Faster call set up for Push-to-Call (PTC) services over cellular networks

The present invention relates to the field of communication, and more particularly to the transfer of signals over a bearer network for low latency services provided by a wireless communication network.

Telecommunications providers are continually improving the services they provide to their customers. Wireless services have become very popular by providing convenience to customers. Wireless services such as cellular and PCS phones are common for personal and professional use. As many telecommunications providers offer basic cellular or PCS services, they are competing to offer other new and useful services.

One service provided by one or more telecommunications providers is the Push to Talk (PTT) service. The PTT service was started by Nextel Communications of Reston and VA. PTT-type services are called Push to Call (PTC) services. Push to Call is a service that allows subscribers to use cellular phones like mobile wireless phones. A subscriber can have one or more other subscribers on the subscriber's group list or "buddy list" maintained on the Push to Call (PTC) server at the push of a button on the phone. Connect to someone instantly. Some subscribers prefer the immediate connection provided by PTC services.

<p> One problem with providing PTC services is that they require a low latency call setup. The end-to-end call setup should be less than about 1 second to provide the subscriber's satisfactory mobile radio phone operation. Low latency call setup may also be required for other services. Unfortunately, some current wireless networks may not be able to provide a call setup that is fast enough for services that require a low latency call setup.</p><p> Wireless networks are usually signals<u style="single">(Signaling)</u>Includes networks and bearer networks. One reason current wireless networks may not be able to provide a sufficiently fast call setup is that the signal network for carrying call setup messages provides a low latency call setup. It's not designed for capacity. Since wireless networks serve millions of subscribers, signal networks are designed to handle as many calls as possible. One way for signal networks to increase capacity is through message bundling. Due to message bundling, the signal network has multiple signals to its destination.<u style="single">(Signaling)</u>Buffer the signal message before sending it. Message bundling can allow the signal network to handle higher call loads, but it can also increase call setup delays. This call setup delay may not be significant in the signal network. This is because this signal network generally carries non-real-time critical signal messages. Signal messages can be delayed without any noticeable effect, as long as the delay is not unusual. The call setup wait time for a normal call may be multiple seconds.</p><p> Unfortunately, many wireless networks are not currently configured to provide low latency call setups. Wireless network call setup latency can be too long to provide low latency services, so telecommunications providers offer customers and potential customers expensive low latency services such as PTC services. It may not be possible to propose a service.</p>

<p> The present invention solves the above problems and other problems by operating the wireless communication network and the wireless communication network of the illustrated embodiment described in the present specification. The wireless communication network that implements the present invention is a call signal for a low latency service via a bearer network.<u style="single">(Call signaling)</u>It is possible to provide a low waiting time service by transporting.</p><p> The wireless communication network consists of a base station system, an exchange system, and a transport network connecting the base station system and the exchange system. The carrier network includes a signal network and a bearer network. The signal network is configured to carry the call signal and the bearer network is configured to carry the bearer traffic.</p><p> The bearer network consists of multiple connections. A special connection is established between the exchange system and the base station system via the bearer network. Using a special connection established, at least a portion of the capacity of the special connection is reserved for carrying the call signal. The size of the reserved capacity of the special connection may be dynamic depending on the needs of the wireless network.</p><p> Upon receiving a call signal from a mobile radio device such as a cell telephone, the base station system determines whether the call signal is for a low latency service. An example of a low latency service is the Push to Call service. If the call signal is for a low latency service, the base station system transfers the call signal over a special connection in the bearer network. If the call signal is not for low latency service, the base station system transfers the call signal over a conventional signal network. In response to receiving a call signal over a special connection or signal network, the exchange system transfers the call signal over the packet data network.</p><p> In another embodiment, the exchange system can receive a call signal from the packet data network. As in the above embodiment, a special connection of the bearer network is established and a portion of the capacity of the special connection is reserved for carrying the call signal. Upon receiving the call signal, the exchange system determines whether the call signal is for low latency service. If the call signal is for a low latency service, the exchange system transfers the call signal over a special connection on the bearer network. If the call signal is not for low latency service, the exchange system transfers the call signal over the signal network.</p><p> Advantageously, the wireless communication network described above can provide a low latency call setup using a special connection on the bearer network for carrying the call signal. Special connections and signal networks on the bearer network make up a parallel signal network. Using both special connections and signal networks to carry call signals, wireless networks can optimize call setup latency without sacrificing capacity. The low call setup latency provided by the special connection can allow the wireless network to provide low latency services. The present invention can include other exemplary embodiments described below. In all drawings, the same reference number indicates the same element.</p>

(Conventional network-Figures 1A and 1B) Figures 1A and 1B show the conventional communication network 100 that is useful for understanding the present invention. In Figure 1A, the communication network 100 is Radio Access Network (RAN) 102, Packet Data Network 143, Packet Data Serving Node (PDSN) Server 141, PDSN Server 146, Push To Call (PTC) Server. Includes 142, and Authentication, Authorization, and Billing (AAA) Server 144. The RAN 102, PDSN server 141, PDSN server 146, PTC server 142, and AAA server 144 all connect to packet data network 143. In Figure 1B, network 100 also includes RAN104, which connects to packet data network 143 (see Connection 145 in Figure 1A). Communication network 100 is a third generation mobile system (3G) that provides voice and data services.

