Patent Application
20150334612
Aspects of this disclosure relate generally to telecommunications, and more particularly to selecting and utilizing an operating channel at a small cell.
Wireless communication systems are widely deployed to provide various types of communication content such as, for example, voice, data, and so on. Typical wireless communication systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple-access systems may include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like. Additionally, the systems can conform to specifications such as third generation partnership project (3GPP), 3GPP long term evolution (LTE), ultra mobile broadband (UMB), evolution data optimized (EV-DO), etc.
To supplement conventional base station coverage in wireless communication systems, additional small cells can be deployed to provide more robust wireless coverage to mobile devices. For example, small cells (e.g., which may include Home NodeBs or Home eNBs, collectively referred to as H(e)NBs, femto nodes, pico nodes, micro nodes, etc.) can be deployed for incremental capacity growth, richer user experience, in-building or other specific geographic coverage, and/or the like. In some configurations, such small cells may be connected to the Internet via a broadband connection (e.g., digital subscriber line (DSL) routers, cable or other modems, etc.), which can provide the backhaul link to the mobile operator's network. In this regard, small cells are often deployed in homes, offices, etc. without consideration of a current network environment.
Small cells may utilize a channel selection (CS) process where a Network Listen Module (NLM) at the small cell measures interference on one or more defined LTE channel frequencies such to select a desirable channel frequency for operation. For example, the NLM can measure interference of the channels (or frequency band) by measuring the signal strength of surrounding small cells and other interfering sources (e.g., macro cells or other network nodes) on one or more of the available channels, and the small cell can select a channel with the least amount of interference. The CS process may also consider an operation, administration, and management (OAM) configuration which can provide an initial list of the LTE channel frequencies, switching thresholds, measurement intervals for measuring interference, and/or the like.
There are limitations, however, in using NLM measurements since these are based on the received signal strength indicator (RSSI) estimates and interference by the NLM, which is located at the small cell. In this regard, for example, it is possible that the small cell selects an operating channel based on a low RSSI of a neighboring cell received at the NLM, but the RSSI of the neighboring cell at a UE served by the small cell may be much larger, and thus the UE may be interfered by the neighboring cell when communicating with the small cell over the operating channel. In addition, other inaccuracies in channel selection using NLM measurements may include RSSI measurements and variance dependent on fading environments and time and duration of measurements. Furthermore, intermittent interference in certain subbands of the serving frequency may also affect the NLM measurements.
The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.
According to an example, a method for selecting an operating channel for a small cell is provided. The method includes determining to select a different operating channel at a small cell based at least in part on at least one of a downlink quality metric, an uplink quality metric, or a combination thereof, causing one or more connected mode user equipments (UE) served by the small cell to handover to one or more neighboring cells based at least in part on determining to select the different operating channel, modifying one or more parameters configured to one or more idle mode UEs camped on the small cell to cause the one or more idle mode UEs to reselect to the one or more neighboring cells, and switching to use the different operating channel at least when the one or more connected mode UEs are handed over to the one or more neighboring cells.
In another aspect, an apparatus for selecting an operating channel for a small cell is provided. The apparatus includes a channel selecting component configured to determine to select a different operating channel at a small cell based at least in part on at least one of a downlink quality metric, an uplink quality metric, or a combination thereof, and a UE migrating component configured to cause one or more connected mode UEs served by the small cell to handover to one or more neighboring cells based at least in part on determining to select the different operating channel, and to modify one or more parameters configured to one or more idle mode UEs camped on the small cell to cause the one or more idle mode UEs to reselect to the one or more neighboring cells. The channel selecting component is further configured to switch to use the different operating channel at least when the one or more connected mode UEs are handed over to the one or more neighboring cells.
In yet another aspect, an apparatus for selecting an operating channel for a small cell is provided. The apparatus includes means for determining to select a different operating channel at a small cell based at least in part on at least one of a downlink quality metric, an uplink quality metric, or a combination thereof, means for causing one or more connected mode UEs served by the small cell to handover to one or more neighboring cells based at least in part on determining to select the different operating channel, and means for modifying one or more parameters configured to one or more idle mode UEs camped on the small cell to cause the one or more idle mode UEs to reselect to the one or more neighboring cells. The apparatus further includes means for switching to use the different operating channel at least when the one or more connected mode UEs are handed over to the one or more neighboring cells.
Still in further aspects, a non-transitory computer-readable medium storing computer executable code for selecting an operating channel for a small cell is provided, which includes code executable to determine to select a different operating channel at a small cell based at least in part on at least one of a downlink quality metric, an uplink quality metric, or a combination thereof, code executable to cause one or more connected mode UE served by the small cell to handover to one or more neighboring cells based at least in part on determining to select the different operating channel, and code executable to modify one or more parameters configured to one or more idle mode UEs camped on the small cell to cause the one or more idle mode UEs to reselect to the one or more neighboring cells. The computer-readable medium further includes code executable to switch to use the different operating channel at least when the one or more connected mode UEs are handed over to the one or more neighboring cells.
To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.
The accompanying drawings are presented to aid in the description of various aspects of the disclosure and are provided solely for illustration of the aspects and not limitation thereof.
The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known components are shown in block diagram form in order to avoid obscuring such concepts.
Described herein are various aspects related to selecting an operating channel for a small cell and switching to the operating channel at the small cell. For example, the small cell can determine whether an interference condition exists at one or more served user equipments (UE) based on measured downlink (DL) or uplink (UL) metrics, and if so the small cell may receive and utilize signal strength measurements of neighboring cells from served user equipment (UE) in determining a different operating channel. In addition, for example, in switching to a new operating channel, the small cell can cause served connected mode UEs to handover to one or more neighboring cells and/or can cause idle mode UEs to reselect to one or more neighboring cells. At least when the connected mode UEs are handed over, the small cell can switch to the new operating frequency such that minimal impact may be caused to a user experience at the connected mode UEs. Moreover, for example, a persistence delay can be configured at the small cell to prevent frequent switching of operating channels at the small cell. In any case, the small cell can continue to evaluate channels for operation to ensure selection of an operating channel that is desirable for the UEs served by the small cell.
As used herein, the term “operating channel” may refer to a portion of frequency or time resources that are defined to comprise a channel over which cells in a wireless technology (e.g., 3GPP LTE) may communicate. The operating channel may include a collection of contiguous frequency resources (e.g., a “band” of frequency) or non-contiguous frequency resources. The operating channel may also be referred to herein as an operating frequency, band, carrier, and/or the like.
