Aspects of the present disclosure relate generally to wireless communication systems, and more particularly to backhaul estimation for small cells and the like.
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. In cellular networks, macro base stations (or macro cells or conventional base stations) provide connectivity and coverage to a large number of users over a certain geographical area. To supplement macro base stations, restricted power or restricted coverage base stations, referred to as small coverage base stations or small cell base stations or small cells, can be deployed to provide more robust wireless coverage and capacity to mobile devices. For example, small cells can be deployed for incremental capacity growth, richer user experience, in-building or other specific geographic coverage, and/or the like.
However, the deployment of small cell base stations may also encroach on the operation of other devices that typically utilize the same space, such as Wireless Local Area Network (WLAN) devices operating in accordance with one of the IEEE 802.11x communication protocols (so-called “Wi-Fi” devices) or other wired or wireless devices sharing the same Internet connection in a user's residence or office building. The unmanaged sharing of common backhaul resources may lead to various throughput and/or data integrity problems for all devices.
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 not 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.
The present disclosure presents an example method and apparatus for calibrating a small cell base station for backhaul management. For example, in an aspect, the present disclosure presents an example method that may include exchanging backhaul probing messages with a probing server by initiating a plurality of probing packets at the small cell base station, wherein the exchanging is performed over a backhaul after determining that a full queue condition associated with the backhaul is satisfied, computing calibration statistics for the backhaul based on characteristics associated with the backhaul probing messages, and adjusting one or more backhaul parameters of the small cell base station based on the calibration statistics.
Additionally, the present disclosure presents an example apparatus for calibrating a small cell base station for backhaul management that may include means for exchanging backhaul probing messages with a probing server by initiating a plurality of probing packets at the small cell base station, wherein the exchanging is performed over a backhaul after determining that a full queue condition associated with the backhaul is satisfied, means for computing calibration statistics for the backhaul based on characteristics associated with the backhaul probing messages, and means for adjusting one or more backhaul parameters of the small cell based on the calibration statistics.
In a further aspect, the present disclosure presents an example computer program product for computer program product for calibrating a small cell base station for backhaul of a backhaul, comprising a computer-readable medium comprising code for exchanging backhaul probing messages with a probing server by initiating a plurality of probing packets at the small cell base station, wherein the exchanging is performed over a backhaul after determining that a full queue condition associated with the backhaul is satisfied, computing calibration statistics for the backhaul based on characteristics associated with the backhaul probing messages, and adjusting one or more backhaul parameters of the small cell based on the calibration statistics.
Furthermore, in an aspect, the present disclosure presents an example apparatus for calibrating a small cell base station for backhaul management that may include a backhaul monitor to exchange backhaul probing messages with a probing server by initiating a plurality of probing packets at the small cell base station, wherein the exchanging is performed over a backhaul after determining that a full queue condition associated with the backhaul is satisfied, a statistical engine to compute calibration statistics for the backhaul based on characteristics associated with the backhaul probing messages, and a parameter adjuster to adjust one or more backhaul parameters of the small cell based on the calibration statistics.
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 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 structures and components are shown in block diagram form in order to avoid obscuring such concepts.
The present disclosure presents a method and apparatus for calibrating a small cell base station for backhaul management that includes exchanging backhaul probing messages with a probing server, computing calibration statistics for the backhaul based on characteristics associated with the backhaul probing messages, and adjusting one or more backhaul parameters of the small cell base station based on the calibration statistics. For example, backhaul parameters of a small cell base station may be adjusted or modified based on computed calibration statistics of a backhaul of the small cell base station.
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 based station 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 wireless relay station, 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.
Each user device 106 may communicate with one or more of the base stations 104 on a downlink (DL) and/or an uplink (UL). In general, a DL is a communication link from a base station to a user device, while an UL is a communication link from a user device to a base station. The base stations 104 may be interconnected by appropriate wired or wireless interfaces allowing them to communicate with each other and/or other network equipment. Accordingly, each user device 106 may also communicate with another user device 106 through one or more of the base stations 104. For example, the user device 106J may communicate with the user device 106H in the following manner: the user device 106J may communicate with the base station 104D, the base station 104D may then communicate with the base station 104B, and the base station 104B may then communicate with the user device 106H, allowing communication to be established between the user device 106J and the user device 106H.
