as) United States
`a2) Patent Application Publication (o) Pub. No.: US 2004/0022208 Al
`(43) Pub. Date: Feb. 5, 2004
`
`Dahodet al.
`
`US 20040022208A1
`
`(54) PROVIDING ADVANCED
`COMMUNICATIONS FEATURES
`
`(52) UESICk: sonsanomenneewcnn 370/328; 370/401
`
`(75)
`
`Inventors: Ashraf M. Dahod, Andover, MA (US);
`Michael Silva, East Sandwich, MA
`(US); Peter Higgins, Sandwich, MA
`(US); Rajat Ghai, West Yarmouth, MA
`(US); John DePietro, Brewster, MA
`(US); Nick Lopez, Sleepy Hollow, IL
`(US); Paul Shieh, Westborough, MA
`(US)
`
`Correspondence Address:
`HALE AND DORR, LLP
`60 STATE STREET
`BOSTON, MA 02109
`
`(73) Assignee: Starent Networks, Tewksbury, MA
`
`(21) Appl. No.:
`
`10/210,897
`
`(22)
`
`Filed:
`
`Aug. 1, 2002
`
`Publication Classification
`
`(ST) Wnts)! asasmasacens H04Q 7/00; HO4L 12/28;
`HO4L, 12/56
`
`(57)
`
`ABSTRACT
`
`Advanced communications features are provided in a mobile
`communications network having at least one mobile switch-
`ing center and at least one mobile station subsystem. The
`mobile switching center and mobile station subsystem each
`communicate signaling messages according to a mobile
`signaling protocol. An indication is received that a half-
`duplex mobile communications session is to be initiated
`between a first mobile station subsystem and a second
`mobile station subsystem. The first and second mobile
`station subsystems include full-duplex communications
`apparatus for use in full-duplex mobile communications
`sessions. The half-duplex mobile communications session
`relies on the first and second mobile station subsystems, and
`all of the relianceis only on the full-duplex communications
`apparatus. Mobile communications telephone calls are
`established with the first mobile station subsystem and the
`second mobile station subsystem. Oneof the first and second
`mobile station subsystems is selected as a voice signal
`source in the half-duplex communications session.
`
`v7 400
`
`
`
`SOFTSWITCH
`
`001
`001
`
`Facebook Ex. 1009
`Facebook Ex. 1009
`U.S. Pat. 8,243,723
`US. Pat. 8,243,723
`
`

`

`Patent Application Publication
`
`US 2004/0022208 Al
`
`Feb. 5, 2004 Sheet 1 of 13
`
`LuvY¥Oldd
`
`002
`002
`
`

`

`Patent Application Publication
`
`Feb. 5, 2004 Sheet 2 of 13
`
`US 2004/0022208 Al
`
`FIG. 2
`PRIOR ART
`
`003
`003
`
`

`

`Patent Application Publication
`
`US 2004/0022208 Al
`
`Feb. 5, 2004 Sheet 3 of 13
`
`LAOS
`
`HOLIMS
`
`VeOla
`
`004
`004
`
`

`

`Patent Application Publication
`
`US 2004/0022208 Al
`
`Feb. 5, 2004 Sheet 4 of 13
`
`cOV
`
`OLV
`
`005
`005
`
`

`

`Patent Application Publication
`
`Feb. 5, 2004 Sheet 5 of 13
`
`US 2004/0022208 Al
`
`USER
`
`525
`
`USER
`
`[is
`
`co
`
`PTTDIRECTORY FIG.4
`
`530
`
`517
`
`515
`
`006
`006
`
`

`

`Patent Application Publication
`
`Feb. 5,2004 Sheet 6 of 13
`
`US 2004/0022208 Al
`
`INDICATE THAT A PTT SESSION SHOULD COMMENCE
`
`
`
`
`
`
`
`ESTABLISH VOICE CONNECTIONTOINITIATOR MS
`AND INTENDED RECIPIENT MS
`
`
`
`REFER TO PTT DIRECTORY}2020
`
`
`
`CLOSE VOICE CONNECTIONS|2260
`
`FIG. 5
`
`007
`
`

`

`Patent Application Publication
`
`Feb. 5, 2004 Sheet 7 of 13
`
`US 2004/0022208 Al
`
`LO
`“
`g
`GN
`Lu
`wor
`-Om
`Zz
`Oy
`- =O
`Or
`=k
`zoOs
`= jt
`
`=o] C286JEe
`
`LO
`—_
`co
`
`QZ
`
`&
`USER|}MS|-]BTS|]BSC
`USER||ms[+4BTS[+]Bsc
`
`FIG.6
`
`822
`
`820
`
`812
`
`810
`
`008
`008
`
`

