1、 Rec. ITU-R M.1651 1 RECOMMENDATION ITU-R M.1651*A method for assessing the required spectrum for broadband nomadic wireless access systems including radio local area networks1using the 5 GHz band (Questions ITU-R 212/8 and ITU-R 142/9) (2003) Summary This Recommendation provides a method for assess
2、ing the required spectrum for broadband nomadic wireless access (NWA) systems including radio local area networks (RLANs). Annex 1 gives a general description of RLANs, the deployment scenarios, an overview of the method for estimating the required spectrum as well as an example calculation in the 5
3、 GHz band. The ITU Radiocommunication Assembly, considering a) that there is a need to estimate the actual spectrum requirement for broadband nomadic wireless access (NWA) systems, including radio local area networks (RLANs), used in various environments; b) that Recommendation ITU-R M.1390, which i
4、s used to calculate the spectrum requirement for the IMT-2000 terrestrial component, would be a suitable basis for the development of a new method as stated in considering a), recommends 1 that the method described in Annex 1 should be used as guidance to estimate the spectrum requirement for broadb
5、and NWA systems, including RLANs, using the 5 GHz band. NOTE 1 Abbreviations used in this Recommendation are given in Table 1. NOTE 2 Reference ITU Recommendations are given in Table 2. *This Recommendation was jointly developed by Radiocommunication Study Groups 8 and 9, and future revisions should
6、 be undertaken jointly. 1In this Recommendation radio local area network (RLAN) is as described in Recommendation ITU-R M.1450. NOTE The United States of America does not agree with this Recommendation and therefore reserves its position on it. 2 Rec. ITU-R M.1651 TABLE 1 Abbreviations used in this
7、Recommendation TABLE 2 Reference ITU Recommendations AP Access point BPSK Binary phase shift keying DLC Data link control HDTV High definition television HiMM High speed interactive multimedia HMM High speed multimedia IP Internet protocol LAN Local area network MAC Medium access control MiMM Medium
8、 speed interactive multimedia MMM Medium speed multimedia MT Mobile terminal NWA Nomadic wireless access PDA Personal digital assistant PER Packet error rate PHY Physical (layer) RLAN Radio local area network QAM Quadrature amplitude modulation QoS Quality of service QPSK Quaternary phase shift keyi
9、ng SDTV Standard definition television VCR Video cassette recorder WAS Wireless access systems VHiMM Very high speed interactive multimedia VHMM Very high speed multimedia Recommendation ITU-R P.1238 Propagation data and prediction methods for the planning of indoor radiocommunication systems and ra
10、dio local area networks in the frequency range 900 MHz to 100 GHz Recommendation ITU-R M.1390 Methodology for the calculation of IMT-2000 terrestrial spectrum requirements Recommendation ITU-R M.1450 Characteristics of broadband radio local area networks ITU-T Recommendation I.356 B-ISDN ATM layer c
11、ell transfer performance Rec. ITU-R M.1651 3 Annex 1 A method for assessing the required spectrum for broadband NWA systems including RLANs using the 5 GHz band 1 Background A key condition for market acceptance of NWA systems is the availability of a sufficient amount of spectrum to allow for a hig
12、h-quality user experience in the presence of other uncoordinated users. A method for estimating the amount of spectrum required to support forecast market penetration, user densities and scenarios and the kind of traffic they generate is therefore needed. A suitable basis for a method of estimating
13、spectrum requirements for NWA systems is available in Recommendation ITU-R M.1390, which was developed for the calculation of IMT-2000 terrestrial spectrum requirements. In fact, the scope of this Recommendation states that the method can be used for other than public land mobile radio systems, and
14、is applicable to both circuit-switched and packet-switch based radio technologies. An example calculation is included as Appendix 1 to illustrate how the method may be implemented. In this example, RLANs are used as a represen-tative model of NWA systems. Section 2 provides a short introduction of N
15、WA systems and introduces user scenarios. Section 3 reviews the methodology. Section 4 then explains the implementation of the methodology for RLAN spectrum requirements. Finally, an example calculation is supplied in Appendix 1. 2 Introduction to NWA systems NWA includes broadband RLANs, which are
16、described in Recommendation ITU-R M.1450. Typical applications include public and private wireless access offered in homes, schools, hospitals, hotels, conference centres, airports, shopping centres, etc. Administrations, through national rules and policies, may either choose to license these device
17、s or to exempt these devices from licensing. Office or indoor environments generally have low e.i.r.p.s and very small radio cells on the order of 30 m radius or less. Outdoor environments generally use higher e.i.r.p.s and have larger radii. Sufficient spectrum, among other factors, is a necessary
