframes to enable the relay nodes to deliver to a base station or eNB the ACK/NACK signals needed to support a hybrid automatic retransmission request (HARQ) scheme by allocation of subframes and physical resources is envisioned as part of the present invention, and such embodiments are within the scope of any claims presented.

Referring now to Figure 1, illustrated is a system level diagram of a radio frequency interface communication system 1, including a wireless communication system that provides an environment for the application of the principles of the present invention. The wireless communication system may be configured to provide features included in the evolved UMTS terrestrial radio access network (e-UTRAN) universal mobile telecommunications services. Mobile management entities (MMEs) and user plane entities (UPEs) 13 provide control functionality for one or more e-UTRAN node B (designated "eNB," or "evolved node B," also commonly referred to as a "base station) 15 via an Sl interface or communication link. The base stations communicate via an X2 interface or communication link. The various communication links are typically fiber, microwave, or other high-frequency metallic communication paths such as coaxial links, or combinations thereof.

The base stations communicate over an air interface with user equipments 11 (designated "UE), which is typically a mobile transceiver carried by a user. Alternatively, the user equipment may be a mobile web browser, text messaging appliance, a laptop with a mobile PC modem, or other user device configured for cellular or mobile services. Thus, communication links (designated "Uu" communication links) coupling the base stations to the user equipment are air links employing a wireless communication signal. For example, the devices may communicate using a known signaling approach such as a 1.8 GHz orthogonal frequency division multiplex (OFDM) signal. Other radio frequency signals may be used.

The eNBs 15 may host functions such as radio resource management (RRM) (e.g., internet protocol (IP), header compression and encryption of user data streams, ciphering of user data streams, radio bearer control, radio admission control, connection mobility control, dynamic allocation of resources to user equipment in both the uplink and the downlink), selection of a mobility management entity at the user equipment attachment, routing of user plane data towards the user plane entity, scheduling and transmission of paging messages (originated from the mobility management entity), scheduling and transmission of broadcast information (originated from the mobility management entity or operations and maintenance), and measurement and reporting configuration for mobility and scheduling. The MME/UPEs 13 may host functions such as distribution of paging messages to the base stations, security control, terminating U-plane packets for paging reasons, switching of U-plane for support of the user equipment mobility, idle state mobility control, and system architecture evolution bearer control. The UEs 11 receive an allocation of a group of information blocks labeled physical resource blocks (PRBs) in messages transmitted from the eNBs. Figure 2 illustrates a simplified system level diagram of an example wireless communication system 2 that provides an environment and structure for application of the principles of the present invention. In Figure 2, an e Node B 21 is coupled to a relay node 23, by a link labeled "backhaul transmission". The relay node 23 is depicted in communication with two UEs labeled 25 over access links. The UEs are registered with the eNode B is such a manner that the presence of the relay node is transparent to the UEs, that is, the messages sent and received by these UEs operate in the same manner as if they were directly connected to the eNB.

Figure 3 depicts in a block diagram the blocks of a communication element 31 coupled to a network by an element 39. The communication element may represent, without limitation, an apparatus including an eNB, a UE such as a terminal or mobile station, a network control element, or the like. The communication element 31 includes, at least, a processor 35, memory 37 that stores programs and data of a temporary or more permanent nature, an antenna, and a radio frequency transceiver 33 coupled to the antenna and the processor 35 for bidirectional wireless communication. Other functions may also be provided. The communication element may provide point-to-point and/or point-to-multipoint communication services. The communication element 31, such as an eNB in a cellular network, may be coupled to a communication network element 39, such as a network control element of a public switched telecommunication network (PSTN). The network control element may, in turn, be formed with a processor, memory, and other electronic elements (not shown). Access to the PSTN may be provided using fiber optic, coaxial, twisted pair, microwave communication, or similar communication links coupled to an appropriate link-terminating element. A communication element 31 formed as a UE is generally a self-contained device intended to be carried by an end user and communicating over an air interface to other communication elements in the network.

The processor 35 in the communication element, which may be implemented with one or a plurality of processing devices, performs functions associated with its operation including, without limitation, encoding and decoding of individual bits forming a communication message, formatting of information, and overall control of the communication element, including processes related to management of resources. Exemplary functions related to management of resources include, without limitation, hardware installation, traffic management, performance data analysis, tracking of end users and mobile stations, configuration management, end user administration, management of the mobile station, management of tariffs, subscriptions, and billing, and the like. The execution of all or portions of particular functions or processes related to management of resources may be performed in equipment separate from and/or coupled to the communication element, with the results of such functions or processes communicated for execution to the communication element. The processor 35 of the communication element may be of any type suitable to the local application environment, and may include one or more of general-purpose computers, special-purpose computers, microprocessors, digital signal processors (DSPs), and processors based on a multi-core processor architecture, as non-limiting examples.

