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EMN/K/A Geert Heijenk (5430)2000-12-21B
QoS in GPRS
Abstract
Mobile telephony has been for many years the most popular application supported by mobile systems such as the Global System for Mobile communications (GSM). Recently, the use of mobile data applications such as the GSM Short Message Service (SMS) has gained popularity. However, the GSM system can only support data services up to 9.6 kbit/s, circuit switched. The General Packet Radio Service (GPRS), developed by the European Telecommunications Standards Institute (ETSI), is a new packet switched data service for GSM that can allow bitrates, theoretically up to 170 kbit/s per user. However, commercial GPRS systems will be able to support rates up to 115 kbit/s. This document presents current developments and research activities in the area of Quality of Service (QoS) provisioning in GPRS Release 1998 and Release 1999. Moreover, new procedures that are used to enable the interworking between the GPRS QoS framework and the IntServ framework and as well the interworking between the GPRS QoS framework and the Diffserv framework are introduced.
EMN/K/A Geert Heijenk (5430)2000-12-21B
Contents
1INTRODUCTION (7)
2TERMINOLOGY (8)
2.1G LOSSARY USED IN GPRS (8)
3GPRS ARCHITECTURE AND PROTOCOLS (13)
3.1I NTRODUCTION (13)
3.2N ETWORK A RCHITECTURE (13)
3.3GPRS TRANSMISSION PLANE PROTOCOL STACK (14)
3.4GPRS SIGNALLING PLANE PROTOCOL STACK (16)
3.4.1Signalling plane MS – SGSN (17)
3.4.2Signalling plane SGSN – HLR and SGSN - EIR (18)
3.4.3Signalling plane SGSN – MSC/VLR (19)
3.4.4Signalling plane GSN – GSN (19)
3.4.5Signalling plane GGSN – HLR (19)
3.5GPRS AIR LOGICAL CHANNELS (20)
4QOS MANAGEMENT AND MOBILITY SUPPORT (23)
4.1I NTRODUCTION (23)
4.2M OBILITY SUPPORT (23)
4.2.1Mobility management (23)
4.2.2Cell selection and reselection (25)
4.2.3Packet Routing (25)
4.3Q UALITY OF S ERVICE (26)
4.3.1Quality of Service attribuites in GPRS Release 1998 (26)
4.3.2Quality of Service attribuites in GPRS Release 1999 (28)
4.3.3QoS Management (29)
5INTEGRATED SERVICES IN GPRS (44)
5.1I NTRODUCTION (44)
5.2R ESOURCE R ESERVATION (44)
5.3A DMISSION C ONTROL IN MS, BSS AND SGSN (48)
5.4F LOW S EPARATION AND S CHEDULING (50)
5.5P OLICING AND SHAPING (51)
5.6S OFT S TATE (55)
5.7S CALABILITY (55)
5.8F AULT T OLERANCE AND R ECOVER (56)
5.9I NDEPENDENCE FROM H IGHER L AYER P ROTOCOL (56)
5.10I NTERWORKING BETWEEN GPRS Q O S MANAGEMENT AND I NTSERV CONCEPT (57)
5.10.1QoS end to end interworking at the MS (57)
5.10.2Proposed QoS end to end interworking at the GGSN (59)
5.11R ECEIVER H ETEROGENEITY (62)
5.12S UPPORT FOR DIFFERENT F ILTER S TYLES (62)
6DIFFERENTIATED SERVICES IN GPRS (64)
6.1I NTRODUCTION (64)
6.2S ERVICE L EVEL A GREEMENTS (64)
6.3M ARKING OF IP PACKETS (64)
6.4C LASSIFICATION, POLICING AND RE-SHAPING (65)
6.5A DMISSION CONTROL (65)
6.6I MPLEMENT A P ER-H OP-B EHAVIOR (65)
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6.7P ROPOSED MECHANISM FOR INTERWORKING BETWEEN GPRS Q O S MANAGEMENT AND THE D IFFSERV CONCEPT (65)
6.7.1GPRS/Diffserv QoS interworking message sequence charts (69)
7CONCLUSIONS (72)
8REFERENCES (73)
8.1B Y ALPHABET (73)
8.2B Y CATEGORY (80)
8.2.13GPP GPRS documents (80)
8.2.2ETSI GPRS documents (80)
8.2.3IETF documents (83)
8.2.4Reports and articles (84)
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List of Abbreviations
2G2nd Generation
3G3rd Generation
3GPP3rd Generation Partnership Project
AA Anonymous Access
APN Access Point Name
BB Bandwidth Broker
BSS Base Station System
BSSAP+Base Station System Application Part +
BSSGP Base Station System GPRS Protocol
BVC BSSGP Virtual Connection
BTS Base Transceiver Station
CAMEL Customised Applications for Mobile Network Enhanced Logic CH Correspondent Host
DHCP Dynamic Host Configuration Protocol
DNS Domain Name Server
ETSI European Telecommunication Standardisation Institute
FA Foreign Agent
GGSN Gateway GPRS Support Node
GMM/SM GPRS Mobility Management and Session Management GPRS General Packet Radio Service
GSN GPRS Support Node
GTP GPRS Tunnelling Protocol
GW GateWay
HA Home Agent
HLR Home Location Register
HO HandOver
IETF Internet Engineering Task Force
IMT2000International Mobile Telecommunications 2000
IP Internet Protocol
IP-M Internet Protocol Multicast
IPR Intellectual Property Rights
IPv4IP version 4
IPv6IP version 6
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ISP Internet Service Provider
ITU International Telecommunication Union
LLC Logical Link Control
MAC Medium Access Control
MIP Mobile IP
MN Mobile Node
MM Mobility Management
MTP2Message Transfer Part layer 2
MTP3Message Transfer Part layer 3
MS Mobile Station
MT Mobile Terminal
MIPv4Mobile IP version 4
MIPv6Mobile IP version 6
NS Network Service
NSAPI Network layer Service Access Point Identifier
NSS Network SubSystem
PDCH Packet Data CHannels
PDN Packet Data Network
PDP Packet Data Protocol, e.g., IP or X.25
PDP (2)Policy Decission Point, this term is used in the Diffserv concept PDU Protocol Data Unit
PEP Policy Enhancement Point
PHB Per Hop Behavior
PPP Point to Point Protocol
PTM Point To Multipoint
PTM-M PTM-Multicast
PTM-G PTM-Group
PTP Point To Point
QoS Quality of Service
RFC Request For Comments
RLC Radio Link Control
RR Radio Resource
RSVP Resource Reservation Protocol
SAP Service Accee Point
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SAPI Service Access Point Identifier
SGSN Serving GPRS Support Node
SLA Service Level Agreement
SLS Service Level Specification
SNDC SubNetwork Dependent Convergence
SNDCP SubNetwork Dependent Convergence Protocol
TBF Temporary Block Flow
TCAP Transaction Capabilities Application Part
TCP Transmission Control Protocol
TFI Temporary Flow Identity
TE Terminal Equipment
TI Transaction Identifier
TID Tunnel Identifier
TLLI Temporary Logical Link Identifier
UDP User Datagram Protocol
UMTS Universal Mobile Telecommunication System
VLR Visitor Location Register
W-LAN Wireless – Local Area Network
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1 Introduction
Until recently, the main application of the most mobile systems, e.g., Global System for Mobile communications (GSM), has been mobile telephony. Recently, the use of mobile data applications such as the GSM Short Message Service (SMS) has gained popularity. However, the GSM system can only support data services up to 9.6 kbit/s, circuit switched. The General Packet Radio Service (GPRS) (see e.g., [GSM02.60], [3GPP22.060], [CaGo97]) developed by the European Telecommunications Standards Institute (ETSI), provides packet switched services in a GSM network that can allow bitrates, theoretically up to 170 kbit/s per user. However, commercial GPRS systems will support a maximum bit rate of 115 kbit/s. Furthermore, GPRS is able to provide additional features such as:
?more efficient use of scarce radio resources;
?faster set-up / access times;
?connectivity to other external packet data networks by using IPv4 [RFC791] or [RFC2460] or X.25 [X25].
