Patent Application
20120243492
Embodiments of this invention generally relate to wireless communications, and examples of embodiments can be applied in cellular communication systems.
Wireless cellular communication networks incorporate a number of mobile UEs and a number of NodeBs. A NodeB is generally a fixed station, and may also be called a base transceiver system (BTS), an access point (AP), a base station (BS), or some other equivalent terminology. As improvements of networks are made, the NodeB functionality evolves, so a NodeB is sometimes also referred to as an evolved NodeB (eNB). In general, NodeB hardware, when deployed, is fixed and stationary, while the UE hardware is portable.
In contrast to NodeB, the mobile UE can comprise portable hardware. User equipment (UE), also commonly referred to as terminal or mobile station, may be fixed or mobile device and may be a wireless device, a cellular phone, a personal digital assistant (PDA), a wireless modem card, and so on. Uplink communication (UL) refers to a communication between the mobile UE and the NodeB, whereas downlink (DL) refers to communication from the NodeB to the mobile UE. Each NodeB contains radio frequency transmitter(s) and the receiver(s) used to communicate directly with the mobiles, which move freely around it. Similarly, each mobile UE contains radio frequency transmitter(s) and the receiver(s) used to communicate directly with the NodeB. In cellular networks, the mobiles cannot communicate directly with each other but have to communicate with the NodeB. Embodiments of the invention, however, can be applied even beyond such cellular networks, since only concepts of wireless transmission and reception are needed. Nevertheless, the present invention will be described in the context of a cellular network.
Control information bits are transmitted, for example, in the uplink (UL), for several purposes. For instance, Downlink Hybrid Automatic Repeat ReQuest (HARQ) requires at least one bit of ACK/NACK transmitted information in the uplink, indicating successful or failed circular redundancy check(s) (CRC). Furthermore, an indicator of downlink channel (CQI) needs to be transmitted in the uplink to support mobile UE scheduling in the downlink. While CQI may be transmitted based on a periodic or triggered mechanism, the ACK/NACK needs to be transmitted in a timely manner to support the HARQ operation. Note that ACK/NACK is sometimes denoted as ACKNAK or just simply ACK, or any other equivalent term. As seen from this example, some elements of the control information should be provided additional protection, when compared with other information. For instance, the ACKNACK information is typically required to be highly reliable in order to support an appropriate and accurate HARQ operation. This uplink control information is typically transmitted using the physical uplink control channel (PUCCH), as defined by the 3GPP working groups (WG), for evolved universal terrestrial radio access (EUTRA). The EUTRA is sometimes also referred to as 3GPP long-term evolution (3GPP LTE). For said reasons, structure of the PUCCH provides for sufficiently high transmission reliability.
In addition to PUCCH, the EUTRA standard also defines a physical uplink shared channel (PUSCH), intended for transmission of uplink user data. The Physical Uplink Shared Channel (PUSCH) can be dynamically scheduled. This means that time-frequency resources of PUSCH are re-allocated every sub-frame. This (re)allocation is communicated to the mobile UE using the Physical Downlink Control Channel (PDCCH). Alternatively, resources of the PUSCH can be allocated semi-statically, via the mechanism of persistent scheduling. Thus, any given time-frequency PUSCH resource can possibly be used by any mobile UE, depending on the scheduler allocation. Physical Uplink Control Channel (PUCCH) is different than the PUSCH, and the PUCCH is used for transmission of uplink control information (UCI). Frequency resources which are allocated for PUCCH are found at the two extreme edges of the uplink frequency spectrum. In contrast, frequency resources which are used for PUSCH are in between. Since PUSCH is designed for transmission of user data, re-transmissions are possible, and PUSCH is expected to be generally scheduled with less stand-alone sub-frame reliability than PUCCH.