As used herein, the term “small cell” may refer to an access point or to a corresponding coverage area of the access point, where the access point in this case has a relatively low transmit power or relatively small coverage as compared to, for example, the transmit power or coverage area of a macro network access point or macro cell. For instance, a macro cell may cover a relatively large geographic area, such as, but not limited to, several kilometers in radius. In contrast, a small cell may cover a relatively small geographic area, such as, but not limited to, a home, a building, or a floor of a building. As such, a small cell may include, but is not limited to, an apparatus such as a base station (BS), an access point, a femto node, a femtocell, a pico node, a micro node, a Node B, evolved Node B (eNB), home Node B (HNB) or home evolved Node B (HeNB). Therefore, the term “small cell,” as used herein, refers to a relatively low transmit power and/or a relatively small coverage area cell as compared to a macro cell.
Aspects of the disclosure provided in the following description and related drawings are directed to specific disclosed aspects. Alternate aspects may be devised without departing from the scope of the disclosure. Additionally, well-known aspects of the disclosure may not be described in detail or may be omitted so as not to obscure more relevant details. Further, many aspects are described in terms of sequences of actions to be performed by, for example, elements of a computing device. It will be recognized that various actions described herein can be performed by specific circuits (e.g., application specific integrated circuits (ASICs)), by computer executable code or instructions being executed by one or more processors, or by a combination of both. Additionally, these sequence of actions described herein can be considered to be embodied or stored entirely within any form of computer readable storage medium, e.g., a medium having stored therein a corresponding set of computer executable code or instructions that upon execution would cause an associated processor to perform the functionality described herein. Thus, the various aspects of the disclosure may be embodied in a number of different forms, all of which have been contemplated to be within the scope of the claimed subject matter. In addition, for each of the aspects described herein, the corresponding form of any such aspects may be described herein as, for example, “logic configured to” perform the described action.
Each small cell 104, 106, 110 may be configured to communicate via (e.g., transmit or receive signals on) one or more radio frequency channels. Moreover, the small cells 104, 106, 110 may be configured to communicate with one another and/or with other access points (e.g., macro base station 102) over one or more wired or wireless backhaul links. For example, the small cells 104, 106, 110 may communicate over the backhaul interface using an X2 interface. When multiple radio frequency (RF) channels (and/or bands) are available, conventionally configured small cells may be configured to select an operating channel by measuring the signal strengths of surrounding small cells, macro cells, or other nodes on one or more of the channels. For example, small cell 106 may be configured to choose a channel having a lowest signal strength measured by a NLM at the small cell 106, such to avoid interference from nodes producing the measured signal strength. Once the operating channel is selected, the small cell is typically configured to maintain the selected channel until powered down or a configured reselection time. In some examples, a half-day or more may elapse before channel reselection. Furthermore, the foregoing channel selection based on measurements at the small cell location. As shown in
Accordingly, small cell 106 (and/or any of the other small cells shown in
Interference experienced by served UEs 114 can be dynamic based on movement of the UEs 114, activation/deactivation of neighboring cells (e.g., small cells 104, 110), other changes in network deployment, etc. Accordingly, DL/UL metrics can be measured and/or received by the small cell 106 to determine whether to evaluate other operating channels for possible switching, and the measurement reports received from the UEs 114 are used to determine an optimal operating channel. Thus, allowing dynamic operating channel selection by small cell 106 can allow the operating channel to change based on different interference conditions at the served UEs 114 (rather than at small cell 106). In addition, when switching operating channels, small cell 106 can cause connected mode UEs 114 to handover to neighboring cells and can cause idle mode UEs 114 to reselect to neighboring cells to minimize impact of the operating channel switch on the UEs 114. In one example, as described further herein, a persistence delay may be configured at the small cell 106 such to avoid frequent operating channel switching, and thus frequent handover/reselection of UEs 114.
Moreover, in an example, because the UE 114 may be able to detect signals from different neighboring cells than the NLM at the small cell 106, small cell 106 may be configured to manage automatic neighbor relations (ANR) based on the received UE 114 measurement reports. For example, small cell 106 can be configured to maintain a neighbor list of neighboring cells for provisioning to one or more other served UEs, where the neighbor list is maintained based at least in part on the measurement reports from the UEs 114. Similarly, small cell 106 may utilize the measurement reports from UEs 114 to determine availability of neighboring cells for handover (e.g., for switching of the operating channel of small cell 106 or otherwise), or other capabilities of the neighboring cells (e.g., X2 interface capabilities).
Processor 204 may comprise or be a component of a processing system implemented with one or more processors. The one or more processors may be implemented with any combination of general-purpose microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate array (FPGAs), programmable logic devices (PLDs), controllers, state machines, gated logic, discrete hardware components, dedicated hardware finite state machines, or any other suitable entities that can perform calculations or other manipulations of information.
The processing system may also include machine-readable media for storing software. Software shall be construed broadly to mean any type of instructions, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Instructions may include code (e.g., in source code format, binary code format, executable code format, or any other suitable format of code). The instructions, when executed by the one or more processors, cause the processing system to perform the various methods described herein.
Small cell 106 may also include a housing 208 that may include a transmitter 210 and/or a receiver 212 to allow transmission and reception of data between the small cell 106 and a remote network node such as UE 114 (
Small cell 106 may also include a signal detector 218 that may be used to detect and quantify the level of signals received by the transceiver 214. Signal detector 218 may detect such signals as total energy, energy per subcarrier per symbol, power spectral density and other signals. Small cell 106 may also include a digital signal processor (DSP) 220 for use in processing signals. The DSP 220 may be configured to generate a packet for transmission.
Small cell 106 may also include a communicating component 221 operable for determining to select an operating channel based on received measurement reports, modifying active and/or idle mode communication parameters to cause active and/or idle mode UEs to handover/reselect, switching to a selected operating channel, etc. For example, communicating component 221 can include a network monitoring component 222. Network monitoring component 222 can be configured to receive certain DL quality metrics from served UEs 114 (e.g., via signals from the UEs 114 received by receiver 212) and/or measure certain UL quality metrics from signals received from served UEs 114. Network monitoring component 222 can accordingly determine whether an interference condition exists for the one or more served UEs 114 such to determine whether to switch to a different operating frequency. Network monitoring component 222 can be configured to obtain quality metrics relating to radio conditions over one or more channels for selecting an operating channel for small cell 106. For example, the quality metrics can include strengths/qualities of a channel including received signal strength indicator (RSSI), reference signal received power (RSRP), reference signal received quality (RSRQ), etc., configuration parameters indicative of signals strength/quality including uplink modulation coding scheme (MCS), power headroom report (PHR), uplink block error rate (BLER), channel quality indicator (CQI), downlink MCS, etc. Network monitoring component 222 can also be configured to receive measurement reports from one or more UEs (e.g., as part of a handover procedure), as described further herein, receive signals from an NLM located at or accessible by small cell 106, and/or the like.