?user differentiation based on Quality of service (QoS) agreements;
In [HoMe98] and [KaMe99], by using simulation and in [ArBi98] by using analytical modelling, is shown that GPRS is suitable to support TCP/IP bursty traffic. GPRS compared to circuit switched networks, allows a better utilisation and end-to-end delay for bursty traffic.
This document, in general, presents recent developments and research activities in the area of QoS provisioning in GPRS Release 1998 and Release 1999. The main difference between GPRS Release 1998 and GPRS Release 1999 is that the first one is capable of supporting GPRS access networks while the later one additionally is capable of supporting Universal Mobile Telecommunications System (UMTS) access networks. Furthermore, the QoS management principles used for GPRS Release 1999 are similar to the ones used for UMTS Release 1999.
In particular, this document emphasises the developments and QoS research topics [ZeAi99] on the integration of the Integrated Services [Intserv] and Differentiated Services [Diffserv] with GPRS. Furthermore, we introduce new procedures that will enable the GPRS technology to support the Intserv and/or Diffserv QoS frameworks.
In this document it is assumed that the reader is familiar with the GPRS, TCP/IP protocol stack, and Integrated and Differentiated Services frameworks.
All the ETSI GPRS specifications used in this document are referring to the GPRS Release 1998. The
3GPP GPRS specifications are referring to the GPRS Release 1999.
The organisation of this document is as follows. Section 3 presents the current status of the GPRS system (Release 1998 and Release 1999). Section 4 describes the QoS management and mobility support provisioning in GPRS. Sections 5 and 6 describe how the Integrated Services requirements and the Differentiated Services requirements, respectively, are fulfilled by GPRS. These requirements are specified in [ZeAi99]. Finally, the conclusions are presented in Section 7. Note that the existing IPRs (Intellectual Property Rights) on QoS over GPRS are listed in [ZeAi99]. Moreover, note that the ideas proposed in this document by the authors do not imply any kind of Ericsson strategy.
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2 Terminology
2.1 Glossary used in GPRS
Note that, parts of this section are copied from [GSM 2.60].
[..
access delay: The value of elapsed time between an access request and a successful access. accuracy: A performance criterion that describes the degree of correctness with which a function is performed..
bearer service: A type of telecommunication service that provides the capability for the transmission of signals between user-network interfaces.
best effort service: A service model which provides minimal performance guarantees, allowing an unspecified variance in the measured performance criteria.
broadcast: A value of the service attribute "communication configuration", which denotes unidirectional distribution to all users.
calling user: Entity which originates a call to the General Packet Radio Service (GPRS). connectionless service: A service which allows the transfer of information among service users without the need for end-to-end call establishment procedures.
dependability: A performance criterion that describes the degree of certainty (or surety) with which a function is performed regardless of speed or accuracy, but within a given observational interval. destination user: Entity to which calls to the General Packet Radio Service (GPRS) are directed. distribution service: Service characterised by the unidirectional flow of information from a given point in the network to other (multiple) locations.
functional group: A set of functions that may be performed by a single equipment.
geographical routing: The conversion of the PDU’s geographical area definition, which specifies the area in which the PDU will be broadcast, into an equivalent radio coverage map.
group: A set of members allowed to participate in the group call service. The group is defined by a set of rules that identifies a collection of members implicitly or explicitly. These rules may associate members for the purpose of participating in a group call, or may associate members who do not participate in data transfer but do participate in management, security, control, or accounting for the group.
guaranteed service: A service model which provides highly reliable performance, with little or no variance in the measured performance criteria.
interactive service: A service which provides the means for bi-directional exchange of information between users. Interactive services are divided into three classes of services: conversational services, messaging services and retrieval services.
mean bit rate: A measure of throughput. The average (mean) bit rate available to the user for the given period of time.
mean transit delay: The average transit delay experienced by a (typically) large sample of PDUs within the same service category.
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mobile station: Equipment intended to access a set of GSM PLMN telecommunication services. Services may be accessed while the equipment capable of surface movement within the GSM system area is in motion or during halts at unspecified points .
mobile termination: The part of the mobile station which terminates the radio transmission to and from the network and adapts terminal equipment capabilities to those of the radio transmission.
multicast service: A unidirectional PTM service in which a message is transmitted from a single source entity to all subscribers currently located within a geographical area. The message contains a group identifier indicating whether the message is of interest to all subscribers or to only the subset of subscribers belonging to a specific multicast group.
multipoint: A value of the service attribute "communication configuration", which denotes that the communication involves more than two network terminations;
network connection: An association established by a network layer between two users for the transfer of data, which provides explicit identification of a set of network data transmissions and agreement concerning the services to be provided by the set.
network operator: Entity which provides the network operating elements and resources for the execution of the General Packet Radio Service (GPRS).
network service data unit (NSDU): A unit of data passed between the user and the GPRS network across a Network Service Access Point (NSAP).
network termination: A functional group on the network side of a user-network.
packet data protocol (PDP): Any protocol which transmits data as discrete units known as packets, e.g., IP, or X.25.
] [GSM 2.60]
PDP (2) (Policy Decission Point): is an enity specified in the Diffserv concept which is responsible for determining the actions that are applicable to packets. The PDP is used to control the actions that are performed by the Policy Enforcement Points (PEP). PEP is usual located in a Diffserv node and is responsible for the enforcement and execution of the policy actions.
PDP context (applied for GPRS Release 1998): information sets held in MS, SGSN and GGSN that are used to specify the tight connection between one PDP address that identifies an application, a PDP type and one QoS profile.
[..
Ericsson’s proposed PDF context: is affiliated to an established PDP context and identifies a data flow of one or several application flow(s). The PDF context consists mainly of a PDF context identifier a QoS profile and optionally of a flow template. PDF contexts provide transmission capabilities for either symmetric or asymmetric flows. An asymmetric PDF context can either be up-link or down-link biased, as indicated by the QoS attributes affiliated to it.
Ericsson’s proposed PDP context: is a logical connection from an MS to a packet data network (i.e. ISP, Intranet or LAN) consisting of a PDP (IP) address, host configuration parameters, tunnel identifiers, etc. A PDP context contains at least one PDF context, the initial PDF context.
Note that a PDP context with it’s initial PDF context corresponds exactly to a PDP context as specified within the PDP context in GPRS Release 1998.] [SMG12 C-99-460].
EMN/K/A Geert Heijenk (5430)2000-12-21B
PDP context (applied for GPRS Release 1999 and UMTS Release 1999): information sets held in MS, SGSN and GGSN that are used to specify the tight connection between one subscriber that identifies an application, a PDP type and one QoS profile. More PDP contexts with different QoS parameters can share the same PDP address. In order to activate PDP contexts two types of procedures can be used. The first procedure, called Activate PDP Context includes subscription checking, APN selection, and host configuration. The second procedure, called Secondary Activate PDP Context procedure may be used to activate a PDP context while reusing the PDP address and other PDP Context information from an already existing PDP Context, but with a different QoS Profile. The later procedure can be repeated. Note that at least one PDP context shall be activated for a PDP address before a Secondary PDP Context Activation procedure may be initiated. The “first” PDP context, defined for GPRS Release 1999 is similar to the PDP Context defined in Ericsson’s proposal. The Secondary PDP Context (s) are similar to the PDF Context (s) defined in Ericsson’s proposal. Furthermore, note that the Release 1999 of the Universal Mobile Telecommunications System (UMTS) uses the same PDP context principles as the Release 1999 of the GPRS system.