The concept of a reference signal (RS) is important for some embodiments of the present invention. The RS is a pre-defined signal, pre-known to both transmitter and receiver. Typically, the transmitted RS signal carries no information. At times though, this requirement can be slightly relaxed, and, the transmitted RS signal can actually carry some small amount of information, in comparison to other signals. Still, for purposes of describing the Present Invention, the RS can mostly be thought as deterministic from the perspective of both transmitter and receiver. The RS is typically transmitted in order for the receiver to estimate the signal propagation medium. This process is also known as “channel estimation.” Thus, RS can be transmitted to facilitate channel estimation. Upon deriving channel estimates, these estimates are used for demodulation of transmitted information. As common in the literature, demodulation is a process of recovering information from the modulated (and transmitted) signal. This type of RS is sometimes referred to as De-Modulation RS or DM RS. Note that RS can also be transmitted for other purposes, such as channel sounding, synchronization, or any other purpose. Also note that Reference Signal (RS) can be sometimes called the pilot signal, or the training signal, or any other equivalent term.
Turbo codes are a class of high-performance error correction codes developed in 1993 which are finding use in deep space satellite communications and other applications where designers seek to achieve maximal information transfer over a limited-bandwidth communication link in the presence of data-corrupting noise. The channel coding scheme for transport blocks in LTE is Turbo Coding with a coding rate of R=⅓, using two 8-state constituent encoders and a contention-free quadratic permutation polynomial (QPP) turbo code internal interleaver. Trellis termination is used for the turbo coding. Before the turbo coding, transport blocks are segmented into byte aligned segments with a maximum information block size of 6144 bits. Error detection is supported by the use of 24 bit CRC. The ⅓ coding rate triples the bit-count for transmission of the block. The general operations of channel coding are described in the EUTRA specifications, for example: “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding (TS36.212, Release 8).”
The 3GPP working groups are developing a set of standards. 3GPP TS 36.211, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)” defines aspects of the physical channels and modulation. 3GPP TS 36.212“3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding (Release 8)” defines aspects of multiplexing and channel coding. Both of these documents as well as other 3GPP standards are evolving over time as the working groups add new concepts and definitions.
Particular embodiments in accordance with the invention will now be described, by way of example only, and with reference to the accompanying drawings:
Certain disclosed embodiments of the present invention include apparatus and methods for transmitting and receiving elements of uplink control information (UCI) on physical uplink shared channel (PUSCH), even in scenarios where PUCCH is actually configured and allocated to a user. In some embodiments of the invention, transmission is made in such a manner that elements of control information are transmitted either on a PUCCH when no other data is available for transmission; otherwise, transmission is made on the PUSCH. By only using one channel at any given time, peak-to-average power ratio (PAPR) is maintained at lower levels.
In the prior art, the PUSCH is designed to principally transport the uplink (UL) user data information. This user data information arrives via transport channels (TrCH), and transport channels are services offered by Physical Layer to higher layers. Thus, user data, which arrives from higher layers, is transported by transport channels. Physical Channels, in contrast, are actually a part of the Physical Layer. Consequently, in the prior art, the PUSCH only serves to provide services to the Uplink Shared Channel (UL-SCH), which is a transport channel (TrCH). In the prior art, the uplink control information is carried by a Physical Uplink Control Channel (PUCCH). Note that, as said earlier, the PUCCH is physical channel which is different from PUSCH, in a number of aspects, including: structure, resource allocation, and time-frequency resources.
In contrast to prior art, embodiments of the present invention incorporate transmission of elements of the Uplink Control Information (UCI) using the PUSCH, even if PUCCH resources may be allocated to a mobile UE. In addition to this, the present invention also describes specifically which PUSCH resources are used to carry elements of the UCI. In order to do so, the present invention first introduces a broader concept of Prioritized Information. Prioritized Information can contain elements of UCI which require additional (or high) transmission reliability.
Prioritized Information can be regarded as the type of information which should be provided higher transmission reliability (in a given stand-alone sub-frame) when compared with the rest of transmitted information. For example, elements of the uplink control information (UCI) can be regarded as Prioritized Information. Since elements of UCI are critical for maintenance of reliable uplink and downlink channels, the UCI should have better protection than Other Information. For this reason, when designing a PUSCH sub-frame structure, where Prioritized Information is multiplexed with other Information, the Prioritized Information should be positioned in the vicinity of the Reference Signal (RS). Thus, channel estimates which are applied to the Prioritized Information are very accurate. Consequently, Prioritized Information (PI) is provided with a sufficient amount of protection. For example, especially in the scenario where the mobile moves with a relatively high velocity, the channel still maintains coherence from the time of transmission and/or reception of the RS to the time of transmission and/or reception of the Prioritized Information. Thus, Prioritized Information (PI) is provided with a needed protection in terms of having accurate channel estimates.