Communicating component 221 may also include a channel selecting component 224. Channel selecting component 224 can be configured to select an operating channel for small cell 106. Channel selecting component 224 may select the operating channel based on received or measured DL/UL quality metrics, measurement reports received from served UEs 114, etc. In addition, for example, channel selecting component 224 may aggregate measurement reports received from served UEs 114 to identify statistically significant quality indicators. Based on a comparison of a statistically significant quality indicator with a threshold quality, for example, channel selecting component 224 may determine that a new operating channel should be selected (e.g., where quality of a current operating channel is below a threshold quality and/or where quality of another operating channel achieves a threshold quality). Statistical significance and/or the threshold quality may be configured at small cell 106 (e.g., based on an OAM configuration message, a configuration stored in memory 206, etc.). The channel selecting component 224 may be further configured to identify the new operating channel for switching based on the measurement reports. A list of available channels may be maintained by small cell 106, such as in the memory 206, which may be determined from various measurement reports, received from an OAM, etc. Based on the received measurement reports, the list of available channels may be sorted (e.g., based on downlink quality indicated or otherwise inferred from the measurement reports, or other configured metric that can be received and/or determined at least based on the measurement reports) for determining an optimal operating channel.
Communicating component 221 may also include a UE migrating component 226 to transition served UEs 114 to other serving cells based on channel selecting component 224 determining to select a new operating channel for small cell 106. UE migrating component 226 may be configured to transmit a message to the UEs served by small cell 106. The message may cause one or more of the plurality of served UEs to disconnect from the small cell 106.
For example, UE migrating component 226 may be configured to initiate handover of served UEs 114 in connected mode to neighboring cells. In such examples, the message transmitted to the served UEs 114 may indicate that the UE 114 is to handover to the other neighboring cell. In some examples, UE migrating component 226 may be further configured to negotiate or otherwise initiate handover with the neighboring cell (e.g., using X2 communications). In other examples, UE migrating component 226 may be configured to modify system parameters of small cell 106 to trigger events at the UEs 114 that cause the UEs to handover to neighboring cells. For example, UE migrating component 226 may modify one or more parameters of small cell 106 related to triggering inter-frequency or intra-frequency A3, A4, or A5 events (see Table 1 below), which are configured to the served UEs 114, to result in a more frequent or immediate triggering of an A3, A4, and/or A5 event. In such examples, the modified parameters can be sent to the UEs 114 in one or more broadcast messages (e.g., system information block (SIB messages) or dedicated messages. Accordingly, the served UEs 114 may receive the parameters and trigger event(s) A3, A4, or A5 based on received parameters of the small cell 106, which can cause the UEs 114 to measure neighboring cells for handover, and send corresponding measurement reports to small cell 106 (which may then make a handover decision for the UEs 114).
In addition, for example, UE migrating component 226 may be configured to initiate idle mode reselection of UEs 114 camped on small cell 106. For example, UE migrating component 226 may be configured to transmit a message causing idle mode UEs (also referred to herein as “camped UEs”) to perform reselection to neighboring cells. In an example, the message can relate to a broadcast message (e.g., SIB messages) or dedicated message that include modified parameters to be configured at the UEs 114 for determining when to perform idle mode reselection. For example, the modified parameters may relate to a hysteresis parameter that specifies a period of time to wait between determining whether to perform reselection, an offset parameter that specifies a period of time after which to determine whether to perform reselection, channel priority parameters related to a priority of one or more channels for camping, and/or the like. UE migrating component 226 may adjust or modify a value of one or more of these parameters, which causes reconfiguration at idle mode UEs upon receipt of the broadcast or dedicated message, thereby causing more definite and/or immediate (e.g., relatively faster by reducing the period of time) idle mode reselecting performed by the idle mode UEs 114 camped on the small cell 106.
The various components of the small cell 106 may be coupled together by a bus system 228. The bus system 228 may include a data bus, for example, as well as a power bus, a control signal bus, and a status signal bus in addition to the data bus. Those of skill in the art will appreciate the components of the small cell 106 may be coupled together or accept or provide inputs to each other using some other mechanism.
Although a number of separate components are illustrated in
In a specific example, channel selection at the small cell 106 may begin when the small cell 106 powers up. Channel selecting component 224 may be configured to download a channel list from an OAM node (not shown) that indicates available operating channels for the small cell 106. Channel selecting component 224 may then be configured to perform an initial channel selection to select one of the channels from the list as an operating channel. In one example, as described, an NLM (not shown) at the small cell 106 may be utilized to measure signals received over at least a portion of the channels in the list, and channel selecting component 224 can initially select a channel having the lowest RSSI or other measure of signal strength or interference as the operating channel for the small cell 106.
Thereafter, for example, network monitoring component 222 may be configured to periodically evaluate the uplink (UL) and/or downlink (DL) metrics reported by UEs 114 served by small cell 106. For example, a UE 114 operating in connected mode may periodically provide DL channel quality metrics (e.g., in channel state information (CSI) feedback, such as CQI reports). Network monitoring component 222 may evaluate the DL channel quality metrics to determine whether an interference condition exists at one or more UEs 114 on the current operating channel, which may cause channel selecting component 224 to determine whether to switch to a different operating channel (e.g., where the DL channel quality metrics are below a threshold). In any case, network monitoring component 222 may determine whether there are statistical distributions of DL quality metrics reported by the served UEs 114 that are below a threshold, and if so there could be a potential need for a new operating channel selection. In another example (e.g., where no interference condition is determined based on DL metrics), network monitoring component 222 can determine one or more UL channel quality metrics (e.g., UL MCS, PHR, UL BLER, etc.) based on communications received from the served UEs 114, which can be evaluated to determine whether channel selecting component 224 should consider switching operating channels (e.g., where the UL channel quality metrics are below a threshold).
Network monitoring component 222 may determine the various thresholds for identifying interference conditions based at least in part on thresholds configured by an OAM, observed thresholds resulting in selection of an optimal operating channel for a certain period of time, simulation studies, network performance counters, etc. In some examples, network monitoring component 222 may generate the thresholds based on determining a density of the small cell deployment (e.g., based on measurement reports from served UEs 114, communications received from small cells in the deployment over an X2 interface, etc.). For statistical distribution and to be able to identify interference conditions of cell-edge UEs, network monitoring component 222 may determine the thresholds as high percentile values of metrics received over a period of time or for a certain number of received metrics (e.g., 95th, 98th, etc. percentile values).
