|
|
|
|
|
|
We shall look at possible solutions or ways that are considered to achieve the requirements.
One way to get more frequency bandwidth is to combine carriers.
Carrier aggregation is already part of LTE-Advanced.
Carrier frequencies above 6 GHz provide bigger frequency bandwidths.
With proper selection of frequency range, capacity density requirements may be achieved.
Higher the carrier frequency, lower its non LOS performance.
However, with carrier frequencies between 6 GHz to 30 GHz, certain outdoor-to-indoor coverage may be provided.
Small cells (few meters to a kilometre) with carrier frequencies between 6 GHz to 30 GHz seem very good fit for urban areas or sites requiring higher capacity density.
In Fronthaul concept, Antenna/RF unit is separated from Baseband unit and the link between these units is called "fronthaul link".
In a deployment with cell hierarchy, front cell use back cells for connectivity to the network via "backhaul links".
For flexible/scalable/energy efficient/cost effective (aka dynamic) radio access networks, fronthaul/backhaul links play a major role.
A new cell or site may be installed with minimal impact/effort.
Also, some of the cells may powered up or down based on dynamic user traffic.
In outdoor cases, fronthaul/backhaul links could as well be wireless, operating at carrier frequencies above 30 GHz.
Refer [10] for more detailed study on bands above 6 GHz.
Another interesting case of wireless backhaul link is its application in public transports (low to high speed).
A moving cell installed inside the moving train/bus/airplane provide best connectivity to passengers
with wireless backhaul to outside cells installed along the route.
To have high data speeds throughout, field cases like cell edge, outdoor-to-indoor are to be considered.
Sub-6 GHz carrier frequencies provide wider coverage; however, at cell edge, another nearer access is needed to maintain the data speed.
Note that having another smaller cell add handover interruption delay.
Split user plane and having user plane connectivity from two cells (one wider area cell and the other smaller area cell) with
right protocols shall help here.
|
|
|
|
|
|
|
|
|
|