Prioritized Information can comprise elements of Layer 1 (L1) and Layer 2 (L2) Control Information. The Prioritized Information can also comprise elements of uplink control information (UCI). More specifically, the Prioritized Information can include ACKNAK (or ACKNACK) feedback, CQI information, Rank Information, PMI information, UE buffer status, UE power status, scheduling request indicator, new data indicator (NDI), or any other L1 and/or L2 control information. Note that certain elements of L1 and L2 control information may not need the said additional protection, and consequently, these do not need to be provisioned as a Prioritized Information. However, the elements or L1 and L2 information which do require the additional protection are provisioned to be Prioritized Information and will be placed in the vicinity of the RS.
The ACKNAK information is the feedback which is sent by the mobile UE to the NodeB, in support of the downlink hybrid automatic repeat request (DL HARQ). The DL HARQ operates as follows. The NodeB transmits a sub-frame or packet of data to the mobile UE, where the sub-frame contains error detection capability, via circular redundancy check (CRC). The UE then decodes the said sub-frame, and performs error detection. If CRC passes, the mobile UE transmits an ACK to the NodeB, thus informing the NodeB of a successful transmission. However, if CRC fails, the mobile UE transmits a NACK (or NAK) to the NodeB, thus informing the NodeB of a transmission failure. Thus, the described feedback (mobile UE to NodeB) is sometimes denoted as ACKNACK or ACKNAK feedback, and is an element of L1/L2 control information. It is generally understood that ACKNACK has to be transmitted with a high reliability. Thus, it is recommended that ACKNACK be mapped in symbols which are adjacent to the RS. The ACKNACK information is a part of uplink control information (UCI). Thus, in some embodiments, the ACKNAK information can be considered to be a Prioritized Information.
In some embodiments of the invention, a symbol is an OFDM symbol. A symbol can be set of digital samples. A symbol can be a set of discrete samples. In some embodiments of the invention, a symbol is preceded by a cyclic prefix transmission. Consecutive symbols are symbols which occur one after another. In some embodiments of the invention, there are no time gaps between consecutive symbols. In some embodiments of the invention, gaps between consecutive symbols are due to cyclic prefix (CP). In some embodiments of the invention, gaps between consecutive symbols are due to guard time.
Channel Quality Indicator (CQI) is obtained by measuring the quality of the downlink (DL) channel, or downlink channels. The measured quality of the DL channel(s) can be fed back (i.e. transmitted), by the mobile UE, to the NodeB. The CQI information is a part of uplink control information (UCI). Thus, in some embodiments, the CQI information can be considered to be a Prioritized Information. Rank information is applicable for MIMO signaling, and CQI is related to the Rank Information. The Rank information can describe, up to a certain precision, and in some embodiments, the matrix rank of the MIMO downlink channel. The Rank information is a part of uplink control information (UCI). Thus, in some embodiments, the Rank information can be considered to be a Prioritized Information. Pre-coder matrix index (PMI) is a type of information by which the receiver indicates (or suggests), to the transmitter, which pre-arranged transmit MIMO pre-coder should be used. Thus, in some embodiments, the PMI information can be considered to be a Prioritized Information. Note that Rank Information can be termed Rank Indicator, Rank Indication, or any other equivalent term. In some embodiments of the invention, Rank Indication is a feedback sent from the mobile UE to the NodeB, suggesting (implicitly or explicitly) the number of Layers in MIMO transmission.
Scheduling request indicator (SRI) is a type of information which indicates that the mobile UE requests an UL transmission of a certain quantity of data. Then, scheduling request may or may not be attended to by the NodeB. In some embodiments, the SRI information can be considered to be a Prioritized Information.
Certain status of the mobile UE can also be prioritized. For instance, in some embodiments, the type of information by which the mobile UE informs the NodeB of its buffer status, can be made a Priority Information. In some embodiments, the type of information by which the mobile UE informs the NodeB of its power status, can be made a Priority Information. In some embodiments, the type of information by which the mobile UE informs the NodeB of its battery status, can be made a Priority Information. Also, in some embodiments, data-associated UL control information can be made a Priority Information as well. The data-associated UL control information is a type of information which is associated with the UL data. For example, the modulation and coding information (which applies to the current PUSCH) can be considered to be data-associated control information.
