Collision avoidance for uplink VoIP transmission

TECHNICAL FIELD

p-0002The exemplary and non-limiting embodiments of this invention relate generally to wireless communication systems, methods, devices and computer program products and, more specifically, relate to techniques for avoiding collisions between transmissions from mobile communication devices.

BACKGROUND

p-0003Various abbreviations that appear in the specification and/or in the drawing figures are defined as follows: <ul><li id="ul0001-0001" num="0003">3GPP third generation partnership project</li><li id="ul0001-0002" num="0004">UTRAN universal terrestrial radio access network</li><li id="ul0001-0003" num="0005">Node B base station</li><li id="ul0001-0004" num="0006">UE user equipment</li><li id="ul0001-0005" num="0007">EUTRAN evolved UTRAN</li><li id="ul0001-0006" num="0008">aGW access gateway</li><li id="ul0001-0007" num="0009">eNB EUTRAN Node B (evolved Node B)</li><li id="ul0001-0008" num="0010">PDU protocol data unit</li><li id="ul0001-0009" num="0011">PRB physical resource block</li><li id="ul0001-0010" num="0012">PHY physical</li><li id="ul0001-0011" num="0013">LTE long term evolution</li><li id="ul0001-0012" num="0014">ARQ automatic repeat request</li><li id="ul0001-0013" num="0015">HARQ hybrid automatic repeat request</li><li id="ul0001-0014" num="0016">OFDMA orthogonal frequency division multiple access</li><li id="ul0001-0015" num="0017">SC-FDMA single carrier, frequency division multiple access</li><li id="ul0001-0016" num="0018">TTI transmission time interval</li><li id="ul0001-0017" num="0019">UL uplink</li><li id="ul0001-0018" num="0020">DL downlink</li><li id="ul0001-0019" num="0021">QoS quality of service</li><li id="ul0001-0020" num="0022">RB resource block</li><li id="ul0001-0021" num="0023">VoIP voice over internet protocol</li><li id="ul0001-0022" num="0024">CATT China Academy of Telecommunications Technology</li><li id="ul0001-0023" num="0025">RITT Research Institute of Telecommunication Transmission</li><li id="ul0001-0024" num="0026">DRX discontinuous reception</li><li id="ul0001-0025" num="0027">AMR adaptive multi-rate</li></ul>

p-0004A proposed communication system known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE or as E-UTRA) is currently under discussion within the 3GPP. The current working assumption is that the DL access technique will be OFDMA, and the UL access technique will be SC-FDMA.

p-0005One specification of interest to these and other issues related to the invention is 3GPP TS 36.300, V8.2.0 (2007-09), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (E-UTRAN); Overall description; Stage 2 (Release 8), incorporated by reference herein in its entirety.

p-0006In LTE the general model for UL resource scheduling is that the eNB allocates resource blocks to UEs based on their UL transmit buffers and QoS profiles and sends scheduling grants to UEs using L1/L2 signaling. Such a model allows for efficient channel sensitive scheduling to maximize throughput. However, this approach to scheduling is not effective for VoIP due to the characteristics of the traffic and the large number of users.

p-0007In general, VoIP originates from a speech coder (e.g., an AMR speech coder) that produces output frames of coded speech at a regular frame rate (typically 20 msec) during periods of speech, or alternatively parameters relating to background noise conditions during silence periods. Unlike circuit switched (CS) speech, VoIP is routed through a packet switched (PS) IP network and typically accumulates a relatively large amount of header information, which is normally compressed. Due to the routing through the PS network there is a certain amount of jitter in the timing of received VoIP packets at an edge node of the radio network.

p-0008A general reference with regard to AMR speech coding and decoding can be found in 3GPP TS 26.071 V7.0.1 (2007-07), Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Mandatory speech CODEC speech processing functions; AMR speech CODEC; General description (Release 7), and in the various documents referenced therein in Section 2, “References”.