The transceiver 33 of the communication element 31 modulates information onto a carrier waveform for transmission by the communication element via the antenna to another communication element. The transceiver demodulates information received via the antenna for further processing by other communication elements.

The memory 37 of the communication element 31, as introduced above, may be of any type suitable to the local application environment, and may be implemented using any suitable volatile or nonvolatile data storage technology, such as a semiconductor-based memory device, a magnetic memory device and system, an optical memory device and system, fixed memory, and removable memory. The programs stored in the memory may include program instructions that, when executed by an associated processor, enable the communication element to perform tasks as described herein. Exemplary embodiments of the system, subsystems, and modules as described herein may be implemented, at least in part, by computer software executable by processors of, for instance, the mobile station and the base station, or by hardware, or by combinations thereof. Other programming may be used such as firmware and/or state machines. As will become more apparent, systems, subsystems and modules may be embodied in the communication element 31 as illustrated and described above.

Figure 4 depicts a block diagram of an embodiment of a UE 11 and an eNB 15 constructed according to the principles of the present invention and coupled to an MME 13. The UE and the eNB each include a variety of layers and subsystems; the physical layer (PHY) subsystem, a medium access control layer (MAC) subsystem, a radio link control layer (RLC) subsystem, a packet data convergence protocol layer (PDCP) subsystem, and a radio resource control layer (RRC) subsystem. Additionally, the user equipment and the mobile management entity (MME) include a non-access stratum (NAS) subsystem. The physical layer subsystem supports the physical transport of packets over the LTE air interface and provides, as non-limiting examples, cyclic redundancy check (CRC) insertion (e.g., a 24 bit CRC is a baseline for physical downlink shared channel (PDSCH), channel coding (e.g., turbo coding based on QPP inner interleaving with trellis termination), physical layer hybrid- automatic repeat or retransmit request (HARQ) processing, and channel interleaving. The physical layer subsystem also performs scrambling, such as transport-channel specific scrambling on a downlink-shared channel (DL-SCH), broadcast channel (BCH) and paging channel (PCH), as well as common multicast channel (MCH) scrambling for all cells involved in a specific multimedia broadcast multicast service single frequency network (MBSFN) transmission. The physical layer subsystem also performs signal modulation such as quadrature phase shift keying (QPSK), 16 quadrature amplitude modulation (QAM) and 64 QAM, layer mapping and pre- coding, and mapping to assigned resources and antenna ports. The media access layer or MAC performs the HARQ functionality and other important functions between the logical transport layer, or Level 2, and the physical transport layer, or Level 1. Each layer is implemented in the system and may be implemented in a variety of ways. A layer such as the PHY in the UE may be implemented using hardware, software, programmable hardware, firmware, or a combination of these as is known in the art. Programmable devices such as DSPs, RISC, CISC, microprocessors, microcontrollers, and the like may be used to perform the functions of a layer. Reusable design cores or macros as are provided by vendors as ASIC library functions, for example, may be created to provide some or all of the functions and these may be qualified with various semiconductor foundry providers to make design of new UEs, or e-Node B implementations, faster and easier to perform in the design and commercial production of new devices.

The e-UTRAN system architecture has several significant features that impact timing in the system. A transmission time interval (TTI) is defined and users (e.g., UE or mobile transceivers) are scheduled on a shared channel every TTI. The majority of UE or mobile transceivers considered in the implementation of the e-UTRAN are full duplex devices. These UEs can therefore receive control and data allocations and packets from the e-Node B or base station they are connected to in any subframe interval in which they are active. The UE detects when resources are allocated to it in the allocation messages on the physical downlink control channel (PDCCH). When downlink resources are allocated to a UE, the UE can determine that data or other packets are going to be transmitted towards it in the present frame or in coming frames. Also, the UE may have uplink resources allocated to it. In this case, the UE will be expected to transmit towards the e-Node B in coming frames on the uplink based on the allocated UL resources. Additional timing related services are present in the environment. The e-UTRAN communications system provides automatic retransmission request (ARQ) and hybrid automatic retransmission request (HARQ) support. The HARQ is supported by the UE and this support has two different aspects. In the downlink direction, asynchronous HARQ processes are supported. However, the uplink or UL channel is a different standard channel that uses single carrier FDMA (SC-FDMA) and as currently provided, requires a synchronous HARQ. That is, in the uplink direction, after a packet is transmitted to the UE, an ACK/NACK (acknowledged/not acknowledged) response is transmitted by the UE towards the eNB within a definite time period later, after which the eNB, in case NACK was received, will retransmit the packet in the DL direction in a given subframe after a predetermined delay. This synchronous HARQ specification puts a timing constraint on the subframe resource allocations. As the LTE specifications are presently configured, the UE has to be able to make a UL transmission at certain points in time.

The e-UTRAN specifications support air interface signaling using both frequency division duplex (FDD), where uplink (signaling from the UE to the eNB) and downlink (signaling from the eNB towards the UE) can occur at the same time instant but are spaced apart at different frequencies, and time division duplex (TDD), where the UL and DL frames are communicated on the same single frequency carrier but spaced apart in time.