Another aspect of prioritization is that control information can be assigned priority levels. For example, ACKNAK can have the highest priority level (e.g. level 0). CQI can have a lower priority level, etc. Note that certain control information can have same priority levels. For example, it would be possible to make ACKNAK and SRI have the same priority level (e.g. level 0), since both them need to be received in a timely fashion with high detection performance.
Prioritized control information can be mapped surrounding the DM RS in decreasing order of priority. For instance, ACKNAK can be immediately surrounding the RS. Then, the next can be SRI, which is then surrounding the ACKNAK information, etc. In general, information of priority level n is surrounding the information of priority level n−1. However, if certain two kinds of information are assigned identical priority levels, then they can be interleaved. In a first embodiment, the order of priority may be as follows: ACKNAK has the priority 0, SRI has the priority 1, and Rank has the priority 2, and CQI has priority 3. In another embodiment, the order of priority may be as follows: ACKNAK has the priority 0, Rank has the priority 1, and CQI has priority 2, when SRI is encoded separately. In yet another embodiment, the order of priority may be as follows: ACKNAK has the priority 0, Rank has the priority 1, and SRI and CQI may be treated separately. Thus, the sequence of mapping this information surrounding the RS is determined based on the priority levels. In some embodiments of the invention, ACKNAK has the priority 0 and Rank has priority 1.
z[k]=βΣ
i
d[i] exp(−j2πki/L),
where sum Σi extends across all indexes “i” in {0, 1, . . . , L−1}, where “j” is the complex unit, where π is the well-known constant (approximately 3.14), where d[i] are symbols of the sequence 200 which enters the Transform Pre-Coder 203, where “L” is the length of both the sequence which enters (200) and the sequence which is outputted (204) by the Transform Pre-Coder 203, where β is a normalization constant (e.g. inverse square root of L). Note the “L” can be the number of tones allocated on PUSCH, for this particular mobile UE. In some embodiments, the Transform Pre-Coder 203 can be implemented using a Discrete Fourier Transform (DFT). Transform Pre-Coder 203 is coupled to the Resource Map 205, which describes the set of PUSCH tones which are allocated to the UE for the present sub-frame. Resource Map 205 is coupled with the Baseband Signal Generator 206. Thus, the Resource Map 205 maps said samples z[k] onto a[m], which is the input to the Baseband Signal Generator. Thus, in some embodiments, sequence of a[m] contains samples of the sequence z[k], along with some other possible samples (e.g. zero-insertion). One possible embodiment of the Baseband Signal Generator 206 is given by the formula
s(t)=Σma[m+c] exp [j2π(m+½)(t−NCPTs)Δf],
where the sum Σm ranges over m. In accordance to the 3GPP specification TS36.211, as Ts=1/(15000×2048) where “x” is just multiplication. Here, Δf is 15 kHz. Here, NCP is the number of Cyclic Prefix (CP) samples, which can be transmitted for every symbol, as common in OFDM-based systems. Also note that NCP can be symbol—dependent. Here, t is the continuous-time variable whose range is as 0≦t≦(N+NCP)Ts where N=2048. Here, sequence a[m+c] is assumed to have M non-zero elements. Here, c is just an offset, which can be equal, for example, to floor(M/2). In this case, the sum Σ ranges over “m” inside the set {−floor(M/2), −floor(M/2)+1, . . . , ceil(M/2)−1}, where floor is the known “floor” function and “ceil” is the known ceiling function. Note that “m+½” in the above sum performs a frequency offset of ½ tone, implemented in the baseband, for purpose of DC-offset mitigation of the Direct Conversion problem. Note that this is just an embodiment of the Baseband Signal Generator 206, and other embodiments, which different specific numbers are possible. Thus, different modifications to the Baseband Signal Generator 206 are possible, which don't affect the scope of the Present Invention. Components of the Baseband Signal Generator can be implemented using the Inverse Discrete Fourier Transform (IDFT).