p-0009Typical VoIP packets can take the form of:

p-0010packets containing uncompressed headers (these are typically large (40 bytes) but also infrequent (arising at session start and occasionally during the session, in particular following a run of block errors)); <br /> packets containing voice and compressed headers; typically, e.g., 28 bytes for 7.95 kbps AMR; <br /> packets containing silence parameters and compressed headers; typically 15 bytes; and <br /> session initiation protocol (SIP) packets (infrequent; mainly at session start).

p-0011Although the uncompressed header packets are infrequent, they require additional air interface resources when they occur.

p-0012In order to avoid echo or delay jitter effects the VoIP packets should have a latency budget, typically 10-20 msec, in the physical layer.

p-0013In that VoIP traffic arrives as small packets that need to be transmitted within a narrow time frame, the scheduling of a large number of users within a TTI would lead to an untenably large L1/L2 control signaling overhead. Further, the QoS requirements limit the effectiveness of time/frequency scheduling.

p-0014Thus, for VoIP traffic the use of so called persistent scheduling is more appropriate. Reference in this regard may be made to R2-070188, “Scheduling for VoIP”. Siemens Networks, 3GPP TSG RAN WG2#56bis, Sorrento, Italy, 15-19 Jan. 2007. In general, persistent scheduling implies that a resource pattern is assigned to a UE for a relatively long period of time, without the need for continual scheduling grants over the L1/L2 control channel. With persistent scheduling, a VoIP UE is allowed to use the allocated physical resource blocks once every 20 ms, as depicted in <figref idrefs="DRAWINGS">FIG. 1</figref>.

p-0015Reduced signaling overhead and simplicity are the two main advantages for supporting persistent scheduling in LTE. Reference in this regard may be had to R2-070041, “Problems of Persistent Scheduling”, Ericsson, 3GPP TSG RAN WG2#56bis, Sorrento, Italy, 15-19 Jan. 2007.

p-0016The main advantage of persistent scheduling is that UL scheduling grants do not need to be transmitted for each VoIP frame, which reduces the control signaling overhead and thereby increases the system capacity. This is particularly beneficial as the L1/L2 control signaling consumes a significant fraction of the entire spectrum and the available transmission power. Another advantage of persistent scheduling is its simplicity, at least in terms of algorithm complexity.

p-0017However, the use of persistent scheduling also has drawbacks, such as wasted resources and the potential for collision with non-adaptive HARQ.

p-0018Further in this regard, synchronous HARQ uses a fixed interval between the current time (frame number) and the corresponding retransmission HARQ process, which has been defined for the LTE uplink in 3GPP TS 36.300.

p-0019Synchronous HARQ schemes are further classified as adaptive or non-adaptive in terms of transmission attributes, e.g., the resource block (RB) allocation, modulation and transport block size, and the duration of the retransmission. Control channel requirements are described for each case in 3GPP TR25.814 V7.1.0 (2006-09), Technical Report, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Physical layer aspects for evolved Universal Terrestrial Radio Access (UTRA) (Release 7), as follows.

p-0020Adaptive HARQ implies the transmitter may change some or all of the transmission attributes used in each retransmission as compared to the initial transmissions (e.g. due to changes in the radio conditions). Hence, the associated control information needs to be transmitted with the retransmission. The changes considered are modulation, resource block allocation and duration of transmission.

p-0021Non-Adaptive HARQ implies that changes, if any, in the transmission attributes for the retransmissions are known to both the transmitter and receiver at the time of the initial transmission. Hence, the associated control information need not be transmitted for the retransmission.

p-0022When using adaptive synchronous HARQ in E-UTRAN, the control signaling overhead must be considered. It was concluded in R2-070115, “Collision Avoidance While Using Synchronous HARQ”, CATT, RITT, 3GPP TSG RAN WG2#56bis, Sorrento, Italy, 15-19 Jan. 2007, that the main difference in control message bits between asynchronous HARQ and adaptive synchronous HARQ is the HARQ process ID. In other words, the major advantage of synchronous HARQ, i.e. reduction of the control signaling overhead, appears not to be so great if one selects to use adaptive synchronous HARQ in E-UTRAN.