In Figure 1A, the RAN 102 performs wireless functions on the communication network 100. The RAN 102 includes a radio network controller (RNC) 110 and a base transceiver station (BRS) 120 connected by a carrier network 130. The transport network 130 consists of a plurality of connections 131 between the RNC 110 and the BTS 120. The transport network 130 includes a signal network 133 and a bearer network 134. The signal network 133 is shown by the dashed line in FIG. 1A. The bearer network 134 is shown in solid line in Figure 1A.

The BTS 120 terminates wireless communication with wireless devices such as the PTC Phone 140. Each BTS 120 contains multiple transceivers (TXR) 122 and channel element (CE) pool 124. Transceiver 122 includes an antenna (not shown) that transmits and receives signals over leased radio frequencies. The transceiver 122 creates a "cell" through which the telephone can communicate with the transceiver 122. Channel element pool 124 represents multiple channel elements for each BTS 120. A channel element is a logical element that represents a BTS 120 resource that executes the process for processing a call.

The BTS 120 communicates with the radio control server (RCS) 136, mobile manager (MM) 138, and RNC 110 over signal network 133 to exchange signals. Generally, there is one RCS 136 for each BTS 120 in RAN 102. The BTS 120 communicates with the RNC 110 over the bearer network 134 to exchange bearer traffic.

The RNC 110 acts as a switch between the BTS 120 and the packet data network 143 to carry packet voice and data. The RNC 110 includes a traffic control server (TCS) 112, a packet control function (PCF) 114, and a frame selector (FS) pool 116. TCS 112 manages RNC 110 resources, such as allocating and deallocating frame selectors for FS pool 116, and manages call setup and call teardown. PCF 114 interfaces RNC 110 with packet data network 143. FS pool 116 represents a pool of RNC 110 frame selectors. A frame selector is a logical element that represents the resources of an RNC 110 that performs the process of processing a cell.

In Figure 1B, the RAN 104 also performs the wireless function of the communication network 100. The RAN 104 includes a radio network controller (RNC) 150 and a base transceiver station (BTS) 160 connected by a carrier network 170. The transport network 170 consists of multiple connections 171 between RNC 150 and BTS 160. The transport network 170 includes a signal network 173 and a bearer network 174. The signal network 173 is shown by the dashed line in FIG. 1B. The bearer network 174 is shown in solid line in Figure 1B.

The BTS 160 terminates wireless communication with wireless devices such as the PTC Phone 180. Each BTS 160 contains multiple transceivers (TXR) 162 and channel element (CE) pool 164. Transceiver 162 includes an antenna (not shown) that transmits and receives signals over leased radio frequencies. The transceiver 162 creates a "cell" through which the telephone can communicate with the transceiver 162. CE pool 164 represents multiple channel elements for each BTS 160.

The BTS 160 communicates with the radio control server (RCS) 176, mobile manager (MM) 178, and RNC 150 over signal network 173 to exchange signals. In general, each BTS 160 in RAN 104 has one RCS 176. The BTS 160 communicates with the RNC 150 over the bearer network 174 to exchange bearer traffic.

The RNC 150 acts as a switch between the BTS 160 and the packet data network 143 to carry packet voice and data. The RNC 150 includes a traffic control server (TCS) 152, a packet control function (PCF) 154, and a frame selector (FS) pool 156. TCS 152 manages RNC 150 resources, such as allocating and deallocating frame selectors in FS pool 156, and manages call setup and call teardown. The PCF 154 interfaces the RNC 150 with the packet data network 143. FS pool 156 represents a pool of RNC 150 frame selectors.

The PTC Phone 140 is a 3G phone that provides voice, data, and Push to Call (PTC) services. The PTC Phone 140 must be registered with the PTC Server 142 in order to be available for the Push to Call (PTC) service. Upon power-on, the PTC Phone 140 generates a registration request and sends the registration request over radio frequency. One of the BTS 120 transceivers 122 receives its registration request from PTC Phone 140. The receiving BTS 120 then sends its registration request over signal network 133. The RNC 110 receives its registration request via signal network 133 and via RCS 136 and MM 138.