`

`Patent Application Publication
`
`Feb. 5, 2004 Sheet 8 of 13
`
`US 2004/0022208 Al
`
`PLAY BACK RECORDING
`
`3080
`
`FIG. ¢
`
`009
`
`

`

`Patent Application Publication
`
`Feb. 5,2004 Sheet 9 of 13
`
`US 2004/0022208 Al
`
`THE SUBSCRIBERDIALS '1-800-888-VIM1"
`
`IMG
`(ST-16)
`
`"ENTER 1 TO CREATE A NEW GROUP, ENTER 2 TO RECORD A MESSAGE, OR 3|ACCESSING
`SYSTEM
`TO OBTAIN STATUS FROM A PREVIOUS VIM SESSION"
`
`Slee oe
`
`DEFINING
`ANEW
`VG.
`
`SUBSCRIBER
`
`"IF YOU WISH TO RECORD A MESSAGE, START RECORDING AT THE TONE,
`OTHERWISE STAY ON THE LINE FOR MORE OPTIONS. ONCE YOU'VE COMPLETED
`RECORDING, YOU MAY HANG-UP TO SEND YOUR MESSAGE."
`
`_
`
`SUBSRIBER ENTERS1
`
`"PLEASE ENTER EACH NUMBER FOLLOWED BYTHE # KEY, WHEN
`FINISHED PLEASE PRESS THE STAR KEY."
`
`THE SUBSCRIBER ENTERS EACH NUMBER AND ENDSWITH THE STAR KEY
`
`THE SYSTEM WOULD THEN PLAY BACK THE NUMBERS FOLLOWED BY
`"TO ACCEPT PRESS 1, TO CHANGE PRESS 2"
`
`SUBSCRIBER ENTERS1
`
`SUBSCRIBER ENTERS THE VIM GROUDID
`
`"AT THE TONE START RECORDING YOUR MESSAGE. HANG-UP WHENFINISHED"
`
`:
`
`RECORD
`AND PLAY
`OUT A
`MESSAGE
`
`THE SUBSCRIBER RECORDS THE MESSAGE AND HANGS-UP
`
`THE SYSTEM STARTSPLACING OUT-BOUND CALLS TO
`THE MEMBERS OF THE VG.
`
`THE SUBSCRIBERDIALS '1-800-888-VIM1'
`
`"ENTER 1 TO CREATE A NEW GROUP, ENTER 2 TO RECORD A MESSAGE,
`OR 3 TO OBTAIN STATUS FROM A PREVIOUS VIM SESSION"
`
`OPTIONAL
`STATUS
`RETRIEVAL
`
`SUBSCRIBER ENTERS3
`
`THE SYSTEM PLAYS OUT THE RECEIVE STATUS
`OR EACH MEMBEROFTH
`
`FIG. 8
`
`010
`010
`
`

`

`Patent Application Publication
`
`Feb. 5, 2004 Sheet 10 of 13
`
`US 2004/0022208 Al
`
`6‘Sls
`
`O1dAVYL,uauwadveeSCSNebv.Cie
`
`OldaVULL‘
`9L-LSa:1Oe(oni)‘,(eR
`
`..DIWVOSW
`
`ovNSaiRecs)(wshi)ved
`
`
`
`(OWI)SEN2
`
`_o”MINOSW»leeWwe
`
`ASVavLvd
`
`WIA
`
`OlasVaL
`
`daYdvagd
`91-15
`
`waYvad
`
`“Didavel
`a~SbZH
`
`MYOMLAN
`
`d|
`
`.. onva_ROH
`
`011
`011
`
`
`
`
`
`
`

`

`Patent Application Publication
`
`Feb. 5,2004 Sheet 11 of 13
`
`US 2004/0022208 Al
`
`aeveaneneens
`
`Anna eeeN LEN LTT NONE TTTERTEEEEET OUNCE SeMeteenens
`
`FIG.10
` IPNETWORK
` DISTRIBUTED VIMDATABASE
` (IMG)
`"eyHLR/weAUCs
`
`ST-16
`
`1
`
`isr (IMG)
`
`
`
`IS-41ORGSM-MAP
`
`012
`012
`
`