[..
packet transfer mode: Also known as packet mode. A transfer mode in which the transmission and switching functions are achieved by packet oriented techniques, so as to dynamically share network transmission and switching resources between a multiplicity of connections;
peak bit rate: A measure of throughput. The maximum bit rate offered to the user for a given time period (to be defined) for the transfer of a bursty signal.
point-to-multipoint (PTM) service: A service type in which data is sent to ”all service subscribers or a pre-defined subset of all subscribers” within an area defined by the Service Requester.
point-to-point (PTP): A value of the service attribute "communication configuration", which denotes that the communication involves only two network terminations.
point-to-point (PTP) service: A service type in which data is sent from a single network termination to another network termination.
protocol: A formal set of procedures that are adopted to ensure communication between two or more functions within the same layer of a hierarchy of functions;
quality of service: The collective effect of service performances which determine the degree of satisfaction of a user of the service. The set of performance parameters that can be directly observed and measured at the point at which the service is accessed by the user. There are three criteria by which performance is measured: speed, accuracy and dependability.
reference configuration: A combination of functional groups and reference points that shows possible network arrangements.
reference point: A conceptual point at the conjunction of two non-overlapping functional groups. service access point (SAP): In the reference model for OSI, the points through which services are offered to an adjacent higher layer.
service attribute: A specified characteristic of a telecommunication service.
service bit rate: The bit rate that is available to a user for the transfer of user.
service category or service class: A service offered to the users described by a set of performance parameters and their specified values, limits or ranges. The set of parameters provides a comprehensive description of the service capability.
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service data unit (SDU): In the reference model for OSI, an amount of information whose identity is preserved when transferred between peer (N+1)-layer entities and which is not interpreted by the supporting (N)-layer entities (source: ITU-T X.200 / ISO-IEC 7498-1).
service delay: The time elapsed from the invocation of the service request, to the corresponding service request indication at the Service Receiver, indicating the arrival of application data.
service provider: Entity which offers the General Packet Radio Service (GPRS) for subscription. The network operator may be the service provider.
service receiver: The entity which receives the service request indication primitive, containing the SDU. service request: This is defined as being one invocation of the service through a service request primitive.
service subscriber: Entity which subscribes to the General Packet Radio Service (GPRS) service. signalling: The exchange of information specifically concerned with the establishment and control of connections, and with management, in a telecommunications network (source: ITU-T I.112).
terminal equipment: Equipment that provides the functions necessary for the operation of the access protocols by the user. A functional group on the user side of a user-network interface.
throughput: A parameter describing service speed. The number of data bits successfully transferred in one direction between specified reference points per unit time.] [GSM 2.60]
[.. Ericsson’s proposed Traffic Flow Template (TFT): specifies how to identify the traffic as well as the rules for policing. It may be affiliated to a PDF context and is applicable for PDP-types IP and PPP. The initial PDF context in a PDP context does not have a TFT, while further PDF contexts must have a TFT affiliated to them.] [SMG12 C-99-460]
[..
GPRS Release 1999 (and UMTS Release 1999) - Traffic Flow Template: TFTs are used by GGSN to distinguish between different user payload packets and transmit packets with different QoS requirements via different PDP context but to the same PDP address.] [3GPP29.060].
[..
transit delay: A parameter describing service speed. The time difference between the instant at which the first bit of a protocol data unit (PDU) crosses one designated boundary (reference point), and the instant at which the last bit of the PDU crosses a second designated boundary (source: ITU-T I.113). user access or user network access: The means by which a user is connected to a telecommunication network in order to use the services and/or facilities of that network.
user-network interface: The interface between the terminal equipment and a network termination at which interface the access protocols apply.
user-user protocol: A protocol that is adopted between two or more users in order to ensure communication between them.
variable bit rate service: A type of telecommunication service characterised by a service bit rate specified by statistically expressed parameters which allow the bit rate to vary within defined limits.
] [GSM 2.60]
RLC/MAC control block: A RLC/MAC control block is the part of a RLC/MAC block carrying a control message between RLC/MAC entities (see subclause 10.3).
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RR connection: An RR (Radio Resource) connection is a physical connection established between a mobile station and the network to support the upper layers’ exchange of information flows. An RR connection is maintained and released by the two peer entities.
RLC data block: A RLC data block is the part of a RLC/MAC block carrying user data or upper layers’signalling data (see subclause 10.2).
Temporary Block Flow (TBF): A Temporary Block Flow (TBF) is used in the RLC/MAC layer and it represents a physical connection used by the two RR (Radio Resource) peer entities to support the unidirectional transfer of LLC PDUs on packet data physical channels. A TBF is temporary and is maintained only for the duration of the data transfer.
TBF abort: The term “abort” as applied to TBF is used when the TBF is abruptly stopped without using the Release of TBF procedures defined in clause 9.
TBF release: The term “release” as applied to TBF is used when the TBF is stopped using one of the Release of TBF procedures defined in clause 9.
Uplink State Flag (USF): The Uplink State Flag (USF) is used on PDCH channel(s) to allow multiplexing of uplink Radio blocks from different mobile stations.
[..
Mapper/translator: is a function that has to play two roles in the edge devices. The first role is the translation between the QoS parameters of the external networks and the QoS attributes of GPRS. The GPRS QoS attributes determine the characteristics of the PDF contexts between the MS and the GGSN. The second role is the classification of packets at the ingress interface and the selection of the correct PDF context to carry each packet. This role is identical to what is described as packet classifier in IP networks.
Monitor: Monitor function measures the amount and characteristics of the traffic. The output of this function is used by the policer function to determine its actions. This functionality is identical to what is described as packet or traffic metering in IP networks.
Policer: Policer function ensures that the traffic at the ingress interface does not exceed the negotiated QoS profile including limits such as data rate, or burst size. The output of this function is the traffic stream to be forwarded from the egress interface. Policer function needs to be configurable such that it can take different actions, e.g., dropping, delaying (also called as shaping), or lowering QoS profile (re-marking) for packets identified as non-conformant. The same functionality is used in different IP network QoS frameworks.] ( [SMG12 C99-462] )
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3 GPRS architecture and protocols
3.1 Introduction
Packet data services, e.g., World Wide Web (WWW) and e-mail, mainly generate traffic that is characterized by periods of alternating high and low traffic loads, i.e., bursty traffic. Up to date the GSM service can not provide efficient ways of supporting such traffic. A solution to this issue is given by GPRS, a new mobile technology developed by ETSI, that can provide an optimal sharing of the available radio resources. These resources are allocated dynamically to the different GPRS users depending on their demands, e.g., delay, and on the provided network and end-terminal capabilities.An extra advantage of GPRS compared to a circuit switched mobile technology, e.g., GSM, is that it provides the possibility to a user to be online connected to the network without being charged for the time it remains in that situation provided that no bandwidth is used. Furthermore, GPRS can provide besides Point to Point (PTP) also Point to Multipoint (PTM) services. The main feature of a PTM service is that it forwards a single packet to multiple receivers. This forwarding process can be accomplished in two different ways. It can be either multicasted, i.e., sent to all receivers located in a geographical area,referred to as PTM-M (PTM-Multicast), IP-M (Internet Protocol Multicast) or forwarded to a predefined group (mainly independent of their geographical location), referred to as PTM-G (PTM-Group).
This section describes the GPRS network architectures for Release 1998 and Release 1999. Moreover,it presents the signaling and transmission protocols used in GPRS.