Within RNC 110, PCF 114 receives the registration request. In response to the registration request, PCF 114 contacts PDSN server 141 to select one PDSN from the pool of PDSNs. The selected PDSN establishes and maintains a point-to-point protocol (PPP) session between the PTC phone 140 and the PDSN server 141. Using the established PPP session, PCF 114 forwards the registration request to PTC server 142. To facilitate future communications, the RNC 110 sets up a record containing the identification and address of the PTC phone 140 for the selected PDSN.

Upon receiving the registration request, the PTC server 142 records the identification of the PDSN server 141 servicing the PTC phone 140. By default, the PTC phone 140 is assigned to the home RAN or home MSC that provides the most frequent calls to the PTC phone 140. Since the PTC Phone 140 is mobile, the PTC Phone 140 can "roam" outside the area served by Home RAN. When the PTC Phone 140 roams, the PTC Server 142 typically produces a record of the location of the PTC Phone 140 by recording the identification of the PDSN Server 141 currently servicing the PTC Phone 140. The PTC server 142 also includes identification of the PTC phone 140, a "buddy list" set for the PTC phone 140, and the like. The PTC server 142 behaves much like a home location register (HLR) to track the location of the PTC phone 140.

In Figure 1B, the PTC phone 180 is also a 3G phone that needs to be registered with the PTC server 142. Upon power-on, the PTC Phone 180 generates a registration request and sends the registration request over radio frequency. One of the BTS 160 transceivers 162 receives its registration request from the PTC phone 180. The receiving BTS 160 then sends its registration request over signal network 173. The RNC 150 receives its registration request via signal network 173 via RCS 176 and MM 178. Within the RNC 150, the PCF 154 receives the registration request. In response to the registration request, PCF 154 contacts PDSN server 146 to select one PDSN from the pool of PDSNs. The selected PDSN establishes and maintains a point-to-point protocol (PPP) session between the PTC phone 180 and the PDSN server 146. Using the established PPP session, PCF 154 forwards the registration request to PTC server 142. RNC to facilitate future communication The 150 sets up a record containing the identification and address of the PTC phone 180 for the selected PDSN.

Upon receiving the registration request, the PTC server 142 records the identification of the PDSN server 146 servicing the PTC telephone 180. When the PTC Phone 180 roams, the PTC Server 142 typically produces a record of the location of the PTC Phone 180 by recording the identification of the PDSN Server 146 currently servicing the PTC Phone 180.

Using both PTC Phones 140 and 180 registered with PTC Server 142, PTC Phone 140 can make PTC-type calls. To initiate a call, the user of PTC Phone 140 presses the Push to Call button on PTC Phone 140. The PTC Telephone 140 generates a PTC request and sends the PTC request over radio frequency. The PTC request can be directed to one or more recipients. One of the BTS 120 transceivers 122 receives a PTC request from the PTC phone 140. The receiving BTS 120 then sends a PTC request over signal network 133. RNC 110 receives its PTC recording request via RCS 136 and MM 138 over signal network 133.

In response to a PTC request from PTC Phone 140, RNC110 retrieves the records set for PTC Phone 140. This record shows the address of the PDSN used to establish a previous PPP session with PDSN Server 141 (referred to as outgoing PDSN). PCF 114 forwards its PTC request to PTC server 142 via PDSN server 141.

In response to the PTC request, the PTC server 142 identifies the recipient for that PTC call. PTC server 142 can retrieve records about the recipient for that call. The PTC server 142 can refer to the buddy list or group list previously set for the PTC phone 140. The recipient in this case is PTC Phone 180.

Since PTC Phone 180 has established a PPP session with PDSN Server 146, PTC Server 142 is the address of the PDSN used to establish the previous PPP session (referred to as Termination PDSN or PDSN Server 146), PTC Phone 180. Has a record including identification of. Based on this record, the PTC server 142 forwards the PTC request to the PCF 154 of the RNC 150 via the PDSN server 146.

The RNC 150 may not know which BTS 160 serves the PTC Phone 180. Therefore, the MM 138 generates a call request to have the BTS 160 "call" the PTC phone 180. The RNC 150 sends its call request over the signal network 173 to all BTS 160s. In response to a call request, each BTS 160 broadcasts the call over the call channel.

When the PTC phone 180 receives the call, the PTC phone 180 sends a response over the radio frequency. One of the BTS 160 transceivers 162 receives a response from the PTC phone 180. The receiving BTS 160 then transmits this response over signal network 173. The RNC 150 receives this response over the signal network 173 and over the RCS 176 and MM 178.

Within the RNC 150, the PCF 154 forwards this response to the PTC server 142 using the PDSN server 146. The PTC server 142 receives this response and forwards this response to the PCF 114 of the RNC 110 using the PDSN server 141. The RNC 110 forwards this response to the BTS 120 via the signal network 133 and via the MM 138 and RCS 136. The RNC 110 may need to send a call request to all BTS 120s to locate the BTS 120 servicing the PTC phone 140.

