Multiplex communications – Diagnostic testing – Determination of communication parameters
Reexamination Certificate
2000-12-07
2004-10-26
Hsu, Alpus H. (Department: 2665)
Multiplex communications
Diagnostic testing
Determination of communication parameters
C370S332000, C370S335000, C370S342000, C455S067700, C455S453000
Reexamination Certificate
active
06810018
ABSTRACT:
I. TECHNICAL FIELD
This application relates generally to communication systems and, more particularly, to a method and apparatus for load balancing in communication networks.
II. BACKGROUND
Referring to
FIGS. 1
,
2
a
,
2
b
, and
3
, an illustrative embodiment of a conventional code division multiple access/high data rate (CDMA/HDR) communication network
10
may include a packet data service node (PDSN)
12
that is operably coupled to the Internet
14
and a base station controller (BSC)
16
that is operably coupled to access points (APs)
18
a
,
18
b
, and
18
c
. Access terminals (ATs)
20
a
,
20
b
, and
20
c
in turn may be operably coupled to one or more of the APs
18
a
,
18
b
, and
18
c.
As will be recognized by persons having ordinary skill in the art, a CDMA/HDR communication network typically utilizes a combination of time division multiple access (TDMA) and CDMA. In an illustrative embodiment, each communication channel is shared among several users, but on an as-needed basis rather than a fixed time slot as in TDMA. An example of a CDMA/HDR communications network is the wireless communication network available from Qualcomm, Inc. that, in an illustrative embodiment, provides a 2.4 Mbps data rate in a standard 1.25 MHZ CDMA bandwidth.
During operation of the network
10
, in an illustrative embodiment, an active set
22
of APs may communicate with the AT
20
a
utilizing a wireless forward communication link
24
and a wireless reverse communication link
26
. In an illustrative embodiment, at any given time period, only one of the APs in the active set
22
may communicate with the AT
20
a
in the forward communication link
24
. By contrast, in the reverse communication link
26
, the AT
20
a
may communicate with one or more of the APs in the active set
22
. As will be recognized by persons having ordinary skill in the art, the active set
22
of APs may include one or more APs
18
.
Furthermore, during operation of the network
10
, in an illustrative embodiment, in the forward communication link
24
, the APs
18
may transmit a power control signal, a pilot signal, and/or a data payload to the ATs
20
using a power control channel
24
a
, a pilot channel
24
b
, and/or a data payload channel
24
c
, respectively. As will be recognized by persons having ordinary skill in the art, the forward communication link
24
may include a plurality of power control signals, pilot signals, as well as other conventional signals. In an illustrative embodiment, the power control signal controls the power of the signals transmitted by the corresponding AT
20
. Thus, in this manner, the power level of signals transmitted by a particular AT
20
is controlled by one or more of the APs
18
. In an illustrative embodiment, in the reverse communication link
26
, the ATs
20
may transmit data rate control signals to the APs
18
using a data rate control channel
26
a
. In an illustrative embodiment, the data rate control signal controls the rate of data transmitted by the corresponding AP
18
to a particular AT
20
as a function of the carrier to interference ratio (C/I) for the pilot signal transmitted by the corresponding AP to the particular AT. Thus, in this manner, the rate of data transmission from a particular AP
18
to a particular AT
20
is controlled as a function of the calculated C/I for the pilot signal that was transmitted from the particular AP
18
to the particular AT
20
.
In a typical CDMA/HDR network, as illustrated in
FIG. 3
, an AT
20
a
may communicate with a plurality of APs,
18
a
and
18
b
, and each AP,
18
a
and
18
b
, in turn may service one or more additional ATs
20
within corresponding wireless cells,
22
a
and
22
b
. One of the shortcomings of such conventional CDMA/HDR networks is that the APs,
18
a
and
18
b
, may be unevenly loaded. Thus, the available capacity for data transmission from the APs,
18
a
and
18
b
, to the ATs
20
serviced by the APs may be uneven. As a result, the level of data throughput from the APs,
18
a
and
18
b
, to the AT
20
a
may be less than desirable.
The present invention is directed to improving the load balancing of CDMA/HDR communication networks.
III. SUMMARY
According to one aspect of the present invention, a method of load balancing in a CDMA/HDR communications network including one or more access points capable of servicing an access terminal is provided that includes the access terminal monitoring the quality of the forward communication links between the access points and the access terminal, the access terminal monitoring the capacity utilization of the access points, and the access terminal requesting data transmission from a selected one of the access points as a function of the monitored quality of the forward communication links and the monitored capacity utilizations of the access points.
According to another aspect of the present invention, a method of determining a forward loading factor for an access point in a CDMA/HDR communications network including an access terminal and an access point is provided that includes monitoring forward activity bits for the access point for a predetermined number of time slots within a time window, counting the number of active slots for the access point, and calculating the forward loading factor for the access point by dividing the number of active slots by the total number of time slots.
According to another aspect of the present invention, a communications network is provided that includes one or more access points, and an access terminal operably coupled to the access points. The access terminal is adapted to: (1) monitor the quality of the forward communication links between the access points and the access terminal, (2) monitor the capacity utilization of the access points, and (3) request data transmission from a selected one of the access points as a function of the monitored quality of the forward communication links and the monitored capacity utilizations of the access points.
According to another aspect of the present invention, a communication network is provided that includes an access terminal, and an access point operably coupled to the access terminal. The access terminal is adapted to: (1) monitor forward activity bits for the access point for a predetermined number of time slots within a time window, (2) count the number of active slots for the access point, and (3) calculate the forward loading factor for the access point by dividing the number of active slots by the total number of time slots.
The present embodiments of the invention provide a number of advantages. For example, the present illustrative embodiments permit load balancing in CDMA/HDR communication networks. In this manner, CMDA/HDR communication networks may be more efficiently utilized. In addition, permitting the access terminal to select the access point to transmit data to the access terminal as a function of the quality of the forward communication link and the available capacity of the access points provides an efficient and reliable method of selection. Furthermore, the use of specific parameters such as the carrier to interference ratio and the forward loading factor permit the ATs
20
to efficiently and reliably calculate the selection parameter P.
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CDMA/HDR: “A Bandwidth-Efficient High-Speed Wireless Data Service for Nomadic Users”, by Paul Bender, Peter Black, Matthew Grob, Roberto Padovani, Nagabhushana Sindhushayana, and Andrew Viterbi, Qualcomm, Incorporated, IEEE Communications Magazine, Jul. 2000, pp. 70-77.
Khafizov Farid
Paranchych David
Wu Geng
Haynes and Boone LLP
Hsu Alpus H.
Nortel Networks Limited
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