3.2 Network Architecture
The packet switched GPRS (Releases 1998 and 1999) service can co-exist with the circuit switched GSM service and therefore, it can utilise the existing GSM physical nodes (see Figure 3-1). However,additional physical nodes are required to support the GPRS functionality. These are the Gateway GPRS Support Node (GGSN) and the Supporting GPRS Support Node (SGSN). Note that the names of the interfaces between the physical nodes are identical to the ones used in the GPRS standards.
GSM based physical nodes
BSS Base Station Subsystem (BTS + BSC)
BSC Base Station Controller
BTS Base Transceiver Station
EIR Equipment Identity Register
HLR Home Location Register
MSC Mobile Switching Centre
MS Mobile Station
MT Mobile Terminal
TE Terminal Equipment
VLR Visitor Location Register Specific (new) GPRS nodes GSN GPRS Support Node GGSN Gateway GSN SGSN Serving GSN Others PDN Packet Data Network PLMN Public Land Mobile Network
Figure 3-1: GPRS system architecture
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The SGSN physical entity is in general responsible for the communication between the GPRS network and all the GPRS users located within its service area. It supports the mobility management (among others storing the Visitors Location Register (VLR), the visitors user profile (International Mobile Subscriber Identity) and the Packet Data Protocol (PDP) context), security management (i.e., authentication and ciphering), charging information and logical link management for each Mobile Station (MS) that is roaming in its service area. A PDP is representing the network protocol used by an external Packet Data Network (PDN) that is interfacing to GPRS. The PDP context represents the relation between a PDP (e.g., IP) address, PDP type (i.e., static or dynamic address), the address of a GGSN that serves as an access point to an external PDN, and a Quality of Service (QoS) profile. The PDP context is stored in the MS, SGSN and GGSN.
The GGSN is the gateway towards external networks, such as GPRS networks operated by different network operators, IP and X.25 networks. It can translate data formats, signalling protocols and address information to allow communication among different networks. Furthermore, the GGSN can provide dynamic allocation of network (e.g., IP) addresses.
The Home Location Register (HLR) contains GPRS subscription, e.g., user profile, and routing information that is mainly used to locate a GPRS subscriber.
The Visitor Location Register (VLR) is a location register that is used in a GSM circuit switched topology, to store location information for a roaming mobile station currently located in its area. Note that in GPRS the fucntionality of the VLR is accomplished by the SGSN.
The Mobile-services Switching Centre (MSC) is used in a GSM circuit switched topology and provides an interface between the GSM radio system and the fixed networks, performing all necessary functions in order to handle the calls to and from the mobile stations.
Similar to VLR and MSC the Equipment Identity Register (EIR) is used in a GSM circuit switched topology and it stores the International Mobile Equipment Identities (IMEIs) information.
The entities MSC and EIR are used in GPRS only for the situations that both circuit switched and packet data services are supported.
The Mobile Station consists of two entities, the Terminal Equipment (TE) and the Mobile Terminal (MT). TE is supporting the exchange of application layer messages with other end user terminals residing in different networks. The main functionality of MT is to manage the terminal capabilities and the radio transmission, e.g., speech encoding/decoding, flow control of signaling and user data and rate adaptation of user data.
3.3 GPRS transmission plane protocol stack
The transmission plane is used to transfer the user data information among the different GPRS physical nodes. The protocol stack used by the GPRS (Releases 1998 and 1999) transmission plane is shown in Figure 3-2. The following protocols can be identified:
?the Application layer transfers application based information among end points (e.g., MS).
?IP (or X25) layers are used as network layers.
?the GPRS Tunnelling Protocol (GTP), specified in [GSM 09.60] and [3GPP29.060], is able to tunnel signalling and user data between the GPRS Support Nodes (i.e., GGSN, SGSN);
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?the network-level characteristics, including the QoS profiles, are mapped onto the characteristics of the underlying network (see Figure 3-3) by the Subnetwork Dependent Convergence Protocol
(SNDCP) layer, specified in [GSM 04.65]. The Logical Link Control (LLC) layer it may support the SNDCP layer or a signalling and session layer. SNDCP, can support a set of different protocol entities, i.e., PDPs, that consists of commonly used network protocols. Furthermore, the SNDCP entity performs multiplexing of data coming from different PDP entities to be sent using the service provided by the LLC layer. The Service Access Point used by the PDP to interact with the SNDCP is called Network Service Access Point Identifier (NSAPI). This is an index to the PDP context of the PDP. Each active NSAPI has to use the services provided by the Service Access Point Identifier (SAPI) in the LLC layer. Furthermore each active SAPI will use the services provided by
theTemporary Logical Link Identifier (TLLI) in the Radio Link Control (RLC) / Medium Access Control (MAC) or Base Station System GPRS Protocol (BSSGP).
?the reliability of the underlying logical link is managed by the Logical Link Control (LLC) layer, specified in [GSM 04.64];
?the Base Station System GPRS Protocol (BSSGP) layer specified in [GSM 08.18] performs the transfer of QoS reIated information and routing between BSS and the SGSN physical nodes. Error correction is not performed by this layer;
?the Radio Link Control (RLC) / Medium Access Control (MAC) layer consists of the RLC and MAC sub-layers. RLC is specified in [GSM 04.60] and it provides a reliable radio link. The MAC, specified in [GSM 04.60], controls radio access signalling procedures, e.g., request and grant. Furthermore, it maps the LLC frames onto the GSM channels. The RLC/MAC layer is a bitmap-based selective ARQ (Automatic Repeat reQuest) type protocol with a slotted ALOHA random-access based packet reservation for uplink transmission. More than one time slots can be used by one MS for packet data transfer.
?in the BSS and SGSN physical nodes interworking functions (Relays) between the RLC and BSSGP and between SNDCP and GTP respectively are required;
?the BSSGP packet data units (PDU) are transferred between the BSS and SGSN by the Network Service (NS) layer, specified in [GSM 08.16] and is based on Frame Relay technology;
?the GPRS radio physical layer (see [GSM 04.60]) consists of two layers. One of them is the Physical Link Layer (PLL), that is providing radio physical channels between the MS and BSS. The other layer is the Physical RF layer (RFL) and is mainly providing modulation and demodulation.
Figure 3-2: GPRS transmission plane protocol stack
EMN/K/A Geert Heijenk (5430)2000-12-21B
Figure 3-3: Mapping of network level characteristics to underlying network level characteristics
3.4 GPRS signalling plane protocol stack
The signalling plane, is used to transfer signalling information between the different GPRS physical nodes. The main GPRS functions that are supported by the signalling plane are related to network access control, e.g., QoS (Quality of Service) management, packet routing and transfer, mobility management, and radio resource management. The complete list of the functions that are supported by GPRS (Releases 1998 and 1999) and their mapping to the GPRS logical architecture is given in Table 3-1. The GPRS signalling plane protocol stack can be separated in the following signalling plane parts:?between MS and SGSN, described in Section 3.4.1;
?between SGSN and HLR, described in Section 3.4.2;
?between SGSN and MSC/VLR, described in Section 3.4.3;
?between GPRS Supporting Nodes (GSNs), described in Section 3.4.4. Note that the GSN nodes can be either SGSN or GGSN;
?between GGSN and HLR, described in Section 3.4.5.