`

`Patent Application Publication
`
`Feb. 5, 2004 Sheet 12 of 13
`
`US 2004/0022208 Al
`
`LVHO10V
`
`YsAdsS
`
`
`
`(dWIS)LaYOVd
`
`LINDUID
`
`
`
`(dS)LSaNOVd
`
`dis
`
`dis
`
`HOLIMSLAOS
`
`HOLIMSLIOS""
`
`dis:i8¥ZH
`
`LLSls
`
`(OWI)
`
`
`
`(dWIS)LaNOVd
`
`LINDYID
`
`013
`013
`
`
`
`
`
`

`

`Patent Application Publication
`
`Feb. 5, 2004 Sheet 13 of 13
`
`US 2004/0022208 Al
`
`or
`
`ASvdd
`
`SOIOA>
` <ZIN-O10NOWIASAV1d91-15
`SIN cbOld
` (ZWOLTVDNMOGHV)40002dis
`LWOLTIVONMOGYV3L)YO00¢dis
`
`LXSLNODSLVIYO*X-O19CAV)$72'H
`
`
`
`
`SOuSSWO|§8_|OSNea|
`|SHOWSSIN/SS,=£JOWSMSINIV,
`
`
`
`‘HL¥d‘HLWdSOlOA>i<bNOIONOWIASAV1d91-LS
`
`(X-910)dNasLSS
`ATIVNOLINSIN|==S39¥SSAIN
`(XOID)ALFIdNOD
`
`(LW-OID)13YZSS
`LW-910)13uZSS
`LW-9}0)WIZSS
`‘LNO1431=ATIVNOLLNALNI
`|PINON
`LNAWNOISSY|<<<<
`'ALFTdOO
`
`SISNOdSSu
`
`(ZW‘LWSWS)
`
`YWWIALAD
`
`014
`014
`
`
`
`
`
`
`