Where a threshold condition is triggered as per the process mentioned above, network monitoring component 222 may be configured to analyze intra- and inter-frequency neighbor signal strength values reported by the served UEs 114 (e.g., RSSI, RSRP, RSRQ, etc.) to determine whether another operating channel may provide improved interference conditions for one or more of the UEs 114. For example, network monitoring component 222 may receive the measurement reports from the served UEs 114 as part of a handover procedure. The measurement reports may include metrics utilized to assess the strength (RSSI, RSRP, etc.) and/or quality (RSRQ) of the neighboring cells, and may be sorted in order of suitability (e.g., lowest RSSI/RSRP/RSRQ). It is to be appreciated that term signal strength, as used herein, may include such strength and/or quality measurements. In addition, measurement reports from the served UEs 114 may also be used by network monitoring component 222 to refine and manage automatic neighbor relations (ANR) as described above, such to define neighbor lists for the small cell 106 based on the UE measurements instead of or in addition to NLM measurements or OAM configurations. Such neighbor lists may be communicated to served UEs for selecting neighboring cells for handover, for determining parameters of the neighboring cells (e.g., backhaul interface parameters), and/or the like.
Where network monitoring component 222 has not received a measurement report from one or more UEs within a period of time or has not received a sufficient number of measurement reports given a number of served UEs 114, network monitoring component 222 may modify event threshold parameters advertised in a broadcast message (e.g., a SIB message) or a dedicated message, such as an A(i) (e.g., A3, A4, A5) event threshold, which can cause UEs 114 retrieving and updating the parameters to trigger the associated events. Such events when triggered can cause the UEs 114 to generate and send measurement reports to small cell 106 (e.g., for the purposes of evaluating neighboring cells for handover). In any case, channel selecting component 224 can determine whether to select a different operating channel based at least in part on the measurement reports received from one or more served UEs 114. For example, channel selecting component 224 can determine a channel for which a received signal strength reported by the UEs 114 (e.g. in total) is lowest, for which a received signal strength reported by the UEs 114 is lowest on average, for which a received signal strength reported by all served UEs 114 does not exceed a threshold, etc. In one example, network monitoring component 222 may rank the channels based on reported signal strength. In any case, channel selecting component 224 can accordingly select a different channel to be the operating channel for the small cell 106 where the different channel has more desirable radio conditions (e.g., lower reported signal strength) than the current operating channel.
UE migrating component 226 can attempt to cause the served UEs 114, in both idle and connected modes, to migrate to neighboring cells or otherwise not attempt to access small cell 106 while the small cell 106 switches to the selected operating channel. For example, UE migrating component 226 can handover connected mode UEs 114 to one or more neighboring cells and/or can cause idle mode UEs 114 to perform idle mode reselection to one or more neighboring cells. For example, UE migrating component 226 may be configured to determine whether the small cell 106 has a connection (e.g., an X2 connection) with any neighboring cells (not shown) such to negotiate handover of one or more connected mode UEs 114. If so, UE migrating component 226 may be configured to negotiate with intra/inter-frequency neighbor cells over the X2 interface and force network-initiated intra/inter-frequency handover of one or more connected mode UEs 114. Intra-frequency handover may be preferred where intra-frequency neighboring cells are present.
In another example, UE migrating component 226 can cause handover of connected mode UEs 114 based at least in part on modifying system parameters sent to UEs in a broadcast message (e.g., a SIB message) or a dedicated message, such as parameters related to triggering A3, A4, A5 events at the UE for sending measurement reports and facilitating intra/inter-frequency handover of the UEs. In this example, intra-frequency handover may be preferred where intra-frequency neighboring cells are present.
In addition, UE migrating component 226 may be configured to modify hysteresis, offset parameters, and/or channel priority parameters broadcasted to idle mode UEs 114 to cause the idle mode UEs 114 to reselect to other neighboring cells. For example, UE migrating component 226 can decrease the hysteresis and/or offset parameters so that the idle mode UEs 114 can attempt reselection sooner than with the previously configured parameters. Furthermore, for example, UE migrating component 226 can decrease the channel priority parameters to make the small cell 106 operating channel less desirable, such to cause idle mode UEs 114 to reselect a neighboring cell that uses a different operating channel in the next reselection opportunity. This can increase the likelihood that the idle mode UEs 114 reselect a neighboring cell where a neighboring cell with a higher priority operating channel is present. In one example, UE migrating component 226 may increase the channel priority of the operating channel to which the small cell 106 plans to switch.
Channel selecting component 224 may be configured to switch to the selected channel based on UE migrating component 226 causing migration of the connected and/or idle mode UEs 114. In one example, channel selecting component 224 may begin switching to the selected channel once the connected mode UEs 114 are handed over and regardless of the idle mode UEs 114. Switching to the selected channel, in this regard, may include switching the transmitter 210 and/or receiver 212 to operate on the selected channel.
In some examples, to avoid excessive signaling burden on the network, channel selecting component 224 may be configured with a persistence delay (e.g., from an OAM, a configuration stored in memory, etc.). Accordingly, in one example, the persistence delay may relate to a timer value, and upon switching to the selected channel, channel selecting component 224 may initialize a timer using the persistence delay timer value such that a subsequent channel selection may not occur until after expiration of the timer. In some examples, network monitoring component 222 can also be configured to refrain from monitoring the DL/UL metrics for the purposes of determining whether a new channel should be selected until after expiration of the timer to conserve resources.
In another example, the configured persistence delay may relate to a number of interference conditions and/or a severity of interference conditions that are to be detected by the network monitoring component 222 until selection to a different operating channel can be performed. The persistence delay may be set based at least in part on interference experienced by the UEs 114 (e.g., in previous operating channel selections), small cell deployment characteristics (e.g., a number of small cells within a proximity of small cell 106), etc., and may be configured by the channel selecting component 224 based on observing such interference or characteristics, by an OAM, and/or the like.
Referring to FIGS. 3 and 4A-4C, methods that may be performed by the apparatuses described herein (e.g., small cell 106, apparatus 504, small cells 710A, 710B, wireless device 910, apparatus 1000, etc.) are depicted. Although the operations described below in FIGS. 3 and 4A-4C are presented in a particular order and/or as being performed by an example component, it should be understood that the ordering of the actions and the components performing the actions may be varied, depending on the implementation. Moreover, it should be understood that the following actions or functions may be performed by a specially-programmed processor, a processor executing specially-programmed software or computer-readable media, or by any other combination of a hardware component and/or a software component capable of performing the described actions or functions. Moreover, in an aspect, a component may be one of the parts that make up a system, may be hardware or software, and/or may be divided into other components.