The wireless communication network 100 may provide service over a large geographic region. For example, the cells 102A-102G may cover a few blocks within a neighborhood or several square miles in a rural environment. In some systems, each cell may be further divided into one or more sectors (not shown). In addition, the base stations 104 may provide the user devices 106 access within their respective coverage areas to other communication networks, such as the Internet or another cellular network. Each user device 106 may be a wireless communication device (e.g., a mobile phone, router, personal computer, server, etc.) used by a user to send and/or receive voice and/or data over a communications network, and may be alternatively referred to as an Access Terminal (AT), a Mobile Station (MS), a User Equipment (UE), etc. In the example shown in
For their wireless air interfaces, each base station 104 may operate according to one of several Radio Access Technologies (RATs) depending on the network in which it is deployed, and may be alternatively referred to as a NodeB, evolved NodeB (eNB), etc. These networks may include, for example, Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, Single-Carrier FDMA (SC-FDMA) networks, and so on. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a RAT such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband-CDMA (W-CDMA) and Low Chip Rate (LCR). cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a RAT such as Global System for Mobile Communications (GSM). An OFDMA network may implement a RAT such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, Flash-OFDM®, etc. UTRA, E-UTRA, and GSM are part of Universal Mobile Telecommunication System (UMTS). One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
Long Term Evolution (LTE) is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS, and LTE are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). cdma2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2).
In cellular networks, macro base stations (or macro cells or conventional base stations) provide connectivity and coverage to a large number of users over a certain geographical area. A macro cell network deployment is carefully planned, designed, and implemented to offer good coverage over the geographical region. Even such careful planning, however, cannot fully accommodate channel characteristics such as fading, multipath, shadowing, etc., especially in indoor environments. Indoor users therefore often face coverage issues (e.g., call outages and quality degradation) resulting in poor user experience. Further, macro cell capacity is upper-bounded by physical and technological factors.
Thus, as discussed above, small cell base stations may be used to provide significant capacity growth, in-building coverage, and in some cases different services than macro cells operating alone, thereby facilitating a more robust user experience.
The small cell base stations may be connected to the Internet and/or a mobile operator's network via a digital subscriber line (DSL) router or a cable modem, for example, often utilizing the existing backhaul infrastructure provided by an Internet Service Provider (ISP) for the residential home or office building in which the small cell base station is installed.
In
Turning to the illustrated connections in more detail, user equipment 220 may generate and transmit a message via a wireless link to the macro cell base station 205, the message including information related to various types of communication (e.g., voice, data, multimedia services, etc.). User equipment 222 may similarly communicate with small cell base station 210 via a wireless link, and user equipment 221 may similarly communicate with small cell base station 212 via a wireless link. The macro cell base station 205 may also communicate with a corresponding wide area or external network 240 (e.g., the Internet), via a wired link or via a wireless link, while small cell base stations 210 and/or 212 may also similarly communicate with network 240, via their own wired or wireless links. For example, small cell base stations 210 and/or 212 may communicate with network 240 by way of an Internet Protocol (IP) connection, such as via a Digital Subscriber Line (DSL, e.g., including Asymmetric DSL (ADSL), High Data Rate DSL (HDSL), Very High Speed DSL (VDSL), etc.), a TV cable carrying IP traffic, a Broadband over Power Line (BPL) connection, an Optical Fiber (OF) cable, or some other link. This connection may utilize the existing backhaul infrastructure provided by, for example, an ISP for the residential home or office building in which small cells 210 and 212 are installed, and may accordingly be shared among other devices operating in the same environment, such as Wireless Local Area Network (WLAN) devices operating in accordance with one of the IEEE 802.11x communication protocols (so-called “Wi-Fi” devices) or other wired or wireless devices sharing the same Internet connection in a user's residence or office building.
