Patent Publication Number: US-11659380-B1

Title: UE-capability-based system information block transmission

Description:
BACKGROUND 
     Master Information Block (MIB) and System Information Blocks (SIBs) contain specific information required for the mobile device or user equipment (UE) to operate in an LTE or 5G NR network. For example, the MIB is the first thing a UE looks for after it completes downlink synchronization. The MIB carries information needed for a UE to acquire other information from the cell. For example, the MIB includes necessary parameters required to decode the first SIB (SIB 1 ). SIB 1  carries information needed to evaluate if a UE can access a cell and defines the scheduling of other system information essential for the operation of the UE. For example, SIBs provide the UE with information required to perform cell selection, re-selection, handover, extended access barring (EAB), interworking with WLAN, device-to-device (sidelink) communication, etc. SIBs other than SIB 1  are carried in System Information (SI) messages and mapping of SIBs to SI messages is flexibly configurable using a Scheduling Info List included in SIB 1 . 
     As the functionality of LTE and NR evolves, new SIBs are added to support new capabilities. For example, 3GPP Release  15  includes SIB 24 . There is therefore a need for an efficient approach for the network to communicate new SIBs to UEs that require the new SIBs without affecting the operation of legacy UEs (e.g., UEs based on older  3 GPP releases) that do not understand the new SIBs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Detailed descriptions of implementations of the present invention will be described and explained using the accompanying drawings. 
         FIG.  1    is a block diagram that illustrates a wireless communications system. 
         FIG.  2    is a flow diagram that illustrates a process for modifying a System Information Block (SIB) messages based on UE capability. 
         FIG.  3    is a flow diagram that illustrates a process for sending on-demand system information messages based on UE capability. 
         FIG.  4    is a block diagram that illustrates an example of a computer system in which at least some operations described herein can be implemented. 
       The technologies described herein will become more apparent to those skilled in the art from studying the Detailed Description in conjunction with the drawings. Embodiments or implementations describing aspects of the invention are illustrated by way of example, and the same references can indicate similar elements. While the drawings depict various implementations for the purpose of illustration, those skilled in the art will recognize that alternative implementations can be employed without departing from the principles of the present technologies. Accordingly, while specific implementations are shown in the drawings, the technology is amenable to various modifications. 
     
    
    
     DETAILED DESCRIPTION 
     In one example aspect of the disclosed technology, the network (e.g., radio access network (RAN), or gNB/eNB) receives capability information from a communication device (e.g., a user equipment (UE)) in a mobile communication network (e.g., a cellular LTE or NR network). The capability information indicates a version of the UE. The network maps the version of the UE to a  3 GPP release version and determines, based on the  3 GPP version, if a system information update is required for the UE. For example, network does this by using a look-up table that maps  3 GPP release versions to system information (e.g., System Information Blocks (SIBs)) relevant to the release versions and comparing that with the system information that the UE has already received via initial SIB broadcast, if any. The network then transmits an updated system information (SI) message to the UE in response to determining that that a system information update is required. The update SI message includes one or more non-legacy SIBs. 
     The description and associated drawings are illustrative examples and are not to be construed as limiting. This disclosure provides certain details for a thorough understanding and enabling description of these examples. One skilled in the relevant technology will understand, however, that the invention can be practiced without many of these details. Likewise, one skilled in the relevant technology will understand that the invention can include well-known structures or features that are not shown or described in detail, to avoid unnecessarily obscuring the descriptions of examples. 
     Wireless Communications System 
       FIG.  1    is a block diagram that illustrates a wireless telecommunication system  100  (“system  100 ”) in which aspects of the disclosed technology are incorporated. The system  100  includes base stations  102 - 1  through  102 - 4  (also referred to individually as “base station  102 ” or collectively as “base stations  102 ”). A base station is a type of network access node (NAN) that can also be referred to as a cell site, a base transceiver station, or a radio base station. The system  100  can include any combination of NANs including an access point, radio transceiver, gNodeB (gNB), NodeB, eNodeB (eNB), Home NodeB or eNodeB, or the like. In addition to being a WWAN base station, a NAN can be a WLAN access point, such as an Institute of Electrical and Electronics Engineers (IEEE)  802 . 11  access point. 
