An Introduction to Neutral Host Distributed Antenna Systems

Transcription

1 An Introduction to Neutral Host Distributed Antenna Systems 99 Pine Street Albany, NY (518)

2 Table of Contents Introduction 3 Overview of Distributed Antenna Systems (DAS) 4 Benefits of a Neutral Host DAS 6 Improved Coverage and Quality of Service:...6 Increased Capacity:...7 Capital Cost Reduction:...7 Speed to Market for Service Providers:...7 Evaluating Neutral Host Opportunities 8 Site Survey 10 System Design 11 Construction 12 Optimization and Verification 13 Summary 14

3 Introduction The demand for seamless voice and data coverage is driving wireless infrastructure. The licensed carriers built their networks to standards that provide voice mobility. With the deployment of wide area high speed data technology CDMA2000, 1xEV-DO and EDGE, the carriers have responded to next generation demands for wireless data communication. Users of wireless services expect them to work where they are. It is a challenge for carriers to provide seamless voice and data coverage indoors. The incumbent wireless infrastructure was not designed to provide in-building service. The concrete and steel materials in our cities and office complexes are barriers to macro network RF signal. The integration of optical technology in RF distributed antenna systems (DAS) provides an efficient indoor coverage system for the licensed 800 and 1900 frequency bands, WLAN, WiFi and 800 MHz public safety bandwidths. For an in-building network a single distribution backbone with a multi-band distributed antenna system can accommodate CDMA, TDMA, GSM, iden, LMR, DCS, GPRS and WiFi x, all in an interference-free environment. An in-building wireless network typically is a series of hubs, repeaters, and multipleband antennae placed within the building to accommodate and extend signals from the wireless carriers. Infrastructure includes a Distributed Antennae System (DAS), an equipment room, cabling and a network operations system, in either an active or passive DAS solution. Active systems use power to transport the RF signal, passive systems do not use power to amplify or convert the RF signal and require only cabling and antennae to operate. Facility size, design, architecture, locations and number of inhabitants determine the network design. Different buildings require different solutions, as such no one vendor or OEM hardware provides a fits-all solution.

4 Overview of Distributed Antenna Systems (DAS) To overcome the coverage and capacity problems inherent in the unique features of subways, parking garages and other in-building environments that make it difficult to provide quality service for mobile users, special antenna systems are deployed and distributed in-building. A typical DAS system, multiple antennas or transmitting elements that cover smaller zones (up to 20,000 square feet) are strategically distributed throughout the facility and connected back to the low power equipment via longer cables and system interconnections. In contrast, a typical macro wireless network antennas are connected to high power transmitting and receiving equipment via shorter cables arranged to cover large geographical areas (miles) from one antenna location. Macro antenna systems tend to be bigger and higher, while the DAS systems have many smaller antennas located very close to the mobile users. DAS systems can be broken down into two main categories; Active or Passive. Active systems use power to transport RF between the service provider s equipment and all parts of the DAS. These systems are generally used within large enclosures having complex wall systems. Figure 1: Active System Diagram

5 Passive systems do not use power to amplify or convert the RF signal and require only cabling, connectors and antennas to operate. Many of the smaller less complex locations can be served with passive systems. The size of the venue, complexity, and other factors will determine the type of system required during the design phase of the process. Figure 2: Passive System Diagram