The network 240 may comprise any type of electronically connected group of computers and/or devices, including, for example, the following networks: Internet, Intranet, Local Area Networks (LANs), or Wide Area Networks (WANs). In addition, the connectivity to the network may be, for example, by remote modem, Ethernet (IEEE 802.3), Token Ring (IEEE 802.5), Fiber Distributed Datalink Interface (FDDI) Asynchronous Transfer Mode (ATM), Wireless Ethernet (IEEE 802.11), Bluetooth (IEEE 802.15.1), or some other connection. As used herein, the network 240 includes network variations such as the public Internet, a private network within the Internet, a secure network within the Internet, a private network, a public network, a value-added network, an intranet, and the like. In certain systems, the network 240 may also comprise a Virtual Private Network (VPN).
Accordingly, it will be appreciated that macro cell base station 205 and/or either or both of small cell base stations 210 and 212 may be connected to network 240 using any of a multitude of devices or methods. These connections may be referred to as the “backbone” or the “backhaul” of the network, and may in some implementations be used to manage and coordinate communications between macro cell base station 205, small cell base station 210, and/or small cell base station 212. In this way, depending on the current location of user equipment 222, for example, user equipment 222 may access the communication network 240 by macro cell base station 205 or by small cell base station 210.
In an aspect, a small cell base station (or a small cell) 320 is installed in user residence 304 and serves one or more nearby user equipments (UE) 322 as described above. The small cell base station 320 via its connection to home router 302 and shared backhaul link 310 may provide access to Internet 306 and core network 316. Since the backhaul link 310 is shared between the traffic managed by small cell 320 (e.g., native traffic) and traffic generated by other devices that home router 302 may be serving (e.g., cross traffic), there is a potential for congestion of uplink (UL) traffic, down link (DL) traffic, and/or both, with varying degrees of impact on the performance of the small cell and/or other devices sharing the backhaul link 310.
Accordingly, improved backhaul aware load management for small cell base stations operating in an increasingly crowded communication environment is needed. Thus, in an aspect, small cell base station 320 may be configured to include a backhaul-aware load management (BALM) component 324 operable to mitigate congestion on backhaul link 310. The operation of BALM component 324 may enable small cell base station 320 to determine various backhaul characteristics such as, for example, sustainable throughput, and corresponding delay and jitter variations, loss, etc., to identify backhaul congestion and/or take appropriate remedial actions. For example, in an aspect, when congestion is present, operation of BALM component 324 may enable small cell base station 320 via its radio resource management (RRM) module to offload one or more UEs 322 to a macro cell base station or otherwise reduce the coverage area of small cell base station 320 in order to reduce the number of UEs 322 being served. In an additional aspect, when congestion is present, operation of BALM component 324 may enable small cell base station 320 via its RRM module to offload one or more low throughput devices to a macro cell base station and/or reduce the coverage area of small cell base station 320 (e.g., by lowering a pilot channel signal strength) in order to reduce the number of UEs 322 being served. In an additional or optional aspect, operation of BALM component 324 may enable small cell base station 320 to limit the data rate of certain flows that are not backhaul-limited (e.g., by changing a video encoding rate). In a further additional or optional aspect, operation of BALM component 324 may enable small cell base station 320 to alert the user of one of the UEs 322 and enable the user to choose one of the above-noted actions and control the operation of the small cell. For instance, a graphical user interface (GUI) may be used to alert the user, thereby allowing the user of the UE to choose one of the above-noted actions.
Referring in more detail to
In an aspect, active initiation/generation/induction of probing packets (when compared to passive initiation/generation/induction of probing packets) can introduce probing packets in the small cell backhaul where they would not have otherwise been introduced. Passively initiated/generated/induced packets can be introduced into the network for purposes other than calibration (e.g. to/from UEs served by small cell, for small cell configuration, etc.) but such packets may to satisfy size, destination, statistics, content conditions required for calibration needs.