In addition, as described, channel selecting component 224 can determine the different operating channel based at least in part on evaluating measurement reports received form one or more UEs 114 to determine an operating channel that has a lowest reported signal strength, or that would otherwise cause the lowest interference to the one or more UEs 114. For example, channel selecting component 224 may select the operating channel with the lowest average reported signal strength (e.g., RSSI, RSRP, RSRQ, etc.), the operating channel for which none of the UEs 114 report a signal strength over a certain threshold, an operating channel for which no more than a threshold number of UEs 114 report signal strength over the certain threshold, etc. In some examples, channel selecting component 224 may determine that the current operating channel is the most desirable based on the measurement reports received from the UEs, in which case channel selecting component 224 may determine not to select a different operating channel at Block 310.
Method 300 also includes, at Block 312, causing one or more connected mode UEs served by the small cell to handover to one or more neighboring cells based at least in part on determining to select the different operating channel. UE migrating component 226 can cause the one or more connected mode UEs served by the small cell 106 to handover to one or more neighboring cells based at least in part on channel selecting component 224 determining to select the different operating channel. As described, for example, UE migrating component 226 can cause the one or more connected mode UEs to handover by negotiating handover with the one or more neighboring cells (e.g., over an X2 interface), by adjusting parameters broadcasted (e.g. in a SIB message) to the UEs for triggering events related to generating measurement reports for facilitating intra-/inter-frequency handover, and/or the like.
Method 300 also includes, at Block 314, modifying one or more parameters configured for one or more idle mode UEs camped on the small cell to cause the one or more idle mode UEs to reselect to the one or more neighboring cells. UE migrating component 226 can modify the one or more parameters configured to the one or more idle mode UEs camped on the small cell to cause the one or more idle mode UEs to reselect to the one or more neighboring cells. For example, UE migrating component 226 can modify a hysteresis, offset, channel priority, or similar parameter in an attempt to effectuate idle mode reselection by the one or more idle mode UEs camped on small cell 106. As described, this can include small cell 106 transmitting the modified parameters in a broadcast message (e.g., a SIB message). Modifying the one or more parameters configured for one or more idle mode UEs may also be based at least in part on determining to select the different operating channel.
Method 300 further includes, at Block 316, switching to use the different operating channel at least when the one or more connected mode UEs are handed over to the one or more neighboring cells. Channel selecting component 224 can switch to use the different operating channel at least when the one or more connected mode UEs are handed over to the one or more neighboring cells. This may include channel selecting component 224 determining whether all or at least a threshold number of connected mode UEs are handed over. In addition, for example, channel selecting component 224 may not determine whether any or some of the idle mode UEs have reselected before determining to switch the operating channel. For example, channel selecting component 224 can switch the operating channel for transmitter 210, receiver 212, etc.
Referring to
Method 400 includes, at Block 406, making an initial channel selection of a least used operating channel using a NLM or based on an OAM database. Channel selecting component 224 may make the initial channel selection of the least used operating channel, as described, based on using an NLM to measure the channels (e.g., and selecting a channel with the lowest measured signal strength), based on determining a number and/or location/distance of neighboring cells using certain channel frequencies (e.g., and selecting a channel not used by any or at least a threshold number of neighboring cells, or a channel at least not used by neighboring cells within a threshold distance of small cell 106), etc.
Based on selecting the initial channel, the small cell 106 can begin advertising service on the selected channel. UEs 114 may accordingly receive signals advertising the service, and may connect to the small cell 106. As part of connecting to the small cell 106, UEs 114 may perform periodic measurement reporting to facilitate considering neighboring cells for handover when radio conditions with the small cell 106 degrade. For example, the 3GPP specification provides a standardized measurement, format, timing, and triggering requirements for connected UEs to report neighboring cell measurements.
At Block 408, DL and UL quality metrics reported by or measured for the connected mode UEs can be periodically evaluated. Network monitoring component 222 may evaluate the reported or measured DL and UL quality metrics, as described. Network monitoring component 222 may receive the reported DL quality metrics from the UEs 114 (e.g., as RSSI, RSRP, RSRQ, CQI or other quality reports), and specified DL MCS, etc., and/or may determine the UL quality metrics based at least in part on MCS, PHR, BLER, etc. for the UEs 114.
At Block 410, it can be determined whether an Nth percentile of the DL quality metrics (RSRQ, CQI, DL MCS, etc.) are less than one or more thresholds. Network monitoring component 222 may determine whether the Nth percentile of the DL quality metrics (RSRQ, CQI, DL MCS, etc.) are less than one or more threshold, which may indicate an interference condition. For example, network monitoring component 222 may determine this at least in part by aggregating DL quality metric values from CSI reports from one or more of the UEs 114, measurement reports, etc. to determine if the metric is statistically significant. As shown in
As shown in
If, at Block 412, the Nth percentile of the UL quality metrics (MCS, PHR, etc.) are not less than one or more thresholds, the method returns to Block 408 to continue the periodic evaluation. If, at Block 410, the Nth percentile of the DL quality metrics (RSRQ, CQI, DL MCS, etc.) are less than one or more thresholds, or, at Block 412, the UL quality metrics (MCS, PHR, etc.) are less than one or more thresholds, then an interference condition may exist, and the method proceeds to Block 414 in
Turning now to
If, at Block 416, intra/inter-frequency events (A1-A5) are not reported by the UEs (or not reported by a threshold number or percentage of connected mode UEs), at block 418, A1, A2, or A3 parameters may be modified to facilitate intra/inter-frequency measurements. Network monitoring component 222 may modify these parameters in a broadcast message (e.g., SIB message), dedicated message, etc., to one or more connected mode UEs to cause the UEs to generate measurement reports. In some examples, though not shown, the method may return to Block 416 to determine whether the reports have been received.
The method also includes, at block 420 (after either determining intra/inter-frequency events have been reported on by the UEs at Block 416 or after modifying parameters to facilitate such reporting at Block 418), determining whether to change the operating channel. Channel selecting component 224 can determine whether to change the operating channel, as described, based at least in part on determining whether one or more channels from the measurement reports are more desirable than the current operating channel (e.g., have a lower average reported signal strength, have a lower reported signal strength for at least a threshold number or percentage of served UEs 114, have no or less than a threshold number of reported signal strengths from the UEs 114 that are over a threshold, etc.). In a specific example, channel selecting component 224 may sort the available channels based on such measurements of signal strength. The sort order may be determined by a configuration for the serving node such as OAM configuration. The channels may be sorted based on one or more signal strength measurements. The sorting provides an ordered list of channels available to the small cell 106, ordered by relative signal strength (e.g., interference). If the highest quality channel is the current channel, no change is identified and the method can return to Block 408 of
Upon determining to change the operating channel at Block 420, at Block 422, it can be determined whether an X2 interface is available. UE migrating component 226 can determine whether the X2 interface is available with one or more neighboring cells for negotiating handover of connected mode UEs. For example, X2 is an example of a communication protocol allowing cells in a wireless network nodes to exchange messages (e.g. to facilitate handover or other functions). It is to be appreciated that other protocols facilitating communications between cells can be used in this example. Some small-cell networks include nodes which all have X2 capabilities. Some small cells or neighboring cells, however, may not have an X2 interface.