Of particular interest to the embodiments of the present invention are the frame structures of TDD radio frames. The frame structures have been selected so that TDD and FDD services may be supported in the same environment and dual-mode devices may be easily implemented. The selection of the FDD or TDD services may depend on the type of data, whether the data transmission is asymmetric (for example, internet browsing tends to be very heavy on the downlink, while voice may be more or less symmetric on both downlink and uplink) the environment, and other parameters, there are advantages and disadvantages to each that are known to those skilled in the art.

The technical specifications (TS) document entitled "3GPP TS 36.300" version 8.5.0 (2008-05) available from the website www.3gpp.org provides in part the specifications for the physical interfaces for the E-UTRAN networks, which document is hereby incorporated by reference in its entirety. The following 3GPP technical specifications are also hereby incorporated by reference in their entirety herein; 3GPP TS 36.213 v860, entitled "Physical Layer Procedures"; and, 3GPP TS 36.212 v860, entitled "Multiplexing and Channel Coding".

Figure 5 depicts, in very simple form, the type 2 transport frame 51 used in the e-UTRAN system to physically communicate packets to and from, for example, an e-Node B device and one or more UE (or relay node) devices over the air interface using TDD. The document TS 36.300 v 8.5.0 incorporated above describes the TDD frame in more detail at pages 19-20. A radio frame in the system is presently defined as having a length of 10 milliseconds. The radio frame is further subdivided into 10 subframes, each having a length of 1 millisecond. Each subframe is further divided again into two slots; each slot has a length of 0.5 milliseconds as shown.

The TDD frame further has three special fields that may be varied in length to form a 1 millisecond subframe. These special fields are the downlink pilot time slot (DwPTS), the guard period (GP) and the uplink pilot time slot (UpPTS). The TDD frame is the same length (10 milliseconds, which is 2 half-frames, or 10 subframes, each having two slots) as the FDD transport frame, making dual mode equipment easier to implement.

The e-UTRAN TDD frame is further designed to have both 5 millisecond and 10 millisecond switch point periodicity. There are seven frame configurations defined for TDD communications that determine which arrangement of downlink and uplink patterns are to be used. Figure 6 presents the TDD configuration patterns, which would be chosen by the radio resource controller (RRC) and communicated to the UE by the eNB, so the configuration pattern selected is known to both the UE and the eNB. Typically, the configuration believed to be chosen for most applications is #1. Another that will be used as a non-limiting example for the discussion that follows is configuration #4. However, the configuration may be chosen to be any of the 7 defined in the specification. Further, the amount of downlink and uplink traffic subframes may be determined in part by the TDD configuration #0-6 that is selected.

TDD signaling may be chosen for a particular portion of the e-UTRAN system to take advantage of several beneficial aspects of TDD. The UE implementation for TDD devices may be kept fairly simple, for example, which lowers the cost of the devices. High peak data rates are provided in a limited frequency spectrum (since all transmissions are in a shared spectrum, unlike FDD). Reciprocity for fast and lean link adaptation and advanced antenna methods are available, including the use of multiple antennas, in both the e-Node B and UE equipments. Finally, the ability to achieve a significant gain in trunking efficiency comes from the ability to dynamically adjust uplink and downlink resources to match the traffic needs in the cell. The LTE specification offers the TDD operator up to 80% of the bandwidth of the system resources for downlink traffic.

Figure 2 depicts a typical wireless communications environment where embodiments of the present invention may be advantageously applied. To enhance understanding, the proposed approaches previously submitted for consideration in the standards bodies will first be discussed in terms of how to provide the needed UL HARQ support (in the form of a UL ACK/NACK message from the UE back to the e-NB, corresponding to an earlier DL packet or packets transmitted on the downlink to the UE) while using a relay node RN. Embodiments of the present invention are now described. These embodiments provide methods and apparatus for splitting previously defined subframes without negative impact on the operation of any UE attached to the relay node, to enable the relay node to perform a backhaul link transmission or uplink resource allocation to the corresponding eNode B.

In the process of setting the standards for use of the relay node, a basic protocol for the relay node communications was agreed to. The RAN document entitled Rl-091361, "Text Proposal for 36.814 on Access-Backhaul Partitioning of Relays", Nokia, Nokia Siemens Networks, which is hereby incorporated by reference in its entirety describes the baseline requirements which are summarized as follows:

• e-NB → RN and RN → UE links are TDM in a single frequency band (only one active at a time) • RN — > e-NB and UE → RN links are TDM in a single frequency band (only one active at a time)

• A scheme supported in FDD: e-NB → RN in DL frequency

RN → e-NB in UL frequency • A scheme supported in TDD: e-NB → RN in DL subframes of the e-NB and RN RN → e-NB in UL subframes of the e-NB and RN