Upon receiving this response, the BTS 120 transmits this response to the PTC telephone 140 over radio frequency. The PTC phone 140 receives this response indicating that the PTC call has been set up.

During the setup of a PTC call, a connection is established and resources are allocated to process the call. To establish the connection, RCS 136 sets up the connection between RNC 110 and BTS 120 via bearer network 134. The connection over the bearer network 134 is for carrying bearer traffic for PTC calls. Similarly, RCS 176 sets up a connection between RNC 150 and BTS 160 via bearer network 174. The connection over Bearer Network 174 is also for carrying bearer traffic for PTC calls.

To allocate resources, RCS 136 selects a channel element (CE) from CE pool 124 to process PTC calls. TCS 112 selects a frame selector (FS) from FS pool 116 to handle the call. The selected frame selector and selected channel element correspond to each other, at least for the duration of the PTC call.

When the call is set up, the user begins speaking to PTC Phone 140. The microphone of the PTC phone 140 produces an analog voice signal that represents the user's voice. The PTC phone 140 then digitizes this analog voice signal and inserts this digitized voice into a frame. The PTC telephone 140 encodes this digitized voice based on the Code Division Multiple Access (CDMA) protocol and transmits the digitized voice frame over radio frequencies.

One of the BTS 120 and any other BTS transceiver 122 within the range of the telephone 150 receives its digitized voice frame. The receiving transceiver 122 sends the digitized voice frame to a channel element designed to handle the call. The channel element performs any other processing of its digitized audio frame. The channel element transports its digitized voice frame over the selected connection of bearer network 134 to the corresponding frame selector in the FS pool 116 of the RNC 110 designed to handle the call. To do. The frame selector further encodes the digitized audio frame and transfers the digitized audio frame to PCF 114. The PCF 114 transfers the digitized audio frame to the PTC server 142 via the PDSN server 141. The PTC server 142 transfers the digitized audio frame to the PCF 154 via the PDSN server 146.

The PCF 154 transfers the digitized voice frame to the frame selector of the FS pool 156 designed to handle the call. The frame selector forwards its digitized audio frame over the selected connection of bearer network 174 to the corresponding channel element in CE pool 164. The channel element performs any other processing of its digitized audio frame. The channel element transfers its digitized audio frame to one of the transceivers 162. Transceiver 162 transmits its digitized audio frame over radio frequencies.

The PTC phone 180 receives its digitized voice frame. The PTC Telephone 180 decodes its digitized voice frame based on the Code Division Multiple Access (CDMA) protocol. The PTC telephone 180 then converts the digitized voice into an analog voice signal and applies the analog voice signal to the speaker. The speaker on the PTC Phone 180 then emits audible voice to the user.

Unfortunately, RAN 102 and RAN 104 are not effectively designed to handle low latency services when low latency services require faster call setups (eg, less than a second). .. The call setup time for RAN 102 and RAN 104 may be at least multiple seconds. RAN 102 and RAN

The higher latency of 104 may be due to BTS 120 and BTS 160 sending call signals such as PTC requests and answers over signal networks 133 and 173. Since capacity is the primary priority over signal networks 133 and 173 and there are hundreds of subscribers, signal networks 133 and 173 are designed to handle as many calls as possible. Due to the high call setup latency of RAN 102 and RAN 104, RAN 102 and RAN 104 cannot adequately provide low latency services such as the Push to Call service.

(Configuration and operation of wireless communication network-Figs. 2-3) FIGS. 2-3 and the following description show specific exemplary embodiments of the invention to teach one of ordinary skill in the art how to create and use the best embodiments of the invention. In order to teach the principles of the invention, some conventional embodiments of the invention will be simplified and omitted. Those skilled in the art will appreciate the variations from this embodiment within the scope of the present invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form a number of variants of the invention. Therefore, the present invention is not limited to the specific embodiments described below, but is limited only by the scope of claims and their equivalents.

FIG. 2 shows a wireless communication network 200 according to an exemplary embodiment of the present invention. The radio access network 200 may include a radio access network (RAN) in some embodiments. The wireless communication network 200 is composed of a base station system 202, an exchange system 204, and a transport network 206 configured to connect the base station system 202 and the exchange system 204. The wireless communication network 200 can include other components, devices, or systems not shown in FIG.

The base station system 202 is configured to communicate with the switching system 204 and the mobile radio device 210. An example of a base station system 202 includes a base transceiver station (BTS). The mobile radio device 210 includes any handheld device, or portable device configured to communicate over a radio signal. The mobile radio device 210 may include a cell phone, a PCS phone, a computer, a personal digital assistant (PDA), or other mobile radio device. Base station system 202 can communicate with mobile radio device 210 using CDMA, TDMA, GSM, UMTS, 802.11b, 802.11g, or other radio protocols. In a GSM or UMTS network, base station system 202 can include node B, which has similar functions to BTS.

