1. Technical Field
The embodiments of the present disclosure relate to wireless communications and, more particularly, to the transmission of multiple carrier signals in down link communications.
2. Description of Related Art
In the mobile communication area, various systems are being implemented throughout the world to increase the amount of voice and data traffic that can be carried over the air to wireless devices. These systems include universal mobile telecommunications system (UMTS), advanced mobile phone services (AMPS), digital AMPS, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS), Enhanced Data rates for GSM Evolution (EDGE), General Packet Radio Service (GPRS), as well as others. One recent development is Long Term Evolution (LTE), which uses a standard developed under the 3rd Generation Partnership Project (3GPP or 3G) and is marketed as 4G communications technology.
As more constraints are placed on mobile network operators to provide improved data throughput and quality of services, new techniques are constantly being sought to provide such improvements or new developments. Network operators are looking to offer more attractive and distinctive services to enhance the end user experience, while device (e.g. phone) manufacturers and chipset vendors are competing to create highly desirable mobile devices and applications. One way to achieve an increase in downstream data rates is to increase the bandwidth of the down link communication.
A new technique is currently being developed utilizing the LTE standard, in which the down link bandwidth is increased via so-called carrier aggregation. For example, Release 10 under the current LTE standard and in a move toward the LTE-Advanced standard, specifies that radio frequency (RF) carriers from one or multiple base stations (Node B) may be aggregated and jointly used for transmissions to/from a single terminal. That is, instead of a single RF carrier being transmitted from a node (such as a cell tower, Node B, etc.) to a mobile device, the new LTE standard allows multiple carriers from one or multiple nodes to be sent down link to a single terminal. Because the use of multiple carriers increases the bandwidth of the transmitted signal, down link data rates to a user terminal or user equipment (UE) may be increased.
However, in order to process a signal carrying multiple carriers, additional radio front-end circuitry and processing circuitry may be needed. In simplistic terms, to process an aggregation of N number of carriers, N radio circuitry would be used, which would significantly increase the number of components used in a mobile phone, as well as an increase in the power requirements for the added circuitry. The solution is to find a way in which a mobile device not only has the capability of receiving and processing multiple component carriers, but to do so efficiently so as not to over-burden the functionality or power requirements of the mobile device.
The embodiments described below may be practiced in a variety of communication networks that utilize wireless technology to communicate between a transmission source or sources and a receiving device utilizing one or more communication protocols to transfer voice, video, data and/or other types of information. The particular technology described below pertains to Long Term Evolution (LTE) or 4th Generation (4G) communication standards as applied to telephone (for example, cellular) devices. However, other embodiments need not be limited to LTE or 4G. Thus, GSM/EDGE, CDMA, Wide-CDMA (W-CDMA), Time Division Synchronous CDMA (TD-CDMA) communication techniques are applicable for use with the described embodiments or other embodiments. The component carrier aggregation allows for applications of both Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD) schemes.
In particular, the multiple component carrier aggregation described herein pertains to an advancement of LTE toward LTE-Advanced and as specified in Release 10 (or subsequent Releases for LTE), but various embodiments may be applicable to other standards or protocols as well. Also, the particular embodiments described herein address the processing of up to three component carriers that are aggregated in a signal to a receiving terminal, such as a User Terminal (UE) in a cellular network, but other embodiments may service more component carriers, as well as utilize various other receiving devices.
In the particular example for system 100, device 102 is a mobile phone (e.g. cell phone, smartphone, etc.), device 103 is a tablet computer with wireless phone capability, device 104 is a device affixed in a vehicle (e.g. a communication device or GPS navigation system with dual communication link), and device 105 is a notebook computer or a personal computer (PC) with wireless phone capability. It is to be noted that other types of devices may be present within system 100.
Devices 102-105, which are sometimes referred to as UEs, communicate with transmission source 101 utilizing one or more communication protocols and/or standards. As noted above, the network of system 100 may use LTE or 4G communication standard/protocol to transmit voice, audio, video, data, etc. from transmitting source 101 to receivers of devices 102-105. In particular, the transmitted signal from transmitting source 101 carries multiple component carrier signals that are aggregated and directed to one of the devices 102-105. Release 10 of the LTE standard permits up to five such component carrier signals to be aggregated. That is, from Release 10 onward, the transmission bandwidth may be extended by means of the so-called Carrier Aggregation (CA) technique, where multiple radio frequency (RF) carriers are aggregated and jointly, or substantially simultaneously, transmitted to a single terminal. This carrier aggregation increases the bandwidth to increase the down link data rate to a user at the receiving terminal. The receiver receiving the multiple component carrier signals processes the different component carrier signals separately and aggregates the processed components to recover the information contained in the multiple component carrier signals.