`

`US 2004/0022208 Al
`
`Feb. 5, 2004
`
`PROVIDING ADVANCED COMMUNICATIONS
`FEATURES
`
`BACKGROUND
`
`[0001] This invention relates to providing advanced com-
`munications features.
`
`(0002] Wireless telecommunication systems are able to
`provide wireless versions of information services tradition-
`ally providedby land-line or copper wire systems. Examples
`of wireless communications applications include Advanced
`Mobile Phone Service (AMPS) analog cellular service and
`Code Division Multiple Access (CDMA) and Advanced
`Mobile Phone Service (AMPS-D)digital cellular service in
`North America, and Group Speciale Mobile (GSM) cellular
`service in Europe.
`
`(0003] Although the particular application may vary, the
`components of a wireless communication system are gen-
`erally similar, as described in more detail below. For
`example, a wireless communication system usually includes
`a radio terminal or mobile station, a radio base station, a
`switch or network control device, often referred to as a
`mobile telephone switching office (MTSO), and a network to
`which the wireless communications system provides access,
`such as the Public Switched Telephone Network (PSTN).
`
`[0004] The various wireless communication applications
`use any of multiple modulation techniques for transmitting
`information to efficiently utilize the available frequency
`spectrum. For example, frequency division multiple access
`(FDMA), time division multiple access (TDMA), and code
`division multiple access modulation techniques are used to
`build high-capacity multiple access systems. Telecommuni-
`cation systems designed to communicate with many mobile
`stalions occupying a common radio spectrum are referred to
`as multiple access systems.
`
`nique for transmitting information over a wireless commu-
`nication system in which the bandwidth occupied by the
`transmitted signal ts significantly greater than the bandwidth
`required by the baseband information signal (e.g., the voice
`signal). Thus, CDMA modulation spectrally spreads a nar-
`rowband information signal over a broad bandwidth by
`multiplex modulation, using a codeword to identify various
`signals sharing the same frequency channel. Recognition of
`the transmitted signal takes place by selecting the spectrally-
`coded signals using the appropriate codeword. In contrast to
`the narrowband channels of approximately 30 kHz used in
`FDMA and TDMA modulation techniques, a CODMAsystem
`generally employs a bandwidth of approximately 1.25 MHz
`or greater.
`
`the mobile communication systems
`‘Typically,
`[0008]
`described above are arranged hierarchically such that a
`geographical “coverage area” is partitioned into a number of
`smaller geographical areas called “cells.” Referring to FIG.
`1, each cell
`is preferably served by a Base Transceiver
`Station (“BTS”) 102¢@. Several BTS 102a-n are centrally
`administered via fixed links 104a-n by a Base Station
`Controller (“BSC”) 106a. The BTSs and BSC are sometimes
`collectively referred to as the Base Station Subsystem
`(“BS”) 107. Several BSCs 106b-n may be centrally admin-
`istered by a Mobile Switching Center (“MSC”) 110 via fixed
`links LO8a-n.
`
`[0009] MSC 110 actsas a local switching exchange (with
`additional features to handle mobility management require-
`ments, discussed below) and communicates with the phone
`network (“PSTN”) 120 through trunk groups. U.S. mobile
`networks include a home MSCand a serving MSC. The
`home MSC is the MSC corresponding to the exchange
`associated with a Mobile Subscriber (also referred to above
`as a mobile station or “MS”); this association is based on the
`phone number, such as the area code, of the MS. Examples
`of an MS include a hand-held device such as a mobile phone,
`a PDA, a 2-way pager, or a laptop computer, or Mobile Unit
`Equipment, such as a mobile unit attached toa refrigerator
`van or a rail car, a container, or a trailer.
`
`For example, in an FDOMA analogcellular system,
`(0005]
`such as an AMPSanalogcellular radio system, the available
`frequency spectrum is divided into a large number of radio
`channels,e.g., pairs of transmit and receive carrier frequen-
`cies, each of which corresponds to a message transmission
`channel. The bandwidth of each transmit and receive fre-
`[0010] The home MSC is responsible for a Home Location
`Register (“HLR”) 118 discussed below. The serving MSC,
`quency channel is narrowband, generally 25-30 kHz. Thus,
`on the other hand, is the exchange used to connect the MS
`the FDMA system permits information to be transmitted in
`call to the PSTN. Consequently, sometimes the home MSC
`a bandwidth comparable to the bandwidth of the transmitted
`and serving MSC functions are served by the same entity,
`information, such as a voice signal. The cellular service area
`but other times they are not (such as when the MS is
`in the FOMAsystem is generally divided into multiple cells,
`roaming). Typically, a Visiting Location Register (“WLR”)
`each cell having a set of frequency channels selected so as
`116 is co-located with the MSC 110 andalogically singular
`to help reduce co-channel interference between cells.
`HLR is used in the mobile network (a logically singular
`[0006]
`Frequency division is often combined with time
`HLR maybephysically distributed but is treated as a single
`division so that
`transmission circuits are distinguished in
`entity). As will be explained below, the HLR and VLR are
`both the frequency and time domain, e.g., in a FD/TDMA
`used for storing subscriber information and profiles.
`system. In a digital FD/TDMA (commonlyreferred to as
`TDMA)cellular system, a narrowband frequency channel is
`reformatted as a digital transmission path which is divided
`into a number of time slots. The data signals from different
`calls are interleaved into assigned time slots and sent out
`with a correspondingly higher bit rate, the time slot assigned
`to each mobile station being periodically repeated. Although
`the TDMA bandwidth may be somewhat
`larger than the
`FDMAbandwidth, a bandwidth of approximately 30 kHz is
`generally used for AMPS-Ddigital TDMA cellular systems.
`
`[0011] Radio channels 112 are associated with the entire
`coverage area. As described above, the radio channels are
`partitioned into groups of channels allocated to individual
`cells. The channels are used to carry signaling information
`to establish call connections and related arrangements, and
`to carry voice or data information once a call connection is
`established.
`
`(0012] Mobile network signaling has at least two signifi-
`cant aspects. One aspect involves the signaling between an
`MSandthe rest of the network. In the case of 2G (“2G”is
`the industry term used for “second generation”) and later
`
`(0007] Another approach to cellular multiple access
`modulation is CDMA. CDMA is a spread spectrum tech-
`
`015
`015
`
`