18、condition to allow satisfactory performance in the presence of other uncoordinated users and is one of the key conditions for market acceptance for these kinds of systems. Most 5 GHz air interface standards have an adaptive feature whereby the physical layer (PHY) mode may automatically adapt to the
19、 radio path characteristics. Table 3 shows the PHY modes and typical throughput for each mode. This allows most efficient use of the radio channel, but has the consequence of service area differences: the highest bit rate is only available over a fraction of the total area coverage of the lowest bit
20、 rate for any specific access point (AP). Hence in the detailed calculations an averaging over the service area is applied. Spectral efficiency in bit/s/Hz as delivered to the network layer is a function of the throughput achievable in the medium access 4 Rec. ITU-R M.1651 control (MAC) layer. The d
21、ifferent 5 GHz RLAN standards considered here employ different MAC strategies and therefore different network layer throughput. For the spectrum requirements calculation, the best achievable throughput has been assumed, as per Table 3. This gives a lower limit for the required spectrum: lower MAC th
22、roughput results in a greater amount of spectrum required in any given environment needed to support the same aggregate user traffic. TABLE 3 Example RLAN MAC throughput with 1 500 byte packets 2.1 Recommendation ITU-R M.1390 terminology in the RLAN context RLANs can be considered a complement to IM
23、T-2000 systems, providing higher data rates and system throughput in geographically limited areas (range of the order of 100 m). Multimedia services are defined in Recommendation ITU-R M.1390 as MMM, HMM and HiMM with user bit rates from 64 kbit/s to 384 kbit/s and up to 2 000 kbit/s. The bandwidth
24、demands of true, high-resolution multimedia communications will require bit rates of the order of 10 Mbit/s and above. RLANs can achieve much higher data rates and system capacity. These data rates can be handled by RLAN standards in the 5 GHz band for several users simultaneously within smaller cel
25、ls than IMT-2000 systems, and normally inside buildings. RLANs are typically deployed in a cellular structure, however not with contiguous area coverage like cellular systems. Even if the RLAN coverage area is limited, the entire spectrum may be needed due to local traffic demands. 2.2 Application e
26、nvironments Typical applications can be found in Recommendation ITU-R M.1450. The environments analysed here are: corporate office environment; public access environment; Maximum throughput PHY mode (Mbit/s) Coding rate Mbit/s Throughput (%) 6 1/2 4.6 77 9 3/4 6.9 77 12 1/2 9.2 77 18 3/4 13.9 77 27
27、9/16 21 77 36 3/4 28 77 54 3/4 42 77 Rec. ITU-R M.1651 5 wide area access environment; home environment. Each of the environments is given attributes in the sections below which should be used in the calculations. 2.2.1 Corporate office environment RLANs can be used for the replacement or extension
28、of wired LANs. Typical cases could be temporary office installations or installations into spaces where building characteristics or protection prohibit the extensive use of cabling. More recently the sheer convenience of untethered connection to the LAN is proving very attractive to users of laptop
29、PCs, and RLAN products are experiencing high growth rates. Terminals typically connected to infrastructure networks are designed for fixed use. Such a terminal could, for example, be a workstation, a PC or any other purpose-specific terminal. The applications are typically broadband applications. In
30、 this scenario the user device is mostly stationary and the main benefit derived from RLANs is the wireless convenience. Thus, it will be a most likely scenario that RLANs should provide or approximate fixed network QoS to a stationary user. The user should not be able to notice the difference betwe
31、en using the wireless system and a wired system. TABLE 4 Characteristics of an office environment 2.2.2 Public access environment Typical places for using the RLAN system outside an office room would be meeting rooms, dining facilities, patient wards, classrooms and auditoria, as well as waiting roo
32、ms/halls. A user may also be able to access the public network through base stations installed in locations such as railway stations, airports and shopping centres. In some cases, connectivity has to be maintained while the user is in transit from one location to another. The terminals in this scena
33、rio are movable. A typical terminal could be built around a laptop computer and a RLAN card. The mobile node will in many cases be a battery driven device so that an economic consumption of power is required. Attribute Requirement End-user equipment Portable PC or workstation, personal digital assis