The exchange system 204 is configured to communicate with the base station system 202 and a packet data network (not shown). The exchange system 204 includes any system or device configured to switch communication between the base station system and the packet data network. An example of an exchange system 204 includes a radio network controller (RNC). In the GSM network, the switching system 204 can include a base station controller (BSC).

The transport network 206 connects the base station system 202 and the exchange system 204. The transport network 206 includes a signal network 212 and a bearer network 214. The signal network 212 is configured to carry the call signal and is shown by the dashed line in FIG. The call signal includes any message or signal used to facilitate call processing, such as call setup and call teardown messages, push to call requests, or another message.

The bearer network 214 consists of one or more connections between the switching system 204 and the base station system 202. Bearer network 214 is configured to carry bearer traffic and is shown in solid line in Figure 2. Bearer traffic consists of voice and / or data sent between the caller and the called party, or between the mobile client and server of the packet data network. In this embodiment, the bearer network 214 is also configured to carry a call signal.

FIG. 3 shows process 300 for the wireless communication network 200, in which the bearer network 214 carries the call signal, in addition to the signal network 212 of the exemplary embodiment of the present invention. In step 302, a special connection 216 of bearer network 214 is established to carry the call signal. The switching system 204, the base station system 202, or another system can establish a special connection 216. The special connection 216 can be established using conventional methods or means. Multiple special connections can be established. In step 304, at least a portion of the capacity of the special connection 216 is reserved for carrying the call signal. The size of the portion of the capacity of the special connection 216 may be dynamic as required by the wireless network 200.

In response to receiving the call signal from the mobile radio device 210, in step 306, the base station system 202 determines whether the call signal is for a low latency service. Low latency services include any communication service to a wireless network that requires even faster call setup times than traditional services, such as less than a second. An example of a low latency service includes a Push to Call service. If the call signal is for a low latency service, in step 308, the base station system 202 transfers the call signal over a special connection 216 of bearer network 214. If the call signal is not for low latency service, in step 310 the base station system 202 transfers the call signal over the signal network 212. In response to receiving a call signal over a special connection 216 or signal network 212, the exchange system 204 forwards the call signal over the packet data network.

Advantageously, the wireless communication network 200 can provide a low latency call setup using the bearer network 124 to carry the call signal. In general, bearer networks carry real-time critical bearer traffic, such as voice calls. Real-time critical bearer traffic is more tolerant of delays and jitter. For example, delays in transporting audio frames for calls on bearer network 214 can be noticeable to the listener. This delay can result in the loss of part of the conversation. Bearer networks are designed to minimize latency and jitter, as delays can have detrimental effects. Therefore, the bearer network 214 is more focused on low latency than the signal network 212, which is more focused on capacity. Bearer network 214 is set up for low latency transmission, so bearer network 214 is pushed to It can provide the low latency call setup required by real-time critical services such as the Call service.

The special connection 216 on the bearer network 214 and the signal network 212 constitutes a parallel signal network. Using both the special connection 216 and the signal network 212 to carry the call signal, the wireless network 200 can optimize the call setup latency without sacrificing capacity.

The special connection 216 can carry bearer traffic in addition to the call signal. To control the latency of the special connection 216, the control system (not shown) can control the amount of bearer traffic allowed for the special connection 216.

In another embodiment, the exchange system 204 is a receiver of a call signal from a packet data network (not shown). As in the previous embodiment, in step 302, a special connection 216 of the bearer network 214 is established, and in step 304, a portion of the capacity of the special connection 216 is reserved for carrying the call signal. In response to receiving a call signal over the packet data network, in step 306, the exchange system 204 determines whether the call signal is for low latency service. If the call signal is for low latency service, in step 308 the switching system 204 transfers the call signal over a special connection 216 of bearer network 214. If the call signal is not for low latency service, in step 310 the switching system 204 transfers the call signal over the signal network 212.

(Communication network configuration and operation-Figs. 4A and 4B) 4A and 4B show the communication network 400 of the exemplary embodiment of the present invention. In Figure 4A, the communication network 400 is Radio Access Network (RAN) 402, Packet Data Network 443, Packet Data Serving Node (PDSN) Server 441, PDSN Server 446, Push To Call (PTC) Server. Includes 442, and Authentication, Authorization, and Billing (AAA) Server 444. RAN 402, PDSN server 441, PDSN server 446, PTC server 442, and AAA server 444 all connect to packet data network 443. In a GSM or UMTS network, the serving GPRS service node (SGSN) and gateway GPRS service node (GGSN) can be used in place of the PDSN server 441 and PCF414. Packet data network 443 may be an Internet Protocol (IP) network, an asynchronous transfer mode (ATM) network, or a combination of the two. In Figure 4B, network 400 also includes RAN404, which connects to packet data network 443 (see Connection 445 in Figures 4A and 4B). Communication network 400 is a third generation mobile system (3G) CDMA network that provides voice and data services. In other embodiments, the communication network 400 may be a GSM, TDMA, or UMTS network.