The basic scheme is therefore that the RN is a TDM device and can only communicate with either the UE or the eNB at a given time, not both; and that the frames used by the RN are the same as for the eNB. This is a simple solution but problems in the actual use of relay nodes implemented in the system are described in more detail below. The embodiments described below provide solutions to these problems. In Figure 7, some simple system timing when a relay node is present is considered, for example for the system of Figure 2 using TDD subframes. In Figure 7, the frames 71 performed by an RN-UE is shown at the bottom of Figure 7. Initially, the RN-UE is first transmitting a UL message towards the eNB. The first subframe is shown as a UL pilot symbol (UpPTS). The attached relay node RN then receives the UL subframes in block 75, and according to the TDD configuration, at time marked 77, switches to a downlink frame. Similarly, the attached eNB frames 79 are shown; first two UL frames are performed, then a switching occurs at time labeled 78, and then a downlink frame 73 is performed. There is a delay time from the UE to the eNB of "TA" shown in Figure 7 as the sum of the propagation time T_prop and the switch time T_Switch. In Figure 8, a case study is shown depicting how the relay node timing impacts the frame allocation and physical resource blocks available. In Figure 8, the RN-UE frames are shown in 81, the RN frames are shown as 83, and the eNB frames are shown as 87. The relay node RN transmits on the backhaul to the eNodeB in the first slot of the first subframe, shown as element 82 in the figure. During this interval, the UE attached to the relay node, RN-UE, is also shown in an uplink subframe; however, the RN does not receive the transmission in the first slot as the RN is then transmitting backhaul UL symbols to the eNB. Then, at event 84 in the figure, the RN switches from transmit to receive mode, and receives the UL communications from the RN-UE in the second slot. Also, as shown in box 88 in the figure, because each slot of the subframe represents a number of symbols transmitted as single carrier, frequency division multiple access signals (sc-fdma), 5 symbols are available for the backhaul UL. In a case where the UL pilot symbol is not needed, UpPTS in the figure, then an extra 6th sc-fdma symbol is also available for backhaul traffic.

Figure 9 depicts, in a signaling block diagram, the frames for the RN-UE 91, the RN 93, and the eNB 95 in a configuration such as shown in Figure 2, when the RN transmits backhaul UL traffic to the eNodeB in the second slot of a subframe. Block 91 shows the subframes at the RN-UE. The RN frames are shown in block 93, where the RN receives traffic from the RN-UE in the first slot, shown as element 92, and switches to transmit on the backhaul link in the second slot, shown as element 94. Box 96 illustrates that, in this example, there are 5 sc-fdma symbols for the backhaul uplink traffic .

As described above, the agreed scheme for the relay node is that it is a single frequency network (SFN) and that transmissions on the backhaul and receipt of traffic on the access link are time division multiplexed. Thus, the RN cannot transmit to the eNB and receive uplink messages from the UE at the same point in time. Therefore, when the RN is transmitting UL backhaul traffic in a subframe, this subframe has to be "blanked" for the attached UE, the RN-UE cannot send uplink HARQ messages in that subframe for previously received DL data transmissions.

Figure 10 illustrates that for an FDD mode system, this aspect of the RN has little impact. In FDD, the downlink and the uplink are separated in frequency, and therefore the RN may send uplink messages and receive downlink messages at the same time. By restricting DL traffic to the UE away from certain subframes, for example, subframe "M" in Figure 10, there will be no corresponding UL subframe at the time the RN needs to "blank" the UL traffic from the UE. Thus, it can be assured that no HARQ is needed in those subframes when the RN is going to be doing backhaul uplink transmissions.

In Figure 11, the problem that various embodiments of the present invention solve is illustrated. In a TDD configured system with a relay node, a repetitive message from the UE to the eNB that is an uplink HARQ message may not be able to be transmitted. In Figure 11, a standard TDD configuration #4 is depicted with the subframes at the eNB, the RN and the PUCCH (physical uplink control channel) process being performed by the RN-UE. A HARQ process line shows HARQ processes 1 and 2, which correspond to DL traffic received by the UE earlier. At the RN, the subframes numbered "3" are used to transmit backhaul uplink traffic to the eNB which is, at those subframes, in UL mode (receiving). However, the HARQ process 2 requires additional uplink subframes at the RN, but because the RN is switched to a transmit backhaul mode at the critical subframe, no uplink between the UE and the RN is available. See element 111. Thus, there is a problem known as "feedback missing" for TDD systems with relay nodes. The example shown in Figure 11 is for TDD configuration #4 (see Figure 4), but this feedback missing issue will arise with other TDD configurations. For example, this problem occurs where one or two UL subframes relate to several DL subframes, i.e., HARQ messages.

A simple approach to reserve all related DL subframes for DL backhaul transmission could be attempted, but this would result in a great DL throughput loss in the relay node RN. Also, this will result in many resources wasted in the backhaul downlink as it may not need so many subframe resources. Further, subframes 0, 1, 5 and 6 in configuration 4 cannot be reserved for downlink backhaul, so this approach is not workable.