In an aspect, if it is determined that the existing throughput is not sufficient (‘no’ at decision 402), the small cell base station via operation of BALM component 324 checks whether it is over-the-air (OTA) capacity that is limiting the throughput (decision 404). If it is determined that the OTA capacity is limiting the throughput (‘yes’ at decision 404), the small cell base station via operation of BALM component 324 may take remedial actions to relieve the congestion on its air link, e.g., marking the UE as a candidate for handout to, e.g., a macro cell base station (block 406). In an alternate aspect, if it is determined that it is not the OTA capacity that is limiting the throughput (‘no’ at decision 404), the small cell base station via operation of BALM component 324 may perform a per-user rate shaping procedure and determine if other UEs being served by the small cell base station are limiting backhaul throughput (decision 408). In an additional aspect, if it is determined that other UEs being served by the small cell base station are limiting the backhaul throughput (‘yes’ at decision 408), the small cell base station via operation of BALM component 324 may take remedial actions, e.g., marking the user equipment as a candidate for handout to a macro cell base station (block 406).
In an aspect, if it is determined that the other UEs being served by the small cell base station are not limiting the backhaul throughput (‘no’ at decision 408), the small cell base station via operation of BALM component 324 may perform a light active estimation procedure to determine if the Internet service provider (ISP) queue is fully utilized (decision 410). A light active estimation procedure can be performed to estimate the backhaul state of actively-induced packets. The estimation procedure can use small overhead or naturally-induced/occurring packets, which are typically used to directly measure backhaul latency and loss. These small overhead or naturally-induced/occurring packets have statistical characteristics that make them a good replacement for actively-induced packets for light active estimation.
If it is determined that the ISP queue does not appear to be full (‘no’ at decision 410), there may be no backhaul capacity problem and the small cell base station via operation of BALM component 324 may revert to performing light passive estimation monitoring as appropriate, as described above. In an alternative aspect, if it is determined that the ISP queue does appear to be full (‘yes’ at decision 410), there may be a backhaul capacity problem and the small cell base station via operation of BALM component 324 may further perform a heavy active estimation procedure to determine if the throughput is being limited by congestion at the Internet peer with which the UE is communicating, rather than by the backhaul link itself (decision 412).
Similar to the light active estimation procedure, a heavy active estimation procedure can be performed to estimate the backhaul state of actively-induced packets. However, in this procedure, instead of using small overhead or naturally-induced/occurring packets, potentially high overhead or naturally-induced/occurring packets that are typically used to directly measure throughput can be used. These potentially high overhead or naturally-induced/occurring packets have statistical characteristics that make them a good replacement for actively-induced packets for heavy active estimation.
In an aspect, if it is determined that throughput is not being limited by congestion at the Internet peer with which the UE is communicating (‘no’ at decision 412), the small cell base station via operation of BALM component 324 may determine that there is a backhaul capacity problem and may take remedial actions, e.g., marking the UE as a candidate for handout to a macro cell base station (block 406). In an alternative aspect, if it is determined that the throughput is being limited by congestion at the Internet peer with which the UE is communicating (‘no’ at decision 412), there may be no backhaul capacity problem and the small cell base station via operation of BALM component 324 may revert to performing light passive estimation monitoring as appropriate, as described above.
In an aspect, in order to optimize BALM component 324 and the different BALM related procedures in
In an aspect, a small cell base station (e.g., small cell base station 320 of
In an aspect, based on respective time stamps of the request probe sending and corresponding response probe reception, the small cell base station via operation of BALM component 324 may determine a RTT sample corresponding to the time delay experienced through the backhaul link (block 508). This procedure may be repeated a number of times over a given duration (e.g., an observation window) to produce a sufficient set of RTT samples. From the RTT samples collected, the small cell base station via operation of BALM component 324 may generate a RTT statistical distribution such as a cumulative distribution function (CDF) characterizing the time delays experienced over the backhaul link during the observation window (block 510).
In an additional or optional aspect, BALM component 324 may use naturally occurring RTT measures for probing and/or calibration. For example, a TCP handshake or other RTT measures with regard to servers known to not suffer from a congested link to the ISP (e.g., geographically close content delivery network (CDN) servers) may provide reliable measure of RTT and any congestion may be attributed to the small cell base station's backhaul link with the ISP rather than other links within the network.