6 Benefits of a Neutral Host DAS Distributed Antenna Systems that are designed and available for use by multiple service providers are commonly referred to as neutral host systems. If a DAS system is designed and deployed properly, common coverage and capacity benefits to more than one provider via a single distribution backbone can be achieved without a need to add a series of independent systems. Each carrier needs to provide only the head end equipment, via a dedicated base station or a donor antenna/amplifier, to connect their macro network to the DAS system. A donor site is one that is not exclusively used for the DAS system but also provides service to areas outside of the DAS. Neutral Host Distributed Antenna Systems are a reliable and innovative solution to poor coverage inside buildings, large venues requiring capacity, and inconsistent RF environments where it is difficult to improve quality. There are numerous benefits associated with these systems not only for the service providers and the consumers, but also for property owners. Improved Coverage and Quality of Service: Wireless devices often encounter difficulties maintaining a reliable connection inside buildings. Subscribers expect and demand wireless access wherever they are, whether it s on the 75th floor of a Class A office building, or in its underground retail concourse, at a shopping mall, casino, convention center, airport, or even on a college campus. Large buildings made of metal and concrete such as malls, or underground environments like subways and parking garages form RF resistant structures where the penetration losses are too great to maintain a reliable link to the outside macro cell sites. This is true even in mature wireless networks that have a high density of macro sites covering the outside environment. Distributed Antenna Systems eliminate poor wireless reception in these types of environments. As with any in-building solution, the primary benefit of a Neutral Host DAS is improved coverage throughout the interior of a building or venue. In general, installation of a DAS will result in increased coverage, improved call clarity and higher data throughput. The wireless service providers benefit by accomplishing two key revenue objectives; increased customer satisfaction / decreased churn, and increased in-building airtime minutes-of-use. Additionally, the end user will experience fewer blocked, dropped and missed calls. The property owner benefits by having their customers connected longer, resulting in more time spent within the property, and increased tenant and visitor satisfaction.

7 Increased Capacity: Wireless carriers often have to off-load traffic from large venues during special events or at peak-usage times by installing dedicated base stations, costly and complex cell splitting or re-sectoring the original macro network. All of these procedures lead to increased capital expenditures and in many cases degraded performance in the surrounding macro network. Using a Neutral Host DAS system to provide capacity for large venues allows macro cells to address other network related issues and allows for reduced power levels, reducing interference and increasing bandwidth. Installation of a Neutral Host DAS provides the opportunity for the wireless service providers to off-load call volume from the existing macro-cell network. The DAS replaces the need for additional base stations or tower locations that may only end up being partially utilized to solve the capacity problem, while the other sectors could be redundant wasted capital. In addition, off-loading subscribers from the macro network to the self contained DAS eliminates any re-sectoring or cell splitting of the surrounding macro cells. The net benefit of a DAS system is a less expensive solution with equipment that is more efficiently utilized, is less intrusive and does not disrupt to the surrounding macro network. Capital Cost Reduction: Equipment, labor, and maintenance costs for deploying in-building systems can be expensive and wireless providers find it difficult to justify the ROI for such systems except for the very top tier venues. By utilizing a neutral host model multiple carriers share the cost associated with these installations while improving subscriber satisfaction and ultimately increasing minutes of use on their system. Since the cost associated with providing service to in-building and other underground or RF resistant environments is shared among multiple carriers in a Neutral Host DAS model, the medium and smaller venues are becoming economically feasible. Speed to Market for Service Providers: Faced with an ever-consolidating market, wireless number portability mandates, and customer churn, carriers need to quickly expand and improve network coverage based on subscriber demand. Well designed Neutral Host DAS networks are an efficient resource for wireless service providers attempting to satisfy the needs of their customers and investors. Continued funding of the current standard solution encompasses incremental costs and time-to-market.