The previously known solutions to the TDD relay node missing feedback problem are clearly not adequate. Embodiments described below are methods to solve this problem. Six different methods are discussed in detail below:

Method 1: In a certain UL subframe, if the RN needs to do UL backhaul transmission, a method to enable this transmission without affecting the UE timing is that the RN receives only part of a PUCCH channel which is transmitted as a UL by RN-UEs, e.g., only receive the first slot to get ACK/NACK and use some of the remaining subframe to perform the backhaul UL to the eNB.

Method 2: In a certain UL subframe, if the RN needs to do UL backhaul transmission, one method is that the RN schedules the attached RN-UEs for a UL PUSCH (physical uplink shared control channel) transmission, where CQI/PMI/RI and ACK/NACK could be included. To create a subframe for the uplink backhaul transmission, the RN only receives part of the PUSCH to get the ACK/NACK information, and then uses some of the remaining symbols in the subframe for the backhaul transmission to the eNB. Method 3: In a certain UL subframe, the relay node may perform a method to determine whether to schedule the UE to perform a PUSCH, or to use PUCCH to deliver ACK/NACK. The method for determining may be determined by a known parameter, such as the RN-UEs channel quality. In this approach the relay node could get the needed ACK/NACK from the UEs from PUCCH or PUSCH, from different UEs, respectively. This method is a combination of Method 1 and Method 2, which will provide the advantages of more stable and higher ACK/NACK performance than Method 1 alone and higher ACK/NACK capacity than Method 2, when used alone. The RN selects the method for the particular RN-UE to use based on the signaling conditions of the RN to get the best result and configures the UE appropriately through resource allocation communications, as presently defined in the LTE specification. This method then further optimizes the system performance.

Method 4: For part of a UL subframe, the RN may perform a method where it switches from Rx mode to Tx mode, and then transmits in UL backhaul for a certain time interval. Advantageously this operation will not be observed by Release 8.0 UEs to maintain backward compatibility, as the Release 8.0 UEs will operate normally and not be aware of the RN operations.

Method 5: In this method, the RN intentionally adjusts its way of resource granting, i.e., more resources will be allocated to increase the control part of the resources in PUSCH to maintain certain link level performance to the scheduled UEs. This kind of resource granting is in the form of higher MCS "offset" for ACK/NACK transmission or more PRBs dynamically scheduled by RN for PUSCH. Advantageously, this method could be implemented based on existing Rel-8 specifications.

Method 6: In this method, when the e-NB schedules relay nodes on the backhaul link, the e-NB could dynamically schedule relays to different slots, and reserved physical resources block for backhaul link transmission will be allocated in a horizontal way (time direction) to minimize the wasted resource. Thus, in this method, the backhaul UL transmissions for multiple relay nodes are frequency division multiplexed plus time division multiplexed in those PRBs reserved for backhauls UL transmission.

In addition to the other method embodiments described above, additional control signaling (at Ll or higher layer) may be designed on the backhaul link to ensure correct backhaul communications .

Figure 12 depicts in a simple resource block diagram an implementation of a first subframe splitting embodiment for providing the required uplink feedback. In the current Release 8.0 Specification for LTE, the uplink channel PUCCH is used for carrying the uplink HARQ feedback in the edge frequency of the uplink subframe. This approach is an efficient way to transmit uplink feedback because large numbers of ACK/NACK messages of different UEs may be multiplexed in one physical resource block (PRB). As currently specified, the PUCCH channel is transmitted in slightly different format in both Slot 0 and in Slot 1 in one transmission time interval (TTI). A method for providing the backhaul uplink needed by the RN is to have the RN receive the PUCCH in one of the two slots, and transmit the backhaul message in the remaining slot. The UE will not be affected and will continue to transmit the PUCCH in both slots as before. In Figure 12, an embodiment is illustrated where the uplink backhaul transmission is performed in the second slot, so the RN has a switching point ("Switching time") in the figure, and during the second slot of the PUCCH, the RN transmits a backhaul UL message to the eNB. Advantages achieved with this approach are that it could provide at high capacity four ACK/NACK messages. For UEs that are in poor signaling conditions, such as longer transmit distances to the RN, the loss of the second slot may impact the performance (bit error rate or BER) during the PUCCH. If the UE has power control available, the RN may be able to configure the UE to use higher power to transmit the PUCCH. However, for an example where the UE has good channel quality and signaling conditions to the RN, this method embodiment is an attractive approach.

Figure 13 depicts the signaling frames for a second method embodiment to add the needed backhaul capacity. In the current release 8.0 specification, the RN could schedule the UE to perform a physical uplink shared control channel (PUSCH) with no uplink data. This channel from the UE has uplink control signaling such as CQI, PMI, and ACK/NACK. In the current technical specification, as illustrated in Figure 13, the ACK/NACK symbols are mapped in the four symbols that neighbor a reference signal RS. In this situation, the RN only needs to receive the ACK/NACK information, and since the ACK/NACK symbols are mapped only to certain symbols, the RN time division multiplex (TDM) receiving the ACK/NACK symbols, and the backhaul transmissions.

