Abstract:
For determining use of receive diversity in a mobile station, a control system ( 210 or 401 ) determines a demand level for use of communication resources. A transmitter ( 300 ) communicates a message indicating use of receive diversity at a mobile station based on the determined demand level. In another aspect, a receiver ( 200 ) receives a channel and determines transmit power level of the channel for being at a lower or upper transmit power level limit. The control system ( 210 or 401 ) controls receive diversity by selecting a number of receiver chains ( 290 ) based on the determined transmit power level. In another aspect, receiver ( 200 ) receives a channel and determines a channel condition of the channel and duration of the channel condition. Control system ( 210 or 401 ) controls receive diversity by selecting a number of receiver chains ( 290 ) based on the determined channel condition and the duration.
Abstract:
Reverse link busy bits are independently generated by each base station (102, 104 and 106) and indicative of whether the transmitting base station (102, 104 and 106) has reached a reserve link capacity limit. In a first exemplary embodiment, the remote station (122) combines the multipath components of the reverse link busy bits from each of the transmitting base stations (102, 104 and 106) in its Active Set and in response transmits a reverse link signal only when all of the reverse link busy bits indicate that the base stations (102, 104 and 106) in the remote stations Active Set have reverse link capacity. In a first alternative embodiment, the remote station weights, the reverse link busy signals in accordance with the signal strength of the base station (102, 104 or 106) transmitting the busy signal and determines whether to transmit based on the weighted sum of the busy signals.
Abstract:
A method and apparatus for controlling the data rates for communications to and from a base station (2) and a plurality of remote users (4). The usage of the communications resource whether the forward link resource, from base station (2) to remote users (4), or reverse link resource, from remote users (4) to base station (2), is measured. The measured usage value is compared against at least one predetermined threshold value and the data rates of communications or a subset of communications on said communications resource is modified in accordance with said comparisons.
Abstract:
In a wireless communication system, in order to determine a level of loading, the system enters a period of silence during which a designated remote unit (42) continues to transmit but other remote unit transmissions are interrupted. The base station (40) and designated remote unit (42) perform closed loop power control on a reverse link signal received from the designated remote. A first series of power control commands accumulated and a first corresponding transmit gain adjustment value is stored. Normal operation is resumed. Once again, the base station (40) and designated remote unit perform closed loop power control on the reverse link signal received from the designated remote unit (42). A second series of power control commands are accumulated and a second corresponding transmit gain adjustment value is stored. A level of loading is determined based upon the first and second transmit gain adjustment values.
Abstract:
A system and method is taught for controlling the power level of transmissions within a communication system having a base station, a mobile station, a communication channel, and a pilot channel. The mobile station determines a signal strength value according to a communication signal received by way of the communication channel. A pilot channel signal is determined according to a pilot signal transmitted by way of the pilot channel. The signal to noise ratio of the communication signal is determined according to the determined signal strength value and the pilot channel signal. The power level of a transmission is controlled according to the signal to noise ratio. The noise level in a communication channel within the communication system is estimated. The pilot channel signal includes pilot energy and pilot noise components. The pilot energy component is removed to provide a remaining pilot signal. Communication system operations are controlled according to the remaining pilot signal. The power levels of transmissions are controlled by determining the signal to noise ratio of a signal within the communication channel and determining a difference signal. The difference signal is formed by determining the difference between determined and desired signal to noise ratios. The difference signal is transmitted between the base station and the mobile station. The pilot channel has at least one frame and the power control signal is inserted into the frame. Thus, information representing the strength of the communication signal is transmitted to the base by way of the pilot channel within the frame. The pilot channel can have two information frames for transmitting the power control signal a plurality of times.
Abstract:
In a communications network, a network user communicates through a remote unit (30) with another user via at least one base station (100). The communications network includes a first mobile switching center (MSC-I) which controls communications through a first set of base stations including a first base station (100). The remote unit (30) stores a list of active base stations which has an entry corresponding to each base station with which active communication is established. The first base station (100) has an entry on the list of active base stations. The first base station (100) measures a round trip delay of an active communication signal between the first base station (100) and the remote unit (30). A handoff of the active communication signal is initiated if the round trip delay of the active communication exceeds a threshold if the first base station (100) is designated as a reference base station. Alternatively, the remote unit (30) also stores a list of candidate base stations comprising an entry corresponding to each base station through which active communication may be possible but is not established. A handoff of the active communication signal is initiated if the list of candidate base stations comprises an entry corresponding to a triggering pilot signal.
Abstract:
An integrated search processor (128) used in a modem (110) for a spread spectrum communications system buffers in a buffer (172) received signals samples and utilizes a time sliced transform processor (120) operating on successive offsets from the buffer (172). The search processor (128) autonomously steps through a search as configured by a microprocessor (136) specified search parameter set, which can include the group of antennas to search over, the starting offset and width of the search window to search over, and the number of Walsh symbols to accumulate results at each offset. The search processor (128) calculates the correlation energy at each offset, and presents a summary report of the best paths found in the search to use for demodulation element (122) reassignment. The search is done in a linar fashion independent of the probability that a signal being searched for was transmitted at any given time.
Abstract:
A plurality of methods for achieving the soft or softer handoff process such that the performance of a system is improved. A first method is based on delaying the softer handoff process. A second method is based on reducing the power of transmissions from the sector having the weakest signal strength. A third method is based on eliminating transmissions from the sector having the weakest signal strength. A fourth method adds a new base station or sector only when the mobile unit is in need of additional power to operate properly. In all four methods, reverse link demodulation in each sector may continue with or without the transmission of the forward link. In all four methods the operation could be based on the signal strength of the reverse link signal or the forward link. It is also possible to combine two or more of these methods to create a hybrid method.
Abstract:
A method and apparatus for matching the location of the forward link handoff boundary to the reverse link handoff boundary. A system constant is chosen which defines the product of the received power and the transmitted pilot power at every base station. The reverse link power level is measured at the base station and the forward link power level is compensated for the reverse link loading to maintain the constant product. Thereby the forward link handoff boundary to the reverse link handoff boundary are aligned to the same location.
Abstract:
A method and apparatus providing softer handoff of a mobile unit (90) between sectors (50, 70 and 80) of a common base station (60). A sectorized base station (60) comprises a set of demodulation elements (240A-204N). Each demodulation element (240A-204N) may be assigned to a signal from one of a plurality of sectors. The output of the demodulators (240A-204N) are combined before the decoding process independent of the sector from which the data originated. This configuration provides improved output data reliability, more stable power control, and more efficient use of resources at the base station.