     The NANs of a network formed by the system  100  also include wireless devices  104 - 1  through  104 - 8  (referred to individually as “wireless device  104 ” or collectively as “wireless devices  104 ”) and a core network  106 . The wireless devices  104 - 1  through  104 - 8  can correspond to or include network entities capable of communication using various connectivity standards. For example, a 5G communication channel can use millimeter wave (mmW) access frequencies of 28 GHz or more. In some implementations, the wireless device  104  can operatively couple to a base station  102  over an LTE/LTE-A communication channel, which is referred to as a 4G communication channel. 
     The core network  106  provides, manages, and controls security services, user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The base stations  102  interface with the core network  106  through a first set of backhaul links  108  (e.g., S 1  interfaces) and can perform radio configuration and scheduling for communication with the wireless devices  104  or can operate under the control of a base station controller (not shown). In some examples, the base stations  102  can communicate, either directly or indirectly (e.g., through the core network  106 ), with each other over a second set of backhaul links  110 - 1  through  110 - 3  (e.g., X 1  interfaces), which can be wired or wireless communication links. 
     The base stations  102  can wirelessly communicate with the wireless devices  104  via one or more base station antennas. The cell sites can provide communication coverage for geographic coverage areas  112 - 1  through  112 - 4  (also referred to individually as “coverage area  112 ” or collectively as “coverage areas  112 ”). The geographic coverage area  112  for a base station  102  can be divided into sectors making up only a portion of the coverage area (not shown). The system  100  can include base stations of different types (e.g., macro and/or small cell base stations). In some implementations, there can be overlapping geographic coverage areas  112  for different service environments (e.g., Internet-of-Things (IoT), mobile broadband (MBB), vehicle-to-everything (V 2 X), machine-to-machine (M 2 M), machine-to-everything (M 2 X), ultra-reliable low-latency communication (URLLC), machine-type communication (MTC)), etc. 
     The system  100  can include a 5G network and/or an LTE/LTE-A or other network. In an LTE/LTE-A network, the term eNB is used to describe the base stations  102  and in 5G new radio (NR) networks, the term gNBs is used to describe the base stations  102  that can include mmW communications. The system  100  can thus form a heterogeneous network in which different types of base stations provide coverage for various geographical regions. For example, each base station  102  can provide communication coverage for a macro cell, a small cell, and/or other types of cells. As used herein, the term “cell” can relate to a base station, a carrier or component carrier associated with the base station, or a coverage area (e.g., sector) of a carrier or base station, depending on context. 
     A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and can allow access by wireless devices with service subscriptions with a wireless network service provider. As indicated earlier, a small cell is a lower-powered base station, as compared with a macro cell, and can operate in the same or different (e.g., licensed, unlicensed) frequency bands as macro cells. Examples of small cells include pico cells, femto cells, and micro cells. In general, a pico cell can cover a relatively smaller geographic area and can allow unrestricted access by wireless devices with service subscriptions with the network provider. A femto cell covers a relatively smaller geographic area (e.g., a home) and can provide restricted access by wireless devices having an association with the femto cell (e.g., wireless devices in a closed subscriber group (CSG), wireless devices for users in the home). A base station can support one or multiple (e.g., two, three, four, and the like) cells (e.g., component carriers). All fixed transceivers noted herein that can provide access to the network are NANs, including small cells. 
     The communication networks that accommodate various disclosed examples can be packet-based networks that operate according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer can be IP-based. A Radio Link Control (RLC) layer then performs packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer can perform priority handling and multiplexing of logical channels into transport channels. The MAC layer can also use Hybrid ARQ (HARQ) to provide retransmission at the MAC layer, to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer provides establishment, configuration, and maintenance of an RRC connection between a wireless device  104  and the base stations  102  or core network  106  supporting radio bearers for the user plane data. At the Physical (PHY) layer, the transport channels are mapped to physical channels. 
