EP0528522A2 — Digital communication network using radio links

Claim 1

Independent Claim 297 words

A digital communications network having a host computer, a communication controller (CC) connected to said host computer, a plurality of base stations (BSs) connected to said communications controller, a like plurality of antennas respectively connected to and included in said base stations, each BS having a predetermined domain within which remote terminals can be attached thereto by radio links operating at a predetermined frequency, said BSs being located so as to provide overlapping domains, and a plurality of remote terminals (RTs) for communicating with said BSs by said radio links, wherein each BS comprising a radio BS transceiver for transmitting and receiving messages to and from RTs located within the predetermined domain of said BS, a digital BS processor connected to said BS transceiver for controlling operation thereof, and a digital BS storage connected to said BS processor for storing BS tables and BS routines to be executed by said BS processor; each RT comprising a radio RT transceiver, a field strength meter connected to said RT transceiver for measuring field strengths of messages received by said RT transceiver from BSs within whose domains said RT is located, a digital RT processor connected to said transceiver for controlling operation thereof, and an RT digital storage connected to said RT processor for storing an RT table and RT routines to be executed by said RT processor; each RT being operative to monitor messages received from BSs, store within said RT table a list of BSs and signal strengths of messages received therefrom, and transmit to the one of said BSs having the strongest signal strength in said RT table a sign-on message; each BS comprising decision making means responsive to sign-on messages directed thereto to decide which BS should be attached to said RTs transmitting said sign-on messages.

Claim 2

Dependent Claim 297 words

A digital communications network having a host computer, a communication controller (CC) connected to said host computer, a plurality of base stations (BSs) connected to said communications controller, a like plurality of antennas respectively connected to and included in said base stations, each BS having a predetermined domain within which remote terminals can be attached thereto by radio links operating at a predetermined frequency, said BSs being located so as to provide overlapping domains, and a plurality of remote terminals (RTs) for communicating with said BSs by said radio links, wherein each BS comprising a radio BS transceiver for transmitting and receiving messages to and from RTs located within the predetermined domain of said BS, a digital BS processor connected to said BS transceiver for controlling operation thereof, and a digital BS storage connected to said BS processor for storing BS tables and BS routines to be executed by said BS processor; each RT comprising a radio RT transceiver, a field strength meter connected to said RT transceiver for measuring field strengths of messages received by said RT transceiver from BSs within whose domains said RT is located, a digital RT processor connected to said transceiver for controlling operation thereof, and an RT digital storage connected to said RT processor for storing an RT table and RT routines to be executed by said RT processor; each RT being operative to monitor messages received from BSs, store within said RT table a list of BSs and signal strengths of messages received therefrom, and transmit to the one of said BSs having the strongest signal strength in said RT table a sign-on message; each BS comprising decision making means responsive to sign-on messages directed thereto to decide which BS should be attached to said RTs transmitting said sign-on messages.

Claim 3

Dependent Claim 90 words

A digital communications network in accordance with claim 1 wherein each RT processor is operative to sort entries in said RT table in a descending order based on signal strength, and said sign-on message is sent to the BS having the strongest signal strength indicated in said table, said sign-on message includes a list of BSs in said table having the strongest signal strengths, and said BS to which the sign-on message is transmitted selects from such list which BS should be attached to the RT sending said sign-on message.

Claim 4

Dependent Claim 42 words

A digital communications network in accordance with claim 1 or 2 wherein each of said transceivers comprises: a transmitter, a receiver, and an antenna connected to said transmitter and to said receiver for transmitting and receiving messages to and from said BSs.

Claim 5

Dependent Claim 62 words

A digital communications network in accordance with claim 1, 2 or 3 wherein: each BS comprises means for monitoring how many RTs are covered by such BS, and said decision making means of such BS is connected to said monitoring means so as to make an attachment decision based at least in part on how many RTs are covered by such BS.

Claim 6

Dependent Claim 72 words

A digital communications network in accordance with claim 1, 2 or 3 wherein said network comprises: storage means for storing indications of which RTs are attached to which BSs; said decision making means being further operative to determine from said indications how many RTs are attached to each BS in said list of BSs identified in each sign-on message and make an attachment decision based at least in part on such determination.

Claim 7

Dependent Claim 47 words

A digital communications network in accordance with claim 5 wherein: said storage means is in said CC; and each BS is operative in response to making an attachment decision of transmitting to and storing in said storage means identifications of which BSs are attached to which RTs.

Claim 8

Dependent Claim 82 words

A digital communications network in accordance with any preceding claim wherein said host computer sends messages to RTs by routing each message through said CC, and identifies in each message the RT to which the message is to be sent; said CC being operative in response to receipt of such message to look up in said storage means which BS is attached to the RT identified in the message and then route such message to such BS for transmission to such RT.

Claim 9

Dependent Claim 71 words

A digital communications network in accordance with any preceding claim wherein an attachment decision is made by selecting the BS having the lowest WEIGHT value determined in accordance with the following formula: where WEIGHT[n] is the WEIGHT value for a given BS[n], CT[n] is the total number of RTs which base station BS[n] can hear, USERS[n] is the number of users attached to BS[n], and "s" and "t" are optimization constants.

Claim 10

Dependent Claim 27 words

A digital communications network in accordance with claim 8 wherein each BS storage includes a table for storing WEIGHT values for each BS attached to said CC.

Claim 11

Dependent Claim 22 words

A digital communications network in accordance with claim 8 wherein the value USERS-[n] is obtained from said storage means in said CC.

Claim 12

Dependent Claim 71 words

A digital communications network in accordance with any preceding claim wherein said CC comprises a plurality of message queues for storing messages to be sent from said CC to said host computer, there being one message queue for each BS connected to said CC; each BS being operative to transmit to said CC all messages received from any RT whereby said message queues may contain duplicate messages from the same RT.

Claim 13

Dependent Claim 30 words

A digital communications network in accordance with claim 11 wherein said CC is operative to recognize duplicate messages and send only one of said duplicate messages to said host computer.

Claim 14

Dependent Claim 67 words

A digital communications network in accordance with claim 12 wherein said messages stored in said queues include identifications of which RT sent each message, said CC being operative upon analyzing a message in a queue and determining such message is from an RT attached to said BS corresponding to such queue to send such message to said host computer and discard any duplicate messages in other queues.

Claim 15

Dependent Claim 57 words

A digital communications network in accordance with claim 11, 12 or 13 wherein said CC is operative in response to analyzing a message in a given queue to determine that such message was intended for a BS corresponding to a different queue and in response to such determination search through said different queue for the same message.

Claim 16

Dependent Claim 59 words

A digital communications network in accordance with claim 14 wherein said CC is further operative in response to said search to move said message from said given queue into said different queue when such message is not found by such search, and to discard said message in said given queue when such message if found in said different queue.

Claim 17

Dependent Claim 45 words

A digital communications network in accordance with any preceding claim wherein each RT includes error monitoring means operative to detect errors in messages sent from a BS attached thereto and request a new sign-on when the number of errors thus detected exceeds a predetermined value.

Digital communication network using radio links

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