`

`US 2004/0022208 Al
`
`Feb. 5, 2004
`
`technology, this signaling concerns access methods used by
`the MS (such as TDMA or CDMA), pertaining to,
`for
`example, assignment ofradio channels and authentication. A
`second aspect
`involves the signaling among the various
`entities in the mobile network, such as the signaling among
`the MSCs, BSCs, VLRs, and HLRs. This second part
`is
`sometimes referred to as the Mobile Application Part
`(“MAP”) especially when used in the context of Signaling
`System No. 7 (“SS7”). SS7 is a common channel signaling
`system by which elements of the telephone network
`exchange information, in the form of messages.
`
`(0013] The various forms of signaling (as well as the data
`and voice communication) are transmitted and received in
`accordance with various standards. For example, the Elec-
`tronics Industries Association (“ELA”) and Telecommunica-
`tions Industry Association (“TIA”) help define many U.S.
`standards, such as IS-41, which is a MAP standard. Analo-
`gously, the CCITT and ITU help define international stan-
`dards, such as GSM-MAP, which is an international MAP
`standard. Information about these standards is well known
`and may be found from the relevant organizing bodies as
`well as in the literature, see, e.g., Bosse, SIGNALING IN
`TELECOMMUNICATIONS NETWORKS(Wiley 1998).
`
`‘To deliver a call from an MS 114, a user dials the
`(0014]
`number and presses “send” on a cell phone or other MS. The
`MS 114 sends the dialed number indicating the service
`requested to the MSC 110 via the BS 107. The MSC 110
`checks with an associated VLR 116 (described below) to
`determine whether the MS 114 is allowed the requested
`service. The serving MSC routes the call
`to the local
`exchange of the dialed user on the PSTN 120. The local
`exchangealerts the called user terminal, and an answer back
`signal is routed back to the MS 114 through the serving MSC
`110 which then completes the speech path to the MS. Once
`the setup is completed the call may proceed.
`
`(0015] To deliver a call to an MS 114, (assuming that the
`call originates from the PSTN 120) the PSTN user dials the
`MS’s associated phone number. At least according to U.S.
`standards, the PSTN 120 routes the call to the MS’s home
`MSC(which mayor may not be the MSC serving the MS).
`The MSC then interrogates the HLR 118 to determine which
`MSCis currently serving the MS. This also acts to inform
`the serving MSCthat a call is forthcoming. The home MSC
`then routes the call to the serving MSC. The serving MSC
`pages the MSvia the appropriate BS. The MS responds and
`the appropriate signaling links are set up.
`
`the BS 107 and MS 114 may
`[0016] During a call,
`cooperate to change channels or BTSs 102, if needed, for
`example, because of signal conditions. These changes are
`known as “handofts,” and they involve their own types of
`known messages and signaling.
`
`[0017] One aspect of MAP involves “mobility manage-
`ment.” Different BSs and MSCs may be needed and used to
`serve an MS, as the MS 114 roamsto different locations.
`Mobility management helps to ensure that the serving MSC
`has the subscriber profile and other information the MSC
`needs to service (and bill) calls correctly. To this end, MSCs
`use VLR 116 and HLR 118. The HLRis used to store and
`retrieve the mobile identification number (“MIN”), the elec-
`tronic serial number (“ESN”), MSstatus, and the MSservice
`profile, among other things. The VLR stores similar infor-
`mation in addition to storing an MSC identification that
`
`In addition, under appropriate
`identifies the home MSC.