     As illustrated, the wireless devices  104  are distributed throughout the system  100 , where each wireless device  104  can be stationary or mobile. A wireless device can be referred to as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a handheld mobile device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a mobile client, a client, or the like. Examples of a wireless device include user equipment (UE) such as a mobile phone, a personal digital assistant (PDA), a wireless modem, a handheld mobile device (e.g., wireless devices  104 - 1  and  104 - 2 ), a tablet computer, a laptop computer (e.g., wireless device  104 - 3 ), a wearable (e.g., wireless device  104 - 4 ). A wireless device can be included in another device such as, for example, a drone (e.g., wireless device  104 - 5 ), a vehicle (e.g., wireless device  104 - 6 ), an augmented reality/ virtual reality (AR/VR) device such as a head-mounted display device (e.g., wireless device  104 - 7 ), an IoT device such as an appliance in a home (e.g., wireless device  104 - 8 ), a portable gaming console, or a wirelessly connected sensor that provides data to a remote server over a network. 
     A wireless device can communicate with various types of base stations and network equipment at the edge of a network including macro eNBs/gNBs, small cell eNBs/gNBs, relay base stations, and the like. A wireless device can also communicate with other wireless devices either within or outside the same coverage area of a base station via device-to-device (D 2 D) communications. 
     The communication links  114 - 1  through  114 - 11  (also referred to individually as “communication link  114 ” or collectively as “communication links  114 ”) shown in system  100  include uplink (UL) transmissions from a wireless device  104  to a base station  102 , and/or downlink (DL) transmissions, from a base station  102  to a wireless device  104 . The downlink transmissions can also be called forward link transmissions while the uplink transmissions can also be called reverse link transmissions. Each communication link  114  includes one or more carriers, where each carrier can be a signal composed of multiple sub-carriers (e.g., waveform signals of different frequencies) modulated according to the various radio technologies. Each modulated signal can be sent on a different sub-carrier and carry control information (e.g., reference signals, control channels), overhead information, user data, etc. The communication links  114  can transmit bidirectional communications using FDD (e.g., using paired spectrum resources) or TDD operation (e.g., using unpaired spectrum resources). In some implementations, the communication links  114  include LTE and/or mmW communication links. 
     In some implementations of the system  100 , the base stations  102  and/or the wireless devices  104  include multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between base stations  102  and wireless devices  104 . Additionally or alternatively, the base stations  102  and/or the wireless devices  104  can employ multiple-input, multiple-output (MIMO) techniques that can take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data. 
     Capability-Based SIB Transmission 
     As the functionality of LTE and NR evolves, new SIBs are added to support new capabilities. The new SIBs provide useful information to new UEs (i.e., UEs compatible with later 3GPP releases), for example, information necessary for mobility, Idle mode Reselection, RAN cell configuration changes, etc. For example, 3GPP Release  15  introduced SIB 24  which provides cell reselection information allowing a UE to move from a Long-Term Evolution (LTE) Radio Access Technology (RAT) to New Radio (NR) RAT while in RRC Idle mode. SIB 24  allows a Standalone (SA) NR UE to roam into LTE and reselect back to NR allowing it to utilize 5G whenever possible. SIB 24  is therefore only relevant to UEs that support both LTE and NR operation. However, some legacy UEs (e.g., UEs based on Release  14  and earlier that support only LTE but not NR) could attempt to read new SIBs such as SIB 24  instead of ignoring such SIBs. Additionally, or alternatively, some legacy UEs may be unable to correctly decode SIB 1  scheduling information, for example, where the legacy UE is unable to correctly decode a SIB-Type information element (IE) that includes extension markers or ellipses (“. . . ”) separating legacy SIBs and new SIBs. These legacy UEs could fail to connect to the network if able to read the new SIBs or if the UEs ignore the entire SIB 1  when the cell is broadcasting the new SIBs (i.e., when the cell is broadcasting SIBs occurring after the extension marker, e.g., when broadcasting SIB 19  and onwards). The legacy UEs could try to decode information in SIB 1  or decode the new SIBs thereby corrupting the UE and leading to failure (e.g., the cell can erroneously be considered as barred or the UEs can crash or their functionality can become otherwise anomalous). This can require the network operator to temporarily disable broadcast of the affected SIB (or disable scheduling, in SIB 1 , of affected SIBs) or require time consuming upgrades of various affected UEs. 
