Power-controlled random access
First Claim
1. In a code-division-multiple-access (CDMA) system employing spread-spectrum modulation comprising a base station (BS) comprising a BS-spread-spectrum transmitter and a BS-spread-spectrum receiver, and a plurality of mobile stations, each mobile station (MS) comprising a MS-spread-spectrum transmitter and a MS-spread-spectrum receiver, a method comprising the steps of:
- computing an initial power estimate for a first access attempt by one of the mobile stations;
transmitting from the MS-spread-spectrum transmitter of the one mobile station a spread-spectrum signal signifying a first attempt to utilize a random access channel, at a power level based on the initial power estimate;
receiving one or more access attempt signals relating to the random access channel at the BS-spread-spectrum receiver;
measuring the one or more access attempt signals received by the BS-spread-spectrum receiver;
computing a closed loop power control symbol specifying an extent that power of the measured one or more received access attempt signals differs from a target power;
broadcasting a control message containing the closed loop power control symbol from the BS-spread-spectrum receiver; and
if the MS-spread-spectrum receiver of the one mobile station does not detect an acknowledgement responsive to the first access attempt of the one mobile station;
(a) receiving the broadcast control message and obtaining the closed loop power control symbol;
(b) processing a signal received from the base station in the MS-spread-spectrum receiver of the one mobile station to produce an open loop power control symbol specifying an extent of a change in power for uplink transmissions regarding the random access channel;
(c) generating a power control command as a function of both the closed loop power control symbol and the open loop power control symbol; and
(d) transmitting from the MS-spread-spectrum transmitter of the one mobile station a spread-spectrum signal signifying a second attempt to utilize the random access channel, at a power level based on the power control command.
5 Assignments
0 Petitions
Accused Products
Abstract
A novel power-controlled random-access method allows a mobile station to gain fast access to the base station. At the mobile station, a composite power control command is devised after an initial access attempt. The determination of the composite command uses an open-loop power-control symbol and a closed-loop power-control symbol, to decide the action of the mobile station upon transmission of its next random-access signal. In the preferred embodiment, the composite power control command can specify different levels of increase or decrease in transmission power, and the composite power control command can specify a back-off by the mobile station. This composite power-control mechanism can help resolve collision between mobile stations accessing the same random access sub-channel and therefore maintain a low-delay in the random-access process and a high-utilization on the access-channel resource.
-
Citations
16 Claims
-
1. In a code-division-multiple-access (CDMA) system employing spread-spectrum modulation comprising a base station (BS) comprising a BS-spread-spectrum transmitter and a BS-spread-spectrum receiver, and a plurality of mobile stations, each mobile station (MS) comprising a MS-spread-spectrum transmitter and a MS-spread-spectrum receiver, a method comprising the steps of:
-
computing an initial power estimate for a first access attempt by one of the mobile stations;
transmitting from the MS-spread-spectrum transmitter of the one mobile station a spread-spectrum signal signifying a first attempt to utilize a random access channel, at a power level based on the initial power estimate;
receiving one or more access attempt signals relating to the random access channel at the BS-spread-spectrum receiver;
measuring the one or more access attempt signals received by the BS-spread-spectrum receiver;
computing a closed loop power control symbol specifying an extent that power of the measured one or more received access attempt signals differs from a target power;
broadcasting a control message containing the closed loop power control symbol from the BS-spread-spectrum receiver; and
if the MS-spread-spectrum receiver of the one mobile station does not detect an acknowledgement responsive to the first access attempt of the one mobile station;
(a) receiving the broadcast control message and obtaining the closed loop power control symbol;
(b) processing a signal received from the base station in the MS-spread-spectrum receiver of the one mobile station to produce an open loop power control symbol specifying an extent of a change in power for uplink transmissions regarding the random access channel;
(c) generating a power control command as a function of both the closed loop power control symbol and the open loop power control symbol; and
(d) transmitting from the MS-spread-spectrum transmitter of the one mobile station a spread-spectrum signal signifying a second attempt to utilize the random access channel, at a power level based on the power control command. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A method of attempting access to a random access channel serviced through a base station of a code-division-multiple-access (CDMA) wireless communication system, the method comprising:
-
transmitting a spread-spectrum signal signifying a first attempt to utilize the random access channel, from a mobile station, at a predetermined power level; and
if the mobile station does not detect an acknowledgement responsive to the first attempt;
receiving a broadcast control message from the base station containing a closed loop power control symbol specifying an extent that power of a signal received at the base station differs from a target power;
processing a signal received from the base station to produce an open loop power control symbol specifying an extent of a change in power for uplink transmissions regarding the random access channel;
generating a power control command as a function of both the closed loop power control symbol and the open loop power control symbol; and
transmitting from the mobile station a spread-spectrum signal signifying a second attempt to utilize the random access channel in a manner controlled as a function of the power control command. - View Dependent Claims (9, 10)
-
-
11. A code-division-multiple-access (CDMA) wireless remote station, comprising:
-
a CDMA transmitter;
a CDMA receiver; and
a controller coupled to the CDMA receiver for responding to signals received via the CDMA receiver and coupled for controlling the CDMA transmitter, such that in operation the CDMA wireless remote station is for performing the following steps;
transmitting a spread-spectrum signal signifying a first attempt to utilize a random access channel, from the wireless remote station, at a predetermined power level; and
if the wireless remote station does not detect an acknowledgement responsive to the first attempt;
receiving a broadcast control message from a base station containing a closed loop power control symbol specifying an extent that power of a signal received at the base station differs from a target power;
processing a signal received from the base station to produce an open loop power control symbol specifying an extent of a change in power for uplink transmissions regarding the random access channel;
generating a power control command as a function of both the closed loop power control symbol and the open loop power control symbol; and
transmitting from the wireless remote station a spread-spectrum signal signifying a second attempt to utilize the random access channel in a manner controlled by the power control command. - View Dependent Claims (12, 13, 14, 15, 16)
-
Specification