8 DIV 1325OT GRE E NSI DE CON F ERE NCE SAND T RAP CON F. RM B1-1 B1-4 CON F. RM EASTERN POINT CON F. RM CON F. RM. V103 V103 V OF F I CE B1-2 B1-3 B1-5 OF F I CE 1326 OF F I CE BL A CK IC E 1222 NUB BL E L IGHT 1220 CONF.RM B1-6 VES T IBU LE V C1-1 C1-2 C1-3 C1-4 D1-1 D1-2 C1-5 D1-3 C1-6 DEM O L A B 1221 V104 V104 A2-7 B2-1 B2-2 IDF 1327 A2-3 A2-4 A3-4 A2-5 A2-8 A2-9 A2-10 A PT R/F AX PT R/F AX PLOTTER ARE A 1327 A2-1 A D2-1 PT R/F AX B2-3 A OPE N 1210A 1330 ELECTRICAL 1210 D A3-1 A3-2 A3-7 A3-10 LIBRARY D2-3 D2-4 D3-4 D2-5 D D2-6 D B3-1 B3-4 B3-7 D3-1 D3-7 D3-1 0 A3-5 A3-8 A3-11 A3-12 A4-4 A3-1 4 A3-1 6 B3-2 B3-8 CONFERE NCE 1308 ROOM A3-3 A4-1 A3-6 A4-2 A3-9 A4-3 A3-15 B3-3 B3-5 B ST ORAGE OF F I CE D3-2 C1 0 4 B3-9 C105 C1 0 5 D3-5 D3-6 D3-11 D3-1 2 OPEN OF FICE C10 5 COR RIDOR C1 0 4 D A4-5 B4-1 B4-2 B4-3 QUI ET 1205A C A D3-8 D3-9 D4-5 EM ER. ELEC. QUI ET 1205B 1205B STOR D4-1 D4-3 D MEN'S LAV V107 V107 VES T IBU LE V OF1313 F ICE HAZ ARD 1312 CONF. RM BADGING 1311 SECURIT Y & S AFET Y A WOMEN' S LAV 1310 D4-2 D4-4 D4-6 D D B5-4 STA GING 1302 B5-1 CAP E NE DDICK CON F. RM. B BUI LDING SERVICES COPY/M AIL TRAMMELL CROW COMPANY B5-5 B BRE AKROOM A TOI LET LOBBY 1001 C106 C1 0 6 C A C101 C1 0 1 V102 V101 V B VES T IBULE V1 02 B5-3 V101 VES T IBUL E V A A 1402 EL E V. M E CH D6-1 D6-3 D6-5 D6-7 D6-9 BENCH L AB LDF ST ORAGE IDF COR RIDOR C C A JAN MEN'S LAV A 1103B A 1108 C1 0 3 SHOW ER BDF ELECTRICAL 140 4A WOMEN' S LAV 1103A D A SHOWER D6-2 D6-4 D A COR RIDOR C D7-1 D7-4 D7-7 D7-1 0 D6-10 D7-1 3 C102 D7-2 D7-5 D7-8 D7-1 1 D A C103 C1 02 OPEN OF FICE D7-3 D7-6 D7-9 D7-1 2 D OF F I CE D D8-4 D8-7 D8-1 0 D8-1 3 CA CU 1106 D D8-5 D8-6 D8-8 D D8-3 D8-9 D8-1 2 D8-1 4 D CHI L L ER PUM P ROOM ST ORAGE V V105 C9-1 D STA ND-BY SW ITCH GEAR 1505 VES TIBULE V1 05 M OTHERS ROOM C9-2 C9-3 C9-4 C9-5 C9-6 D D9-3 D9-4 D9-5 D9-6 BL I ZZ ARD CON F RM TEL EPHONE BLDG. EL ECTRIC 1501 V106 VES T IBULE V106 V1 06 RECEIVING WATER ROOM FIRE PUM P ROOM BIRD ISL AND CONF.RM EM ER ELECTRIC Evaluating Neutral Host Opportunities Proper evaluation of capacity, signal strength and signal quality for each of the mobile service providers is required to assess the need for a neutral host system. Capacity is evaluated both within the venue of interest as well as in the surrounding macro network. A venue may have adequate signal strength but if the venue hosts a significant number of subscribers, the sites that serve the area may be over utilized. In this scenario a neutral host system may be driven by either a dedicated base station or a repeater that is fed from a less utilized site. Signal quality is an important factor in determining the need for a neutral host system and must be considered for multiple carriers. Signal quality can be measured by using equipment that utilizes sophisticated algorithms to generate Mean Opinion Scores (MOS). Alternative technology specific indicators are also used, such as Bit Error Rate (BER) for GSM networks, Frame Error Rate (FER) for CDMA Networks and Signal Quality Estimate (SQE) for iden networks. Adequate signal strength should not be equated to good signal quality. While signal strength is certainly a factor in determining signal quality it is not uncommon for good signal strength to be present within a building while the signal quality is poor. Interference in one form or another is generally the cause of poor quality occurring in an environment of good signal strength. An example of this is shown in figures 3 and 4 below. Note that in these figures the received signal strength (RSSI) is adequate at the outer edges of the building, but the signal quality (using FER as an indicator) is marginal to poor. Carrier 1 RSSI -85 to 0 dbm -90 to -85 dbm -95 to -90 dbm Less Than -95 dbm NO. 1 ELEV. NO. 2 EL E V. feet Figure 3: Carrier 1 RSSI