If, at Block 422, the X2 interface is available, at Block 424, intra/inter-frequency neighbor cells can be negotiated with over X2 to cause network initiated intra/inter-frequency handover of connected mode UEs. UE migrating component 226 can negotiate with the intra/inter-frequency neighbor cells over X2 to cause the network initiated intra/inter-frequency handover of the connected mode UEs. As described, UE migrating component 226 may prefer to perform intra-frequency handover where intra-frequency neighboring cells are reported in the measurement reports from the connected mode UEs 114.
If, at Block 422, X2 is unavailable, at Block 426, intra/inter-frequency A3, A4, A5 parameters can be modified for the UEs to trigger the events, which facilitate intra/inter-frequency handover of connected mode UEs. UE migrating component 226 can modify the intra/inter-frequency A3, A4, A5 parameters for the UEs to trigger the events that facilitate intra/inter-frequency handover of connected mode UEs. For example, intra/inter-frequency A3, A4, or A5 parameters (e.g., cell specific offset to neighbor cell (Ocn)) may be adjusted and communicated by the UE migrating component 226 to the connected UEs. Table 1 below lists example parameters that may be adjusted for intra-frequency and inter-frequency handovers. Upon receipt, a connected UE may trigger a corresponding A3, A4, or A5 event, thus initiating inter or intra frequency handover. As with Block 424, if possible, UE migrating component 226 and/or the UEs may be configured to prefer intra-frequency handover. In one example, A1-A5 events that are detectable at the UE may be summarized as follows, and may have the following tunable parameters (e.g., that may be modified by UE migrating component 226 as described herein) in some wireless communication technologies (e.g., LTE):
where Ofn is the frequency specific offset of the frequency of the neighbor cell (e.g., offsetFreq defined within a measObjectEUTRA object corresponding to the frequency of the neighbor cell), Ofs is the frequency specific offset of the frequency of the serving cell (e.g., offsetFreq defined within a measObjectEUTRA object corresponding to the frequency of the serving cell), Ocn is the cell specific offset of the neighbor cell (e.g., cellIndividualOffset defined within a measObjectEUTRA object corresponding to the frequency of the neighbor cell and set to zero if not configured for the neighboring cell), Ocs is the cell specific offset of the serving cell (e.g., cellIndividualOffset defined within a measObjectEUTRA object corresponding to the frequency of the serving cell and set to zero if not configured for the serving cell), Hys is the hysteresis parameter for this event (e.g., hysteresis as defined within a reportConfigEUTRA object for this event), Off is the offset parameter for this event (e.g., a3-Offset as defined within a reportConfigEUTRA object for this event), Thresh1 is the threshold parameter for this event (e.g., a5-Threshold1 as defined within a reportConfigEUTRA object for this event), Thresh2 is the threshold parameter for this event (e.g., a5-Threshold2 as defined within a reportConfigEUTRA for this event), and timeToTrigger is the time during which specific criteria for the event may be met in order to trigger a measurement report.
In either case, it can be determined, at Block 428, whether there are any more connected
UEs. UE migrating component 226 may determine whether there are any more connected mode UEs in the small cell 106. If so, at Block 430, it may optionally be determined whether the number of connected mode UEs is less than a threshold. UE migrating component 226 may optionally determine whether the number of connected mode UEs is less than a threshold. If not, the method can proceed to Block 422 to again attempt to cause handover of the connected mode UEs.
If, at Block 428, there are no more connected mode UEs at the small cell, or, at Block 430, the number of connected mode UEs is less than a threshold, the process continues to
Turning now to
At Block 436, a transition can occur to re-synchronize to a highest ranked inter-frequency operating channel. Channel selecting component 224 can transition to re-synchronize to the highest ranked inter-frequency operating channel (e.g., the operating channel with the lowest reported signal strengths from the UEs, as described above).
At Block 438, it can optionally be determined whether a persistence delay is satisfied. Channel selecting component 224 can determine whether the persistence delay is satisfied before determining whether to evaluate operating channels for switching. For example, determining whether the persistence delay is satisfied can relate to determining whether a persistence timer, which can be set when transitioning to the new operating channel at Block 436, has expired. In another example, determining whether the persistence delay is satisfied may include determining whether a number of interference conditions have occurred since transitioning operating channels at Block 436.
Once the persistence delay is satisfied (or otherwise), the method can proceed back to starting Block 402 in
The apparatus 502 and the apparatus 504 each include at least one wireless communication device (represented by the communication devices 508 and 514) for communicating with other nodes via at least one designated radio access technology. Each communication device 508 includes at least one transmitter (represented by the transmitter 510) for transmitting and encoding signals (e.g., messages, indications, information, and so on) and at least one receiver (represented by the receiver 512) for receiving and decoding signals (e.g., messages, indications, information, pilots, and so on). Similarly, each communication device 514 includes at least one transmitter (represented by the transmitter 516) for transmitting signals (e.g., messages, indications, information, pilots, and so on) and at least one receiver (represented by the receiver 518) for receiving signals (e.g., messages, indications, information, and so on).
A transmitter and a receiver may comprise an integrated device (e.g., embodied as a transmitter circuit and a receiver circuit of a single communication device) in some examples, may comprise a separate transmitter device and a separate receiver device in some examples, or may be embodied in other ways in other examples. In some aspects, a wireless communication device (e.g., one of multiple wireless communication devices) of the apparatus 504 comprises a network listen module, as described.
The apparatus 506 may include at least one communication device (represented by the communication device 526) for communicating with other nodes. For example, the communication device 526 may comprise a network interface that is configured to communicate with one or more network entities via a wire-based or wireless backhaul. In some aspects, the communication device 526 may be implemented as a transceiver configured to support wire-based or wireless signal communication. This communication may involve, for example, sending and receiving: messages, parameters, or other types of information. Accordingly, in the example of
The apparatuses 502, 504, and 506 also include other components that may be used in conjunction with signal processing operations as taught herein. The apparatus 502 includes a processing system 532 for providing functionality relating to, for example, communicating with an access point to support functions as taught herein and for providing other processing functionality. The apparatus 504 includes a processing system 534 for providing functionality relating to, for example, functions as taught herein and for providing other processing functionality. The apparatus 506 includes a processing system 536 for providing functionality relating to, for example, functions as taught herein and for providing other processing functionality. The apparatuses 502, 504, and 506 include memory devices 538, 540, and 542 (e.g., each including a memory device), respectively, for maintaining information (e.g., information indicative of reserved resources, thresholds, parameters, and so on). In addition, the apparatuses 502, 504, and 506 include user interface devices 544, 546, and 548, respectively, for providing indications (e.g., audible and/or visual indications) to a user and/or for receiving user input (e.g., upon user actuation of a sensing device such a keypad, a touch screen, a microphone, and so on).