EMN/K/A Geert Heijenk (5430)2000-12-21B
Function MS BSS SGSN GGSN HLR
Network Access Control:
Registration X
Authentication and Authorisation X X X
Admission Control X X X
Message Screening X
Packet Terminal Adaptation X
Charging Data Collection X X
Packet Routeing & Transfer:
Relay X X X X
Routeing X X X X
Address Translation and Mapping X X X
Encapsulation X X X
Tunnelling X X
Compression X X
Ciphering X X X
Mobility Management:X X X X
Logical Link Management:
Logical Link Establishment X X
Logical Link Maintenance X X
Logical Link Release X X
Radio Resource Management:
U m Management X X
Cell Selection X X
U m-Tranx X X
Path Management X X
Table 3-1: Mapping of functions to Logical Architecture (based on [GSM03.60] and [3GPP23.060])
3.4.1 Signalling plane MS – SGSN
The signalling plane protocol stack used between the MS and SGSN consists of the protocol layers depicted in Figure 3-4. Except the GPRS Mobility Management and Session Management (GMM/SM) layer, all other layers depicted in Figure 3-4 are described in Section 3.3.
The GMM/SM layer is described in [GSM 03.60], [3GPP23.060] and it supports mobility management procedures, such as GPRS attach and detach, security, routing area update, location update and PDP context activation, modification and deactivation. Note that the PDP specifies a protocol that is used by an external packet data network interfacing to GPRS. Furthermore, the PDP context represents the information sets that are stored and held in the MS, SGSN and GGSN. These information sets mainly contain the required information that has to be used during the mobility management and QoS management, e.g., QoS profiles (see Section 4).
EMN/K/A Geert Heijenk (5430)2000-12-21B
Figure 3-4: Signalling plane between MS - SGSN
3.4.2 Signalling plane SGSN – HLR and SGSN - EIR
The signalling planes between the SGSN and HLR or SGSN and EIR consists of the protocol layers depicted in Figure 3-5. The protocol layer used at the top of the protocol stack, i.e., Mobile Application Part (MAP) is a specific GSM / GPRS layer. The layers used below the MAP layer are Signalling System 7 (SS7) protocol layers specified by the International Telecommunication Union (ITU).
?the Mobile Application Part (MAP) layer is specified in [GSM 09.02], with enhancements that are described in [GSM 03.60] and is providing the support of mainly mobility management signalling exchange between the SGSN and HLR;
?the Message Transfer Part (MTP) layer is specified in [ITU: Q701] and it consists of three levels, MTP1, MTP2 and MTP3. MTP1 corresponds to the physical layer and it provides bidirectional
transmission path for signalling. MTP2 is a data link layer and it provides error detection, correction and monitoring as well as flow control. MTP3 realises the signalling message handling and the signalling network management functions. The signalling message handling function manages the interaction between signalling points and messages. The signalling network management function is responsible for network management in e.g., situations of signalling link failures.
?the Transaction Capabilities Application Part (TCAP) layer is specified in [ITU: Q771], [ITU: Q772], [ITU: Q773] and [ITU: Q774] and it realises the dialog between applications running on different nodes through a query/ response interaction.
?the Signalling Connection Control Part (SCCP) layer is specified in [ITU: Q711], [ITU: Q712], [ITU: Q713] and [ITU: Q714] and it extends the MTP3 addressing capabilities by identifying and delivering messages to SCCP users and translating the logical addresses to MTP3 parameters.
?the L1 layer represents the MTP1 physical layer.
Figure 3-5: Signalling plane between SGSN – HLR or SGSN – EIR
EMN/K/A Geert Heijenk (5430)2000-12-21B
3.4.3 Signalling plane SGSN – MSC/VLR
Figure 3-6 shows the protocol stack used to support the signalling exchange between SGSN and
MSC/VLR. This signalling exchange is applied for the situation that the GPRS system is able to co-operate with a GSM circuit switched network. Compared to the protocol stack described in Section
3.4.2, this protocol uses in place of the MAP protocol layer, the Base Station System Application Part + (BSSAP+). This protocol layer specified in [GSM 03.60] and [3GPP23.060] is an enhanced version of the BSSAP layer specified in [GSM 09.18] and it mainly supports mobility management signalling between the SGSN and MSC/VLR when the co-ordination between GPRS and conventional GSM functions is necessary.
Figure 3-6: Signalling plane between SGSN and MSC/VLR
3.4.4 Signalling plane GSN – GSN
The protocol layers used for signalling exchange between either two GGSN’s or between two SGSN’s or between one SGSN and one GGSN are depicted in Figure 3-7. The GPRS Tunnelling Protocol (GTP) supports multiprotocol signalling (and user data) to be tunnelled through the GPRS network between GSN’s. A GTP tunnel is required to transfer packets from an external network to the MS. This tunnel is characterised by two PDP contexts located in different GSN’s and is identified by a Tunnel ID. The User Datagram Protocol (UDP) described in [RFC 768] and the Internet protocol (IP) are specified by the Internet Engineering Task Force (IETF).
Figure 3-7: Signalling plane between GSN’s
3.4.5 Signalling plane GGSN – HLR
The signalling plane between the GGSN and HLR can be realised in two different manners. The first manner is shown in Figure 3-8, where it is assumed that the SS7 layers described in 3.4.2, are supported by the GGSN. The second manner of realising the signalling plane between the GGSN and HLR is depicted in Figure 3-9, where the originating GGSN does not support the SS7 protocols. The signalling exchange between the originating GGSN and the HLR is accomplished via an intermediate GSN physical node, i.e., SGSN or GGSN. This intermediate node is able to support two protocol stacks, i.e., the one that is supported by the originating GGSN and another one that is SS7 specific.
EMN/K/A Geert Heijenk (5430)2000-12-21B
Figure 3-8: Signaling Plane between GGSN and HLR (SS7 available at the GGSN)
Figure 3-9: Signaling Plane between GGSN and HLR (SS7 is not available at the originating
GGSN)
3.5 GPRS air logical channels
The logical channels (see [GSM 04.60], [GSM 03.60] and [3GPP23.060]) used in the GPRS (Releases 1998 and 1999) air interface are briefly described in Table 3-3. These are the following:
?The Packet Common Control Channel (PCCCH) type comprises channels for common control signalling. These are:
?Packet Random Access Channel (PRACH): used by a MS to initiate an uplink transfer for user data or signalling;
?Packet Paging Channel (PPCH): the network pages a MS to downlink packet transfer. This can be used for both circuit switched and packet data services;
?Packet Access Grant Channel (PAGCH): is used only on downlink direction during the packet transfer establishment phase by the network to send resource assignment to an MS before
packet transfer;
?Packet Notification Channel (PNCH): is used only in the downlink direction and is used by the network prior a PTM-M transfer, to send to a group of MS users a PTM-M notification.?Another type of packet data channel is the Packet Broadcast Control Channel (PBCCH) that is used only in the downlink direction by the network to send data specific System Information.
?The Packet Data Traffic Channel (PDTCH) is allocated for uplink or downlink data transfer.
?The Packet Dedicated Control Channels type consists of the following channels:?Packet Associated Control Channel (PACCH) that conveys information, e.g., acknowledgements and Power Control information, related to a given MS.
?Packet Timing advance Control Channel, uplink (PTCCH/U) is used uplink to transmit random access bursts to allow estimation of the timing advantage for one MS in packet transfer mode.
?Packet Timing advance Control Channel, downlink (PTCCH/D) is used by the network to send timing advantage information updates to several MS’s.