In Figure 4A, the RAN 402 performs wireless functions on the communication network 400. RAN 402 includes a radio network controller (RNC) 410 and a base transceiver station (BTS) 420 connected by carrier network 430. In a GSM or UMTS network, the RNC 410 may be a base station controller (BSC). Transport network 430 consists of multiple connections 431 between RNC 410 and BTS 420. The transport network 430 includes a signal network 433 and a bearer network 434. The signal network 433 is shown by the dashed line in FIG. 4A. The bearer network 434 is shown in solid line in Figure 4A.

The BTS 420 terminates wireless communication with wireless devices such as the PTC Phone 440. Each BTS 420 includes multiple transceivers (TXR) 422, detection system 423, and channel element (CE) pool 424. Transceiver 422 includes an antenna (not shown) that transmits and receives signals over the leased radio frequency. The transceiver 422 creates a "cell" through which a cellular phone, PCS phone, or other radio device can communicate with the transceiver 422. CE pool 424 represents multiple channel elements for each BTS 420. A channel element is a logical element that represents a resource in the BTS 420 that executes the process for processing a call.

The BTS 420 communicates with the Radio Control Server (RCS) 436, Mobile Manager (MM) 438, and RNC 410 over the signal network 433 to exchange signals. Generally, there is one RCS 436 for each BTS 420 in RAN 402. The BTS 420 communicates with the RNC 410 over the bearer network 434 to exchange bearer traffic. In GSM or UMTS networks, the RCS 436 can also be referred to as the Radio Resource Controller (RRC).

The RNC 410 acts as a switch between the BTS 420 and the packet data network 443 to carry packet voice and data. The RNC 410 includes a traffic control server (TCS) 412, a packet control function (PCF) 414, and a frame selector (FS) pool 416. The RNC410 can also communicate with other BTSs (not shown), other RNCs (not shown), and mobile exchange centers (MSCs) (not shown). TCS 412 manages the resources of RNC 410. For example, the RNC 410 can include 20 processors that work in combination. The TCS 412 can manage the workload processed by each processor. The TCS 412 allocates and deallocates frame selectors in FS pool 416 and manages call setup and call teardown. PCF 414 interfaces RNC 410 with packet data network 443 via PDSN server 441. FS pool 416 is RNC Represents a pool of 410 frame selectors. The frame selector is a logical element that represents the resources of the RNC 410 that performs the process of processing the cell. In a GSM or UMTS network, the frame selector can be referred to as the data channel and the FS pool 416 can be referred to as the data channel pool.

In Figure 4B, the RAN 404 also performs the wireless function of the communication network 400. The RAN 404 includes a radio network controller (RNC) 450 and a base transceiver station (BTS) 460 connected by a carrier network 470. The transport network 470 consists of multiple connections 471 between the RNC 450 and the BTS 460. The transport network 470 includes a signal network 473 and a bearer network 474. The signal network 473 is shown by the dashed line in FIG. 4B. The bearer network 474 is shown in solid line in Figure 4B.

The BTS 460 terminates wireless communication with wireless devices such as the PTC Phone 480. Each BTS 460 includes multiple transceivers (TXR) 462, detection system 463, and channel element (CE) pool 464. Transceiver 462 includes an antenna (not shown) that transmits and receives signals over leased radio frequencies. Transceiver 462 creates a "cell" through which cellular phones, PCS phones, or other radios can communicate with transceiver 462. CE pool 464 represents multiple channel elements within each BTS 460.

The BTS 460 communicates with the Radio Control Server (RCS) 476, Mobile Manager (MM) 478, and RNC 450 over signal network 473 to exchange signals. Generally, there is one RCS 476 for each BTS 460 in a RAN 404. The BTS 460 communicates with the RNC 450 over the bearer network 474 to exchange bearer traffic.

The RNC 450 acts as a switch between the BTS 460 and the packet data network 443 to carry packet voice and data. The RNC 450 includes a Traffic Control Server (TCS) 452, a Packet Control Function (PCF) 454, and a Frame Selector (FS) pool 456. The RNC 450 can also communicate with other BTSs (not shown), other RNCs (not shown), and Mobile Exchange Centers (MSCs) (not shown). The TCS 452 manages RNC 450 resources, including assigning and deallocating frame selectors in FS pool 456, and manages call setup and call teardown. The PCF 454 interfaces the RNC 450 with the packet data network 443 via the PDSN server 446. FS pool 456 represents a pool of frame selectors within RNC 450.