For convenience, the apparatus 502 is shown in
The components of
Some of the access points referred to herein may comprise small cells, as described, to provide voice and high speed data service for access terminals supporting cellular radio communication (e.g., CDMA, WCDMA, UMTS, LTE, etc.).
Small cells may be configured to support different types of access modes. For example, in an open access mode, a small cell may allow any access terminal to obtain any type of service via the small cell. In a restricted (or closed) access mode, a small cell may only allow authorized access terminals to obtain service via the small cell. For example, a small cell may only allow access terminals (e.g., so called home access terminals) belonging to a certain subscriber group (e.g., a closed subscriber group (CSG)) to obtain service via the small cell. In a hybrid access mode, alien access terminals (e.g., non-home access terminals, non-CSG access terminals) may be given limited access to the small cell. For example, a macro access terminal that does not belong to a small cell's CSG may be allowed to access the small cell only if sufficient resources are available for all home access terminals currently being served by the small cell.
Thus, small cells operating in one or more of these access modes may be used to provide indoor coverage and/or extended outdoor coverage. By allowing access to users through adoption of a desired access mode of operation, small cells may provide improved service within the coverage area and potentially extend the service coverage area for users of a macro network.
Thus, in some aspects the teachings herein may be employed in a network that includes macro scale coverage (e.g., a large area cellular network such as a third generation (3G) network, typically referred to as a macro cell network or a WAN) and smaller scale coverage (e.g., a residence-based or building-based network environment, typically referred to as a LAN). As an access terminal (AT) moves through such a network, the access terminal may be served in certain locations by access points that provide macro coverage while the access terminal may be served at other locations by access points that provide smaller scale coverage. In some aspects, the smaller coverage nodes may be used to provide incremental capacity growth, in-building coverage, and different services (e.g., for a more robust user experience).
In the description herein, a node (e.g., an access point) that provides coverage over a relatively large area may be referred to as a macro access point while a node that provides coverage over a relatively small area (e.g., a residence) may be referred to as a small cell. It should be appreciated that the teachings herein may be applicable to nodes associated with other types of coverage areas. For example, a small cell may provide coverage (e.g., coverage within a commercial building) over an area that is smaller than a macro area. In various applications, other terminology may be used to reference a macro access point, a small cell, or other access point-type nodes. For example, a macro access point may be configured or referred to as an access node, base station, access point, eNodeB, macro cell, and so on. In some examples, a node may be associated with (e.g., referred to as or divided into) one or more cells or sectors.
Each small cell (e.g., small cells 710A and 710B) may be coupled to a wide area network 740 (e.g., the Internet) and a mobile operator core network 750 via a DSL router, a cable modem, a wireless link, or other connectivity means (not shown). As will be discussed below, each small cell (e.g., small cells 710A and 710B) may be configured to serve associated access terminals (e.g., access terminal 720A) and, optionally, other (e.g., hybrid or alien) access terminals (e.g., access terminal 720B). In other words, access to small cells (e.g., small cells 710A and 710B) may be restricted whereby a given access terminal may be served by a set of designated (e.g., home) small cell(s) but may not be served by any non-designated small cells (e.g., a neighbor's small cell).
In an example, the owner of a small cell 710 may subscribe to mobile service, such as, for example, 3G mobile service, offered through the mobile operator core network 750. In addition, an access terminal 720 may be capable of operating both in macro environments and in smaller scale (e.g., residential) network environments. In other words, depending on the current location of the access terminal 720, the access terminal 720 may be served by a macro cell access point 760 associated with the mobile operator core network 750 or by any one of a set of small cells 710 (e.g., the small cells 710A and 710B that reside within a corresponding user residence 730). For example, when a subscriber is outside his home, he is served by a standard macro access point (e.g., access point 760) and when the subscriber is at home, he is served by a small cell (e.g., small cell 710A). Here, a small cell 710 may be backward compatible with legacy access terminals 720.
A small cell 710 may be deployed on a single frequency or, in the alternative, on multiple frequencies. Depending on the particular configuration, the single frequency or one or more of the multiple frequencies may overlap with one or more frequencies used by a macro access point (e.g., access point 760).
In some aspects, an access terminal 720 may be configured to connect to a preferred small cell (e.g., the home small cell of the access terminal 720) whenever such connectivity is possible. For example, whenever the access terminal 720A is within the user's residence 730, it may be desired that the access terminal 720A communicate only with the home small cell 710A or 710B.
In some aspects, if the access terminal 720 operates within the macro cellular network 750 but is not residing on its most preferred network (e.g., as defined in a preferred roaming list), the access terminal 720 may continue to search for the most preferred network (e.g., the preferred small cell 710) using a better system reselection (BSR) procedure, which may involve a periodic scanning of available systems to determine whether better systems are currently available and subsequently acquire such preferred systems. The access terminal 720 may limit the search for specific band and channel. For example, one or more operating channels for the small cells may be defined whereby all small cells (or all restricted small cells) in a region operate on the operating channel(s). The search for the most preferred system may be repeated periodically. Upon discovery of a preferred small cell 710, the access terminal 720 selects the small cell 710 and registers on it for use when within its coverage area.
Access to a small cell may be restricted in some aspects. For example, a given small cell may only provide certain services to certain access terminals. In deployments with so-called restricted (or closed) access, a given access terminal may only be served by the macro cell mobile network and a defined set of small cells (e.g., the small cells 710 that reside within the corresponding user residence 730). In some examples, an access point may be restricted to not provide, for at least one node (e.g., access terminal), at least one of: signaling, data access, registration, paging, or service.
In some aspects, a restricted small cell (which may also be referred to as a Closed Subscriber Group Home NodeB) is one that provides service to a restricted provisioned set of access terminals. This set may be temporarily or permanently extended as necessary. In some aspects, a Closed Subscriber Group (CSG) may be defined as the set of access points (e.g., small cells) that share a common access control list of access terminals.