In some embodiments, the Prioritized Information occupies fraction(s) of one or more symbols which are adjacent to the RS, as shown in
A possible embodiment of Second Modulator 607 is shown in 702 of
As discussed earlier control information can be assigned priority levels. For example, ACKNAK can have the highest priority level (e.g. level 0). Therefore, in one embodiment, prioritized information 823 and 825 is ACKNAK information. The ACK information may be encoded as follows: each positive acknowledgement (ACK) is encoded as a binary ‘1’ and each negative acknowledgement (NAK) is encoded as a binary ‘0’. If ACK consists of 1-bit of information, i.e., [o0ACK], may be is encoded according to Table 1. If ACK consists of 2-bits of information, i.e., [o0ACKo1ACK] with o0ACK corresponding to ACK/NACK bit for codeword 0 and o1ACK corresponding to that for codeword 1, it may be encoded according to Table 2 where o2ACK=(o0ACK+o1ACK)mod 2.
The “x” and “y” in Table 1 and Table 2 are placeholders to scramble the ACK bits with other information 822, 824 in a way that maximizes the Euclidean distance of the modulation symbols carrying ACK information.
Similarly, if the highest priority information is rank indication (RI), the corresponding bit widths for rank indication feedback for PDSCH transmissions are given by Table 3 and Table 4. If RI consists of 1-bit of information, i.e., [o0RI], it may be encoded according to Table 3. If RI consists of 2-bits of information, i.e., [o0RI o1RI] with O0RI corresponding to MSB of 2-bit input and O1RI corresponding to LSB, it may be encoded according to Table 4 where o2RI=(o0RI+o1RI)mod 2.
The “x” and “y” in Table 3 and Table 4 are placeholders to scramble the RI bits with other information 822824 in a way that maximizes the Euclidean distance of the modulation symbols carrying rank information.
Note that, when Prioritized Information is transmitted in the PUSCH, certain samples (in the base-band) of the Other Information may have to be punctured, in order to provide space for Prioritized Information. This puncturing can be pre-arranged and according the 3GPP puncturing convention described in the specification. However, since Other Information can already be encoded, it is typically possible to infer the Other Information (as well) at the receiver.
Referring still to
RF transceiver 1006 includes a receiver for receiving a stream of coded data frames and commands from a cellular base station via antenna 1007 and a transmitter for transmitting a stream of coded data frames to the cellular base station via antenna 1007. Transmission of the PUSCH data is performed by the transceiver using the PUSCH resources designated by the serving NodeB. In some embodiments, frequency hopping may be implied by using two or more bands as commanded by the serving NodeB. In this embodiment, a single transceiver can support multi-standard operation (such as EUTRA and other standards) but other embodiments may use multiple transceivers for different transmission standards. Other embodiments may have transceivers for a later developed transmission standard with appropriate configuration. RF transceiver 1006 is connected to DBB 1002 which provides processing of the frames of encoded data being received and transmitted by the mobile UE unite 1000.
Note that the EUTRA defines SC-FDMA (via DFT-spread OFDMA) as the uplink modulation, which is reflected in the described embodiments of the Channelizer 201 in
DBB unit 1002 may send or receive data to various devices connected to universal serial bus (USB) port 1026. DBB 1002 can be connected to subscriber identity module (SIM) card 1010 and stores and retrieves information used for making calls via the cellular system. DBB 1002 can also connected to memory 1012 that augments the onboard memory and is used for various processing needs. DBB 1002 can be connected to Bluetooth baseband unit 1030 for wireless connection to a microphone 1032a and headset 1032b for sending and receiving voice data. DBB 1002 can also be connected to display 1020 and can send information to it for interaction with a user of the mobile UE 1000 during a call process. Display 1020 may also display pictures received from the network, from a local camera 1026, or from other sources such as USB 1026. DBB 1002 may also send a video stream to display 1020 that is received from various sources such as the cellular network via RF transceiver 1006 or camera 1026. DBB 1002 may also send a video stream to an external video display unit via encoder 1022 over composite output terminal 1024. Encoder unit 1022 can provide encoding according to PAL/SECAM/NTSC video standards.