The communication network 400 is set up and behaves differently from traditional networks to handle low latency services. A special connection 435 is pre-established on the bearer network 434 to carry the call signal. The special connection 435 can be supported via a frame relay, ATM, or IP network. The network 400 can pre-establish multiple special connections, depending on the bandwidth required and the number of BTSs the RNC 410 serves. The special connection 435 consists of a separate and parallel signal network of RAN 402.

The special connection 435 reserves a portion of the capacity of the special connection 435 to carry the signal message. For example, suppose the special connection 435 contains one T-1 line. That portion of the capacity of the special connection 435 can include a small portion of the DS0, i.e. one or more DS0s. In another embodiment, the special connection 435 comprises fiber equipment. That portion of the capacity of the special connection 435 reserved for carrying the call signal includes at least one small portion of the bandwidth of the fiber equipment.

When establishing a special connection 435, the BTS 420 and / or RCS 436 specifies a special channel element (s-CE) from CE pool 424 to process the call signal. The TCS 412 of the RNC 410 or RNC 410 reserves a small pool of frame selectors 418 from the FS pool 416 exclusively for processing call signals from the BTS 420. Special Frame Selector Pool 418's special frame selector (s-FS) corresponds to the BTS 420's special channel element (s-CE). Each BTS 420 directly or indirectly connected to the RNC 410 can establish a special connection as described above.

That portion of the capacity of the special connection 435 reserved for the call signal can be scaled according to the needs of the RAN 402. As the traffic associated with low latency signals increases, the RNC 410 can adjust the size of a special FS pool 418 reserved exclusively for processing call signals. It is assumed that the RNC 410 contains 20 processors, each processor capable of performing the functions of 100 frame selectors. The RNC 420 can reserve frame selectors from FS pools 416 to 200 exclusively for processing call signals for low latency services. This means that two of the 20 processors can be reserved exclusively for processing call signals for low latency services. If the RAN 402 handles an increased amount of low latency service, the RNC 410 may reserve more frame selectors in a special FS pool 418 dedicated to processing call signals for low latency services. it can. More processors can be added to the RNC 410 if desired. Also, each BTS The 420 may reserve a number of special channel elements (s-CE) exclusively for processing call signals, if desired. With reference to Figure 4B, a special connection 475 can be set up with a RAN 404 in a similar way.

For this embodiment, it is assumed that the PTC phone 440 and the PTC phone 480 are registered on the PTC server 442, as described above with respect to FIGS. 1A and 1B. The PPP session between PTC Phone 440 and PDSN Server 441 and the PPP session between PTC Phone 480 and PDSN Server 446 are inactive. Both PTC Phones 440 and 480 are 3G phones that provide voice, data, and Push to Call (PTC) services. The PTDC Phone 440 can make PTC-type calls using both the PTC Phones 440 and 480 registered with the PTC Server 442. To initiate a call, the user of PTC Phone 440 presses the Push to Call button on PTC Phone 440. The PTC Phone 440 generates a call setup message, such as a PTC request, and sends the call setup message over radio frequency. PTC requests can be directed to one or more recipients.

One of the BTS 420 transceivers 422 receives a call setup message from the PTC phone 440. The receiving transceiver 422 forwards the call setup message to detection system 423. Discovery system 423 processes the call setup message to determine if it is for a low latency service. If the call setup message is not for low latency service, then BTS The 420 forwards PTC messages over signal network 433 in the conventional manner described in FIGS. 1A and 1B. If the call setup message is for low latency service, detection system 423 sends the call setup message to a special channel element (s-CE) in CE pool 423 dedicated to processing call signals. Forward. A special channel element (s-CE) sends its call setup message to a special frame selector (s-FS) in a special FS pool 418 via a special connection 435 in bearer network 434. Forward.

A special frame selector (s-FS) then forwards its call setup message to PCF 414. A special frame selector (s-FS) can encode or further process the call setup message. Upon receiving the call setup message, PCT 414 retrieves records for PTC Phone 440. This record shows the address to the PDSN used to establish a previous PPP session with PDSN Server 441 (referred to as outgoing PDSN). PDF 414 forwards call setup messages to PTC server 442 via PDSN server 441. In a GSM or UMTS network, the PCF 414 and PDSN server 441 may be a serving GPRS service node (SGSN) and a gateway GPRS service node (GGSN).

In response to the call setup message, PTC Server 442 identifies the recipient for the PTC call. PTC server 442 can retrieve records about the recipient for that call. PTC server 442 can refer to an already established "buddy list" or group list for PTC phone 440. The recipient in this case is PTC Phone 480.