     The disclosed technology provides a network-based solution to identify a UE&#39;s 3GPP release and/or the UE&#39;s capability and appropriately target on-demand SIB messages to newer UEs that can understand newer SIBs while transmitting only legacy SIBs to older UEs that cannot understand the newer SIBs (e.g., using new layer  3  messaging to target legacy UEs, such as LTE UEs, with on-demand SIB messages providing the UEs only the SIBs they need). That is, the disclosed technology ensures that UEs are provided with only the system information or SIBs that they need and can act upon and no more. This makes LTE, non-standalone (NSA) NR, and standalone (SA) NR modes coexistence more robust. 
       FIG.  2    is a flow diagram that illustrates a process  200  for modifying System Information Block (SIB) messages based on UE capability. At  210 , the radio access network (RAN)  203 , e.g., the LTE eNB or NR gNB sends a Master Information Block (MIB) message  210 , to the UE  202 . The MIB  210  is sent to the UE over a broadcast transport channel (BCH) and a physical broadcast physical channel (PBCH). The MIB  210  provides the UE with parameters that the UE needs to acquire the first System Information Block (SIB), i.e., SIB type  1  (SIB 1 ). For example, the MIB  210  includes information required for the UE to monitor the Physical Downlink Control Channel (PDCCH) for scheduling of the Physical Downlink Shared Channel (PDSCH) that carries SIB 1 . 
     The RAN  203  also sends to the UE a SIB Type  1  (SIB 1 ) message  215 . The SIB 1   215  carries information required by the UE to access the cell. For example, SIB 1   215  includes random access parameters, PLMN list, tracking area codes, UE&#39;s timers and constants, access control information, etc. SIB 1   215  also includes information regarding the availability and scheduling of other SIBs, e.g., the mapping of SIBs to system information (SI) message, periodicity of the SI messages, SI-window size, etc. As disclosed herein, instead of the LTE or NR RAN (e.g., LTE eNB and NR gNB) scheduling all the SIBs available for the RAN (e.g., for a 3GPP Release  15  RAN, scheduling up to SIB 24 ), SIB 1   215  only schedules the legacy SIBs (i.e., SIBs known not to cause problems with older UEs, e.g., SIB 2  to SIB 18  or SIB 2  to SIB 9 , or SIBs preceding the extension marker in SIB-Type IE). As a result, legacy/older UEs have no opportunity to try and decode or read newer SIBs that they do not need or understand and that could result in the UE crashing or UE being considered as barred from the cell. 
     At  220 , the UE  202  sends its Capability Information to the RAN  203  (e.g., via Radio Resource Control (RRC) messages). In some implementations, the UE sends the Capability Information in response to a Capability Enquiry message from the network. The UE Capability Information is contained in an Abstract Syntax Notation One (ASN. 1 ) data structure defining “release” information that informs the network of the release or version of the UE (e.g., includes a flag for UE release). 
     At  230  the network maps the ASN. 1  Release information received from the UE to a 3GPP Release version. Knowing the 3GPP Release version allows the network, at  233 , to determine if the SI messages scheduled in SIB 1   215  suffices for the UE, or if the UE requires additional SIBs. For example, if the Capability Information indicates that the UE is a Release  15  UE capable of operating in an LTE and NR RAT, the network can determine that the UE would need SIB 24  which provides information that would allow the UE to roam from LTE to NR. 
     At  235 , the network determines if a SIB update is required for UE  202  based on the UE Capability Information received at  220 . In some implementations, determining if a SIB update is required comprises comparing the 3GPP release determined at  233  with a look-up table or other data stored in a memory in the UE or in the network that indicates what SIBs are relevant to what  3 GPP releases (e.g., querying the memory with the 3GPP release version and receiving a list of SIBs relevant to the 3GPP release in response to the query). For example, the lookup table or memory can store information indicating that if UE&#39;s release is Release  15 , SIB 24  would be required because SIB 24  provides cell reselection information allowing a UE to move from LTE to NR. If a SIB update is required, the network sends an updated SIB 1  and updated SI message at  240  and  260  (or in some implementations, the network schedules the required SI messages directly). 