In an aspect, BALM component 324 may use the generated backhaul RTT statistics for a variety of calibration procedures. For example, BALM component 324 may use the generated statistics for active and passive components of the BALM related procedures in
In an additional aspect, BALM component 324 may perform calibration across several different link conditions related to the subscriber's allocated data queue at the ISP, ranging from “empty” to “full” DL and/or UL queue conditions (e.g., identified as “empty DL/UL queue calibration,” “full DL/UL queue calibration” respectively), and in different ways, making use of both natural and/or induced testing conditions (e.g., existing traffic and/or simulated traffic conditions. For example, in an aspect, BALM component 324 may assume an empty queue condition (e.g., zero or minimal traffic) and may perform calibration at certain times of day (e.g., late-night), but these conditions/calibrations may also be verified by RTT CDF characteristics generated in accordance with
In an aspect, BALM component 324 may perform the calibration periodically or otherwise in a periodic or repeated manner to keep the information and settings current. For example, in aspect, BALM component 324 may perform the empty queue calibration initially at boot-up and later at other configured times, which may be periodic. The periodicity may be shortened under certain conditions, however, such as if a previous empty queue calibration was determined to be insufficiently reliable (e.g., based on a scaled variance or 10%-90% scaled slope of the RTT CDF indicating excessive jitter). Further, BALM component 324 may apply a delay to active generation of calibration packets if traffic is determined to be present (e.g., UEs communicating over the small cell base station, the last calibration of probe packets having encountered a high variance (or similar statistic) of the RTT CDF, etc.).
Similarly, BALM component 324 may perform the full DL/UL queue calibration initially at boot-up and later at other configured times, which may be periodic, for example. For an actively induced full DL/UL queue condition (e.g., simulated queue conditions), BALM component 324 may advance or delay the calibration operation to coincide with other small cell traffic, so as to minimize the induced traffic load on the network. In this way, the proportion of traffic used solely for inducing the full DL/UL queue condition as compared to real user traffic may be reduced, or eliminated. Conversely, BALM component 324 may advance or delay the calibration operation based on actively-induced packets, to avoid other small cell traffic, so as to minimize the impact of the inducement on the real user traffic itself. Further, BALM component 324 may advance or delay the calibration operation to avoid cross-traffic from other devices sharing the backhaul link (e.g., as indicated by a high variance of the RTT CDF).
In an aspect, for certain backhaul estimation procedures such as light active estimation discussed above, BALM component 324 may perform an intermediate or “partial” DL/UL queue calibration. Partial DL/UL queue calibration may be performed at different times, e.g., whenever there are UEs present, and can be assisted by additional actively-induced traffic flows from the small cell base station acting as a transmitter for UL calibration, a receiver for DL calibration, or both.
Once the backhaul link has been sufficiently loaded to induce a full queue condition, the small cell base station via operation of BALM component 324 may perform full queue calibration (block 608). This multi-flow procedure ensures that the backhaul link is sufficiently loaded to induce a full queue condition while avoiding the potential problem of flow limiting, where a single larger flow may be prevented from occupying the entire subscribed bandwidth due to (calibration) server limitation, ISP flow control policy, and/or path loss or delay characteristics.
In an aspect, in order to accurately measure the average throughput on the backhaul link, BALM component 324 may allow each flow to run for a given duration (e.g., about five seconds) before determining that flow's impact on queue loading. In some aspects, BALM component 324 may run the first flow, for example, for a longer time (e.g., about thirty seconds), to exhaust a so-called “PowerBoost” credit that may be part of the subscriber's plan. For example, PowerBoost and other similar technologies may be employed by an ISP to allow higher-than-subscribed initial throughput (e.g., on the UL, DL, or both) for a short duration (or partial function of data volume), which may temporarily skew the average throughput calculation. By exhausting PowerBoost with the first flow (or a combination of first and/or subsequent flows), BALM component 324 may bring back the average throughput calculation into accordance with the sustained subscribed data rates.