34、tant (PDA) Usage environment Corporate offices, etc. Range Up to 50 m for indoor systems QoS expectation Basically same as fixed installation Applications Basically same as fixed installation Mobility Limited Coverage Continuous within the workspace 6 Rec. ITU-R M.1651 Public wireless access applica
35、tions are in principle similar to office environment applications. However, the users can be located in a wider variety of building types and the ranges are typically greater than in office environments. Furthermore, there may be uncoordinated networks with different owners, which can interfere with
36、 a given terminal. The QoS expected from the RLAN system in this scenario could be somewhat lower than the QoS expected of an office or home system. The user can be assumed to accept that a small loss in QoS is the price paid for the mobility gained. For example, the connection might tolerate a shor
37、t interruption because of a cell change (resulting in momentary disturbance in the video picture), and the required video picture size and definition for a person temporarily in the access area is also lower. TABLE 5 Characteristics of a public access environment It is envisaged by some administrati
38、ons that RLANs could be used for public access. User devices for such public access should have the same air interface as those for private access. A user device, therefore, can access both public and private networks. 2.2.3 Wide area access environment It is envisaged by some administrations that W
39、AS/RLANs could be used for wireless access on a wide area coverage basis. The terminals for such access should have the same air interface as indoor WAS/RLAN devices, but would likely use modified antennas and MAC protocols that allow greater range and deal with the longer propagation and multiple a
40、ccess delays resulting from outdoor operation. Sectoral or high-gain omnidirectional antennas, or repeaters, could be used to create micro-cells in which operational ranges of 300 to 3 000 m are possible, depending on the outdoor propagation conditions. In such deployments, the antennas are usually
41、highly directive and are oriented toward a central AP. Attribute Requirement End-user equipment Portable computer, e.g. notebook or PDA Usage environment Offices, schools, hospitals, airports, railway stations, shopping centres, etc. Range Up to 50 m for indoor systems Up to 150 m for outdoor system
42、s QoS expectation Somewhat lower than desktop Applications Similar to desktop Mobility Limited Coverage Continuous within defined area, e.g. airport hall Rec. ITU-R M.1651 7 The applications are classified as nomadic since the terminals are capable of being moved from location to location. Some exam
43、ples of nomadic applications are the provisioning of services to small transient businesses operating from industrial parks, or the linkage of several buildings in close proximity to each other to form a “campus” wireless network. TABLE 6 Characteristics of wide area access environment 2.2.4 Home en
44、vironment A home network generally covers a much smaller area than either factory or office environments. The rooms tend to be smaller when compared to work environments and have more compartmentalized structure (storage spaces and en-suites). In the home environment, many appliances, e.g. PC laptop
45、, printer/fax machines, security systems, home appliances, digital HDTV/SDTV sets, digital video cassette recorder (VCR), speakers and more could be linked in various ways. A typical scenario would be: An entertainment cluster (video and sound) located in the living room transmitting to television s
46、ets located in the living room, kitchen and bedroom. The wireless link provides a “bridge” between the clusters, avoiding the use of cable. A music system in the living room transmitting to speakers located in the living room, bedroom or dining room. Security features outside the home such as wirele
47、ss security camera or remote sensors. These could either be located on the external walls of the property or at the boundary wall, or a remote building such as a garage or recreation facility. RLAN allowing sharing of home computer resources and sharing of Internet access between several computers o
48、r PDAs for simultaneous use by several family members. From the above, it is obvious that the domestic network should allow access to external networks, e.g. digital television or be capable of working with no external links, e.g. a music system with remote speakers. Attribute Requirement End-user e
49、quipment Desktop and laptop computer, home entertainment centre, small office network Usage environment Inter-building, industrial parks (campus) and communities Range 300 to 3 000 m QoS expectation Basically same as a wireline installation Applications Basically same as a wireline installation Mobility Limited Coverage Dependent on outdoor environment and restricted to the range of cell 8 Rec. ITU-R M.1651 The home network is expected to require streaming video with high QoS, thus requiring intensive use of a high bit-rate channel. TABLE 7 Characteristics of a home envir