     At  240 , the RAN  203  sends to the UE  202  an updated SIB 1   240  with an updated SIB mapping information that is determined based on the UE Capability Information (e.g., an updated SIB 1  format bitmap that is based the UE&#39;s 3GPP Release). SIB 1   240  schedules SI messages pertinent for the UE based on the UE Capability Information, and sends the Updated Periodic SI messages to the UE at  260  based on the updated SIB 1   240  scheduling information. That is, the updated SIB 1   240  schedules the transmission of non-legacy SIBs to UEs that are determined to be capable of acting on the non-legacy SIBs based on the received Capability Information (i.e., legacy UEs receive only legacy SIBs but non-legacy or newer UEs can receive both the legacy SIBs and one or more non-legacy SIBs). For example, the network could determine that a 3GPP Release  15  UE needs to receive scheduling information for SIB 24 . The network would then include SIB 24  scheduling information in the updated SIB 1   240  and send SIB 24  in the Updated Periodic SI Message  260 . On the other hand, the network could determine that a 3GPP Release  8  UE does not need SIB 24  and thus would not include scheduling information for SIB 24  in the updated SIB 1  message  240 . 
     To ensure that legacy UEs do not get an opportunity to read SIBs that are not intended for their release, the UEs can be targeted directly and individually with layer  3  messaging (e.g., Radio Resource Control (RRC) layer messaging) carrying information on SIBs relevant to the UE (relevance being determined by the UEs&#39; capability information). This unicast message can use the Physical Downlink Control Channel (PDCCH) with SIB-updates based on a C-RNTI (cell radio network temporary identifier) instead of using broadcast system update messages which would be decodable by all legacy UEs (e.g., PDCCH scrambled with system information RNTI (SI-RNTI)). 
     In some implementations, the updated SIB 1   240  and the updated SI messages  260  can be unicast on a downlink shared channel (DL-SCH). Additionally, or alternatively, the SI messages  260  can be broadcast on-demand or periodically broadcast on DL-SCH based on the network&#39;s determination at  235  on what SI messages the UEs&#39; need based on the UEs&#39; capability information received at  220 . 
     The UE  202  acquires system information using process  200  in various situations including on cell selection (e.g., after power on), on cell reselection (e.g., when roaming), when the UE returns from out of coverage, after reconfiguration with synchronization completion, after switching Radio Access Technologies (RATs), upon receiving an indication that the SI has changed, upon receiving a Public Warning System (PWS) notification, whenever the UE does not have a valid version of a stored SIB, etc. 
       FIG.  3    is a flow diagram that illustrates a process  300  for sending on-demand system information messages based on UE capability. At  310 , the UE  202  synchronizes with a cell and reads the Master Information Block (MIB) and System Information Block Type  1  (SIB 1 ), collectively, minimum system information (SI). For example, UE  202  can read MIB message  210  and SIB 1  message  215  shown in process  200  of  FIG.  2   . 
     At  320 , UE  202  sends its Capability Information to the RAN  203  (e.g., via RRC messages). In some implementations, the UE sends the Capability Information in response to a Capability Enquiry message from the network. The UE Capability Information includes a flag for ASN. 1  Release that informs the network of the release or version of the UE. 
     At  330  the network maps the ASN. 1  Release information received from the UE to a 3GPP Release version. At  333 , the network determines based on the 3GPP Release version if the global SIBs broadcast to the UE suffice for the UE. That is, at  333  the network determines if the SIBs broadcasts based on scheduling information in SIB 1  that the UE reads at  310  include all the SIBs that the UE needs based on the UE Capability Information or if the UE needs additional SIBs that are not already scheduled in SIB 1  to be broadcast to the UE. 
     At  340 , the networks initiates SIB on demand messages targeted to the UE to resolve the contention between the SIBs that are already being broadcast to the UE and the SIBs that the UE needs based on the UE&#39;s 3GPP release (i.e., based on the UE capability information received at  320 ). In some implementations, the SIB on-demand message  340  includes SI messages sent to the UE  202  without a corresponding request (e.g., without a System Information Request from the UE to the RAN  203  (eNB/gNB)). This is because, the RAN already knows what SI messages the UE needs based on the UE capability information sent at  320 . As a result, the RAN  203  can send non-legacy SIBs to the UE  202  in a dedicated manner (e.g., on DL-SCH). 