In this way, the small cell base station via operation of BALM component 324 may implement an automatic determination of the number of flows need for calibration via an iterative method which checks if the aggregate throughput is within a given percentage for two sets of flows in which one has exactly one more flow than the other. Once the number of flows has been determined, BALM component 324 may use the determined number of flows as a starting point (or operating point) for subsequent calibration attempts.
In an aspect, BALM component 324 may assume the calibration statistics determined in accordance with the procedures described herein to be valid for a configured period (e.g., one week, one month, etc.), after which it may be desirable to re-run the calibration to ensure current and up-to-date information (e.g., in case the user's subscription has changed, etc.). The configured period may vary depending on several factors. For example, in an aspect, BALM component 324 may generate a statistic quality metric to identify changes in conditions that may signal the need for recalibration, e.g., the variance of probes during empty queue estimation. For example, if empty queue RTT estimates drop from a steady value of 12 ms to a new value of 5 ms, example, e.g., BALM component 324 may determine that this indicates that the user has subscribed to a higher date from the ISP. Similarly, BALM component 324 may use the scaled slope between 10% and 90% of the RTT CDF points on a sliding window as a measure of confidence related to the accuracy of the previous calibration, with more tightly clustered samples indicating a higher level of confidence.
In an aspect, there may also be variation of the derived statistics at various times of day, e.g., between times of low use (e.g., in the middle of the night) and times of high use (e.g., in the evening), and therefore BALM component 324 may run the calibration at different times of day to ensure accuracy.
In some cases, BALM component 324 may use natural calibration conditions (e.g., calibration based on traffic conditions observed during the operation of the small cell and/or UE) to trigger early recalibration. For example, if BALM component 324 observations of peak throughput during “natural” periods fail to match average observations during actively induced calibration, then BALM component 324 may determine that recalibration is needed and therefore BALM component 324 may provide an early trigger for such recalibrations in order to reconcile the discrepancy.
In an aspect, once determined, BALM component 324 may use the various calibration statistics in a variety of ways. For example, BALM component 324 may determine the subscription rate in a given DL/UL direction based on the observed full queue loading RTT. As such, BALM component 324 may use the determined subscription rate to limit the small cell bandwidth in that direction to a percentage of that rate in order to avoid unduly impacting cross-traffic from other devices sharing the backhaul link. For example, in an aspect, the small cell base station via operation of BALM component 324 may limit its bandwidth allocation to no more than 50% of the DL bandwidth or 90% of the UL bandwidth so that there will be sufficient bandwidth for cross-traffic video streaming, video conferencing, etc.
In an aspect, the example percentages described above may be fixed or variable, such that they are activated or otherwise enforced only when congestion is observed, e.g., observed via light active probing estimation. In an additional aspect, the value of the variable percentage may also be subject to calibration. For example, BALM component 324 may determine the percentage to limit the UL by jointly running UL and DL calibrations and determining the level of UL rate limitation above which the DL experience drops below an acceptable amount (e.g., when throughput drops below 90% of the subscribed level, or video pixilation or excessive buffering begins to arise), and vice versa. This addresses the problem where UL congestion may cause uneven delay and loss of UL control (e.g., TCP ACK) messages, which, in turn, limit DL throughput (and vice versa in the opposite UL/DL direction).
In an aspect, BALM component 324 may use natural calibration opportunities instead of or as an enhancement to the statistics derived from induced calibration conditions. For example, BALM component 324 may improve light active calibration based on observed statistics during light active probing. For example, the “leftmost” (e.g. low CDF percentile) RTT CDF samples can be used to improve empty queue statistics. For example, in some designs, the “leftmost” shorter RTT CDF samples may be included only if passive estimation shows low small cell usage. In an additional example, the “rightmost” (e.g. high CSF percentile) RTT CDF samples may be used to improve full queue statistics. In an aspect, heavy active probes may also be improved based on observed statistics during normal small cell operation.