第三方登陆授权与实现
背景 虽然在界面上，第三方账号注册往往被称为“第三方账号登录”，但其实用户第一次使用第三方账号登录也是在创建一个新的账号。因此，我将第三方账号注册也算成是一种注册类型。 第三方账号注册的好处是显而易见的：极致的简单和方便。但不利之处也非常明显：企业无法与用户之间产生任何连接，这对部分公司来说是完全无法接受的。 对于第三方账号注册，几条优化建议是： 1.第三方注册一般是和其他注册方式共存的。因此在设计上要注意分清 主次。一般来说，第三方注册都是出于次要的位置。但也有部分APP将 其作为主要注册方式，看需要。 2.第三方注册成功后，不再要求用别的方式注册，否则就是一个骗子， 用户会很不爽。还不如不用第三方呢。 3.第三方注册成功后，如果还需要完善别的信息，则在需要这些信息时 再要求用户填写，否则一个简单方便的注册就没有意义了。 授权登录实现 一．简要概述 1.先取第三方取access_token 和openid(uid)，openid是唯一的，表明 用户身份的 2.将openid和token传给服务器，服务器拿openid进行注册，并生成 openid对应的密码 3.当注册成功后服务器返回sessionid和对应密码
4.将openid和对应密码加密后存在本地，本地需要记录的是:openid、 对应密码、上一次登录时的登录方式.(qq登录、微信登录，微博登录，或者用户自己输入账号密码登录) 5.客户端每次启动都登录，如果发现上一次登录方式是第三方登录，且 此时本地存的openid有对应密码就将openid和对应密码传服务器进行登录。这样好处是客户端只走一次授权，将openid在自己公司服务器注册后以后就再也不走了(不再走指的是你项目不关闭，如果tokenid超时，此时不用和第三方再对接，而是直接拿本地的openid和对应密码进行登录，不会在项目使用过程中，跳到授权页)，当然取消授权，然后重新登录时要重新授权，此时还是会重新跳到授权页的，另外tokenid在有效时间内不会随着不同设备登录而改变，只有超时时才会重新产生新的 tokenid，且过期时间根据最后一次登录重新计算。 二．服务端实现 1.数据库创建tb_user、tb_user_phone、tb_user_qq和tb_user_wx 表；tb_user表就不详说了，这是基本表；tb_user_phone也不说了；重点说一下tb_user_qq和tb_user_wx表；这两个表各自储存对应的授权返回信息（请参考第三方授权返回） 2.根据客户端的登录类型（type=1：手机type=2：QQ type=3：微 信）取出对应的openid查询对应的表（如type=2，查询tb_user_qq是否有对应的信息），如果有，直接返回tb_user表的对应信息，如果没有，通知客户端未查询到对应的用户信息。 3.根据客户端的注册类型（type=1：手机type=2：QQ type=3：微 信）取出对应的授权信息存入对应的表（如type=2，直接存入 tb_user_qq），并判断是否需要绑定手机号码，如果需要，则判断手机号码是否是已注册用户，如果是，直接把第三方账户绑定的手机号码对应的账户下，如果不存在，直接在tb_user表创建新用户，并绑定手机号码（不需要绑定手机号的情况就不多说了）。成功后返回用户信息。 4.服务端应定时刷新用户的授权信息（已知微信的token是30天， 具体的请参考第三方平台授权文档）。 三．客户端实现
openssh6.8升级方案V2.0
openssh6.8升级参考指南(仅供参考，请自行测试) 务必开启telnet防止登不上 系统信息如下： 系统版本：Red Hat Enterprise Linux Server release 6.5 (Santiago) 64位 openssl和openssh版本OpenSSH_5.3p1, OpenSSL 1.0.0-fips 29 Mar 2010 1.升级所需要的安装包 不同的环境需要不同的安装包，此次安装需要安装包如下 GCC环境所需的安装包： ppl-0.10.2-11.el6.x86_64.rpm cloog-ppl-0.15.7-1.2.el6.x86_64.rpm mpfr-2.4.1-6.el6.x86_64.rpm cpp-4.4.7-4.el6.x86_64.rpm gcc-4.4.7-4.el6.x86_64.rpm 编译安装openssl和openssh所需的安装包 zlib-devel-1.2.3-29.el6.x86_64.rpm pam-devel-1.1.1-17.el6.x86_64.rpm OpenSSH 升级所需安装包： openssl-1.0.0s.tar.gz openssh-6.8p1.tar.gz 2.升级相关步骤
2.1安装GCC环境所需的安装包和相关软件包 [root@localhost opt]# rpm -ivh ppl-0.10.2-11.el6.x86_64.rpm [root@localhost opt]# rpm -ivh cloog-ppl-0.15.7-1.2.el6.x86_64.rpm [root@localhost opt]# rpm -ivh mpfr-2.4.1-6.el6.x86_64.rpm [root@localhost opt]# rpm -ivh cpp-4.4.7-4.el6.x86_64.rpm [root@localhost opt]# rpm -ivh gcc-4.4.7-4.el6.x86_64.rpm [root@localhost opt]# rpm -ivh zlib-devel-1.2.3-29.el6.x86_64.rpm [root@localhost opt]# rpm -ivh pam-devel-1.1.1-17.el6.x86_64.rpm 2.2卸载系统自带的openssh，同时清除系统/etc/ssh目录 备份openssh的配置文件 [root@localhost opt]#cp -r /etc/ssh /etc/ssh_bak [root@localhost opt]# cp/etc/init.d/sshd /etc/init.d/sshd_bak [root@localhost opt]#cp/usr/sbin/sshd /usr/sbin/sshd_bak
等离子处理技术在汽车工业中的应用
Openair等离子处理技术在汽车工业中的应用 作者：德国Plasmatreat公司来源：AI汽车制造业 在众多的预处理方法中，常压等离子工艺在汽车工业中显示出了日益重要的作用。它不仅能够为塑料零部件提供极其洁净的表面，而且还可以提高表面的粘附能力，在应用多样性方面几乎不存在任何限制。和传统的处理方法相比，其经济性更好，并且对环境绝对没有任何负作用。 对于大多数塑料件的加工而言，为了确保塑料粘合面的粘合品质及其承载性能的长期稳定性，需要对材料表面进行正确的预处理，这已成为塑料件加工过程中的关键一步。正因如此，一种被称为“Openair常压等离子处理技术”的预处理工艺获得了越来越多的应用。 Openair常压等离子工艺使预处理工作更加简便、可靠，并且由于无需溶剂而更为环保。因此在汽车工业里，目前约有30多个不同的制程已经采用了该工艺：从汽车挡风玻璃粘合前预处理到汽车引擎控制器盒的封装，从冷藏卡车冷藏货柜的结构粘合到汽车车身部件的粘合等，Openair常压等离子工艺均显示出了其独有的技术优势。 图1 等离子体产生的原理，通过放电给气体施加更多的能量， 使物质从气态转变为等离子态 Openair常压等离子工艺基本原理 等离子体是指物质处于高能、非稳定的一种状态。通常，通过能量（比如加热）输入的方式，可以使物质从固态变为液态再到气态。等离子体就是在这一过程中再进一步，即通过放电将更多的能量注入物质中，电子获得更多动能后脱离其在原子中既有的轨道，从而产生自由电子、离子以及分子碎片，如图1所示。然而，由于这种物质状态不稳定，因此基本上不能在常 压下应用。
图 2 根据喷嘴的几何形状，在最宽50 mm 的处理范围内或者40 mm 的处理距离内都可获得有效的等离子体（图片来源于Plasmatreat 公司） 迄今为止，只有获得专利的Openair常压等离子工艺开创了这一新工艺应用的可能性：通过采用等离子喷枪，使在常压下产生的稳定的等离子体能够成功地应用于工业生产过程中，甚至还可以实现“在线处理”。一般，导入到等离子喷枪中籍以产生等离子的仅仅是空气和高电压，当然如果工艺需要也可以采用其它工艺气体。根据喷嘴的几何形状，可以在最大50 mm 宽度范围内或者40 mm 的距离范围内获得有效的等离子体，如图2 所示。通常，所形成的等离子体束还有一个独特的性质，即电中性，这极大地扩展了它的应用领域，并大大提升了操作便利性。发射出的等离子体温度取决于电源和等离子体源的配置，可以在300℃～1500℃之间变化，从而可以兼顾最佳处理效果和最高的处理效率。利用这种处理方式，在处理塑料表面时，典型的温度变化范围小于20 ℃。 冷藏车货柜的结构粘合 早在20世纪90年代，随着新一代车型的开发，Schmitz Cargobull公司就已将电中性常压等离子体的应用扩展到了一个新的领域。该公司计划将结构粘合作为冷却货柜装配的唯一方法，如图3所示。