     In some implementations, the SIB on-demand message  340  includes unicasting SIB 1  on DL-SCH where the SIB 1  indicates that non-legacy SIBs (e.g., newer SIBs introduced in current 3GPP release or in later 3GPP releases) are only provided on-demand. In this implementation, the SIB can also provide a physical random access channel (PRACH) configuration that UE  202  can use to request one or more non-legacy SIBs from the RAN  203  (i.e., from the network or eNB/gNB). 
     Computer System 
       FIG.  4    is a block diagram that illustrates an example of a computer system  400  in which at least some operations described herein can be implemented. As shown, the computer system  400  can include: one or more processors  402 , main memory  406 , non-volatile memory  410 , a network interface device  412 , video display device  418 , an input/output device  420 , a control device  422  (e.g., keyboard and pointing device), a drive unit  424  that includes a storage medium  426 , and a signal generation device  430  that are communicatively connected to a bus  416 . The bus  416  represents one or more physical buses and/or point-to-point connections that are connected by appropriate bridges, adapters, or controllers. Various common components (e.g., cache memory) are omitted from  FIG.  4    for brevity. Instead, the computer system  400  is intended to illustrate a hardware device on which components illustrated or described relative to the examples of the FIGS. and any other components described in this specification can be implemented. 
     The computer system  400  can take any suitable physical form. For example, the computing system  400  can share a similar architecture as that of a server computer, personal computer (PC), tablet computer, mobile telephone, game console, music player, wearable electronic device, network-connected (“smart”) device (e.g., a television or home assistant device), AR/VR systems (e.g., head-mounted display), or any electronic device capable of executing a set of instructions that specify action(s) to be taken by the computing system  400 . In some implementation, the computer system  400  can be an embedded computer system, a system-on-chip (SOC), a single-board computer system (SBC) or a distributed system such as a mesh of computer systems or include one or more cloud components in one or more networks. Where appropriate, one or more computer systems  400  can perform operations in real-time, near real-time, or in batch mode. 
     The network interface device  412  enables the computing system  400  to mediate data in a network  414  with an entity that is external to the computing system  400  through any communication protocol supported by the computing system  400  and the external entity. Examples of the network interface device  412  include a network adaptor card, a wireless network interface card, a router, an access point, a wireless router, a switch, a multilayer switch, a protocol converter, a gateway, a bridge, bridge router, a hub, a digital media receiver, and/or a repeater, as well as all wireless elements noted herein. 
     The memory (e.g., main memory  406 , non-volatile memory  410 , machine-readable medium  426 ) can be local, remote, or distributed. Although shown as a single medium, the machine-readable medium  426  can include multiple media (e.g., a centralized/distributed database and/or associated caches and servers) that store one or more sets of instructions  428 . The machine-readable (storage) medium  426  can include any medium that can store, encoding, or carrying a set of instructions for execution by the computing system  400 . The machine-readable medium  426  can be non-transitory or comprise a non-transitory device. In this context, a non-transitory storage medium can include a device that is tangible, meaning that the device has a concrete physical form, although the device can change its physical state. Thus, for example, non-transitory refers to a device remaining tangible despite this change in state. 
     Although implementations have been described in the context of fully functioning computing devices, the various examples are capable of being distributed as a program product in a variety of forms. Examples of machine-readable storage media, machine-readable media, or computer-readable media include recordable-type media such as volatile and non-volatile memory devices  410 , removable flash memory, hard disk drives, optical disks, and transmission-type media such as digital and analog communication links. 
     In general, the routines executed to implement examples herein can be implemented as part of an operating system or a specific application, component, program, object, module, or sequence of instructions (collectively referred to as “computer programs”). The computer programs typically comprise one or more instructions (e.g., instructions  404 ,  408 ,  428 ) set at various times in various memory and storage devices in computing device(s). When read and executed by the processor  402 , the instruction(s) cause the computing system  400  to perform operations to execute elements involving the various aspects of the disclosure. 
     Some portions of the disclosure can be presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm can refer to a sequence of operations leading to a desired result. The operations are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. 
     It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussion, it is appreciated that throughout the description, discussions utilizing terms such as “processing,” “computing,” “calculating,” “determining,” “displaying,” “generating,” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. 