In Figure 14, a first approach to using the method described above is illustrated. In Figure 14, four symbols in the middle of the subframe labeled element 141 are used for the backhaul transmission. That is, during these symbols the RN switches to transmit, and transmits the ACK/NACK symbols on the backhaul link, and then switches back to the receive mode. However, there are only two symbol periods remaining for the backhaul transmission as shown at 141.

Figure 15 depicts a second approach to the subframe splitting of the PUSCH channel. In Figure 15, the relay node can select either slot 0 or slot 1 of the PUSCH to receive the ACK/NACK, and then the relay can switch to transmit mode and perform the uplink backhaul transmission to the eNB. The RN-UEs will again transmit the entire (repetitive) PUSCH channel and the RN-UEs are otherwise not affected. There may be some loss of performance with this approach, as the RN only receives half the ACK/NACK symbols. However, Release 8.0 of the LTE spec allows the RN to configure the UEs to have either more physical resource blocks for ACK/NACK, and thereby decrease the coding rate and improve performance, or in another approach using features of Release 8.0 of the LTE standard, the RN can use higher level signaling to the UE to provide a larger offset of ACK/NACK, thereby decreasing the coding rate of the ACK/NACK symbols and to boost the performance,

Note that in Figure 15, the RN could perform the backhaul transmission in the upper half of the PRBs (Slot 0) and receive the PUSCH from the UEs in the lower half (Slot 1). Figure 16 depicts the effect of additional resources used for ACK/NACK in the PUSCH messages. In Figure 16, block diagram 161 indicates the default PRB allocation. In block 163, the resources for ACK/NACK are increased, and the number of symbols for ACK/NACK is shown as taking more of the PRB capacity.

In a simulation result shown in Figure 17, two bit error rate (BER) results were obtained and compared. In the first one, the upper trace in plot 171, both slots of the PUSCH were available to receive the ACK/NACK information from two receivers as shown in the signal block diagram 173. In the second simulation, shown as the lower trace in plot 171, one slot was stolen (e.g. used for backhaul) and the resources were increased for ACK/NACK as shown in the signal block diagram 175. In the simulation, the BER performance for receiving the ACK/NACK for the single slot with increased resource allocations was even better (lower bit error rate) than for receiving both slots with lower allocations. Thus, by increasing the resource allocations for ACK/NACK in the PUSCH channel from the UE, the RN may use one of the two slots of the PUSCH for the backhaul UL transmission to the eNB without any loss of performance in the system. Figure 18 depicts the use of yet another embodiment in a system with a relay node 183.

Again, a backhaul link (labeled Backhaul transmission) couples the relay node 183 to the eNb 181. Two UEs are shown, both attached to the relay node 183. UE 185 has a good access link to RN 183. Relay 187 has a bad link (poor signal quality, CQI or other indicia of poor SNR) to the relay node 183. As depicted in Figure 18, the RN may configure UE 185 to use the first approach for backhaul transmissions described above, that is, the RN may allocate a PUCCH channel to UE 185 and then use the second slot (or the first slot) of two slots for the backhaul transmission as shown in signal block diagram 186.

Signal block diagram 188 depicts the use of the PUSCH channel approach, with the possibility of additional ACK/NACK resource allocations. So in this method embodiment, the RN may determine from known signaling conditions which approach to use for an RN-UE to get the best result.

Figure 19 illustrates another aspect of the implementation of the relay feature in the existing LTE Release 8.0 standard. UE timing for the PUSCH channel is shown as element 191. The first slot and the second slot have the same information. The RN timing is shown as 193. The slot #0 may be used, as described above, to receive the UL traffic from the UE performing the PUSCH or PUCCH channel. The second slot, as proposed above, may be used to transmit the backhaul uplink to the eNB. However, the first slot in the frame at the eNB 195 is not available under current Release 8.0 specifications, because the definition of both of the PUCCH/PUSCH channels is that the UL message takes both slots. For an eNB configured as a "macro cell", that is with multiple RN devices attached, this problem of efficiency gets even worse.

Another exemplary method embodiment is now described where resources are allocated by the eNB. In this method, a resource reservation scheme is utilized to multiplex, in the frequency domain, multiple backhaul communications from RNs, and also, these may be multiplexed in the time domain.