p-0023At least one currently perceived problem relates to the fact that the use of synchronous non-adaptive HARQ implies that retransmissions are restricted to occur at the same resource blocks and known time instants. This can lead to collisions when other mechanisms are adopted at the same time, such as in persistent scheduling. One such collision is depicted in <figref idrefs="DRAWINGS">FIG. 2</figref>. If the dynamically scheduled transmission of UE_<b>2</b> does not succeed in the first HARQ transmission attempt, a synchronous HARQ retransmission of UE_<b>2</b> will collide with the persistently scheduled transmission of UE_<b>1</b>. The occurrence of a collision will result in a decoding error at the receiver side (at the eNB) due to orthogonal resource usage. What is more, because the HARQ retransmission probability is not low (10%˜20%), the collision probability is high (>10%). Thus, certain procedures are needed to overcome the collision problem.

p-0024Various techniques that have been proposed to overcome the collision problem include the following.

p-0025One solution is presented in the above referenced R2-070115, “Collision Avoidance While Using Synchronous HARQ”. In this approach it is proposed to avoid collision while using non-adaptive HARQ with a resource prohibit. The initial transmission of the synchronous HARQ is forbidden when its retransmission may conflict with persistent scheduling. This method needs to reserve resources to avoid a collision, even if the collision would not occur. <figref idrefs="DRAWINGS">FIG. 3</figref> illustrates this approach.

p-0026In <figref idrefs="DRAWINGS">FIG. 3</figref>, the time/frequency resource indicated with an asterisk (*) is allocated to a UE_<b>1</b> with persistent scheduling having a 20 ms period. If a synchronous HARQ UE (the retransmission interval is 5 ms) whose maximum retransmission number is 2, performs its initial transmission at one of the time/frequency resources indicated with #, it is possible to produce a collision during TTI T. The conflict is eliminated, however, if the initial transmission of the synchronous HARQ with two retransmissions is, at most, forbidden to occur in those RBs indicated with the * time/frequency.

p-0027One advantage of avoiding collisions in the initial transmissions is reducing control overhead of non-adaptive synchronous HARQ, while making it unnecessary to modify the mechanism of the currently specified synchronous HARQ. However, a disadvantage of this technique is the significantly reduced efficiency of resource utilization.

p-0028Another proposed solution to the collision problem is found in R2-070055, “Scheduling for maximizing VoIP capacity”, Ericsson, 3GPP TSG RAN WG2#56bis, Sorrento, Italy, 15-19 Jan. 2007. R2-070055 presents a semi-dynamic scheduling of VoIP to overcome the collision problem, which is shown in <figref idrefs="DRAWINGS">FIG. 4</figref>. The resource for UL VoIP transmission is allocated by the eNB dynamically and is sent to the UE via a scheduling grant. To reduce the L1/L2 signaling overhead, the eNB is said to pre-configure a set of resource assignments and transport formats for VoIP scheduling. Thus, a short grant can be used to indicate when the pre-configured resource shall be used by the UE. The short grant only has to indicate the UE identification (id) and an index to one of the pre-allocated resource sets.

p-0029In that a VoIP UE is scheduled dynamically within a pre-configured set, the collision may be avoided, or the potential for a collision to occur may be reduced (dependent on the set size). However, the control signaling overhead is a significant disadvantage as compared to persistent scheduling.

p-0030In R2-070020, “Scheduling of LTE UL VoIP”, Nokia, 3GPP TSG RAN WG2#56bis, Sorrento, Italy, 15-19 Jan. 2007, incorporated by reference herein in its entirety, there is presented a semi-persistent scheduling of UL VoIP, shown herein in <figref idrefs="DRAWINGS">FIG. 5</figref>. In this approach the initial transmission of VoIP is allocated persistently without L1/L2 control signaling, and retransmissions are allocated dynamically using the L1/L2 control channel. The UE monitors the L1/L2 control channel in all, or in preconfigured, TTIs (DRX).

