A cellular telephone system and a method of conducting an inter-system soft handoff

BACKGROUND OF THE INVENTION

I. Field of the Invention

the This invention relates to a base station controller and a method for performing a soft handoff between systems or an inter-system soft handoff. More particularly, the present invention relates to a novel and improved method and apparatus for performing Telephone calls and other communications between wireless Telecommunications systems that support inter-system soft handoff.

II. Description of the Related technology

<figref idrefs="S23">1</figref> is a diagram of a cellular telephone system according to the use of the IS-95 over the Air-interface standards is configured. The IS-95 CDMA over-the-air interface standard (IS-95) by the Telecommunications Industry Association (TIA) released was, defines a protocol for providing a wireless telephone service via code division Multiple access modulated RF signals (CDMA = code division multiple access). IS-95 has many derivatives and related standards, the IS-95-A, ANSI J-STD-008, IS-99 and IS-657 include, on which herein is summarized based as "IS-95". A cellular Telephone system which is substantially in accordance with the use of IS-95 is configured, is described in U.S. Patent 5,103,459, entitled "System and Method for Generating Signal Waveforms in a CDMA Cellular Telephone described "system, assigned to the assignee of the present invention.

During the perform operation subscriber units <figref>10</figref> (Typically cellular telephones) Communications by, by connecting with base stations <figref>12</figref> among Using CDMA modulated RF signals. From base stations<figref>12</figref> will the communications continue to be performed using the base station controller means (BSCs = base station controllers) <figref>14</figref> and mobile switching centers (MSC's mobile switching = center) <figref>16</figref> with the public Telephone network (PSTN = Public Switched Telephone Network) <figref>18</figref> or other subscriber units <figref>10</figref>, BSCs<figref>14</figref> see a call mobility function before, as in greater detail further described below and MSC's <figref>16</figref> see a call forwarding feature, an accounting function and an interface switching function before. In addition, the data that the between the different systems, which in <figref idrefs="S23">1</figref> shown will be replaced, and the subscriber units <figref>10</figref> and base stations <figref>12</figref> include, processed in the framework. These data can on the one hand be traffic data which include voice information or signaling, which is used to the various shown configure systems or adjust and control.

the Use of CDMA technology allows adjacent base stations in an IS-95 system, communications over the same RF bandwidth perform, which the frequency reuse factor of the cellular telephone system elevated, compared to other types of cellular telephone technology. Combined with a wide transmission power control, elevated with the increase the frequency reuse factor, the efficiency with which the cellular phone system uses the existing RF bandwidth, which is one the advantages of the IS-95 standard is.

On Another advantage of allowing through the use of the same RF bandwidth adjacent base stations <figref>12</figref> is that "soft handoff" can be used, a subscriber unit <figref>10</figref> of the coverage area a first base station <figref>12</figref> to a coverage area a second base station <figref>12</figref> to revert or change. Soft handoff includes the simultaneous connection of a subscriber unit <figref>10</figref> with two or more base stations, if the subscriber unit between the associated coverage areas of two base stations <figref>12</figref> changes. One of subscriber units <figref>10</figref>, in the <figref idrefs="S23">1</figref> shown is, is in soft handoff. Soft handoff may juxtaposed hard handoff be where the interface with the first base station <figref>12</figref> completed is before the connection with the second Basisstati constructed on has been. Maintaining at least one connection to each Time improves reliability and the quality of communication performed is. WO 93/12588 describes a method for determining whether a Handoff request is acceptable, depending on whether there are any available voice channels is in the target cell. A system and method for performing Soft handoff is described in U.S. Pat. No. 5,101,501 entitled "Method and System for Providing a Soft Handoff in Communications in a CDMA Cellular Telephone System "and in US Pat. No. 5,267,261, entitled "Mobile Station Assisted Soft Handoff in a CDMA Cellular Communications System ", both the assignee of the present associated invention. Soft handoff is described in WO 95/15665.

&lt;?page 3?&gt;

As mentioned above, to lead BSCs <figref>14</figref> various Functions that allow mobile communications to be conducted, Functions including allowing soft handoff. In particular, the lead BSCs <figref>14</figref> "Frame selection" and "frame distribution" for the group from base stations <figref>12</figref> from that in the soft handoff call are involved. Frame selection is the selection of a frame for the Further processing of the group of frames received from the Group of the base stations, during the a soft handoff may be used. Frame selection maintains the highest quality connection by selecting the best available framework anytime upright.

Setting distribution is the duplication and distribution of frames directed to the subscriber unit <figref>10</figref> to the set of base stations <figref>12</figref>Which involved in the call are. Frame distribution allows each base station<figref>12</figref> a Copy of the frame to the subscriber unit <figref>10</figref> Send to, the probability of successful reception of at least a framework to increase.

As in <figref idrefs="S23">1</figref> shown, the subscriber unit combines <figref>10A</figref> With a single base station <figref>12A</figref> and is located in the near the Cover preparation Ches a second base station <figref>12B</figref>, the base stations <figref>12A</figref> and <figref>12B</figref> but are at different BSCs <figref>14</figref> coupled. This ver complicates the process of performing soft handoff because no BSC <figref>14</figref> access to both base stations <figref>12A</figref> and <figref>12B</figref> Has. Running soft handoff between two base stations <figref>12</figref>, Of two different BSCs <figref>14</figref> being controlled, is referred to as "inter-system soft handoff." inter-system soft handoff may result in a "soft handoff provided within systems or internal system soft handoff "against be where a soft handoff between two base stations <figref>12</figref> is carried out, controlled by the same BSC.

