TD 92422GB System Planning Ascom IP-DECT System 18 February 2010 / Ver.
System Planning Ascom IP-DECT System TD 92422GB Contents 1 Introduction............................................................................................................. 1 1.1 Abbreviations ..................................................................................................... 1 1.2 Glossary ............................................................................................................. 1 2 Wired LAN/Backbone Requirement ...............................................
System Planning Ascom IP-DECT System TD 92422GB 7.2.2 In systems where only roaming is required between buildings .................. 16 7.3 Sync Slave IPBS ................................................................................................ 16 7.4 Sync Master IPBS .............................................................................................. 17 7.5 Standby Sync Master IPBS ................................................................................ 17 7.
System Planning Ascom IP-DECT System 1 TD 92422GB Introduction This document gives a description on how to plan the Ascom IP-DECT system. The Ascom IP-DECT system is an IP based cordless telephony and messaging system for connection to private telephone exchanges. The Ascom IP-DECT system supports the DECT standard which gives a full integration of messaging and voice functions. The Ascom IP-DECT system can be integrated with external applications such as different alarm systems, networks and e-mail.
System Planning Ascom IP-DECT System TD 92422GB SARI The SARI, Secondary Access Rights Identity, is the broadcast identity which uniquely identifies an Ascom IP-DECT system. Cover Radius The radius of the circle (circular radiation patterns of the base station antennas are assumed), around a particular base station, in which portable parts can communicate with that base station.
System Planning Ascom IP-DECT System 2 TD 92422GB Wired LAN/Backbone Requirement It is highly recommended that a Network Assessment of the LAN is carried out before an installation or when new applications and/or user density is added to secure the voice quality. There are several things to consider when designing a network: • In order to achieve optimal performance the infrastructure should be connected to a switched network (no hubs or repeaters).
System Planning Ascom IP-DECT System 3 TD 92422GB Base Station Planning The major task in installing an Ascom IP-DECT system is defining the number of base stations required to cover an area to a satisfactory level. This chapter describes how a base station planning can be made in order to gain full area coverage. Small sites usually have a homogeneous layout, it is therefore easy to predict the field pattern of the base station which makes the planning relatively easy.
System Planning Ascom IP-DECT System 4 TD 92422GB Client’s Requirements The most important thing when planning an Ascom IP-DECT system is that the system meets the needs and requirements of the customer. Discuss with the customer where high quality is of absolute necessity and whether there are areas where it is sufficient for people to be available but with lower sound quality, for example outdoors or in a production hall.
System Planning Ascom IP-DECT System 5 TD 92422GB Traffic Capacity of the System The traffic capacity of the Ascom IP-DECT system is mainly determined by the number of base stations and in exceptional cases also by the LAN bandwidth. A single base station has a capacity of 8 simultaneous calls and a single gateway has a capacity of 40 simultaneous calls. The traffic capacity of the Ascom IP-DECT system is determined by: • Grade Of Service (GOS) accepted by the customer.
System Planning Ascom IP-DECT System TD 92422GB Example: A customer ordering a system with 55 cordless phones, generating 200 mE each in average, requires a system with a traffic capacity of 11 E. With an accepted GOS of 0.5% the number of base stations is found as follows: The total traffic is 11 E. In the column of 0.5% GOS, the next higher value of 11 E is 14.2 E, resulting in 3 base stations. The system shall be equipped with 3 base stations, offering the client 14.4 E instead of 11.
System Planning Ascom IP-DECT System 6 TD 92422GB Base Station Coverage This section describes how architecture, building elements, and special areas affect the coverage and the placing of the base stations. The radio environment or the cell that is covered by a base station is not of a spherical shape as often suggested in figures. If a snapshot could be taken of its form, it would become clear that its shape is much more irregular.
System Planning Ascom IP-DECT System 6.2 TD 92422GB Building Elements This section describes how different building elements can affect the coverage. • The cell size is dependant on the material of which walls, ceilings and floors are made. • Plain, light or reinforced concrete, wood and plaster absorb and pass radio waves in different ways. • Metal walls and large metal cabinet rows reflect all signals, resulting in a greatly reduced coverage in areas behind these objects.
System Planning Ascom IP-DECT System TD 92422GB 2nd floor Open stairwell or atrium 007 1st floor Figure 2. Base station covering two floors 6.2.3 Fire-resistant walls/doors The same facts applies for fire walls as for normal walls mentioned in the section above. However, fire doors are usually open during the site survey, it is important to close the fire doors before doing the final site survey measurement and before finalising the base station plan.