SUMMARY

p-0031The foregoing and other problems are overcome, and other advantages are realized, by the use of the exemplary embodiments of this invention.

p-0032In a first aspect thereof the exemplary embodiments of this invention provide a method that includes determining if a collision will occur between a transmission from a first user equipment that uses a persistently assigned uplink resource and a retransmission from a second user equipment that uses a synchronous non-adaptive automatic repeat request procedure. If it is determined that a collision will occur, the method dynamically allocates the first user equipment to another uplink resource to avoid the collision, while if it is determined that the collision will not occur, the first user equipment is not dynamically allocated another uplink resource so that the first user equipment sends its transmission using the persistently assigned uplink resource.

p-0033In another aspect thereof the exemplary embodiments of this invention provide an apparatus that includes a radio frequency transceiver configurable to perform uplink and downlink radio frequency communications with a plurality of user equipment. The apparatus further includes a scheduler responsive to a determination being made that a collision will occur between a transmission from a first user equipment, that is allocated a persistently assigned uplink resource, and a retransmission from a second user equipment that uses a synchronous non-adaptive automatic repeat request procedure, to allocate the first user equipment a different uplink resource for the transmission to avoid the collision.

p-0034In another aspect thereof the exemplary embodiments of this invention provide an apparatus that includes means for transceiving uplink and downlink radio frequency communications with a plurality of user equipment, and means for determining if a collision will occur between a transmission from a first user equipment, that uses a persistently assigned uplink resource for transmitting VoIP packets, and a retransmission from a second user equipment that uses synchronous non-adaptive HARQ for retransmitting data in response to receipt of a NACK. The determining means is configurable to respond to a determination that the collision will occur for dynamically allocating the first user equipment a different uplink resource block for transmission of a next VoIP packet to avoid the collision, and for signaling information to the first user equipment via the transceiver means for identifying the different uplink resource block.

p-0035In a further aspect thereof the exemplary embodiments of this invention provide a method that includes monitoring a downlink control channel when operating a user equipment with a persistently assigned uplink resource and, in response to receiving an allocation of a different uplink resource from the downlink control channel, using the allocated different uplink resource to transmit a next packet.

p-0036In a still further aspect thereof the exemplary embodiments of this invention provide an apparatus having a radio frequency transceiver configurable to perform uplink and downlink radio frequency communications with a base station and a controller, coupled with the transceiver, and configurable to monitor a downlink control channel, when operating with a persistently assigned uplink resource, to receive an allocation of a different uplink resource from the downlink control channel, said controller further configurable to use the allocated different uplink resource to transmit a next packet.

BRIEF DESCRIPTION OF THE DRAWINGS

p-0037In the attached Drawing Figures:

p-0038<figref idrefs="DRAWINGS">FIG. 1</figref> is a simplified illustration of persistent scheduling.

p-0039<figref idrefs="DRAWINGS">FIG. 2</figref> shows the collision of a dynamically scheduled first UE (HARQ retransmission) with a persistent allocation of a second UE.

p-0040<figref idrefs="DRAWINGS">FIG. 3</figref> shows a previously proposed technique to avoid the situation shown in <figref idrefs="DRAWINGS">FIG. 2</figref> by the use of a resource prohibit.

p-0041<figref idrefs="DRAWINGS">FIG. 4</figref> shows a previously proposed technique to avoid the situation shown in <figref idrefs="DRAWINGS">FIG. 2</figref> by the use of semi-dynamic scheduling.

p-0042<figref idrefs="DRAWINGS">FIG. 5</figref> shows a previously proposed technique that employs semi-persistent allocation of UL VoIP.

p-0043<figref idrefs="DRAWINGS">FIG. 6</figref> shows a simplified block diagram of various electronic devices that are suitable for use in practicing the exemplary embodiments of this invention.

p-0044<figref idrefs="DRAWINGS">FIG. 7</figref> illustrates, in accordance with exemplary embodiments of this invention, an adaptive scheduling of UL VoIP to avoid collisions.

p-0045<figref idrefs="DRAWINGS">FIG. 8</figref> illustrates two Tables, where Table 1 tabulates relative signaling requirements, and Table 2 tabulates the relative performance, of various prior proposals and the exemplary embodiments of this invention.