SpringSecurity_openId完整配置攻略
Spring Security2.04+OpenID 配置攻略 目录 1.QQ互联中的O PEN ID (3) ２.配置环境 (3) ３、S PRING S ECURITY的XML配置 (3) ４、ＯＰＥＮＩＤ登录页 (17) ５、申请O PEN ID账号 (17)
６、在本地登录O PEN ID (18) ７、其他注意事项 (19)
1.QQ互联中的OpenID QQ互联接口中，在QQ登陆成功后，会返回一个ＯｐｅｎＩＤ，但是此OpenID是一个大写字母和数字的组合。与一般的OpenID的格式不同，正常的ＯｐｅｎＩＤ应该是http 开头的URL格式，例如https://www.wendangku.net/doc/1c6962920.html,/,本文介绍的是国际通用的OpenID认证协议＋Spring Security配置过程。 ２.配置环境 本文的介绍的配置过程是在OpenJWeb2.63环境下配置的，OpenJWeb2.63集成了S2SH 和Spring Security2.0.4，大家也可以自己搭建一个S2SH+Spring Security2.04的环境，在环境搭建好以后，我们需要从网上找到openid4java-0.9.8.jar，放到WEB-INF\lib目录下。有了这个驱动，我们就可以在spring security中进行openID的认证登陆。 另外，我们需要将spring-security-openid-2.0.4.jar放到lib目录中。 在web.xml文件中，我们需要增加一段配置以支持openID认证过滤器：
OpenReports中文支持完全解决方案(新)
目录 一、主要解决的问题 (2) 1 页面显示支持中文 (2) 2 与服务器或数据库的交互支持中文 (2) 3 查询结果支持中文 (2) 4 导出文件名及内容支持中文 (2) 二、解决方案及方法 (2) 1 增加的类 (2) 1.1 cn.ExportDelegate (2) 1.2 cn.ResponseOverrideFilter (3) 1.3 cn.SetCharacterEncodingFilter (3) 1.4 org.displaytag.export.PdfView (4) 2 在web.xml中配置两个Filter，字符编码过滤器字符集设置为GBK (6) 3 增加PDF中文支持的JAR包 (6) 4 struts.properties配置文件字符编码改为GBK (7) 5 国际化配置文件 (7) 6修改displaytag.properties配置文件 (8) 7JSP页面文件字符集全部改为GBK (10)
OpenReports中文支持完全解决方案 一、主要解决的问题 1 页面显示支持中文 2 与服务器或数据库的交互支持中文 3 查询结果支持中文 4 导出文件名及内容支持中文 二、解决方案及方法 1 增加的类 1.1 cn.ExportDelegate 直接来自原文件org.displaytag.filter.ExportDelegate，只是将文件名转码， 解决中文表格数据和导出中文文件名时，会产生乱码现象。被cn.ResponseOverrideFilter调用。
1.2 cn.ResponseOverrideFilter 直接来自原文件org.displaytag.filter.ResponseOverrideFilter，原有ResponseOverrideFilter路径指向新建Filter的路径，必须。 1.3 cn.SetCharacterEncodingFilter 是一个标准的自定义字符集转换Filter，必须。
《高职高专教育英语课程教学基本要求》
《高职高专教育英语课程教学基本要求》所列常用短语 A be able to do sth. 能，会along with 和…一起，除了…之外 be about to do sth. 刚要，即将not only…but also 不但而且 above all 首先，尤其是amount to 总计，等于 have access to 有…的机会，有…权利be angry with 生（某人的）气 by accident 偶然one after another 一个接一个地，接连地according to 根据。按照one another 相互 on account of 因为，由于be anxious about 为…而忧虑 take into account 把…考虑进去any but 除….之外人和事（物），绝非accuse of 指控，控告apart from 除…之外 be accustomed to 习惯于appeal to 吸引，呼吁，上诉 adapt to 适应apply to 应用 add to / add… to 为…增添，增加apply for申请 add up to 合计达as…as 象…一样 in addition 另外，加之as for / to 至于，关于 in addition to 除…之外，（还））as if / as though 好像，仿佛 adjust to / adjust …to 适应于as soon as …possible 尽快 in advance 预先，提前as / so long as 只要，如果 gain / have an advantage over 胜过，优于as well 也，又 take advantage of 利用，趁….之机as well as 也，既…又 be afraid of 害怕aside from …暂且不谈，除…之外 again and again 反复地，再三地ask for 要，要求 once again 再一次assign sth. to sb. 分配，布置 aim at 瞄准associate with / associate … with 联系，交往 in the open air 在户外，在野外attend to 专心于，致力于 on the air (用无线电、电视)播送pay attention to 注意 above all 首先，尤其是on (the / an) average 平均，通常 after all 毕竟，终究be aware of 察觉到，了解 all in all 大体而言right away 立刻，马上 all but 几乎，差不多，除了…都 all over 到处，遍及 all right 良好的，对的/ （口语）行，可以 at all （用于否定句）丝毫（不），一点（不） in all 总共，合计 B back and forth 来回地，反复地bear on / upon 压迫，依靠；与…有关 back up 倒退，支持，备份because of…因为，由于 be bad for 对…有害的before long 不久以后 go bad 变坏，坏掉on behalf of 代表，为了 keep one’s balance 保持平衡begin with 从…开始，以…为起点 be based on / upon 把…建立在…基础上believe in 相信，信任 on the basis of 根据belong to 属于 bear…in mind 记住benefit from 有益于，得益 at best 充其量，至多build up 逐步建立，增长，集聚，增强…的体力
CANopen综合开发方案
CANopen协议综合开发方案 （V3.1） 中国单片机公共实验室 2006年7月
关于CANopen CANopen协议集定义了基于CAN的分布式工业自动化系统的应用标准以及CAN应用层通信标准。CANopen是CAN-in-Automation(CiA)定义的标准之一，并且在发布后不久就获得了广泛的承认。尤其是在欧洲，CANopen被认为是在基于CAN的工业系统中占领导地位的标准。CANopen协议集基于所谓的“通信子集”，该子集规定了基本的通信机制及其特性。 大多数重要的设备类型，例如数字和模拟的输入输出模块，驱动设备，操作设备，控制器，可编程控制器或编码器，都在称为“设备子集”的协议中进行描述。设备子集定义了不同类型的标准设备及其相应的功能。依靠CANopen协议集的支持，可以对不同厂商的设备通过总线进行配置和系统重构。 CANopen标准最核心的部分是通过对象字典（Object Dictionary）对设备功能进行描述。对象字典分为两部分，第一部分包括基本的设备信息，例如设备ID，制造商，通信参数等等。第二部分描述了特殊的设备功能。 一个16位的索引和一个8位的子索引唯一确定了对象字典的入口。通过对象字典的入口可以对设备的“应用对象”进行基本网络访问，设备的“应用对象”可以是输入输出信号，设备参数，设备功能和网络变量等等。 CANopen设备的功能及特性以电子数据单（EDS）的形式描述，EDS采用ASCII格式，可以将EDS理解成某种形式的表格。实际的设备设置通过所谓的设备配置文件（DCF）进行描述。 EDS和DCF都可以从Internet上下载，并可以存储在设备之中。