Thus, for system 100, the wireless link implements component carrier aggregation in transmitting an RF signal from source 101 (or a plurality of sources 101) to devices 102-105. In the description below, a scenario illustrates the use of up to three such component carrier signals that are aggregated. The transmitted signal from source(s) 101 to respective devices 102-105 may have one, two or three component carrier signals. Depending on the order of allocation in the network, the three component carriers are referred to as Primary Component Carrier (PCC), Secondary Component Carrier (SCC) and Tertiary Component Carrier (TCC). When only one component carrier is present, only the PCC is used. When two component carriers are present, the carriers are PCC and SCC. When all three are present, the carriers are PCC, SCC and TCC.
Although a single transmitting source 101 is illustrated in
Depending on the network, which may depend on the geographic location of the network, the various RF frequency bands and carrier frequency allocations for the network may differ. In some networks, the network frequency allocation allows for two or more carriers to be in the same range of frequencies allocated as a particular band (e.g. frequency band) so that the multiple component carriers reside within the same allocated band (intra-band), whereas in other applications, one or more carriers reside in different allocated frequency bands (inter-band).
When two or more component carriers are allocated within the same allocated frequency band, the CA may be contiguous or non-contiguous. In Contiguous Carrier Aggregation (CCA), component carriers are located in adjacent channels. For example, with two contiguous component carriers, a first channel having a bandwidth (BW) of 20 MHz may be combined with an adjacent channel (having 20 MHz BW) to effectively provide a super BW channel of 40 MHz. Non-Contiguous Carrier Aggregation (NCCA) uses carriers that are located in the same allocated band, but in non-adjacent channels.
The particular example shown for receiver 200 has antenna 210 coupled to one side of a diplexer (DPXL) 211 and the other side of diplexer 211 has two connections, respectively coupled to RF switches 213a and 213b. Diplexer 211 splits the incoming RF signal from antenna 210 to switches 213a and 213b. Switch 213a switches the incoming RF signal to one or more filters of filter assembly 212a, while switch 213b switches the incoming RF signal to one or more filters of filter assembly 212b-212d. It is to be noted that the RF switches 213a-b may be replaced with a diplexer configuration based on simultaneous operation of certain bands and that the use of diplexers and switches, as well as the actual number of such diplexers and switches, may vary from embodiment to embodiment. Furthermore, the filters of filter assemblies 212a-d may be stand-alone filters or the filters could be a component part of the receiver, such as a filter portion of duplexers that support full duplex (FDD) operations for the radio transceiver. What is to be noted is that some filtering operation is performed to filter the incoming RF signal containing multiple component carrier signals and this filtering operation directs the component carriers into one or more separate input paths based on the frequency or frequency band.
It is also to be noted that diplexer 211 may be one diplexer or multiple diplexers to couple the incoming RF signal to a plurality of filters, where the input path may include one or more RF switches for switching the input to the filters. Although diplexers 211 and filter assemblies 212a-d are shown for the receiver, the same (or equivalent) components may be included for use with the transmission side of a transceiver, wherein the filters may operate as part of a duplexer to multiplex the outgoing and incoming signals to/from antenna 210. Note that the transmission path is not shown in
It is to be further noted that a variety of radio front-ends may be used, instead of the example shown in
In the particular receiver 200, a respective one of the filters is designed to filter carriers that fall within a certain frequency range (e.g. filter bands) and the filters are further grouped into filter groupings to provide respective frequency band groupings (e.g. grouping of frequency bands), as noted by filter groupings of filter assemblies 212a-d. It is to be noted that the filter groupings may coincide with an allocated frequency spectrum for a given network or the grouping of the filters may be independent of such standard based frequency spectrum allocations.
