Increasing the capacity of a cellular radio network

Details Increasing the capacity of a cellular radio network Increasing the capacity of a cellular radio network

1997-06-12

2000-07-18

Nguyen, Lee

Telecommunications

Radiotelephone system

Zoned or cellular telephone system

455444, 455450, H04Q 736

Patent

active

060919558

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to cellular radio networks and particularly to methods for increasing the capacity of a cellular radio network.


BACKGROUND OF THE INVENTION

The most significant factor reducing the capacity of radio systems is the limited frequency spectrum available. The capacity of a radio system is thus dependent on how efficiently the radio frequencies allocated to the system can be utilized. In cellular radio networks, enhanced utilization of radio frequencies is based on frequency reuse; the same frequency is reused at several locations that are sufficiently spaced apart, which affords a vast increase in system capacity. This is counteracted by increased complexity in the network as well as in the mobile units which must be capable of selecting a base station from among several possible base stations. For example, if the same frequency is reused in every ninth cell, the spectral allocation of N frequencies permits the use of N/9 carriers simultaneously in any cell. Diminishing the cell size or reducing the distance between cells using the same frequency will enhance capacity on the one hand, but also increases co-channel interference. Therefore, selection of the reuse factor is often a compromise between co-channel interference and the traffic carrying capacity of the system.
Since the frequency spectrum allocated to a cellular radio network is fixed and the number of subscribers is rapidly increasing, efficient use of the allocated frequency spectrum is vital to any network operator. Hence, various features increasing the traffic carrying capacity in the cellular network will provide much-needed relief to operators, particularly in crowded urban areas. Radio network evolution towards high-capacity radio networks has the following main alternatives: increasing the number of channels, splitting the cells (small cells), microcellular networks, multi-layered networks, underlay-overlay networks, and other capacity enhancement concepts, such as half-rate channels, frequency hopping, and power control. In the following, these alternatives will be described in more detail.


Increasing the Number of Channels

The simplest way to supplement capacity is by increasing the number of channels. Since the allocated cellular spectrum per network operator is very limited, this method does not give relief from capacity problems.


Splitting Cells (Small Cells)

When cell sizes are reduced below a radius of 1 km, there generally is a need to lower the antenna height below rooftop level. This is because coverage to localized areas at street level cannot be efficiently engineered from a rooftop installation. Such lowering of antennas causes problems in designing coverage. Prediction of ranges for these types of installations is less well understood than in cases of macrocells. Furthermore, interference management becomes more difficult from below rooftop installations, as overspill into co-channel base stations cannot be equally controlled. Cell overspill may eventually reduce cell sizes to the point where conventional planning practices and radio systems do not work efficiently. Additionally, any significant capacity enhancement is accompanied by major in vestments in BTS sites and transmission connections. Splitting of cells is a good method for capacity relief up to a certain point. Unfortunately, urban area capacity requirements are so high that this method does not offer help in the long run. Cell splitting can therefore only be used for short term relief.


Microcellular Network

There is no exact definition of "microcellular network". A cell having a small coverage area and antennas below rooftop level could be the characteristics in the definition of a "microcell". Microcellular concepts are often mistakenly referred to as "multi-tiered", but a "microcell" can be deployed without a multi-layer architecture. In implementing cell splitting below a certain limit and placing antennas below rooftop level or in buildings, advanced solution radio network planning and radio resour

REFERENCES:
patent: 5038399 (1991-08-01), Bruckert
patent: 5285447 (1994-02-01), Hulsebosch
patent: 5357559 (1994-10-01), Kallin et al.
patent: 5506869 (1996-04-01), Royer
patent: 5557657 (1996-09-01), Barnett

Affiliated with

Also associated with

Rating

Increasing the capacity of a cellular radio network does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Increasing the capacity of a cellular radio network, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Increasing the capacity of a cellular radio network will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2046872