9 DIV 1325OT GRE ENSI DE CONFERE NCE SAND TRAP CONF. RM B1-1 B1-4 CONF. RM EASTERN POINT CONF. RM V1 03 VES TIBULE V1 0V B1-2 B1-3 B B1-6 V DEM O LAB BLACK ICE CONF. RM C1-1 C1-2 C1-3 C1-4 D1-1 NUBBLE LIGHT CONF.RM D1-2 C1-5 D1-3 C1-6 V1 04 V1 04 A2-7 B2-1 B2-2 IDF 1327 A2-3 A2-4 A3-4 A2-5 A2-8 A2-9 A2-10 A PLOTTER AREA 1327 A2-1 A D2-1 B2-3 A OPE N OF FICE 1210A 1330 ELECTRI 1210 CAL D A3-1 A3-2 A3-7 A3-10 LIBRARY D2-3 D2-4 D3-4 D2-5 D D2-6 D B3-1 B3-4 B3-7 D3-1 D3-7 D3-1 0 A3-5 A3-8 A3-11 A3-12 A4-4 A3-14 A3-16 B3-2 B3-8 CONFERE NCE 1308 ROOM A3-3 A4-1 A3-6 A4-2 A3-9 A4-3 A3-15 B3-3 B3-5 B D3-2 C104 B3-9 C105 D3-5 D3-6 D3-11 D3-12 OPE N OF FICE 1230 C105 C1 0 4 D A4-5 B4-1 B4-2 B4-3 QUI ET 1205A C A D3-8 D3-9 D4-5 EM ER. ELEC. QUI ET 1205B 1205B STOR D4-1 D4-3 D MEN'S LAV V107 V107 V HAZ ARD CONF RM BADGING 1311 SECURIT Y & SAFET Y 1305A WOM EN' S LAV 1310 D4-2 D4-4 D4-6 D D B5-4 STAGING 1302 B5-1 CAP E NE DDICK CONF. RM B5-2 TRAMMELL CROW COMPANY 1303 BUI LDING SERVICES 1303 B5-5 B COPY/MAIL BREAKROOM A TOILET LOBBY 1001 C1 0 6 C106 C A C101 V102 V101 V102 V101 V B V1 02 B A A 1402 ELEV. M E CH JAN D6-1 D6-3 D6-5 D6-7 D A 1404A SHOWER 1404A BENCH L AB 1410 C MEN'S LAV A 1103A SHOWER D6-2 D6-4 D6-6 D A C B 1103 WOMEN' S LAV D7-1 D7-4 D7-7 D7-1 0 D6-1 0 D7-1 3 C102 C A D7-2 D7-5 D7-8 D7-1 1 D7-1 4 C A C OPE N OF FICE LDF 1415 BDF D7-3 D7-6 D7-9 D7-1 2 D D D8-4 D8-7 D8-1 0 D IDF ELECTRI CAL 1108 D D8-5 D8-6 D8-8 D D8-3 D8-9 D8-1 2 D8-14 D CHI L L ER PUM P ROOM V V105 M OTHERS ROOM 1109 C9-1 D STA ND-B Y SW ITCH GEAR 1505 V C9-2 C9-3 C9-4 C9-5 C9-6 D D9-3 D9-4 D9-5 D9-6 BLIZZARD CONF. 1120RM TEL EPHONE BLDG. EL ECTRIC 1501 V106 V106 V1 06 RECEIVING WA TER ROOM FIRE PUM P ROOM BIRD ISL AND CONF.RM EM ER ELECTRI C Data collection software is used to produce coverage plots as shown in Figures 1 and 2 for each provider. This data can then be used to assess the suitability of the building for neutral hosting as well as to identify the areas of the building that require coverage enhancement. Carrier 1 Frame Error Rate 0 to 2 2 to 3 3 to 5 Greater Than 5 PTR /FAX C105 C101 NO. 1 ELEV. NO. 2 ELEV. C feet Figure 4: Carrier 1 Frame Error Rate