Various relationships may thus exist between a given small cell and a given access terminal. For example, from the perspective of an access terminal, an open small cell may refer to a small cell with unrestricted access (e.g., the small cell allows access to any access terminal). A restricted small cell may refer to a small cell that is restricted in some manner (e.g., restricted for access and/or registration). A home small cell may refer to a small cell on which the access terminal is authorized to access and operate on (e.g., permanent access is provided for a defined set of one or more access terminals). A hybrid (or guest) small cell may refer to a small cell on which different access terminals are provided different levels of service (e.g., some access terminals may be allowed partial and/or temporary access while other access terminals may be allowed full access). An alien small cell may refer to a small cell on which the access terminal is not authorized to access or operate on, except for perhaps emergency situations (e.g., emergency-911 calls).
From a restricted small cell perspective, a home access terminal may refer to an access terminal that is authorized to access the restricted small cell installed in the residence of that access terminal's owner (usually the home access terminal has permanent access to that small cell). A guest access terminal may refer to an access terminal with temporary access to the restricted small cell (e.g., limited based on deadline, time of use, bytes, connection count, or some other criterion or criteria). An alien access terminal may refer to an access terminal that does not have permission to access the restricted small cell, except for perhaps emergency situations, for example, such as 911 calls (e.g., an access terminal that does not have the credentials or permission to register with the restricted small cell).
For convenience, the disclosure herein describes various functionalities in the context of a small cell. It should be appreciated, however, that a pico access point may provide the same or similar functionality for a larger coverage area. For example, a pico access point may be restricted, a home pico access point may be defined for a given access terminal, and so on.
The teachings herein may be employed in a wireless multiple-access communication system that simultaneously supports communication for multiple wireless access terminals. Here, each terminal may communicate with one or more access points via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the access points to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the access points. This communication link may be established via a single-in-single-out system, a multiple-in-multiple-out (MIMO) system, or some other type of system.
MIMO system employs multiple (NT) transmit antennas and multiple (NR) receive antennas for data transmission. A MIMO channel formed by the NT transmit and NR receive antennas may be decomposed into NS independent channels, which are also referred to as spatial channels, where NS≦min {NT, NR}. Each of the NS independent channels corresponds to a dimension. The MIMO system may provide improved performance (e.g., higher throughput and/or greater reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized.
A MIMO system may support time division duplex (TDD) and frequency division duplex (FDD). In a TDD system, the forward and reverse link transmissions are on the same frequency region so that the reciprocity principle allows the estimation of the forward link channel from the reverse link channel. This enables the access point to extract transmit beam-forming gain on the forward link when multiple antennas are available at the access point.
The TX data processor 914 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data. The coded data for each data stream may be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (e.g., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream may be determined by instructions performed by a processor 930. A data memory 932 may store program code, data, and other information used by the processor 930 or other components of the device 910.
The modulation symbols for all data streams are then provided to a TX MIMO processor 920, which may further process the modulation symbols (e.g., for OFDM). The TX MIMO processor 920 then provides NT modulation symbol streams to NT transceivers (XCVR) 922A through 922T. In some aspects, the TX MIMO processor 920 applies beam-forming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.
Each transceiver 922 receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. NT modulated signals from transceivers 922A through 922T are then transmitted from NT antennas 924A through 924T, respectively. For example, transceivers 922A through 922T, or related receiver portions, can implement the process described in method 400 above.
At the device 950, the transmitted modulated signals are received by NR antennas 952A through 952R and the received signal from each antenna 952 is provided to a respective transceiver (XCVR) 954A through 954R. Each transceiver 954 conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding “received” symbol stream.
A receive (RX) data processor 960 then receives and processes the NR received symbol streams from NR transceivers 954 based on a particular receiver processing technique to provide NT “detected” symbol streams. The RX data processor 960 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by the RX data processor 960 is complementary to that performed by the TX MIMO processor 920 and the TX data processor 914 at the device 910.
A processor 970 periodically determines which pre-coding matrix to use (discussed below). The processor 970 formulates a reverse link message comprising a matrix index portion and a rank value portion. A data memory 972 may store program code, data, and other information used by the processor 970 or other components of the device 950.
The reverse link message may comprise various types of information regarding the communication link and/or the received data stream. The reverse link message is then processed by a TX data processor 938, which also receives traffic data for a number of data streams from a data source 936, modulated by a modulator 980, conditioned by the transceivers 954A through 954R, and transmitted back to the device 910.
At the device 910, the modulated signals from the device 950 are received by the antennas 924, conditioned by the transceivers 922, demodulated by a demodulator (DEMOD) 940, and processed by a RX data processor 942 to extract the reverse link message transmitted by the device 950. The processor 930 then determines which pre-coding matrix to use for determining the beam-forming weights then processes the extracted message.
It will be appreciated that for each device 910 and 950 the functionality of two or more of the described components may be provided by a single component. It will be also be appreciated that the various communication components illustrated in
The functionality of the modules of
In addition, the components and functions represented by
In some aspects, an apparatus or any component of an apparatus may be configured to (or operable to or adapted to) provide functionality as taught herein. This may be achieved, for example: by manufacturing (e.g., fabricating) the apparatus or component so that it will provide the functionality; by programming the apparatus or component so that it will provide the functionality; or through the use of some other suitable implementation technique. As one example, an integrated circuit may be fabricated to provide the requisite functionality. As another example, an integrated circuit may be fabricated to support the requisite functionality and then configured (e.g., via programming) to provide the requisite functionality. As yet another example, a processor circuit may execute code to provide the requisite functionality.
It should be understood that any reference to an element herein using a designation such as “first,” “second,” and so forth does not generally limit the quantity or order of those elements. Rather, these designations may be used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements may be employed there or that the first element must precede the second element in some manner. Also, unless stated otherwise a set of elements may comprise one or more elements. In addition, terminology of the form “at least one of A, B, or C” or “one or more of A, B, or C” or “at least one of the group consisting of A, B, and C” used in the description or the claims means “A or B or C or any combination of these elements.” For example, this terminology may include A, or B, or C, or A and B, or A and C, or A and B and C, or 2A, or 2B, or 2C, and so on.
Those of skill in the art will appreciate that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
Further, those of skill in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.
The methods, sequences and/or algorithms described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An example storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor.
Accordingly, an aspect of the disclosure can include a computer readable medium embodying a method as described herein for processing signals from various radio access technologies. Accordingly, the disclosure is not limited to the illustrated examples.
While the foregoing disclosure shows illustrative aspects, it should be noted that various changes and modifications could be made herein without departing from the scope of the disclosure as defined by the appended claims. The functions, steps and/or actions of the method claims in accordance with the aspects of the disclosure described herein need not be performed in any particular order. Furthermore, although certain aspects may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.
The present Application for Patent claims priority to Provisional Application No. 61/992,795 entitled “INTELLIGENT SMALL-CELL CHANNEL SELECTION THROUGH UE REPORTS” filed May 13, 2014, which is assigned to the assignee hereof and hereby expressly incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61992795 | May 2014 | US |