PTC server 442 retrieves records for PTC phone 480. This record shows the address of the PDSN used to establish the previous PPP session (referred to as the termination PDSN), the identification of the PTC phone 480, and so on. Based on this record, the PTC server 442 forwards the call setup message to the PCF 454 of the RNC 450 via the PDSN server 446.

Upon receiving this call setup message, the RNC 450 determines if the call setup message is for a low latency service. If the call setup message is for a low latency service, the RNC 450 forwards the call setup message to each special frame selector (s-FS) in the special FS pool 458. The RNC 450 may not know which BTS 460 serves the PTC phone 480. Therefore, the RNC 450 also generates a call request to have the BTS 460 "call" the PTC phone 480. The RNC 450 forwards this call request to each special frame selector (s-FS) in the special frame selector pool 458, and each special frame selector (s-FS) then then Call requests and call setup messages are forwarded through the special connection 475 of bearer network 474 to the corresponding special channel element (s-CE) in CE pool 464.

In response to a call request received by a special channel element (s-CE), each BTS460 sends a call over the call channel. When the PTC phone 480 receives the call and subsequently receives the call setup message, the PTC phone 480 sends a response message over the radio frequency. One of the BTS 460 transceivers 462 receives a response message from the PTC phone 480.

The receiving BTS 460 then forwards the response message to detection system 423. The detection system 423 processes the response message to determine if the response message is for a low latency service. If the response message is not for a low latency service, the BTS 460 forwards the response message over the signal network 473 in the conventional way shown in Figures 1A and 1B. If the response message is for a low latency service, detection system 423 forwards the response message to a special channel element (s-CE) in CE pool 464 dedicated to processing call signals. The special channel element (s-CE) forwards the response message through the special connection 475 of bearer network 474 to the special frame selector (s-FS) of the special FS pool 458.

A special frame selector (s-FS) then forwards the call setup message to PCF 454. The PCF 454 forwards the response message to the PTC server 442 using the PPP session established between the PTC phone 480 and the PDSN server 446. The PTC server 442 receives the response message and forwards the response message to the PCF 414 of the RNC 410 using the PPP session established between the PTC phone 440 and the PDSN server 441.

The RNC 410 determines if the response message is for a low latency service. If the response message is for a low latency service, the RNC 410 forwards the response message to a special frame selector (s-FS) in FS pool 418. The special frame selector (s-FS) then forwards its response message to a special channel element (s-CE) in CE pool 424 via a special connection 435 in bearer network 434.

In response to receiving the response message, the BTS 420 sends a response message to the PTC phone 440 over the radio frequency. PTC Phone 440 receives a response message indicating that the PTC call has been set up.

Once the call is set up, the user of PTC Phone 440 can talk to the user of PTC Phone 480. The exchange of packet voice traffic between telephones 440 and 480 takes place over bearer networks 434 and 474. While special connections 435 and 475 are established and used to transmit call signals, they are traditional (if capacity allows) to maximize the efficiency of the transport function (T1 and E1). It is also used to carry voice and data bearer traffic. Control systems such as RCS 436 and RCS 437 can control the amount of bearer traffic allowed for special connections 435 and 475 to help ensure latency for special connections 435 and 475. .. Bearer traffic restrictions also minimize the impact on the quality of voice and data calls carried over special connections 435 and 475.

By establishing special connections 435 and 475 to carry the call signal, network 400 can favorably handle low latency services. The network 400 can provide even faster call setups, such as less than a second, by using special connections 435 and 475 to carry the call signal.

Bearer networks 434 and 474 are configured to carry real-time critical communications, such as voice calls. Real-time critical communications are more tolerant of latency and jitter, so bearer networks 434 and 474 are designed and configured to minimize latency and jitter. Since Bearer Networks 434 and 474 focus on low latency, Bearer Networks 434 and 474 can be used to provide low latency services.

At the same time, if low latency call setup is not required, network 400 carries the call signal over signal networks 433 and 473. Signal networks 433 and 473 are capacity-focused and are therefore capable of handling high volume calls. By using a parallel signal network, the communication network 400 can advantageously optimize call setup latency without sacrificing capacity.

<figref num="1A">It is a figure which shows the conventional communication network which is useful for understanding of this invention.</figref><figref num="1B">It is a figure which shows the conventional communication network which is useful for understanding of this invention.</figref><figref num="2">It is a figure which shows the wireless communication network of the Example Embodiment of this invention.</figref><figref num="3">In addition to the signal network of the exemplary embodiment of the present invention, it is a diagram showing a process for a wireless communication network in which a bearer network carries a call signal.</figref><figref num="4A">It is a figure which shows the communication network of the Example Embodiment of this invention.</figref><figref num="4B">It is a figure which shows the communication network of the Example Embodiment of this invention.</figref>