As shown, the mobile UE device 1101 comprises a processor 1103 coupled to a memory 1107 and a Transceiver 1104. The memory 1107 stores (software) applications 1105 for execution by the processor 1103. The applications 1105 could comprise any known or future application useful for individuals or organizations. As an example, such applications 1105 could be categorized as operating systems (OS), device drivers, databases, multimedia tools, presentation tools, Internet browsers, e-mailers, Voice-Over-Internet Protocol (VoIP) tools, file browsers, firewalls, instant messaging, finance tools, games, word processors or other categories. Regardless of the exact nature of the applications 1105, at least some of the applications 1105 may direct the mobile UE device 1101 to transmit UL signals to the NodeB (base-station) 1102 periodically or continuously via the transceiver 1104. In at least some embodiments, the mobile UE device 1101 identifies a Quality of Service (QoS) requirement when requesting an uplink resource from the NodeB 1102. In some cases, the QoS requirement may be implicitly derived by the NodeB 1102 from the type of traffic supported by the mobile UE device 1101. As an example, VoIP and gaming applications often involve low-latency uplink (UL) transmissions while High Throughput (HTP)/Hypertext Transmission Protocol (HTTP) traffic can involve high-latency uplink transmissions.
As shown in
As shown in
Transceiver 1110 comprises an uplink Resource Manager 1122, which enables the NodeB 1102 to selectively allocate uplink PUSCH resources to the user device 1101. As would be understood by one of skill in the art, the components of the uplink resource manager 1112 may involve the physical (PHY) layer and/or the Media Access Control (MAC) layer of the transceiver 1110. Transceiver 1110 includes a Receiver 1111 for receiving transmissions from various UE within range of the NodeB.
As information is provided for transmission on the uplink channel, prioritized information is classified 1304 to distinguish it from the other information. As discussed earlier, prioritized information may be ACKNACK information, CQI information, Rank information, PMI information, SRI information, or other types of critical system information.
Once classified, digital samples are produced 1306 using an element of the prioritized information (PI), as described with regard to
The priority symbols are transmitted 1312 via the PUSCH by placing the priority symbol in close proximity to a reference symbol. It is preferable to locate the priority symbol such that separation of the priority symbol and a reference symbol does not exceed a time duration of one symbol, t(s). As discussed with regard to
If data is not available for transmission 1406, then control information is transmitted 1408 from the UE to the eNB using the PUCCH, as described earlier.
If data is available for transmission 1406, then priority information such as control information is mapped 1410 to one or more symbols adjacent an RS symbol using a Channelizer as discussed above with reference to
At any given time, the UE uses only either the control channel (PUCCH) or the shared channel (PUSCH) for transmission of control information and data information. By only using one channel at any given time, peak-to-average power levels are maintained at lower levels.
Depending on operating mode, a physical uplink shared channel (PUSCH) may also be allocated. The PUSCH may be allocated in response to a request by the UE, or may be allocated in response to a command or directive by the eNB. In other modes of operation, no PUSCH is allocated. If a UE determines 1506 that a PUSCH is not allocated, then the UE transmits 1508 control information on the PUCCH.
If the UE determines 1506 that a PUSCH has been established between it and the eNB, then, then priority information such as control information is mapped 1510 to one or more symbols adjacent to or within one symbol time (T) of an RS symbol using a Channelizer as discussed above with reference to
If other information is available for transmission from the UE, then symbols representing the other information are transmitted 1512 on the PUSCH in available symbol locations, as discussed with reference to
At any given time, the UE uses only either the control channel (PUCCH) or the shared channel (PUSCH) for transmission of control information and data information. By only using one channel at any given time, peak-to-average power levels are maintained at lower levels.
As used herein, the term “coupled” or “connected,” means electrically connected, wire-line or wireless, including where additional elements may be in the electrical connection path. While the invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various other embodiments of the invention will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover most such modifications of the embodiments as fall within the true scope and spirit of the invention.
This application is a continuation of U.S. Non-Provisional application Ser. No. 12/364,499 filed on Feb. 2, 2009; Which claims priority to and incorporates by reference U.S. Provisional Application No. 61/026,215, filed on Feb. 5, 2008 entitled “Considerations on Data and Control Multiplexing on PUSCH.”
| Number | Date | Country | |
|---|---|---|---|
| 61026215 | Feb 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12364499 | Feb 2009 | US |
| Child | 13491155 | US |