p-0046<figref idrefs="DRAWINGS">FIG. 9</figref> is a logic flow diagram that is descriptive of a method, and the execution of computer program instructions stored in a tangible, computer-readable storage medium of a base station, such as an eNB, in accordance with exemplary embodiments of this invention.

p-0047<figref idrefs="DRAWINGS">FIG. 10</figref> is a logic flow diagram that is descriptive of a method, and the execution of computer program instructions stored in a tangible, computer-readable storage medium of a user equipment, in accordance with exemplary embodiments of this invention.

DETAILED DESCRIPTION

p-0048The inventors have realized that the use of semi-persistent scheduling alone cannot solve the collision problem discussed above, and that the use of adaptive HARQ for all users is needed to avoid collision. In <figref idrefs="DRAWINGS">FIG. 2</figref>, if the UE_<b>2</b> (a normally scheduled UE) uses adaptive HARQ, the retransmissions of UE_<b>2</b> can be allocated on any free resources and can thus avoid collision with VoIP UE_<b>1</b>.

p-0049Reference is made first to <figref idrefs="DRAWINGS">FIG. 6</figref> for illustrating a simplified block diagram of various electronic devices that are suitable for use in practicing the exemplary embodiments of this invention. In <figref idrefs="DRAWINGS">FIG. 6</figref> a wireless network <b>1</b> is adapted for communication with a plurality of UEs <b>10</b> via an eNodeB (base station) <b>12</b>, also referred to herein as eNB <b>12</b>. The network <b>1</b> may include a network control element (NCE) <b>14</b>. The UE <b>10</b> includes a data processor (DP) <b>10</b>A, a memory (MEM) <b>10</b>B that stores a program (PROG) <b>10</b>C, and a suitable radio frequency (RF) transceiver <b>10</b>D for bidirectional wireless communications with the eNB <b>12</b>, which also includes aDP <b>12</b>A, a MEM <b>12</b>B that stores a PROG <b>12</b>C, and a suitable RF transceiver <b>12</b>D. The eNB <b>12</b> is coupled via a data path <b>13</b> to the NCE <b>14</b>, such as an aGW, that also includes a DP <b>14</b>A and a MEM <b>14</b>B storing an associated PROG <b>14</b>C.

p-0050It may be assumed that the UE <b>10</b> will include a suitable voice coder (VC) <b>10</b>E, such as an AMR voice coder, that is used at least when functioning in a VoIP mode of operation. The UE <b>10</b> will also include a HARQ functional block or module <b>10</b>F.

p-0051The eNB <b>12</b> is shown to include a scheduler module or function (SCHED) <b>12</b>E that is operated in accordance with the exemplary embodiments of this invention, as described below, and will also include a HARQ functional block or module <b>12</b>F. The various modules and functions <b>10</b>F, <b>12</b>E and <b>12</b>F, as well as the voice coder scheduler module <b>10</b>E, may be implemented using hardware, software (including firmware), or with a combination of hardware and software.

p-0052The PROGs <b>10</b>C and <b>12</b>C may thus be assumed to include program instructions that, when executed by the associated DP, enable the electronic device to operate in accordance with the exemplary embodiments of this invention, as will be discussed below in greater detail. That is, the exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP <b>10</b>A of the UE <b>10</b> and by the DP <b>12</b>A of the eNB <b>12</b>, or by hardware, or by a combination of software and hardware.

p-0053In general, the various embodiments of the UEs <b>10</b> can include, but are not limited to, cellular telephones, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions.

p-0054The MEMs <b>10</b>B, <b>12</b>B and <b>14</b>B may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The DPs <b>10</b>A, <b>12</b>A and <b>14</b>A may be of any type suitable to the local technical 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.