In an aspect, during natural calibration monitoring, BALM component 324 may determine peak throughput from the highest or second highest (non-zero) CDF statistical mode observed (e.g., as derived from a Fast Fourier Transform (FFT) of the CDF). The use of the second highest mode may be useful to filter out PowerBoost spikes of the type noted above, which may artificially inflate the observed throughput. In addition, DL and UL throughput will usually be different, and can be identified based on different CDF modes, with the DL mode typically appearing in a lower RTT range as compared to the UL mode. For example, if one mode appears around 20 ms whereas a second mode appears around 100 ms, the 20 ms mode will most likely correspond to the DL RTT and associated throughput while the slower 100 ms mode will most likely correspond to the UL RTT and associated throughput.
In some situations, there may not be a single set of statistics that accurately reflects an entire time period of interest (e.g., an entire day or week or month). This is because the calibrated statistics may change over time, but nevertheless may follow certain periodic patterns. For example, RTT observations taken during the middle of the night may be representative of nightly observations but different from those taken in the evening or afternoon. Similarly, RTT observations taken on weekends may be representative of week-end observations but different than those taken on weekdays. Accordingly, BALM component 324 may associate different sets of statistics with the different time periods (e.g., hourly RTTs, hourly UL peak rates, etc.) and may independently determine/employ such sets of statistics (e.g., Monday's calibration data at 1 pm may be used for next Monday's calibration at 1 pm, with other sets of statistics being used for other intervening time periods). In an additional aspect, BALM component 324 may give a higher weight, e.g., greater consideration, to more recent RTT observations.
Returning to
In an aspect, at block 710, methodology 700 may include exchanging backhaul probing messages with a probing server by initiating a plurality of probing packets at the small cell. For example, in an aspect, BALM component 324 may cause backhaul probing messages to be exchanged between small cell base station 320 and a probing server. The exchanging of the probing messages is performed over backhaul 310. In an additional aspect, the exchanging of the probing message is performed after determining that a full queue condition (e.g., a potential full queue condition based on determining that there is no further increase in throughput, or a set/computed number of maximum number of induced flows has been reached) associated with backhaul 310 is satisfied. In an additional aspect, the probing packets may be initiated passively or actively.
In an aspect, at block 720, methodology 700 may include computing calibration statistics for the backhaul based on characteristics associated with the backhaul probing messages. For example, in an aspect, BALM component 324 may compute calibration statistics (e.g., sustainable throughput, corresponding delay, loss and jitter variations, etc.) at small cell base station 320 based on characteristics associated with the backhaul probing messages.
In an aspect, at block 730, methodology 700 may include adjusting one or more backhaul parameters of the small cell based on the calibration statistics. For example, in an aspect, BALM component 324 may adjust backhaul parameters (e.g., thresholds corresponding to full and empty queue states) of the small cell 320 based on the computed calibration statistics. In an additional aspect, traffic rate allocation (e.g. to cellular traffic, Wi-Fi traffic) thresholds may be adjusted as a function of observed (e.g., via calibration) subscription rates. In a further additional aspect, bandwidth reservation may be performed for particular kinds of traffic (e.g. bandwidth reserved for non-small cell traffic sharing backhaul with the small cell, by rate-limiting small cell traffic). In yet another aspect, calibrated observation may inform decision about the acceptability of serving particular kinds of traffic (e.g. voice traffic may not be served on a high-latency, high-loss, or high jitter backhaul). In yet another aspect, calibrated rates may inform small cell configuration (e.g., transmit power, schedule) priorities.
In general, the small cell base station 800 and/or BALM component 324 includes various components for providing and processing services for the client devices 840. For example, the small cell base station 800 may include a transceiver 812 for wireless communication with the one or more of the clients 840 and a backhaul controller 814 for backhaul communications with other network devices, such as the router 830. These components may operate under the direction of a processor 816 in conjunction with memory 818, for example, all of which may be interconnected via a bus 820 or the like.
In addition and in accordance with the discussion above, the small cell base station 800 and/or BALM component 324 may also further include a backhaul monitor 822 for exchanging backhaul probing messages with a probing server, a statistical engine 824 for computing calibration statistics for the backhaul based on characteristics associated with the backhaul probing messages (e.g., from an RTT sample database 819 stored in the memory 818), and a parameter adjuster 826 for adjusting one or more backhaul parameters of the small cell base station 800 based on the calibration statistics.
