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1、 CEA Standard Symbol-Encoding Sublayer ANSI/CEA-600.37 November 1997 Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:18 MDTNo reproduction or networking permitted without license f
2、rom IHS -,-,- NOTICE CEA Standards, Bulletins and other technical publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting a
3、nd obtaining with minimum delay the proper product for his particular need. Existence of such Standards, Bulletins and other technical publications shall not in any respect preclude any member or nonmember of CEA from manufacturing or selling products not conforming to such Standards, Bulletins or o
4、ther technical publications, nor shall the existence of such Standards, Bulletins and other technical publications preclude their voluntary use by those other than CEA members, whether the standard is to be used either domestically or internationally. Standards, Bulletins and other technical publica
5、tions are adopted by CEA in accordance with the American National Standards Institute (ANSI) patent policy. By such action, CEA does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the Standard, Bulletin or other technical publication. Thi
6、s CEA Standard is considered to have International Standardization implication, but the International Electrotechnical Commission activity has not progressed to the point where a valid comparison between the CEA Standard and the IEC document can be made. This Standard does not purport to address all
7、 safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations before its use. (From Project Number 3482, formu
8、lated under the cognizance of the CEA R7 Home Networks Committee.) Published by CONSUMER ELECTRONICS ASSOCIATION 2002 Technology CEBus has physical channels available on its media which can be allocated through resource management to various applications. This document specifies the following: 1. Th
9、e Physical Layer of Control Channel 2. The physical medium and device interface to the medium 3. Restrictions on the Physical Layer outside the frequency band of the control channel. Figure 1.1 below shows the scope of this specification in reference to the entire CEBus model. Here, only those aspec
10、ts of the model relevant to RF are specified. Anything outside of the boundary is either specific to another medium distinct from RF, or is generic in nature and applies across all CEBus media. Similar specifications exist for the other CEBus media. Copyright Consumer Electronics Association Provide
11、d by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:18 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-600.35 RF Physical Layer and Medium Specification Figure 1.1 Relation of RF to CEBus Model 2. General
12、 Description This Section provides a general description of RF physical layer and medium requirements. In order to simplify the specification, the physical and medium layers are logically divided into different physical parts described in the following subsections. This Section also overviews the fr
13、equency allocation of the medium and the role of the control and data channels. 2.1 Description of User Service Levels This specification defines a set of “Service Levels“ for RF devices. Service levels allow devices that provide reduced CEBus functionality by transmitting only. Service levels on th
14、e RF (and IR) mediam allow devices to be built to a level of service commensurate with economic and functional requirements of the application. 2.1.1 Control Channel Service There will be two levels of control channel service: unidirectional (one-way), and bidirectional (two-way). 2.1.1.1 Unidirecti
15、onal Control Channel Service This service is represented by a transmit-only device without listening capability. Transmission speed is 10K one bits per second. Unidirectional devices begin transmission without regard to occupancy of the medium and have no ability to detect transmission collisions an
16、d in no way conform to CSMA/CD protocol. User feedback or verification of control operation is only present in the fo rm of the visible and/or audible response of equipment responding to user commands. Access to other CEBus devices may only be realized through active two-way “gateways“ . 3 Copyright
17、 Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:18 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-600.35 RF Physical Layer and Medium Specification 4 2.1.1.2
18、Bidirectional Control Channel Service This level of service conforms to the CSMA/CD protocol used on other CEBus media and assumes complete two-way communication capability for message acknowledgement, enquiry and reply. Transmission speed is 10K one bits per second. Bidirectional control channel de
19、vices have the ability to receive unidirectional messages and detect a collision with a unidirectional transmitter during the preamble of the unidirectional transmission and cease operation prior to the end of the preamble to avoid damage to the packet. 2.1.2 Data Channel Services It is anticipated
20、that additional levels of data channel service will be defined for RF medium. These levels are currently under study. 2.2 Functional Partitioning of RF Specification This specification divides the RF environment into three basic parts: the network topology, the physical medium, and the device physic
21、al access specification. Figure 2.1 illustrates the partitioning of the specification as it relates to each part of the RF environment: Figure 2.1 RF Specification Partitioning The Topology specification deals with the anticipated configurations of RF Devices likely to be found in the majority of in
22、stallations. The Device specification deals with the physical properties of that part of the device which makes contact with the medium. Also described is the interface between the physical layer and the symbol encoding sublayer. The Medium specification concerns the capabilities and properties of t
23、he physical medium. This encompasses such items as its bandwidth, frequency allocation, physical properties, etc. Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:18 MDTNo reproduct
24、ion or networking permitted without license from IHS -,-,- CEA-600.35 RF Physical Layer and Medium Specification 2.3 Frequency Allocation The current RF specification only allows for a control channel frequency allocation. It is anticipated that in future releases of this document, a data channel ca
25、pability will be developed for RF occupying additional frequency ranges. 2.3.1 Control Channel A control channel frequency space is reserved on each media for the exchange of control information and user data concerning the state of the CEBus system and its applications. The control channel does not