微信公众平台入门到精通Vol精编版
微信公众平台入门到精 通V o l GE GROUP system office room 【GEIHUA16H-GEIHUA GEIHUA8Q8-
紧接着14期的内容，在基本规划做好以后咱们先把数据库建好。昨天有人建议我按照QQ 企业邮箱的来做，这个可能太复杂了，怕大家更加迷茫，我做案例更多是希望朋友们通过案例举一反三，从简单的产品推导出复杂的应用。 第十四章公司通讯录开发 二、公司通讯录数据库建立 第13期里有SAE数据库的介绍，如果没有开通的请先移步把SAE的数据库服务开启，点击“管理MySQL”进入到数据库的图形管理界面，如下图： 数据库里目前没有任何数据表，所以我们先来建立第一张数据表“员工表”，取名为“roster”，员工表我调整了下结构增加了几项，最后的项目为：序号、姓名、工号、照片、性别、生日、手机、电话、部门、邮箱、微信号、微信OPENID、员工状态、入职日期、添加时间、更新时间、记录状态。 在建表之前其实还要设定每个字段项的属性，我这里简单写一下，后面在解释建表的时候大家可以参照看： 字段名类型长度其他 序号数字 5 自增、主键 姓名字符 10 工号字符 10
照片字符 50 性别数字 1 0为女，1为男 生日日期 手机字符 15 电话字符 15 部门数字 4 邮箱字符 50 微信字符 30 openid 字符 50 员工状态数字 1 1为在岗，-1为离职 2为休假 入职日期 添加时间 更新时间 记录状态数字 1 1为正常0为删除
字段数根据上面的规划应该是15个字段，所以应该填写15，但我这里填写3是为了后面切图片和讲解的方便，大家如果填写15看到的样式会不同，没有关系，另外建立过程中还可以增加字段数的。 点击执行按钮，就切换到表设计界面，如下图： 在上图中每一列就是一个字段，如果大家前面填写字段数超过5的则视图中每一行就是一个字段，但不管如何显示，每个字段都有下面这些属性： 1.字段名称，用来描述字段的名称，它可以用中文、英文字母、数字等字符来描述。 但是建议不用中文或者纯数字，命名最好使用表名+下划线+该字段的英文名或者拼音缩写。 2.字段类型，用来限定数据格式，同一字段的数据类型都是一样的。点击类型的选项 菜单会出来一大堆，不用怕很多我们是不太会用的，常用到的类型如下： TINYINT：一个很小的整数。有符号的范围是-128到127，无符号的范围是0到 255。 SMALLINT：一个小整数。有符号的范围是-32768到32767，无符号的范围是0到 65535。 MEDIUMINT：一个中等大小整数。有符号的范围是-8388608到8388607，无符号的范围是0到16777215。
微信公众号(获取用户基本信息)
1. 用户关注以及回复消息的时候，均可以获得用户的OpenID
Openstack云平台实施方案
云平台实施方案
文档属性 文件修订记录
目录 一、概述 (4) 1.1 方案编写目的 (4) 1.2 方案适用人员 (4) 1.3 方案内容与范围 (5) 二、项目总架构图 (5) 2.1 物理拓扑设计图............................................................................................. 错误！未定义书签。 2.2 软件架构图 (10) 三、网络规划 (11) 3.1网络VLAN规划 (11) 3.2网络IP规划 (11) 四、OpenStack组件HA及分布 (13) 4.1控制节点服务HA (13) 4.2所有节点服务列表 (15) 五、分布式存储设计 (17) 六、服务器需求 (22) 6.1云平台服务器磁盘RAID配置 (22) 6.2云平台服务器BIOS配置 (23) 七、服务器网卡接线示意图 (24) 八、云平台实施步骤 (25)
一、概述 1.1 方案编写目的 撰写此文的主要目的是为了指导“云平台项目” 的顺利实施，根据客户的现状和发展需求，确定云平台的实施方案。 在实际实施工作中，将网络和服务器的需求任务明确。 1.2 方案适用人员 本文档主要面向负责“云平台项目”的设计和实施的网络设 计人员、管理人员、管理人员以及实施小组成员，以便通过参考 本文档资料顺利完成项目沟通和实施。
1.3 方案内容与范围 本方案主要就以下几点进行了分析和阐述： 项目总架构 网络规划明细 OpenStack 组件分布HA 服务器配置需求 分布式存储 Ceph 需求 服务器接线示意 云平台项目实施步骤 二、项目总架构图 云平台部署简述：
微信消息接口指南
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网址接入 公众平台用户提交信息后，微信服务器将发送GET请求到填写的URL上，并且带上四个参数： 开发者通过检验signature对请求进行校验（下面有校验方式）。若确认此次GET请求来自微信服务器，请原样返回echostr参数内容，则接入生效，否则接入失败。
signature结合了开发者填写的token参数和请求中的timestamp参数、nonce 参数。 加密/校验流程： 1. 将token、timestamp、nonce三个参数进行字典序排序 2. 将三个参数字符串拼接成一个字符串进行sha1加密 3. 开发者获得加密后的字符串可与signature对比，标识该请求来源于微信消息推送 当普通微信用户向公众账号发消息时，微信服务器将POST该消息到填写的URL 上。结构如下： 文本消息
高中英语会考说明词语翻译
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后盾PHP微信网页授权接口技术文档
为什么要学习网页授权接口 如果用户在微信接口通过微信客户端中访问第三方网页，就可以通过网页授权接口来获取用户数据，就是在获取到用户的唯一openid后实现登陆状态 几乎所有的微信站点业务逻辑都需要用户信息来实现登陆,这样可以免去繁琐的再注册环节，那么微信网页授权就是我们在实现微信开发的第一道门槛，另外在微信支付等接口中也会运用到网页授权接口的部分功能 微信网页授权是基于oauth2.0协议实现的 实现网页接口首先需要配置授权回调地址 如果没有授权回调地址，无法请求回调地址 测试号可以使用ip,域名地址回调,服务号只能使用域名回调 如图: 第一步：用户同意授权，获取code 若提示“该链接无法访问”，请检查参数是否填写错误，是否拥有scope参数对应的授权作用域权限。 请求接口后回调到redirect_uri连接地址 https://https://www.wendangku.net/doc/1c6962920.html,/connect/oauth2/authorize?appid=APPID&red irect_uri=REDIRECT_URI&response_type=code&scope=SCOPE&state=STATE# wechat_redirect 若提示“该链接无法访问”，请检查参数是否填写错误，是否拥有scope 参数对应的授权作用域权限。
注意: scope 是应用授权作用域，snsapi_base （不弹出授权页面，直接跳转，只能获取用户openid），snsapi_userinfo （弹出授权页面，可通过openid拿到昵称、性别、所在地。并且，即使在未关注的情况下，只要用户授权，也能获取其信息） snsapi_base授权: 是用来获取进入页面的用户的openid的，是静默授权后进入redirect_uri回调页需要用户关注过 静默获取用户无感知不会弹出授权页面获取用户的openid snsapi_userinfo网页授权: 获取用户的基本信息的。 但这种授权会弹出授权框需要用户手动同意， 并且由于用户同意过，所以无须关注，就可在授权后获取该用户的基本信息。 需要用户手动同意，才能获取对应的用户数据 认证服务号可以获取未关注用户数据 对于已关注公众号的用户，如果用户从公众号的会话或者自定义菜单进入本公众号的网页授权页，即使是scope为snsapi_userinfo，也是静默授权，用户无感知。 code作为换取access_token的票据，每次用户授权带上的code将不一样，code只能使用一次，5分钟未被使用自动过期 在php中直接使用$_GET['code']就能获取 授权后重定向的回调: 先请求微信获取用户数据接口，访问后跳转到redirect_url回调地址中注意:REDIRECT_URL回调跳转路径需要urlencode转译后的url跳转地址
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