摘要:
Beacon symbols are sent periodically from the base stations in an OFDM system. The entire power of the base station, or a large portion of it is concentrated in these symbols, thus they are very easily recognized by the mobile stations. The frequencies upon which these symbols are transmitted and the time at which they are transmitted communicates information such as the base station/sector identity and the preferred carrier of the given base station/sector to the mobile station. In order to avoid collision between the beacon symbols of different base stations and sectors, the beacon symbols from different base stations/sectors are transmitted at different symbols times and on different subcarriers.
摘要:
A channel estimation system comprises a filtering component that selectively scales a plurality of carriers as a function of location of the plurality of carriers within a frequency band, wherein the plurality of carriers comprises at least one data carrier and at least one pilot carrier. A component thereafter extrapolates an observation from the at least one pilot carrier, wherein a channel is estimated as a function of the extrapolated observation. The scaling of the carriers facilitates reducing a flooring effect associated with channel estimation. The filtering component can be employed at a transmitter and/or at a receiver, and can be activated and/or deactivated as a function of a sensed data packet type.
摘要:
Techniques for transmitting data with short-term interference mitigation in a wireless communication system are described. In one design, a first station (e.g., a base station or a terminal) may receive a message sent by a second station to request reduction of interference on at least one resource. In response to receiving the message, the first station may determine a first transmit power level to use for the at least one resource based on one or more factors such as a priority metric sent in the message, the buffer size at the first station, etc. The first station may send a power decision pilot on the at least one resource at a second transmit power level determined based on the first transmit power level.
摘要:
Providing for interference reduction and/or avoidance utilizing backhaul signaling between wireless access points (APs) of a wireless access network (AN) is described herein. By way of example, an interference avoidance request (IAR) can be issued by an AP to reduce signal interference on forward link (FL) and/or downlink (DL) transmissions by neighboring APs. The IAR can be routed via a backhaul network and/or over-the-air via access terminals (ATs) coupled with the AP or one or more interfering APs. Upon receiving the IAR, an interfering AP can determine reduced transmit power levels for FL and/or RL transmissions and respond to the IAR. The response can include reduced power levels and can be sent via the backhaul network or OTA. By employing the backhaul network in full or in part, interference avoidance can be conducted even for semi-planned or unplanned heterogeneous networks coupled by the backhaul.
摘要:
Techniques for sending control messages are described. In an aspect, assignment messages may be acknowledged based on either linked or dedicated acknowledgement (ACK) resources. A terminal may receive an assignment message from a base station, determine whether to acknowledge the assignment message, and determine ACK resources to use to acknowledge the assignment message. The ACK resources may be linked to a control block on which the assignment message was received, linked to resources given by the assignment message, or assigned to the terminal. The terminal may send the acknowledgement on the ACK resources. In another aspect, a control message may be acknowledged based on ACK resources determined based on the control message or the control block. The ACK resources may be linked to resources assigned by the control message or linked to the control message. The terminal may send an acknowledgement for the control message on the ACK resources.
摘要:
Estimation of channel characteristics and interference level in a time-varying multi-carrier multi-user systems is carried out concurrently. To perform the estimation, a multitude of data symbols and dedicated pilot symbols are transmitted over the channel. Next, an initial estimate value is selected for the interference level. The initial estimate value for the interference level is used together with the received pilot symbols to provide a first estimate of the channel. The first estimate of the channel is used to determine a new updated value for the interference level, which in turn, is used to update the value of the first estimate of the channel iteratively. The iterations continue until the iteratively updated values of the interference level and channel satisfy predefined limits. The data symbols and the final updated value of the channel are subsequently used to provide a second estimate for the channel.
摘要:
Techniques for mitigating temporary loss of synchronization in a wireless communication system are described. In an aspect, a cell may periodically broadcast a mode indicator to indicate synchronous operation or asynchronous operation by the cell. The cell may also broadcast its cell identity (ID), which may omit the mode indicator and would then remain unchanged when the cell switches between asynchronous and synchronous operation. In another aspect, the cell may send system time information indicative of its updated system time when switching from asynchronous operation to synchronous operation. The updated system time may be used for communication with terminals after the switch to synchronous operation. In yet another aspect, the cell may decrease its transmit power prior to switching synchronization mode, switch synchronization mode when its transmit power reaches a predetermined power level, and thereafter increase its transmit power.
摘要:
Providing for management of wireless communications in a heterogeneous wireless access point (AP) environment is described herein. By way of example, system data of an over-the-air message can be configured to include information identifying a distinct type of transmitting base station. In some aspects, the information can include an access type of the base station and/or a sector ID for distinguishing the base station among large numbers of other base stations. According to other aspects, the information can include wireless channel resources designated for a particular type of base station, or blanked by the transmitting base station, to facilitate interference reduction on such resources. By employing aspects of wireless communication management disclosed herein, efficient and reliable communication can be affected in large heterogeneous AP networks.
摘要:
Techniques for transmitting data with short-term interference mitigation in a wireless communication system are described. In one design, a serving base station may send a message to a terminal to trigger short-term interference mitigation. In response, the terminal may send a message to request at least one interfering base station to reduce interference on at least one resource. Each interfering base station may determine a transmit power level to be used for the at least one resource and may send a pilot at this transmit power level. The terminal may estimate the channel quality of the at least one resource based on at least one pilot received from the at least one interfering base station. The terminal may send information indicative of the estimated channel quality to the serving base station. The serving base station may send a data transmission on the at least one resource to the terminal.
摘要:
Techniques for sending signaling information using hierarchical coding are described. With hierarchical coding, individual messages for users are encoded using multiple interconnected encoders such that (1) the message for each user is sent at a data rate suitable for that user and (2) a single multicast message is generated for the messages for all users. A base station determines data rates supported by the users and the code rates to achieve these data rates. Each data rate is determined by one or more code rates. Signaling information for the users is mapped to data blocks to be sent at different data rates. Each data block is then encoded in accordance with the code rate(s) associated with the data rate for that data block. A final coded block is generated for all users and transmitted. Each user performs the complementary decoding to recover the message sent to that user.