RFIC 201 generally includes a Low Noise Amplifier (LNA) module or assembly (module/assembly) 202, mixer module/assembly 203, a local oscillator (LO) module/assembly 204, baseband (BB) module/assembly 205, Analog-to-Digital Converter (ADC) module/assembly 206, and some form of digital signal processing module/assembly 207. RFIC 201 is shown as a direct conversion receiver, but other embodiments may implement a heterodyne receiver where down-conversion of the incoming RF signal to baseband is done in multiple steps. The LNAs of LNA module/assembly 202 amplify the RF input signal from the filters and the mixer module/assembly 203 down-converts the inbound RF signal to baseband, based on a local oscillation signal provided by the LO module/assembly 204. The BB module/assembly 205 baseband processes the down-converted baseband signal and the ADC module/assembly 206 converts the baseband analog signal to an inbound digital signal. Digital signal processing module/assembly 207, typically using a digital signal processor (DSP), processes the digital signal to provide a digitally processed signal as an output from RFIC 201. The output signal from RFIC 201 may be coupled to modems, application processors, peripheral devices, host processors, etc. for whatever application the particular device does with incoming signals received by the device.
The one or more components of the radio front-end (e.g. filters, switches, diplexers, etc.) may also be included within RFIC 201. However, in a typical implementation, a chip vendor supplies the RFIC and the device manufacturer (e.g. phone OEM) designs the front-end for the device. Accordingly, the embodiment of
For a device to receive and process the multiple component carrier signals described above in a platform designed for a single carrier, it would be advantageous for the phone manufacturer to maintain the same radio front-end, provided that the allocated frequency spectrum and designated frequency bands do not change in the network. That is, the added capability for multiple component carrier signal processing for carrier aggregation may be designed into RFIC 201, so that a radio front-end of the device (in front of RFIC 201) designed for a single carrier platform could still be used. Accordingly, the embodiments shown in
For example, in one embodiment, the following frequency allocation is used:
Thus, for example, the six filters (shown having inputs A-F) of band grouping LB are configured to respectively pass different frequency bands that fit within 600-1000 MHz. Filters 301 may all have the same bandwidth characteristics or some (or all) may have different bandwidth characteristics. As noted above, the component carriers being transmitted may have a bandwidth of 1.4, 3, 5, 10, 15 or 20 MHz per carrier in one embodiment, so that the filter bandwidths may be selected based on these values. The actual number of filters 301 used per band grouping, as well as the band-pass setting for each filter, are design factors to allow for the filtering of the different carrier signal that are received by the receiver. Note that the number of filters shown in
A particular component carrier received at the antenna is filtered by one of the filters 301 based on its frequency. For inter-band carrier aggregation cases, three component carriers would be passed through three different filters based on the carrier frequencies. For any intra-band carrier aggregation cases, the intra-band carriers would be filtered through the same (common) filter. Respective filter outputs are coupled to a pair of LNAs 302, in which a filter output is coupled to a first set of LNAs (shown in lighter color) and also to a second set of LNAs (shown in darker color). This is done separately for each respective band grouping. The LNA outputs from the first set of LNAs for a particular band grouping are combined together and the outputs from the second set of LNAs for that particular band grouping are combined together. This is also done for the respective band groupings.
The first set of LNA outputs are coupled to a first mixer having a LO1 as the LO frequency and to a second mixer having LO3 as the LO frequency. The second set of LNA outputs are coupled to a third mixer having LO2 as the LO frequency and to a fourth mixer having LO3 as the LO frequency. This arrangement is also done for the respective filter band groupings. When only one carrier is received, only one mixer and one LO signal is used. When two component carriers are received, two mixers and two different LO signals are used. When three carriers are received, three mixers and three different LO signals are used.
The outputs from the mixers 303 are coupled to respective BB#304 for baseband processing and the outputs from the different BB# are then sent to respective ADC#305. The output of the ADC is in digital format and subsequently sent to a digital processor, such as DSP 207 of RFIC 201 shown in
A control mechanism is used to activate (or switch in) only one mixer per signal path, so that either LO1 or LO3 is used to down-convert the first set of LNA outputs and either LO2 or LO3 is used to down-convert the second set of LNA outputs. The outputs from mixers utilizing LO 1 are coupled to provide the down-converted output to BB1. The outputs from mixers utilizing LO2 are coupled to provide the down-converted output to BB2 and the outputs from mixers utilizing LO3 are coupled to provide the down-converted output to BB3. Those mixers 303 and BB#304 not being utilized for processing the received component carrier(s) may be made inactive.
Thus, the particular implementation of receiver 300 allows for three component carriers to be processed in the receiver, in which two of the component carriers may be intra-band carriers. With the two intra-band component carriers, the two intra-band component carriers would be both filtered by a common filter and then the filtered output provided to the two LNA input paths for that filter (a path for each of the two intra-band component carriers). A mixer corresponding to the one path down-converts the first filtered component carrier signal and a different mixer corresponding to the second path down-converts the second filtered component carrier signal. The third component carrier is in a different band grouping. Only two intra-band carriers are capable of being processed in a given band grouping due to the band groupings having two LNA paths.