`MAPprotocols, location update procedures (or registration
`notifications) are performed so that
`the home MSCof a
`Mobile Subscriber can locate its users. These procedures are
`used when an MS roams from one location to another or
`when an MSis powered on and registers itself to access the
`network. For example, a location update procedure may
`proceed with the MS 114 sending a location update request
`to the VLR 116 via the BS 107 and MSC 110. The VLR 116
`
`sends a location update message to the HLR 118 serving the
`MS114, and the subscriber profile is downloaded from the
`HLR 118 to the VLR 116. The MS 114 is sent an acknowl-
`edgement of a successful
`location update. The HLR 118
`requests the VLR (if any) that previously held profile data to
`delete the data related to the relocated MS 114.
`
`[0018] FIG. 2 shows in more detail the signaling and user
`traffic interfaces between a BS 107 and an MSC 110 ina
`
`CDMA mobile network. The BS 107 communicates signal-
`ing information using an SS7-basedinterface for controlling
`voice and data circuits known as the “Al” interface. An
`interface known as “A2” carries user traffic (such as voice
`signals) between the switch component 204 of the MSC and
`the BS 107. An interface known as “A5” is used to provide
`a path for user traffic for circuit-switched data calls (as
`opposedto voice calls) between the source BS and the MSC.
`Information about one or more of Al, A2, AS may be found
`in CDMA Internetworking—Deploying the Open-A Inter-
`face, Su-Lin Low, Ron Schneider, Prentice Hall, 2000, ISBN
`0-13-088922-9.
`
`[0019] Mobile communications providers are supplying
`newerservices, ¢.g., “data calls” to the Internet. Forat least
`some of these services, MSCsare not cost effective because
`they were primarily designed for voice calls. Integration of
`new services into the MSCisdifficult or infeasible because
`of the proprietary and closed designs used by many MSC
`software architectures. Thatis, the software logic necessary
`to provide the services is not easy to add to the MSC 110.
`Often, a switch adjunctis used to provide such services. For
`example, an Inter-Working Function (“IWF”) is an adjunct
`to route a data call
`to the Internet. Either approach—
`integrating functionality into the MSC oradding a trunk-side
`adjunct—involves the MSC in the delivery of service.
`Integrating new services via MSCdesign changes or through
`trunk-side adjuncts can increase network congestion at the
`MSCand consume costly MSC resources.
`[0020] Data calls typically make use ofthe Internet, which
`is an example of a packet-switching medium. A packet-
`switching medium operates as follows. A sequence of data
`is to be sent from one host to another over a network. The
`data sequence is segmented into one or more packets, each
`with a header containing control
`information, and each
`packet is routed through the network. A common type of
`packet switching is datagram service, which offers little or
`no guarantees with respect
`to delivery. Packets that may
`belong together logically at a higher level are not associated
`with each other at the network level. A packet mayarrive at
`the receiver before another packet sent earlier by the sender,
`may arrive in a damaged state (in which case it may be
`discarded), may be delayed arbitrarily (notwithstanding an
`expiration mechanism that may cause it to be discarded),
`may be duplicated, and may be lost.
`[0021] With respect to the Internet, multicast communi-
`cation refers to the transmission of identical data packets to
`
`016
`016
`
`