p-0055The exemplary embodiments of this invention avoid the occurrence of a collision between a UE <b>10</b> having a HARQ retransmission and another UE <b>10</b> having a persistent scheduling for, as a non-limiting example, a VoIP application. In the exemplary embodiments of this invention the allocation of a VoIP UE <b>10</b> is adjusted or controlled while maintaining the mechanism of synchronous non-adaptive HARQ. Thus, and as is depicted in <figref idrefs="DRAWINGS">FIG. 7</figref>, an adaptive scheduling of UL VoIP is employed to avoid collisions.

p-0056If the eNB scheduler <b>12</b>E has knowledge that a collision will occur at time T, an UL allocation is sent to VoIP UE_<b>1</b>, where the UE_<b>1</b> is allocated dynamically to other free UL resource to avoid the collision. Thus, VoIP UEs <b>10</b> monitor the L1/L2 control channel in pre-configured (pre-determined) TTIs for initial transmission. If no valid UL allocation is given to the VoIP UE <b>10</b>, the VoIP UE <b>10</b> sends its transmission using the persistently assigned resource. Because synchronous non-adaptive HARQ is assumed to also be in operation, the retransmission of VoIP UE_<b>1</b> at time T+5 will use the newly allocated resource if UE_<b>1</b> is allocated dynamically to the another free resource at time T.

p-0057In other words, the adaptive scheduling of the UL VoIP functions as persistent scheduling when no collision is expected to occur, and it functions as dynamic scheduling when a collision is expected to occur.

p-0058Unlike the previous proposal in R2-070041, the VoIP UE <b>10</b> is scheduled dynamically only when a collision can be expected to occur. In that the collision probability is generally about 10%˜20%, the use of the exemplary embodiments of this invention beneficially reduce the L1/L2 control signaling overhead as compared to the proposal in R2-070041. It should be noted that the short grant that is proposed in R2-070055, or another similar or equivalent approach, can be employed to further reduce the L1/L2 control signaling overhead.

p-0059As such, it can be appreciated that the exemplary embodiments of this invention enable the eNB scheduler <b>12</b>E to adjust the UL allocation of the VoIP UE <b>10</b>, while preserving the use of the synchronous non-adaptive HARQ.

p-0060When a collision will occur, the UL allocation signaling is sent to the VoIP UE <b>10</b>. The UE <b>10</b> is thus allocated dynamically to another free UL resource block (RB) to avoid the collision. When it is known that a collision will not occur, no UL allocation signaling need be sent to the VoIP UE <b>10</b>, and the VoIP UE then sends its transmission using the persistently assigned resource.

p-0061Note in <figref idrefs="DRAWINGS">FIG. 7</figref> that if a retransmission by UE_<b>1</b> is required then UE_<b>1</b>, after it is assigned to the new UL resource at time T, uses the newly assigned UL resource for the retransmission at T+5. Note further that if there is no subsequent UL allocation, then UE_<b>1</b> automatically returns to the originally allocated UL resource. That is, when the eNB scheduler <b>12</b>E determines that a collision will not occur between UE_<b>1</b> and UE_<b>2</b>, when UE_<b>1</b> uses its original persistently assigned UL RB, then the absence of an UL allocation from the eNB <b>12</b> is interpreted by the UE <b>10</b> as permission to return to the originally assigned UL resource for the next UL transmission (e.g., to transmit the next new VoIP packet).

p-0062The current assumptions in RAN <b>1</b> indicate that the size of the scheduling information needed for uplink grants is about 46 bits (see R2-062263, “First quantification of downlink control channel overhead”, Samsung, 3GPP TSG RAN2#54, Tallinn, Estonia, 28 Aug.-2 Sep. 2006). The adaptive synchronous HARQ is 5 bits (HARQ process ID) less than the asynchronous HARQ. For simplicity, assume a case where the control signaling requires 40 bits for adaptive synchronous HARQ, the HARQ retransmission probability is 10%, as is the collision probability, the HARQ retransmission number is set to 1, and that there are 10 dynamically scheduled UEs <b>10</b> and 5 VoIP UEs <b>10</b> per TTI. In this example, it may also be assumed that the short grant is used. According to R2-070055, the short grant averages about 10 bits. If it is further assumed that the proposal of R2-070115 (persistent scheduling of VoIP+synchronous non-adaptive HARQ) requires K bits for signaling, the proposal found in R2-070020 will need K+(10+5)*40*0.1 bits for signaling, and the proposal of R2-070041 needs K+5*10 bits signaling, then the use of the exemplary embodiments of this invention uses K+5*10*0.1 bits for signaling. Table 1 in <figref idrefs="DRAWINGS">FIG. 8</figref> tabulates the relative signaling requirements, while Table 2 tabulates the relative performance of the various proposals and the exemplary embodiments of this invention.