In Figure 20, the eNB 201 may reserve resources for PRBs such that the RNs 205, 203, 207, 209 use the frequency subchannels (PRBs) and the time slots to fill each frame of the eNB UL with backhaul traffic. In block 210, the even (or alternatively, odd, respectively) numbered RNs operate in receiving ACK/NACK information with slot #0 and transmit backhaul information in slot #1. In contrast, in Format 2, block 212, the odd (or even, respectively) RNs receive the ACK/NACK information from their UEs in slot #1, and use slot #0 for the backhaul transmissions to the eNB. So in this manner, by assigning the RNs to particular slots, the eNB utilizes the PRBs as efficiently as possible. At least the approach is much more efficient, even if each slot cannot be used, than wasting the first slot of each pair of slots as would happen if 5 communication was with Release 8.0 UEs. Block 213 illustrates the result.

While this scheme is described with respect to RNs that the eNB can schedule in this manner, because Release 8.0 UEs cannot split the slots of the PUCCH/PUSCH, in the future, a useful improvement will be to allow the Release 9.0 UEs and more advanced UEs to split the subframe slots and thus reduce the wasted resources that are otherwise now caused by the rules 10 presently in place.

In order to implement the method where the eNB reserves resources for the backhaul transmission as described, additional control signals are needed. One non-limiting example of a method to provide these is to add control bits in a resource allocation message transmitted to the RN as shown in Table 1:

1.5

Table 1 Signaling design for backhaul link resource reservation scheme

The method embodiments above may be implemented in software, hardware, or firmware, and may be stored on a computer readable medium such as an optical disk, memory, flash drive, stored location, hard drive etc. as executable code which, when executed by a 0 programmable processor, perform the methods described above to split subframes in the relay node to enable the needed uplink backhaul communications.

The advantages obtained by use of the methods described above are that the needed UL HARQ feedback and UL backhaul transmission is performed in one UL subframe in a baseline relay system without the need to modify existing equipment such as Release 8.0 UEs in most of 5 the methods described. The methods provide efficient use of system resources. Generally, the methods described above enable the HARQ UL feedback to the eNB in one transmission time interval (TTI).

Note that the implementation of any of the embodiments above may be performed in software, hardware, or firmware, and may be provided as a set of instructions that are retrieved 30 from storage and executed by a programmable processor or other programmable device that is part of a UE, RN or eNB implementation including, without limitation, core processors such as RISC, ARM, CPU, DSP and microcontroller cores, or standalone integrated circuit devices. The method may be implemented as a state machine with associated logic circuitry. An FPGA or CPLD, ASIC, semi-custom IC or the like may be used. The storage may be non- volatile memory such as FLASH or programmed memory such as PROM, ROM, EPROM and the like. The storage may be a CD or DVD program storage medium containing the executable instructions for performing the embodiments. In one embodiment, executable instructions are provided on a computer readable medium that when executed, perform the methods of determining the subframe splitting to be performed in a relay node to allow for backhaul uplink transmissions of ACK/NACK messages. The illustrative embodiments described above are directed to an LTE or LTE-A 3GPP communications system with relay nodes in TDD configuration. However, the embodiments are not limited to this illustrative, non-limiting example application and the use of the embodiments in other communications systems to provide rules for the advantageous splitting of subframes in a time division duplexed communication system with relay nodes is envisioned as part of the present invention and within the scope of any claims presented.

Claims

WHAT IS CLAIMED IS:

1. An apparatus, comprising: at least one processor; and memory including computer program code; the computer program code configured to, with the at least one processor and the memory, cause the apparatus to perform at least the following: receive symbols in a first time interval of uplink subframes comprising a first portion of an uplink message frame from a user equipment device over an air interface; and transmit symbols in a second time interval of uplink subframes as an uplink backhaul message over the air interface.

2. The apparatus according to claim 1 wherein the memory including the computer program code is configured to, with the at least one processor, cause said apparatus to ignore symbols in a second time interval of uplink subframes comprising a second portion of the uplink message frame transmitted over the air interface by the user equipment device.

3. The apparatus according to claim 1 or claim 2 wherein the memory including the computer program code is configured to, with the processor, cause the apparatus to receive a first time interval of uplink subframes comprising the first portion of the uplink message frame as part of a physical uplink channel communication.

4. The apparatus according to any of claims 1-3 wherein the memory including the computer program code is configured to, with the at least one processor, cause the apparatus to receive symbols during the first portion of a first time interval of uplink subframes comprising the first portion of the uplink message frame comprising at least the acknowledge/not acknowledge symbol(s).

5. The apparatus according to any of claims 1 - 4 wherein the memory including the computer program code is configured to, with the processor, cause the apparatus to receive allocations of communication resources for transmitting backhaul messages over the air interface corresponding to symbols in a time interval of uplink subframes.

6. The apparatus according to any of claims 1 - 5 wherein the memory including the computer program code is configured to, with the processor, cause the apparatus to allocate to the user equipment communication resources selected from a physical uplink control channel and a physical uplink shared channel for transmission of symbols in frames over the air interface.

7. The apparatus according to any of claims 1 - 6 wherein the memory including the computer program code is configured to, with the processor, cause the apparatus to determine a channel quality indicator field for the user equipment and to allocate communication resources responsive to the determination.

