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Digital-Over-Fiber RF Router System Spans 40 km

The introduction of high-speed data services delivered via LTE or HSPA+ marked the first time that wireless operators could provide data rates high enough for video streaming and other bandwidth-intensive services. Along with this sea change came the need to maintain these data rates virtually anywhere the service was offered. To achieve this, what began in the early 2000s as “in-building” signal distribution via purely analog means rapidly evolved, with coaxial cable and RF and microwave transmission line hardware slowly being replaced by optical fiber. Digital signal processing, Web-based element, network, and capacity management software, and a host of other capabilities have been introduced as well. The RF Router wireless distribution system from Dali Wireless is representative of what can be achieved when digital, optical, RF and microwave technologies are combined.


The RF Router system has the greatest reach over a single fiber (40 km) of any commercially-available solution, smaller host and remote units, low-power consumption, fanless low and high-power remotes, and the ability to be configured in star, daisy-chain, or hybrid star/daisy chain configurations. It can also monitor, operate, and reconfigure a network of indoor and outdoor remotes via software from nearly anywhere using its Web-based user interface.


The system has several capabilities unique to the company such as (when configured in a daisy-chain configuration) to bypass a failed remote in milliseconds, allowing the remainder of the network to function while the failed unit is swapped out. The system can also be configured with a loop-back feature in which an additional fiber fed from the furthest point in the network complements the primary signal path to ensure that the network will continue to operate if a remote fails or a fiber is damaged or severed somewhere along the route.


Traditional RF signal routing systems combine signals from multiple operators, feed them through a single host, and simulcast them to the remotes, which means that each operator must share power and gain adjustments with other operators. In contrast, Dali’s system assigns tHost network routers to each operator, so each one can allocate and modify its power levels at every remote as desired without affecting the other operators’ resources.


System Overview


The Dali Wireless RF distribution system is based on the company’s tSeries hardware platform, which consists of the tHost that accepts the RF signals from the base stations of one more operators in wireless bands at 700, 850, 1900, and 1700/2100 MHz, and digitally multiplexes them for optimum transmission. It then sends them over a single optical fiber to remote t30 low-power indoor transceivers and t43 outdoor transceivers that convert the signals back to analog form, amplify them, and transmit them via an integrated antenna to the end user. Reception from the user is the reverse of this process.


The optical transport is based on the Common Public Radio Interface (CPRI) standard embraced by nearly every base station manufacturer for defining the interface between base stations and remote radio units. The system’s uplink and downlink paths each have 164 MHz of instantaneous RF bandwidth and communication is at 5.856 Gb/s per direction. The hardware is complemented by software consisting of a Network Management System (NMS), Element Management System (EMS), and Capacity Management System (CMS), all of which can be used from anywhere via a Web browser.


The tHost is housed in a 1U 19-in rack-mount enclosure and simultaneously transmits and receives in parallel on the four bands, performing digital signal processing, routing, network switching, and optical bidirectional communication with the system’s remotes. Major functions include network management, capacity-on demand, channelization, network self-optimization, Wi-Fi and camera surveillance integration, real-time location positioning, and hardware integration. Customer-specified functions can be added as well.


Each tHost supports 36 remotes via its six fiber interfaces over distances up to 40 km, and with system bandwidth of 328 MHz there is capacity to add Ethernet backhaul at 1 Gb/s for Wi-Fi, security cameras, and other features. Wi-Fi service is completely separated on the system from other wireless traffic to ensure the highest possible security. The tHost also provides SNMP-based remote monitoring, alarm, and control functions, and allows remotes to be upgraded via the Web. The unit consumes 65 W from a 120/240 VAC supply.


The t30 quad-band, low-power remote transceiver is designed for indoor applications and produces RF output of 1 W (30 dBm) per band and bi-directionally transmits and receives on four sets of uplink and downlink channels. The fanless unit is virtually silent and consumes only 130 W. It also employs Dali’s patented adaptive equalization and linearization circuits that significantly enhance EVM, efficiency, and additive system noise performance. The remotes have monitoring, alarm, and control capabilities that are monitored and can be changed via the EMS. The unit measures only 12.9 x 18.9 x 4.6 in.


The t43 dual-band remote is designed to withstand outdoor use and produces RF output power of 20 W (43 dBm) per band. When combined with a second t43, a quad-band transceiver is created in a compact form factor. The t43 has the same uplink and downlink bandwidth, adaptive equalization and linearization circuits, and other features as the t30. However, unlike many high-power remotes, the t43 is fanless and very quiet, which is increasingly important as more and more remotes are deployed outdoors in residential areas. The unit consumes between 350 and 480 W (depending on its configuration) from a 120 or 240 VAC supply and measures 10.8 x 28 x 6.5 in.


The NMS is a standards-based, scalable, Web-enabled software platform and provides centralized monitoring of the network, performance tracking, diagnostics, quick fault identification, and problem rectification. It can be located at the head-end in a “base station hotel” or within the operator’s Network Operations Center. The NMS connects to the tHosts over a secure IP network.


The EMS integrates within the NMS, manages the entire system inventory employed by the RF Router system, and is accessible using a laptop or other computer connected to a tHost or a remote. The user interface displays an overall view of each frequency band, including input and output levels, power thresholds, attenuator settings and alarms, as well as a navigation tree.

The CMS enables dynamic capacity allocation that allows resources to be placed where they are needed based on user traffic patterns, known events using its scheduler, or on-demand when unknown changes in traffic occur. By effectively sharing resources in areas that have different user traffic patterns, utilization of resources can be maximized and capital expenditure greatly reduced. The CMS integrates within Dali’s NMS and complements its tool set, simplifying provisioning and maintenance through drag-and-drop actions in the user interface.


A Typical Application


A representative example of a Dali Wireless network, in which four wireless bands are served in a daisy-chain configuration. At the left in the figure is the base station hotel, which houses base stations for one or more operators. The signals from these base stations are aggregated by cascading the tHost units using digital signal processing software.

The tHost then frames and serializes data onto one optical fiber or more if the network configuration is a star or hybrid, and sends it to Dali’s remote units. The three types of network configurations in which the three sectors of a base station are routed in star, hybrid, and daisy-chain configurations. More information about the Dali Wireless RF Router system, including details of all hardware, software, and support services is available at our website, (604) 420-7760, e-mail: information@daliwireless.com.

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