System Planning Ascom IP-DECT System 6.3.2 TD 92422GB Lift If coverage in lifts are desired, locate the base station close to the lift, preferably at the front in a way that the base station can ‘see’ the front1. This is because a lift is usually surrounded on three sides by a reinforced lift shaft, with the only opening being at the front. Locating a base station in front of a lift is usually not the most ideal position for the planning as a whole.
System Planning Ascom IP-DECT System 6.4 TD 92422GB Reflective Environment When providing coverage in a metal hall (for example, a production hall or storage building), there are a number of issues which call for additional attention. The dimensions of the hall and the material used (metal, concrete, brick etc.) are important deciding factors in the hall’s radio reception. Every hall is different, and it is very difficult to predict the radio reception.
System Planning Ascom IP-DECT System 6.4.2 TD 92422GB How to Identify Reflective Environment A high time delay spread will only have influence if the delayed signal is strong. In office environment we also have signals arriving to the receiver with high delay but since these signals have travelled trough walls, been reflected in attenuation materials (wood, cement, etc) the reflections are highly attenuated. These signals with low power level will not cause any problem.
System Planning Ascom IP-DECT System 7 TD 92422GB Synchronization 7.1 Air Synchronization This section is a brief description about the air synchronization procedure. IP-DECT base stations use the DECT air interface to synchronize to each other. The DECT signals have to be able to travel in the air between the base stations. This means that the placement of the base stations has to be planned to fullfill this requirement. For an individual IPBS it is not needed to configure which IPBS to synchronize to.
System Planning Ascom IP-DECT System TD 92422GB There is one Air Sync Master per building, hence the installation consists of three regions. The regions are synchronized to each with a reference sync as follows: The Air Sync Master in region 1 has been configured to receive a reference sync from one IPBS in region 2 and the Air Sync Master in region 3 has been configured to receive a reference sync from one IPBS in region 1.
System Planning Ascom IP-DECT System 7.2.2 TD 92422GB In systems where only roaming is required between buildings In figure 5 below there is an example of an installation with three separate buildings with no synchronization coverage between them. There is one Air Sync Master per building, hence the installation consists of three regions synchronized separately. Note: Regions cannot be configured for IPBLs. The IPBLs will always belong to region 0.
System Planning Ascom IP-DECT System TD 92422GB In addition to the above automatic synchronization procedure there is also possible to use static synchronization by manually lock on to a specific RFPI. However when specifying a specific RFPI the RFPI must be for a RFP within the same synchronization region. 7.4 Sync Master IPBS Radios configured as sync master will report to the Pari Master that it wants to be a sync master. The Pari Master will select one of them to be the active sync master.
System Planning Ascom IP-DECT System TD 92422GB The fibre modem is used for conversion between fibre optic/copper cables. The following conditions must be met: • Jitter and wander must be less than ± 50 ns • Delay over media (incl. cabling) must be less than 50 µs • Transparent mode Example: Westermo ODW-631 SM-LC15, ODW-631 MM-LC2 Each synchronization port sends and receives (both directions) synchronization signals.
System Planning Ascom IP-DECT System TD 92422GB IPBL1 Ring out IPBL2 Ring in IPBL2 Ring out 010 IPBL3 Ring in Figure 7. Non redundant synchronization Reference synchronization The reference ports are used to synchronize two separate rings, for example between two buildings.
System Planning Ascom IP-DECT System 8 TD 92422GB Site Survey with IPBS Base Station If the planned system shall have an IPBS, both speech coverage and sync coverage have to be considered. If the system only consists of IPBL, only speech coverage has to be considered. Speech coverage: the radius of the circle (circular radiation patterns of the IPBS antennas are assumed for reasons of simplicity), around a particular IPBS, in which portable parts can communicate with that IPBS, see figure 9.
System Planning Ascom IP-DECT System 8.2 8.3 TD 92422GB Check the speech coverage for base station A 7 Check on the portable device that the signal strength is > -68 dBm which is the normal case to get sufficient speech quality within each base station. 8 Verify that the speech quality is sufficient by listening on a call. When the off-hook key is pressed, the speech is looped back.
System Planning Ascom IP-DECT System ms 50 50 50 50 50 TD 92422GB 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 1,2 sec A B C A = Good sync coverage Green B = Inadequate sync coverage Yellow C = No sync coverage Red Figure 11. LED2 deployment indications. 8.4 11 Use the GUI web interface on base station B and check the signal strength on the actual synchronization coverage and name it X. 12 Perform an RFP scan.