`

`US 2004/0022208 Al
`
`Feb. 5, 2004
`
`selected, multiple destinations on an Internet Protocol net-
`work. (In contrast, broadcast communication refers to the
`indiscriminate transmission of data packets to all destina-
`tions, and unicast communication refers to the transmission
`of data packets to a single destination.)
`(0022] Each participant in a multicast receives informa-
`tion transmitted by any other participant in the multicast.
`Users connected to the network who are not participants in
`a particular multicast do not receive the information trans-
`mitted by the participants of the multicast. In this way, the
`multicast communication uses only the network components
`(¢.g., switches and trunks) actually needed for the multicast
`transmission.
`
`In multicast processing, when a potential partici-
`{0023]
`pant (“host”) is directed to join a particular IP multicast
`group, the host sends a “request to join” message to the
`nearest multicast-capable router to request to join the mul-
`ticast group and receive information sent to this group. For
`example, a host A sends a message to join multicast group
`Y, and a host B sends a message to join multicast group X.
`Arouter R propagates the request up to the multicast source
`if the data path is not already in place.
`for
`for group X,
`[0024] Upon receiving an IP packet
`example, the router R maps an IP multicast group address
`into an Ethernet multicast address, and sends the resultant
`Ethernet packet to the appropriate switch or switches.
`[0025] According to the Internet Group Management Pro-
`tocol (“IGMP”), a host’s membership in a multicast group
`expires when the router does not receive a periodic mem-
`bership report from the host.
`[0026] With respect to interaction among MSs, a Nextel
`service (known as Nextel Direct Connect®, using Special-
`ized Mobile Radio technology, and described at http://
`www.nextel.com/phone_services/directconnect.shtml) hav-
`ing two versions has been proposed for special connection
`calls among MSs. Both versions of the special connection
`calls require special-purpose MSs.In the first version, a one
`to one conversation is allowed between two mobile tele-
`phone subscribers, e.g., A and B. When A wishes to have
`special connection communication with B, A enters B’s
`private identification number, holds down a push to talk
`(“PTT”) button, waits for an audible alert signifying that B
`Is ready to receive, and starts speaking. Tolisten, A releases
`the PTTbutton. If B wishes to speak, B holds down the PTT
`button and waits for an audible confirmation that A is ready
`to receive, The service allows a subscriber to choose private
`identification numbers from scrollable lists displayed on
`mobile telephone handsets or to search a list of pre-stored
`names of subscribers.
`
`text
`includes instant
`[0028] Technology on the Internet
`messaging (IM), which lets users receive text messages
`moments after the messages are sent. IM provides a way to
`chat with friends and also provides a useful tool for business.
`IM provides the convenience of electronic mail (e-mail) and
`the immediacy of a telephone call. The text messages arrive
`in real time (or nearly so) because both parties are constantly
`connected to the network. Recipients receive messages as
`fast as the data can travel across the Internet. (E-mail is less
`immediate, E-mail technology sends messages to a server
`that stores the items until the messages are downloaded by
`the recipient's e-mail software.) When a user logs on to an
`IM service, the software lets a server know that the user is
`available to receive messages. To send a message to some-
`one else, the user begins by selecting that person’s name,
`usually from a contact list the user has built. The user then
`enters the message and clicks a “Send”button. A data packet
`is sent that contains address informationfor the recipient, the
`message, and data identifying the sender. Depending on the
`particular service, the server either directly relays the mes-
`sage to the recipient or
`facilitates a direct connection
`between the user and the recipient.
`
`[0029] An IM service typically uses one of three mecha-
`nisms to transport messages: a centralized network, a peer-
`to-peer connection, or a combination of both a centralized
`network and a peer-to-peer connection. In the case of a
`centralized network (used by, e.g., MSN Messenger), users
`are connected to each other through a series of servers that
`are linked to form a large network. When a user sends a
`message, servers locate the recipient’s computerstation and
`route the message through the network until the message
`reachesits destination.
`
`[0030] According to the peer-to-peer approach (used by,
`e.g., ICQ), a central server keeps track of which users are
`online
`and the users’ unique
`Internet Protocol
`(IP)
`addresses.
`(An IP address identifies a computer, which
`allows the computer to send and receive data via the
`Internet.) After a user logs on, the server providesthe user’s
`computer with the IP addresses of each other user on the
`user’s contactlist who is currently logged on, When the user
`creates a message to send to another user, the user’s com-
`puter sends the message directly to the recipient’s computer,
`without
`involving the server. Messages traverse only the
`network portion between the sender’s and recipient’s com-
`puters, which speeds transfers by helping to avoid network
`traffic.
`
`[0031] America Online, Inc. (AOL) supplies AOL Instant
`Messenger (AIM) which combinesthe centralized and peer-
`to-peer methods, When a user sends a text message,
`the
`In the second version, conversations are allowed
`[0027]
`message travels along AOL’s centralized network. However,
`among members of a pre-defined group of subscribers,
`when the user sendsafile, the users’ computers establish a
`known as a Talkgroup, which is identified by a number, The
`peer-to-peer connection.
`mobile telephone handset may allow Talkgroup numbers to
`be searched through the control surface of the handset. In
`order to place a groupcall, the initiating subscriber, ¢.g., A,
`locates a Talkgroup number in the handset, holds down the
`PTT button, and, upon receiving an audible confirmation
`such as a chirp, can start speaking. All of the other Talkgroup
`members on the group call can only listen while A is holding
`down the PTTbutton. If A releases the PTTbutton, another
`member on the group call may hold down the PTT button,
`acquire control signaled by the audible confirmation, and
`start speaking.
`
`In another variation of Internet technology,at least
`[0032]
`one wireless Internet system has been proposed that pro-
`vides reliable access to tens of megahertz of bandwidth
`across a wide geographic area, using local wireless trans-
`ceiver technology(e.g., in a nanocell system). In contrast to
`the cellular wireless voice system, which relies on tens or
`hundredsof cells in a region, the local wireless transceiver
`system relies on thousands or tens of thousands of trans-
`ceivers in the region. In such a system, each transceiver may
`cover, ¢.g., 0.05 square kilometers, which is about one-
`
`017
`017
`
`