For example, in an aspect, backhaul monitor 822 may be configured to exchange backhaul probing messages with a probing server by initiating a plurality of probing messages at the small cell base station (e.g., small cell base station 320). In an additional aspect, the exchanging of the probing messages may be performed over a backhaul (e.g., backhaul 310) after determining that a full queue condition associated with the backhaul is satisfied.
For example, in an aspect, statistical engine 824 may be configured to computing calibration statistics for the backhaul (e.g., backhaul 310) based on characteristics associated with the backhaul probing messages. Additionally, for example, in an aspect, parameter adjusted 826 may be configured to adjusting one or more backhaul parameters of the small cell base station based on the calibration statistics.
In an aspect, the small cell base station 800 and/or BALM component 324 may further include an ISP queue controller 828 for determining that an ISP data queue associated with an ISP subscriber is substantially full or empty prior to performing the exchanging, and in some aspects inducing the ISP data queue to be substantially full prior to performing the exchanging by starting one or more traffic flows. In an additional aspect, the small cell base station 800 and/or BALM component 324 may further include a throughput monitor 829 for deriving an average uplink or downlink throughput of the backhaul link from a corresponding CDF distribution. It will be appreciated that in some designs one or more or all of these operations may be performed by or in conjunction with the processor 816 and memory 818.
At the device 910, traffic data for a number of data streams is provided from a data source 912 to a transmit (TX) data processor 914. Each data stream may then be transmitted over a respective transmit antenna.
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 (i.e., 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.
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 down converts) 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.
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.
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 invention.
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 exemplary 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 disclosed can include a computer readable media embodying a method for calibrating a small cell base station for management of a backhaul link to an ISP. Accordingly, the invention is not limited to illustrated examples and any means for performing the functionality described herein are included in aspects disclosed.
While the foregoing disclosure shows illustrative aspects disclosed, it should be noted that various changes and modifications could be made herein without departing from the scope of the invention as defined by the appended claims. The functions, steps and/or actions of the method claims in accordance with the aspects described herein need not be performed in any particular order. Furthermore, although elements disclosed may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.
In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium. The computer-readable medium may be a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disk (CD), digital versatile disk (DVD)), a smart card, a flash memory device (e.g., card, stick, key drive), random access memory (RAM), read only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer.
The computer-readable medium may also include, by way of example, a carrier wave, a transmission line, and any other suitable medium for transmitting software and/or instructions that may be accessed and read by a computer. The computer-readable medium may be resident in the processing system, external to the processing system, or distributed across multiple entities including the processing system. The computer-readable medium may be embodied in a computer-program product. By way of example, a computer-program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.
It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited therein.
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a; b; c; a and b; a and c; b and c; and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”
The present application for patent claims priority to U.S. Provisional Application No. 61/897,061, filed Oct. 29, 2013, entitled “Backhaul Estimation for Small Cells—Calibration,” U.S. Provisional Application No. 61/897,064, filed Oct. 29, 2013, entitled “Backhaul Aware Load Management for Small Cells—Passive Estimation,” U.S. Provisional Application No. 61/897,069, filed Oct. 29, 2013, entitled “Backhaul Estimation for Small Cells—Light Active Estimation,” U.S. Provisional Application No. 61/897,114, filed Oct. 29, 2013, entitled “Method and Apparatus for Backhaul Congestion Estimation Using Heavy Active Probing for Small Cells,” U.S. Provisional Application No. 61/897,098, filed Oct. 29, 2013, entitled “Apparatus and Method for Off-Loading User Equipment from a Small Cell,” U.S. Provisional Application No. 61/933,732, filed Jan. 30, 2014, entitled “Backhaul Management of a Small Cell,” all assigned to the assignee hereof and hereby expressly incorporated by reference herein.
Number | Date | Country | |
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61897061 | Oct 2013 | US | |
61897064 | Oct 2013 | US | |
61897069 | Oct 2013 | US | |
61897114 | Oct 2013 | US | |
61897098 | Oct 2013 | US | |
61933732 | Jan 2014 | US |