10 DUM PL ING ROCK 2223 CONF. RM A1-1 A1-4 B1-1 C1-4 C1-7 C1-1 0 D1-1 NOR'EASTER CONF.RM NOR TH E ND 2220 CONF.RM A1-2 A1-5 OPE N OF FICE 2330 B1-2 B1-4 B1-5 B1-7 C B1-8 C1-5 C1-6 C1-8 C1-9 C1-1 1 C1-1 2 D1-2 A1-3 A1-6 B1-3 B1-6 B1-9 C1-2 C1-3 D PTR /FAX D2-1 D2-3 A2-1 A2-3 A2-5 A2-7 A IDF D2-2 D2-4 D2-5 D2-6 D2-7 D ELECTRI CAL A2-2 A2-4 A2-6 A2-8 A A OPE N OF FICE D3-1 D3-4 D3-7 D A3-1 A3-4 A C2 0 5 A C D3-2 D3-5 D D3-1 1 A3-2 A3-5 A3-8 A3-11 B3-1 B3-3 B STOR OPEN OF FICE 2230 A3-3 A3-6 A3-9 A3-12 B3-2 B3-4 B3-6 C2 0 5 C206 D3-3 JAN D3-6 D4-3 D3-9 C QUI ET 2205A 2205A QUI ET 2205B 2205B D4-1 D4-5 D3-1 2 D4-7 CONF.RM MEN'S 2303LAV WOM EN' S LAV SNOW BANK A D4-2 D4-4 D4-6 D4-8 D C201 STOR BRE AKROOM 2202 CUT TYHUNK L IGHT CONF.RM MAIL/COPY DAT A CE NTER NOC C2 0 7 C201 C207 C201 V20 1 V201 1 PDU PDU 2405A C FM NOC A A STAGING DAT A CE NTER D6-1 D6-2 D6-3 D6-5 D6-7 CAC U RM D6-4 D6-6 D6-8 D6-9 D A WOMEN'S LAV A CAC U QUI E2105A T 210 5A QUI E T B 5B 2410D MEN'S 2406 LAV C D7-1 D7-4 D7-7 D7-1 0 D6-1 3 C2 0 2 C202 IDF C2 0 3 D7-2 D7-5 D7-8 D7-1 1 D7-1 4 C STOR OPE N 2130 C D7-3 D7-6 D7-9 D7-1 2 D7-1 5 D D8-4 D8-1 0 D A ELE CTRI CAL D8-2 D8-5 D8-7 D8-8 D8-11 D8-14 BENCH L AB D8-3 PTR /FAX D8-6 D8-9 D8-1 2 D C9-1 C9-4 D9-1 D9-4 C9-2 C9-5 D9-2 D9-5 BIG DIG 2120 CONF.RM C9-3 C9-6 D9-3 D B 2410C CAC U 2115 DEE R ISL AND CONF.RM Site Survey A site survey is performed prior to the final design. The objective of the survey is to characterize signal propagation within the building, investigate donor signal options and to investigate equipment space and cable routing issues. Proper engineering and planning will minimize capital expenditures while ensuring that coverage goals for each of the mobile service providers are met. Several factors must be considered when designing a neutral hosts system. Assuming the target coverage area has been identified as described above, the first of these is to characterize signal propagation within the target area. To characterize the building test transmitters are located at various locations within the building. A receiver and mapping software is used to record the signal strength at various locations within the building. A sample transmitter test is shown in Figure 5 below. Transmitter Location Transmitter Test Path Loss -85 to 0-90 to to -90 all others ELEV. NO. 1 NO. 2 ELEV feet Figure 5: Transmitter/Building Characterization Test Various transmitter tests are performed so that a thorough understanding of the building s propagation characteristics is obtained. As can be seen from the transmitter test in figure 3 signal loss does not degrade in direct proportion to the distance from the transmitter but is largely dependant on the building structure. Using the proper tools and procedures to characterize signal loss helps to insure that the system is not over designed but meets customer requirements.

