International Business Machines Corporation

Dinesh Kashinath Anvekar

Manpreet Singh Dang

Amol Prakash

Rajeev Shorey

Manika Kapoor

A method and apparatus of combating the problem of interference in master-slave time division duplex indoor wireless networks based on standards, such as the Bluetooth&#x2122; standard, is proposed. The method involves a frequency look-ahead scheme in frequency hopping systems, a scheme of monitoring states of master-slave wireless communication links through values recorded in link history counters, and a scheme of scheduling an appropriate slave unit and choosing a suitable packet size to overcome the effect of interfering sources, if any, in the pico-cell.

Frequency look-ahead and link state history based scheduling in indoor wireless pico-cellular networks

Password entry is done by displaying to a user distinct codes corresponding to characters in the user's password. The user then serially enters codes corresponding to characters while concealing the entry. Only a limited number of keys are used for password entry. In one example, two keys, a &ldquo;HIT&rdquo; key and a &ldquo;NEXT&rdquo; key, are provided within a concealing hood, and the password in entered serially as a number of &ldquo;HIT&rdquo; key hits. The user is prompted to enter digits corresponding to symbols of his or her password with a display of unique m-ary number codes assigned mutually exclusively to different characters. The scheme can be easily implemented in existing computer systems entirely through a conventional ASCII keyboard or mouse, by using adjacent keys on the keyboard or left and right mouse buttons. As the method requires only a few keys, concealing the keys to prevent viewing of key entry is possible.

Method for non-disclosing password entry

A method and apparatus minimize battery discharge of mobile communication devices in short range wireless radio communication networks by switching receiving antennas to minimize transmitted power for a mobile communication device. Multiple receiving antennas and at least one transmitting antenna are used. The receiving antennas are switched for each mobile communication device to minimize transmitted power required by a mobile communication device. Switching between receiving antennas is accomplished by measuring power of a signal received from a mobile communication device at each receiving antenna, and selecting a receiving antenna based on the measured power. A database of switchings is maintained for the mobile communication devices, and an initial selection of a receiving antenna is based on the last switching or a trend indicated by most recent switchings. Alternatively, the initial switching is to a centrally located receiving antenna.

Mobile battery discharge minimization in indoor wireless networks by antenna switching

A data communication for a handoff mobile unit is maintained by data forwarding through neighboring mobile units in indoor wireless cellular communication networks operates such that, when the master unit has no available channels, the mobile unit switches over to master status to create an ad hoc cell. The mobile unit then pages neighboring slave mobile units for data forwarding assistance. The mobile unit chooses one or more slave mobile units and establishes wireless links with the chosen slave mobile units. These chosen mobile units then have two masters; one the master unit of the cell and the other the handoff mobile unit which has created the ad hoc cell. A list of the slave mobile units in the ad hoc cell is sent to the network server, and data communication proceeds with data forwarding through the chosen mobile slave units. When a channel becomes available with the master unit for the cell, the handoff mobile unit becomes a slave mobile unit to the master unit and the ad hoc cell is dissolved.

Maintaining data communication through neighboring mobile units during handoff

Pointer positioning device based on infrared light sources and detectors that is compact, rugged and ergonomically easy to use such as can be used in laptop computers and similar devices. The pointer positioning device fits in the same area as a conventional touch-pad device in a portable computing device. It detects movement in a movement area by scanning for shadow information with infrared (IR) light sources. To increase the resolution of scanning and to avoid non-uniform beam widths, the scanning of the touchpad area may be carried out by using low power IR laser beams produced by a single IR laser source each for x and y directions and a plurality of optical fibers to transmit the laser beams in the x and y directions. Optionally, this divergency is minimized by positioning IR light sources and light detectors in an alternating pattern around the periphery of a movement area. A mouse device with an opaque plunger depressed with a finger is used as an object to create a well defined shadow in the x and y directions of a movement area.

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New Delhi, India

Dinesh Kashinath Anvekar