26、 have to allocate its frequency space on the medium since this space is permanently reserved as part of this specification. Use of the control channel must be in conformance with the established CEBus protocol on all implemented layers. This channel may not be used in any other fashion. Only those p
27、ortions of the control channel that are specific to RF are discussed in this document. 2.3.2 Data Channel The specifications for a data channel(s) on RF are under study. 3. RF Network Topology The following section deals with the physical topology of the RF network. Described are the anticipated con
28、figurations of RF devices, interaction, and minimum and maximum configurations. 3.1 RF Network Description and Components Figure 3.1 is a schematic representation of a general RF “network“. Figure 3.1 RF Network Topology 5 Copyright Consumer Electronics Association Provided by IHS under license with
29、 CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:18 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-600.35 RF Physical Layer and Medium Specification 6 A Network may consist of any number of unidirectional and bidirectional devi
30、ces operating on the same medium. Figure 3.1 is intentionally drawn to physically represent a typical RF network to make clear several unique topological conditions found in these networks. First, any RF device in any home may communicate (and interfere) with any RF device in any other home within t
31、he range of the RF signal. Second, sources of network noise and interference are not isolated to a single home on the network. A device “attaches“ to the medium through an RF wavelength transmitting element and an RF wavelength detecting sensor element capable of operating at the response times and
32、levels specified in this document (Section 5). 3.2. Allowed Topologies Since RF devices place no load on the medium, there are no restriction on the number of RF devices that the medium (in a home) can support. 4. RF Medium Specifications This Section specifies properties to which RF medium must con
33、form in order to support information transfer within the CEBus RF environment and the frequency resource usage of the medium. 4.1 Frequency Allocation CEBus divides frequency resources into two basic types: Open frequency resources and Reserved frequency resources. Open resources are frequency parti
34、tions of the medium that any CEBus device may request access to and constitute the majority of data channel resources. Open resources are further divided into defined service and undefined service. There are currently no open data channel resources on the RF medium. Reserved frequency resources are
35、intended for a specific CEBus functions. On the RF medium, the control channel is the only reserved resources. 4.1.1 Control Channel The control channel occupies bandwidth at a frequency of 915 MHz in the form of a Binary phase shift modulated spread spectrum carrier. This channel is used to exchang
36、e information in CEBus protocol. No other CEBus use of this channel is permitted. The rules established in the CEBus Media Access Control (MAC) Layer, and the Logical Link Control (LLC) Layer, must be followed for bidirectional Control Channel usage. The signaling characteristics of the Control Chan
37、nel are described elsewhere in this document. 4.1.2 Data channel(s) The data channel levels of service are currently under study. 4.2 Environmental Requirements This Section specifies the environment in which the RF network is assumed to function. Certain regulatory requirements are outside the scop
38、e of this standard; in these cases, Copyright Consumer Electronics Association Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:18 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-600.35 RF Physi
39、cal Layer and Medium Specification requirements or guidelines set by other regulatory bodies should be observed. 4.2.1 Temperature and Humidity The RF network is expected to operate within electrical specifications over a temperature and humidity range appropriate to the application. It is the respo
40、nsibility of the manufacturers of CEBus compatible equipment to design to an adequate temperature and humidity operating range that will insure reliable operation in the intended areas of use in the home. The manufacturer should inform the user of the range selected for the product. 4.2.2. Radiated
41、RFI/EMI CEBus RF equipment shall meet the applicable requirements of FCC Part 15 rules for intentional radiators. 5. RF Device Specifications This Section covers the Physical Layer specifications of the RF device including: the Physical Layer interface to the Symbol Encoding Sublayer, the Physical L
42、ayer interface to the Application Layer, the physical signaling characteristics used on the RF medium, the specification of the transmitter needed to generate the necessary RF CEBus signals, the specification of the receiver needed for proper reception of RF CEBus signals. 5.1 Signal Characteristics
43、 This Section describes the encoding, data rate, and symbol definition for CEBus signal trans- mission on the RF network for both the control channel and data channel. 5.1.1 Control Channel Two control channel levels of service will be allowed: a unidirectional control channel that initiates transmi
44、ssions without regard to occupancy of the medium and has no ability to detect transmission collisions and in no way conforms to CSMA/CD protocol; and a bidirectional control channel that can detect collisions and execute the full CEBus protocol. 5.1.1.1 State Encoding The RF control channel will use
45、 pulse width encoding to represent the symbols “1“, “0“, “EOF“, “PEOF”, “EOP“. These symbols are generated using a binary phase shift keyed spread spectrum carrier transmitted on the medium. The characteristics of the carrier are defined in Section 5.3.1. 7 Copyright Consumer Electronics Association
46、 Provided by IHS under license with CEA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 20:58:18 MDTNo reproduction or networking permitted without license from IHS -,-,- CEA-600.35 RF Physical Layer and Medium Specification 8 The encoding of the symbols will be perfo
47、rmed using the SUPERIOR and INFERIOR states on the RF medium. During the preamble portion of the CEBus message, the presence of the spread spectrum carrier will represent the SUPERIOR state, and the absence of the carrier will represent the INFERIOR state. During the non-preamble portion of the mess
48、age, the spread spectrum carrier is continually transmitted and different symbols are encoded by the use of two different “SUPERIOR“ states. In this document, the different encoded “versions“ of the SUPERIOR state will be denoted by SUPERIOR1 and SUPERIOR2. Also, SUPERIOR1 will be used exclusively as the superior state during the message preamble. Each of the two superior states is represented by a unique carrier spreading sequence. One complete spreading sequence represents the shortest symbol time (“1“, or one unit symbol timeUST). During lo