11 Suitable equipment room space and it s proximity to the coverage objective can affect the type of system installed and overall cost of the system. These issues are investigated at the time of the site survey. Potential donor signals are also investigated for neutral host opportunities that may not require dedicated base stations. These measurements are generally performed at the roof level. A receiver capable of measuring multiple technologies and frequencies is required for these measurements. Alternatively phones from various carriers with an accessible diagnostic or debug mode can be used. Potential donor antenna locations and roof penetration issues also need to be investigated at this stage. System Design The building characterization along with available equipment space determined during the site survey is the basis for system design. The propagation model is optimized for accuracy using the transmitter tests performed in the site survey. Each wall type within a building affects signal propagation differently therefore each wall type must be identified in the propagation model and assigned attenuation values obtained from the information in the transmitter tests. This allows for optimum transmitter location and minimizes required capital. The system design determines which OEM hardware solution is appropriate for the venue. A partial design (one floor of a multi story building) is shown in figure 6 below. Figure 6: System Design

12 Construction Once the proposed design is approved for installation by the building manager, a preconstruction site visit is completed. During this visit, equipment locations and cable routes are verified, as well as acceptable contractors to perform any electrical or roofing work that may be required. If any of the locations proposed in the design are not acceptable to the building manager, the design is modified to allow for these changes. Once final approval is obtained, the actual installation of equipment begins. Construction begins with the installation of cabling, typically both fiberoptic and coaxial. Cabling is routed from the main equipment room throughout the building to all the antenna locations. A DAS system allows for the reuse of many network elements such that trunking and hubbing minimize the amount of new cable required. Cable is run in existing cable trays or utility chases where available. The equipment deployment is fairly straight forward. The main equipment room typically needs dedicated electrical services to handle both the DAS equipment and the carrier equipment. The remote units and the antenna use minimal power and usually only involve a 10v outlet.

13 Optimization and Verification Upon completion of the construction phase, the system is tested and optimized. Each coax and fiber optic cable is swept, isolation tests are performed, sources of interference are investigated, donor signal levels are verified, and a final coverage assessment is performed. The results of the coverage analysis reflect both coverage provided by the external macro cell and enhanced coverage provided by the DAS. Figures 7 and 8 below show sample plots that can be used to measure the success of the installation. Figure 7: Carrier 1 RSSI - Post Activation

14 Figure 8: Carrier 1 Frame Error Rate - Post Activation The results of the post activation survey can be used to evaluate the success of the installation and used as a baseline to help troubleshoot problems if they arise in the future. Summary A well designed Distributed Antenna Systems (DAS) can provide a cost efficient interference-free environment for indoor CDMA, TDMA, GSM, iden, LMR, DCS, GPRS and WiFi x networks. Using a combination of high-tech test equipment, custom software applications, and engineering procedures, a design-driven neutral host DAS network can be implemented that minimizes capitol investment, controls operating expenses, and meets the network coverage objectives.