p-0063In accordance with the exemplary embodiments of this invention, adaptive scheduling of the UL of the VoIP UE <b>10</b> is performed to avoid a collision for the persistently scheduled LTE uplink (VoIP transmission). If a collision occurs, an UL allocation is sent to the VoIP UE <b>10</b>. The VoIP UE <b>10</b> is dynamically allocated to another free RB to avoid collision. When the collision does not occur, no UL allocation need be given to the VoIP UE <b>10</b>, and the VoIP UE sends its transmission using the persistently assigned resource. The use of the exemplary embodiments thus avoids collisions while achieving high resource utilization with low control signaling overhead.

p-0064Based on the foregoing it should be apparent that the exemplary embodiments of this invention provide a method, apparatus and computer program product(s) to enable an adjustment of the allocation of the VoIP UE while maintaining the use of synchronous non-adaptive HARQ.

p-0065Referring to <figref idrefs="DRAWINGS">FIG. 9</figref>, in accordance with a method of this invention, and the execution of computer program instructions stored in a tangible, computer-readable storage medium (such as the program <b>12</b>C stored in the memory <b>12</b>B), at Block <b>9</b>A a determination is made if a collision will occur between a transmission from a VoIP UE, that uses a persistently assigned UL resource, and a retransmission from another UE that uses synchronous non-adaptive HARQ. Note that because the scheduler <b>12</b>E of the eNB <b>12</b> is aware of all UL allocations, the retransmission status, and the operating mode of each UE <b>10</b>, the scheduler <b>12</b>E is enabled to detect that a collision will occur between a VoIP UE and another UE using synchronous non-adaptive HARQ. At Block <b>9</b>B, if it is determined that a collision will occur, the VoIP UE is dynamically allocated another free UL resource (RB) to avoid the collision, while at Block <b>9</b>C, if it is determined that the collision will not occur, the VoIP UE is not dynamically allocated another free UL resource (RB) and the VoIP UE sends its transmission using the persistently assigned UL resource.

p-0066The method of the preceding paragraph, where the VoIP UE is dynamically allocated the another free UL resource using L1/L2 control signaling.

p-0067The method of the preceding paragraphs, where the VoIP UE is dynamically allocated the another free UL resource using a short grant.

p-0068The method of the preceding paragraphs, executed at least in part by a scheduler function of an eNB.

p-0069Further in accordance with an apparatus of this invention, an eNB comprises a scheduler function that is configurable to determine if a collision will occur between a transmission from a VoIP UE, that uses a persistently assigned UL resource, and a retransmission from another UE that uses synchronous non-adaptive HARQ. If the scheduler function determines that a collision will occur, the VoIP UE is dynamically allocated another free UL resource (RB) to avoid the collision, while if it is determined that the collision will not occur, the VoIP UE is not dynamically allocated another free UL resource (RB) such that the transmission from the VoIP UE is received from the persistently assigned UL resource.

p-0070The apparatus of the preceding paragraph, where the VoIP UE is dynamically allocated the another free UL resource using L1/L2 control signaling.

p-0071The apparatus of the preceding paragraphs, where the VoIP UE is dynamically allocated the another free UL resource using a short grant.

p-0072Note that the exemplary embodiments of this invention also provide a method and apparatus, and computer program instructions, to operate the UE to monitor a L1/L2 control channel to receive, when functioning as a VoIP UE with a persistently assigned UL resource, a dynamic allocation of another UL resource that is predetermined to avoid a collision with a retransmission from another UE that uses synchronous non-adaptive HARQ.