8. An apparatus, comprising: means for allocating communication resources including physical uplink channels to a user equipment over an air interface; means for receiving symbols in a first time interval of uplink subframes comprising a first portion of an uplink message frame from a user equipment device over an air interface; and means for transmitting symbols in a second time interval of uplink subframes as an uplink backhaul message to a base station over the air interface.

9. The apparatus according to claim 8 and further comprising means for allocating a communications resource over the air interface based on a determination of a channel quality indicator corresponding to the user equipment.

10. The apparatus according to claim 8 wherein the symbols received include at least the acknowledgement/non acknowledgement symbol(s).

11. A computer program product comprising a program code stored in a computer readable medium , which, when executed by an apparatus including a programmable processor and a memory, is configured to cause the apparatus to: determine the channel quality indicator for a plurality of communication devices coupled to the apparatus using shared radio resources in over the air communications; allocate communication resources that are selected from one of a physical uplink control channel and a physical uplink shared channel to at least one of the communication devices, responsive to the determining; receive symbols in a first time interval of uplink subframes comprising a first portion of an uplink message frame from at least one of the communication devices over the air interface; and during a second portion of the uplink message frame, transmit symbols in a second time interval of uplink subframes over the air interface as a backhaul message.

12. The computer program product as recited in claim 11 wherein the program code stored in the computer readable medium is configured to cause the apparatus to ignore symbols in a second time interval of uplink subframes comprising the second portion of an uplink message frame transmitted over the air interface from the at least one of the communication devices while the apparatus is transmitting the backhaul message.

13. The computer program product as recited in claim 11 wherein the program code stored in the computer readable medium is configured to cause the apparatus to allocate the communication resources using a physical downlink channel.

14. A method, comprising: determining the channel quality information for a plurality of communication devices using shared radio resources in over the air communications; allocating uplink message communication resources to the plurality of communication devices using the shared radio resources; receiving symbols in a first time interval of uplink subframes over the air interface from at least one of the communication devices during a first portion of an uplink message frame; and transmitting symbols during a second time interval of uplink subframes over the air interface as a backhaul message.

15. The method according to claim 14 wherein allocating the uplink message communication resources further comprises allocating a physical uplink channel resource.

16. The method according to any of claims 14-15 and further comprising determining that a channel quality indicator for a communications device is above a threshold; and based on the determination, allocating an uplink communications resource one selected from a physical uplink control channel and a physical uplink shared channel.

17. An apparatus, comprising: at least one processor; and memory including computer program code; the memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform at least the following: receive a communication containing one or more backhaul transmission resource allocations to be used in transmitting backhaul messages over a pre-assigned communications resource, receive symbols in a first time interval of uplink subframes comprising a first portion of an uplink message frame from a communications device over an air interface; and transmit symbols in a second time interval of uplink subframes as an uplink backhaul message over the air interface using the allocated resources on the pre assigned communications resource.

18. The apparatus according to claim 17 wherein the backhaul transmission resource allocation is provided via radio resource control signaling over a physical downlink channel.

19. The apparatus according to claim 18 wherein the memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform at least the following: allocate communication resources one selected from a physical uplink control channel and a physical uplink shared channel to the communications device over the air interface.

20. The apparatus according to claim 19 wherein the backhaul transmission resource allocation further comprises a selected slot in a two slot frame of a physical uplink channel.

21. The apparatus according to claim 20 wherein the selected slots in the two slot frame are time division multiplexed.

22. The apparatus according to claim 20 wherein the slots in the two slot frame are frequency division multiplexed.

23. The apparatus according to any of claims 17-22 wherein the apparatus further comprises a relay node device coupled between a base station and a plurality of user equipment devices.

24. An apparatus, comprising: means for receiving a communication containing one or more backhaul transmission resource allocations to be used in transmitting backhaul messages over a pre- assigned communications resource, means for receiving symbols in a first time interval of uplink subframes transmitted from a communications device over an air interface during a first portion of an uplink message frame; and means for transmitting symbols in a second time interval of uplink subframes as a uplink backhaul message using the backhaul transmission resources allocated on the pre assigned communications resource.

25. A method, comprising: receiving a communication from a communications device containing acknowledge/not acknowledge information over an air interface using a pre-assigned communications resource during a first portion of an uplink message frame, and transmitting the acknowledge information as a backhaul message during a second portion of the uplink message frame to at least one other communications device using a shared radio resource.

26. The method according to claim 25 and further comprising: ignoring communications received from the communications device over the air interface during the second portion of the uplink message frame.

27. The method according to claim 25 or claim 26 wherein the first portion of the uplink message frame precedes the second portion in a transmission time interval for the uplink message frame.

28. The method according to claim 25 or claim 26 wherein the second portion of the uplink message frame precedes the first portion in a transmission time interval for the uplink message frame.

28. The method according to any of claims 25-28 and further comprising performing device to device communications using the shared radio resource over an air interface.