It is to be noted that other embodiments may readily implement a third (or more) LNA path per RF input at each filter to provide for a third down-conversion path for a third (or more) carrier in the same frequency band grouping. However, such a third path may add considerable number of LNAs and mixers, as well as other components (e.g. control circuitry, switches, etc.), so that there may be a trade-off on whether it is desirable to process a third intra-band component carrier.
The embodiment of
Accordingly, receiver 300 allows for the substantially simultaneous processing of up to three component carrier signals, in which:
all three component carriers are in different frequency band groupings (all inter-band);
two component carriers are in one frequency band grouping, but filtered using different filters, and the third component carrier is in a different frequency band grouping (all are inter-band); and
two component carriers are in one frequency band grouping and filtered using the same filter (intra-band), and the third component carrier is in a different frequency band grouping (inter-band).
It is to be noted that in some instances, where the two intra-band component carrier signals are contiguous (CCA), the same filter and the same LNA path may be capable of processing the two CCA carriers, since the two carriers' bandwidths are contiguous.
With the various embodiments shown in
Likewise, diagram 702 shows that if the PCC and SCC are selected to be both in the MB, then TCC cannot be in the MB as well. Likewise, diagram 703 shows that if the PCC and SCC are selected to be both in the HB, then TCC cannot be in the HB too and diagram 704 shows that if the PCC and SCC are selected to be both in the HRB, then TCC cannot be in the HRB too. Diagram 700 illustrates the flexibility of employing the embodiments described in reference to
It is to be noted that the embodiments are not limited to just those illustrated in the disclosure. Although a receiver would add complexity and component count, embodiments may be implemented where more than two LNA output paths are constructed per RF input to a filter. The number of frequency band groupings may be increased as well. Other embodiments may also be readily designed within the framework of the embodiments described above, but taking into account the complexity versus flexibility for a particular application and/or a network in which the device operates, the examples described herein utilizing a plurality of band groupings with two LNA paths per filter input and combining the LNA outputs paths per band grouping for coupling a respective mixer, allows for a less complex and flexible system, while capable of substantially simultaneously processing the aggregation of up to three component carrier signals.
Although a two amplifier structure is shown with the LNAs in
Thus, a flexible receiver architecture for multiple component carrier aggregation in down link is described. The disclosure pertains to a particular down-link LTE or 4G standard, but is not limited to such down-link transmission. With the embodiments described herein, a device manufacture may use present devices (or with slight modification) that received a single carrier to now receiving multiple component carriers, by replacing only the RFIC chip. Since the design of the RFIC takes into account the front-end components, the device manufacturer may retain the current device front-end. Only the back end for processing the new RFIC chip would be modified or replaced. Furthermore, the embodiments described provide for a flexible scheme in processing up to three component carrier signals. However, other embodiments may be readily implemented to process and aggregate more than three component carrier signals.
As may be used herein, the term(s) “configured to”, “operably coupled to”, “coupled to”, and/or “coupling” includes direct coupling between items and/or indirect coupling between items via an intervening item (e.g., an item includes, but is not limited to, a component, an element, a circuit, and/or a module) where, for an example of indirect coupling, the intervening item does not modify the information of a signal but may adjust its current level, voltage level, and/or power level.
As may also be used herein, the terms “processing module”, “processing circuit”, “processor”, “processing unit”, “baseband processor”, “signal processor” may be a single processing device or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on hard coding of the circuitry and/or operational instructions.
The term “module”, “assembly”, or “stage” is used in the description of one or more of the embodiments. Such terms may be applicable to a circuit, part of a circuit or grouping of circuits that provide a particular function.
The one or more embodiments are used herein to illustrate one or more aspects, one or more features, one or more concepts, and/or one or more examples that may be implemented. While particular combinations of various functions and features of the one or more embodiments have been expressly described herein, other combinations of these features and functions are likewise possible. The disclosure is not limited by the particular examples disclosed herein and expressly incorporates other combinations as well.
The present U.S. Utility Patent Application claims priority pursuant to 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 61/884,879, entitled, “ Flexible Receiver Architecture for Multiple Component Carrier Aggregation in Down Link,” filed Sep. 30, 2013, which is incorporated herein by reference in its entirety for all purposes.
Number | Date | Country | |
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61884879 | Sep 2013 | US |