New Network Architecture
Digivance
®
Simulcast Networks Reduce
Network Costs and Improve Quality of Service
WHITE PAPER
Improving Grade of Service (GOS) While
Reducing RF Channels
Wireless service providers are adopting new deployment strategies
to reduce network costs and improve quality of service. In one
urban market, a major national wireless service provider has
improved network traffic loading and significantly boosted network
RF performance by centralizing radio equipment and deploying
digital RF transport technology. The digital RF transport systems
operate in simulcast mode and reproduce the signal at radiating
points throughout the network. The new network architecture has
produced trunking and channel re-use performance gains that
enable the service provider to deliver greater GOS while reducing
the number of RF channels.
To achieve greater capacity with fewer RF channels, network
designers used two or more ADC Digivance digital RF transport
systems operating in “simulcast” mode at radiating points
throughout the network. This white paper describes that simulcast
network architecture, network traffic loading improvements and
how the team determined the number of RF channels needed to
achieve the desired GOS.
Digivance
®
Simulcast Networks
Reduce Network Costs and Improve Quality of Service
New Network Architecture

provider’s urban network are due to a reduction in the
number of BTS sectors and an increase in channel loading
per sector. This improves trunking efficiency (remember:
calls cannot trunk between sectors). In the urban LRCS
network, the new architecture reduced by 30 percent or
more of the total number of RF channels required on a
multiple link transport system for a specified amount of
user grade of service. The percentage reduction
depended on the number of radiating points and trunks
required for the coverage area.
In all communications systems that carry more than one
user at a time, several communication links (i.e. voice
“trunks”) must be provisioned to allow for all
anticipated users to gain reasonable access to the
network. What determines “reasonable access” is the
designated “grade of service” (GOS), which is the
acceptable amount of network blocking of incoming call
attempts. Typical wireless network designs in the United
States provision channels to provide voice services at a
GOS of approximately 2 percent, with data services
typically provisioned at a GOS of 4 to 5 percent.
To determine the number of RF channels (voice trunks),
the GOS and anticipated traffic intensity (Erlangs) must
be known. Conversely, if you know the number of
voice trunks available and the GOS, you can calculate
traffic intensity supported.
“Trunking efficiency” is simply the observation that the
more voice trunks available - the less the chance of
blocking, and is best explained by the Erlang B (non-
queuing requests) formula:

Remote
3
Remote
4
Remote
5
A
N
N!
B=
i
i!
i=0
N
A
∑
Core Urban Market - A “Real World”
Case Study
Here is an actual service provider’s market application of
LRCS in two separate 2:1 simulcast configurations. In
the original metro “RF hotel” configuration of five
radiating points (a traditional BTS deployment of one
radiating point per sector), the service provider
operated five BTS sectors dedicated to five separate
radiating points in strategic locations to obtain desired
capacity and coverage in the metro core, as shown in
diagram below:
With average Radio Frequency channel (RFc)
provisioning for this configuration of six RFcs (a
maximum of 17 interconnect voice trunks) per sector,

In this network deployment, the service provider
realized significant cost savings and found that they
could actually reduce to one sector with nine RFcs from
two sectors averaging 13 RFcs (2 sectors of 6RFc + 7
RFc), a BTS radio reduction of 31percent.
In addition, it was observed that low cost/low power
2:1 splitters and combiners could be used for forward
and reverse paths to couple signals between a single
interface and two host units. This reduced the amount
of interface circuitry required in the network and
produced another cost savings from the simulcast
system. After realizing this savings (and being assured
by continued excellent system performance statistics
and RF measurements) the service provider repeated
this 2:1 simulcast process again with the same results.
New Network Architecture
Page 4
BTS
Site A
Controller
BTS
Site B
Controller
Sector 1
(6RFc)
Sector 2
(6RFc)
Sector 3
(6RFc)
Sector 4

BTS
Interface
BTS
Interface
Host 1 Remote 1
Host 2
Host 3
Remote 2
Remote 3
A N
N
N! (N-A)
i
i!
P(>0)=
A
∑
N-1
+
A N
N
N! (N-A)
i=0
New Network Architecture
Page 5
Final Configuration:
The estimated equipment savings realized for the
service provider’s three sector simulcast application vs. a
five sector application were as follows:
Estimated savings in required BTS and LRCS equipment:

Sector 4
(9RFc)
Sector 5
BTS
Interface
BTS
Interface
BTS
Interface
BTS
Interface
BTS
Interface
Host 1 Remote 1
Host 2
Host 3
Host 4
Host 5
Remote 2
Remote 3
Remote 4
Remote 5