     The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems can be used with programs in accordance with the described teachings, or it can prove convenient to construct more specialized apparatus to perform the methods of some implementations. The required structure for a variety of these systems will appear from the description. In addition, the techniques are not described with reference to any particular programming language, and various implementations can thus be implemented using a variety of programming languages. 
     In some circumstances, operation of a memory device, such as a change in state from a binary one to a binary zero or vice-versa, for example, can comprise a transformation, such as a physical transformation. With particular types of memory devices, such a physical transformation can comprise a physical transformation of an article to a different state or thing. For example, but without limitation, for some types of memory devices, a change in state can involve an accumulation and storage of charge or a release of stored charge. Likewise, in other memory devices, a change of state can comprise a physical change or transformation in magnetic orientation or a physical change or transformation in molecular structure, such as from crystalline to amorphous or vice versa. The foregoing is not intended to be an exhaustive list in which a change in state for a binary one to a binary zero or vice-versa in a memory device can comprise a transformation, such as a physical transformation. Rather, the foregoing is intended as illustrative examples. 
     Remarks 
     The terms “example”, “embodiment” and “implementation” are used interchangeably. For example, reference to “one example” or “an example” in the disclosure can be, but not necessarily are, references to the same implementation; and, such references mean at least one of the implementations. The appearances of the phrase “in one example” are not necessarily all referring to the same example, nor are separate or alternative examples mutually exclusive of other examples. A feature, structure, or characteristic described in connection with an example can be included in another example of the disclosure. Moreover, various features are described which can be exhibited by some examples and not by others. Similarly, various requirements are described which can be requirements for some examples but no other examples. 
     The terminology used herein should be interpreted in its broadest reasonable manner, even though it is being used in conjunction with certain specific examples of the invention. The terms used in the disclosure generally have their ordinary meanings in the relevant technical art, within the context of the disclosure, and in the specific context where each term is used. A recital of alternative language or synonyms does not exclude the use of other synonyms. Special significance should not be placed upon whether or not a term is elaborated or discussed herein. The use of highlighting has no influence on the scope and meaning of a term. Further, it will be appreciated that the same thing can be ssbcaid in more than one way. 
     Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” As used herein, the terms “connected,” “coupled,” or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof. Additionally, the words “herein,” “above,” “below,” and words of similar import can refer to this application as a whole and not to any particular portions of this application. Where context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word “or” in reference to a list of two or more items covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. The term “module” refers broadly to software components, firmware components, and/or hardware components. 
     While specific examples of technology are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. For example, while processes or blocks are presented in a given order, alternative implementations can perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified to provide alternative or sub-combinations. Each of these processes or blocks can be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks can instead be performed or implemented in parallel, or can be performed at different times. Further, any specific numbers noted herein are only examples such that alternative implementations can employ differing values or ranges. 
     Details of the disclosed implementations can vary considerably in specific implementations while still being encompassed by the disclosed teachings. As noted above, particular terminology used when describing features or aspects of the invention should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the invention with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the invention to the specific examples disclosed herein, unless the above Detailed Description explicitly defines such terms. Accordingly, the actual scope of the invention encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the invention under the claims. Some alternative implementations can include additional elements to those implementations described above or include fewer elements. 
     Any patents and applications and other references noted above, and any that may be listed in accompanying filing papers, are incorporated herein by reference in their entireties, except for any subject matter disclaimers or disavowals, and except to the extent that the incorporated material is inconsistent with the express disclosure herein, in which case the language in this disclosure controls. Aspects of the invention can be modified to employ the systems, functions, and concepts of the various references described above to provide yet further implementations of the invention. 
     To reduce the number of claims, certain implementations are presented below in certain claim forms, but the applicant contemplates various aspects of an invention in other forms. For example, aspects of a claim can be recited in a means-plus-function form or in other forms, such as being embodied in a computer-readable medium. A claim intended to be interpreted as a mean-plus-function claim will use the words “means for.” However, the use of the term “for” in any other context is not intended to invoke a similar interpretation. The applicant reserves the right to pursue such additional claim forms in either this application or in a continuing application.