p-0073Further in this regard reference is made to <figref idrefs="DRAWINGS">FIG. 10</figref>, where in accordance with a method of this invention, and the execution of computer program instructions stored in a tangible, computer-readable storage medium (such as the program <b>10</b>C stored in the memory <b>10</b>B), at Block <b>10</b>A′ there is performed a step of monitoring a downlink control channel when operating a user equipment in a voice over internet protocol mode with a persistently assigned uplink resource and, at Block <b>10</b>B′, in response to receiving an allocation of a different uplink resource from the downlink control channel, using the allocated different uplink resource to transmit a next voice over internet protocol packet.

p-0074In accordance with the exemplary embodiments the allocated different uplink resource is predetermined to avoid a collision between the transmission of the next voice over internet protocol packet and a retransmission from another user equipment.

p-0075The method may further include, at Block <b>10</b>C′, in response to retransmission being needed for the transmitted next voice over internet protocol packet, retransmitting the voice over internet protocol packet using the allocated different uplink resource.

p-0076The method may further include, at Block <b>10</b>D′, in response to not receiving a subsequent uplink allocation, reverting to using the persistently assigned uplink resource for a next uplink transmission.

p-0077The various blocks shown in <figref idrefs="DRAWINGS">FIGS. 9 and 10</figref> may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function(s).

p-0078The exemplary embodiments of this invention also provide an apparatus, such as the eNB <b>12</b>, that includes means for transceiving uplink and downlink radio frequency communications with a plurality of user equipment, and means for determining if a collision will occur between a transmission from a first user equipment, that uses a persistently assigned uplink resource for transmitting VoIP packets, and a retransmission from a second user equipment that uses synchronous non-adaptive HARQ for retransmitting data in response to receipt of a NACK. The determining means is configurable to respond to a determination that the collision will occur for dynamically allocating the first user equipment a different uplink resource block for transmission of a next VoIP packet to avoid the collision, and for signaling information to the first user equipment via the transceiver means for identifying the different uplink resource block.

p-0079In general, the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the exemplary embodiments of this invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

p-0080As such, it should be appreciated that at least some aspects of the exemplary embodiments of the inventions may be practiced in various components such as integrated circuit chips and modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be fabricated on a semiconductor substrate. Such software tools can automatically route conductors and locate components on a semiconductor substrate using well established rules of design, as well as libraries of pre-stored design modules. Once the design for a semiconductor circuit has been completed, the resultant design, in a standardized electronic format (e.g., Opus, GDSII, or the like) may be transmitted to a semiconductor fabrication facility for fabrication as one or more integrated circuit devices.

p-0081It should be noted that the terms “connected,” “coupled,” or any variant thereof, mean any connection or coupling, either direct or indirect, between two or more elements, and may encompass the presence of one or more intermediate elements between two elements that are “connected” or “coupled” together. The coupling or connection between the elements can be physical, logical, or a combination thereof. As employed herein two elements may be considered to be “connected” or “coupled” together by the use of one or more wires, cables and/or printed electrical connections, as well as by the use of electromagnetic energy, such as electromagnetic energy having wavelengths in the radio frequency region, the microwave region and the optical (both visible and invisible) region, as several non-limiting and non-exhaustive examples.

p-0082Various modifications and adaptations to the foregoing exemplary embodiments of this invention may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments of this invention.

p-0083For example, while the exemplary embodiments have been described above in the context of the E-UTRAN (UTRAN-LTE) system, it should be appreciated that the exemplary embodiments of this invention are not limited for use with only this one particular type of wireless communication system, and that they may be used to advantage in other wireless communication systems. Further, the exemplary embodiments are not limited for use with only VoIP packet transmissions that are subject to persistent scheduling, and they may be used with other types of UL transmissions that benefit from the use of persistent scheduling.

p-0084Furthermore, some of the features of the various non-limiting and exemplary embodiments of this invention may be used to advantage without the corresponding use of other features. As such, the foregoing description should be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.