`

`US 2004/0022208 Al
`
`Feb. 5, 2004
`
`telephone system and constitutes a completed message.
`Based on an indication from the mobile station subsystem,
`a set of mobile station subsystem destinations is determined
`for the message data. For each of the mobile station sub-
`system destinations,
`it
`is determined whether the mobile
`station subsystem destination is ready to play back the
`message data. Each of the mobile station subsystem desti-
`nations includesreal-time communications apparatus for use
`in real-time communications sessions. The readiness deter-
`mination relies on the mobile station subsystem destinations.
`All of the reliance is only on the real-time communications
`apparatus.
`
`Implementations of the invention may provide one
`[0038]
`or more of
`the
`following advantages. By supplying
`enhancedservices that do not require new hardware at the
`user end, service providers can achieve additional revenue
`and profits with little or no investment of time or resources
`into changesat the user end. Users gain mobility, flexibility,
`and time efficiency by being able to make more use of voice
`input for user control and content entry, so that interaction
`with communications resources is less demanding on eyes
`and fingers. The user experience is improved over conven-
`tional offerings so that the stability and loyalty of the user
`base is improved.
`
`[0039] Other advantages and features will become appar-
`ent from the following description, including the drawings,
`and from the claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIGS. 1-2, 3A-3B, 4, 6, 9-11 are block diagrams of
`[0040]
`communications systems.
`
`[0041] FIGS. 5, 7 are flow diagrams of procedures in
`communications systems.
`[0042]
`FIGS.8, 12 are call flow diagrams of sequencesin
`communications systems.
`
`DETAILED DESCRIPTION
`
`{0044] The enhanced mobile communications system has
`an Internet media gateway mechanism (“IMG”) and a Soft-
`switch mechanism that may be used as described below.
`FIG.3A illustrates an example system 400 having an IMG
`410A connected between BSC 415A and MSC 420A and
`communicating with a Softswitch 425A. IMG 410A com-
`municates with BSC 415A by Al, A2, and A5 interfaces. As
`described below, Softswitch 425A coordinates pathway
`setup and communication between BSC 415A and MSC
`420A through IMG 410A. IMG 410A also communicates
`with the Internet 430, through which IMG 410Ais able to
`direct messages to a mail server 440, as described below.
`Other IMGsand Softswitches may be provided similarly in
`connection with other BSCs and MSCs as exemplified in
`FIG. 3A by IMG 410B, Softswitch 425B, BSC 415B, and
`MSC 420B. MSCs 420A, 420B are connected to, and can
`communicate with each other through, PSTN 460. Soft-
`Switches 425A, 425B are connected to, and can communi-
`
`[0043] An enhanced mobile communications system pro-
`vides advanced communications features. As described
`below, the features may include a half-duplex mobile com-
`In an aspect of the invention, an indication is
`(0036]
`
`received that a half-duplex mobile communications session munications session (e.g., walkie-talkie style) betweenafirst
`conventional MS and a second conventional MS, and/or an
`is to be initiated between a first mobile station subsystem
`and a second mobile station subsystem. (As used herein,
`instant voice message system.
`“half-duplex” refers to a session in which at most one MSat
`a time is considered a transmission source; “half-duplex”
`does not necessarily mean the sharing, alternating or other-
`wise, of any channel or medium for
`transmission and
`reception.) The first and second mobile station subsystems
`include full-duplex communications apparatus for use in
`full-duplex mobile communications sessions. The half-du-
`plex mobile communications session relies on the first and
`second mobile station subsystems, and all of the relianceis
`only on the full-duplex communications apparatus. Mobile
`communications telephone calls are established with the first
`mobile station subsystem and the second mobile station
`subsystem. One of the first and second mobile station
`subsystems is selected as a voice signal source in the
`half-duplex communications session.
`
`hundredth the coverage of a conventional cell. High spatial
`reuse of the radio frequency (RF) spectrum allowsthe local
`wireless transceiver system to accommodate many more
`active devices at a given data rate than a conventional cell
`system. In addition, since users are closer to access points,
`the local wireless transceiver system accommodates lower-
`power transmissions. The local wireless transceiver system
`can support
`large numbers of devices, running at high
`speeds, with relatively little drain on the devices’ batteries.
`
`For example, in a citywide local wireless trans-
`[0033]
`ceiver system network of 10,000transceiver access points
`(cell centers), if each point provides its users with 1-Mb/s
`collective throughput, 10 active devices per transceiver can
`be supported at 100 kb/s each, which amounts to 100,000
`active devices in the city. If each device is active 10 percent
`of the time, such a network can support a million devices,
`although some accounting would need to be made for
`bandwidth consumed by overhead for channel access, hand-
`offs, and any provision for asymmetric traffic (¢.g., in which
`more bits flow toward a device than from it).
`
`(0034] Each local wireless transceiver system access point
`may be or resemble access points for wireless local area
`network (LAN) technology such as IEEE 802.11. An asyn-
`chronousdigital subscriber line (ADSL), or a cable modem
`line may be used to provide a link between each access point
`and the Internet (a wireless link may be used as well or
`instead). With respect to the siting of access devices, since
`each device requires electrical power and is preferably
`elevated for adequate radio frequency coverage, sites on
`utility poles and buildings are typical candidates, with the
`high-speed neighborhood Internet access infrastructure serv-
`ing as a backbone.
`
`SUMMARY
`
`[0035] Advanced communications features are provided
`in a mobile co