System Planning Ascom IP-DECT System 9 TD 92422GB Location of the Base Stations Once the surroundings are analysed, an exact position for each base station must be decided. The most important thing when deciding the location is to ensure sufficient coverage and traffic capacity. Other things to consider are: • LAN access, see 9.1 LAN Access. • Power the base stations, see 9.2 Power the Base Stations. • Antennas, see 9.3 Antennas. 9.
System Planning Ascom IP-DECT System 9.3.2 TD 92422GB Directional Antennas It is possible to use directional antennas in small corridors and halls. Give careful consideration to the type of antenna that you intend using for your application: why that antenna in particular? The fact is that there are many different types of antenna, all with a different radiation pattern. It is difficult to summarize the type of antenna and the application; it is often a question of experience and empiricism.
System Planning Ascom IP-DECT System 9.4 TD 92422GB Base Station Planning Tips All information needed to do a solid base station planning are given in sections 4 to 9. Below is a list of some other important issues to consider: • Always involve the client in the site survey. Ensure that the client shares the responsibility for the decision on the siting of base stations.
System Planning Ascom IP-DECT System 10 TD 92422GB Making a Base Station Plan 1 Make a sketch of all base station positions for each floor of the buildings. 2 Indicate the expected speech coverage and in case of a IPBS system also the air sync coverage for each base station on the map. 3 It is strongly recommended that each IPBS is able to synchronize with at least two other base stations.
System Planning Ascom IP-DECT System TD 92422GB Location area A Location area B A B B A A B B 000 A Figure 13. A one-floor building, seen from above Location area A Second floor A A A A A B B First floor B B 000 B Location area B Figure 14. A two-floor building, seen from the side 10.
System Planning Ascom IP-DECT System 11 TD 92422GB Multiple Master Systems 11.1 Why Multiple Master Systems The need for a Multiple Master systems arises in the following cases: • • • • The amount of handsets in the system exceeds 1000. To make it scalable from small to large systems. The need for local functionality when connection to a central site has been lost. The need for fixed connections load balancing when the number of Portable Devices exceeds what an IP-PBX is able to register.
System Planning Ascom IP-DECT System 12 TD 92422GB Related Documents System Description, Ascom IP-DECT System TD 92375GB Data Sheet, IP-DECT Base Station TD 92370GB Data Sheet, IP-DECT Gateway TD 92430GB Installation and Operation Manual for IP-DECT Base Station and IP-DECT Gateway (software version 3.0.
System Planning Ascom IP-DECT System TD 92422GB Document History For details in the latest version, see change bars in the document. Version Date A 2007-01-15 First released version. B 2007-04-20 IP-DECT Gateway added. C 2007-10-25 Minor changes after input from field trial. D 2009-02-02 Update of the document with the introduction of the Multiple Master system concept. E 2010-02-18 New chapters about air synchronization and site survey with IPBS. New appendix A. 18 February 2010 / Ver.
System Planning Ascom IP-DECT System TD 92422GB Appendix A: Multiple DECT Systems This section describes issues and recommendations about installations of multiple DECT systems and how the interference between them affect the available capacity in the radio environment. To enable the best possible performance it is important to know that there are base station planning issues that must be considered.
System Planning Ascom IP-DECT System TD 92422GB dummy bearer is due to that the portable device listens to one dummy bearer and uses the information to lock-on to the system; synchronize, check base station identity, system capabilities, status and paging information for incoming voice and data call set-ups as well as for preparing handover, call setups etc. This means that a base station is always transmitting information regardless of which type, resedential or multiple base station system.
System Planning Ascom IP-DECT System A.5 TD 92422GB Unsynchronized Systems If two systems operating in the same cell/coverage area are synchronized with each other they will dynamically share the available 120 channels capacity. However, if the two systems are unsynchronized, each call and/or dummy bearer in any of the two systems will steal two channels from the dynamically shared resources. If more unsynchronized systems are installed, the issue will grow.
System Planning Ascom IP-DECT System TD 92422GB portable devices subscribed in the multiple base station system shall be made. In an office environment with high call traffic only very few DECT systems may be operational. In a low traffic environment a few resedential base stations may be used within the enterprise and will most certainly not be a problem. If unsynchronized systems are installed, the radio units should be placed as far as possible apart from each other to limit the interference.