For inter-system soft handoff , the frame selection can not be so easily carried out because no BSC <figref>14</figref> access has to the group of frames from the two base stations <figref>12</figref> produced were. additionally is the frame distribution even more difficult because no BSC group of frames for the base stations are generated, can send. Nevertheless, it is necessary, two or more BSC's <figref>14</figref> in many large metropolitan to use areas, because the number of base stations required, to ensure adequate provide coverage, the options a single cellular system formed using a individual BSC <figref>14</figref>, Exceeds, which in turn creates the need to conduct inter-system soft handoff.

On System and method for performing an inter-system soft handoff is described in US Pat. No. 5,940,762, entitled "Inter System Calling Supporting inter-system soft handoff ", the assignee of the present associated invention. In this application, a channel between the two BSCs <figref>14</figref> constructed a Connection for exchanging the data necessary to soft handoff perform. additionally will each BSC to needed to store information or to collect typically pursued in an MSC, and therefore must interact with an MSC in order to soft-handoff perform to. Preferably, the compound has a standard T-1 or E-1 compound , which are known in the art and therefore relatively inexpensive to are implemented. In order to build the channel, signaling messages between the two BSCs <figref>14</figref>. which are involved in the call, exchanged. As noted above, needed the information contained in the signaling messages, is, each BSC <figref>14</figref>To certain information, such as the number the calls that carried out the connection were to follow, or to interact with an MSC that this Information tracked, and to the other BSC <figref>14</figref> with certain to provide pre-defined types of information. The number calls on the connection or interconnection is following or recorded to overload to avoid the connection.

however is the need of BSC's <figref>14</figref>. in order to obtain certain types of information to staple or track or provide is highly restrictive and may for some manufacturers of BSCs be difficult to implement. In addition, it requires a significant Degree of coordination and cooperation between the BSC and MSC manufacturers, which is not always feasible. Thus, a system and method would be for perform of inter-system soft handoff, which less cooperation and coordination between BSCs <figref>14</figref> and MSC's <figref>16</figref> needed highly desirable.

SUMMARY THE INVENTION

Of the Purpose of the present invention resides in the provision of a new and improved methods and apparatus for operating a cellular Telephone system performing the support inter-system soft handoff.

&lt;?page 4?&gt;

In one aspect, the invention provides a method for carrying out a made soft handoffs of a call from a subscriber unit between the first and second base station, the first and second from one base station controller be appropriately controlled before. The method comprises monitoring a traffic level or levels the which along a connection means exchanged between the first and second base station controller will and granting a soft handoff request based on this level of traffic. The Monitor has a monitoring of at least an average frame reception rate on the Interconnect and a peak queue length at a Interface between the first and second base station control device on.

In In another aspect the invention provides a base station controller for performing a soft handoff between first and second base station before, the correspondingly from the base station control device and a second base station control device can be controlled. The base station controller means for monitoring comprises a traffic level which along an intermediate connection of the two Base station controller means is replaced, and means If allowed to determine due to the traffic level of the handoff is. The means for monitoring have a cellular system interface port on the adjusted is at least an average frame reception rate on the monitor interconnect and a peak queue length at an interface between the first and second base station control devices.

In one embodiment, the invention generates a subscriber unit a pilot strength measurement report, if the pilot channel is detected by a base station. When a Base station controller, which receives the pilot strength measurement report, determined, that the base station part of a second cellular telephone system is an inter-system soft handoff request is generated. An admission control subsystem receives the inter-system soft handoff request and either grants or denies the request based on the traffic level on the interconnect with the second cellular telephone system. For example, if the Traffic level is too high, the inter-system soft handoff request rejected. In a preferred embodiment of the invention is the transport level based on the link load message determined that periodically received from the admission control subsystem is the coupled by an interface port to an intermediate compound ers between the ten cellular telephone system and the second cellular Telephone system are generated. The link load message includes a Peak queue length and an average frame reception rate information.

SHORT DESCRIPTION THE DRAWINGS

the Features, objects and advantages of the present invention will be more clearly, starting from the detailed description of a embodiment of the invention, which is described further below, when used in conjunction brought with the drawings, throughout which numeral are assigned accordingly, and wherein:

<figref idrefs="S23">1</figref> on configured block diagram of a group of cellular systems according to the known Art;

<figref idrefs="S24">2</figref> on configured block diagram of a set of cellular telephone systems according to one embodiment of the invention;

<figref idrefs="S25">3</figref> on Flow diagram of a the steps for granting or refusing Inter-system soft handoff request executed according to an embodiment the invention demonstrates is.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

On Method and apparatus for the operation of a cellular telephone system, the inter-system soft handoff supports, is described. In the following description, the invention is set forth in the context of a radio frequency signal interface, the according to the physical operated signal modulation techniques of the IS-95 over the air protocol is and the use of CDMA signal modulation includes. While the Described embodiment of the invention is specially adapted for the use of such signal modulation techniques, the use of other wireless telecommunications protocols Accordance with the application of the present invention, the protocols includes the CDMA signal processing techniques use or protocols that are capable of providing soft handoff functionality. Furthermore, it should be understood that the present invention for the Use with various &lt;?page 5?&gt;Communication types and is intended while both said based communications as well as communications while which digital data representing Information is transmitted unlike language includes.

Continuous in this specification is the use and transmission of different types of information described including of data and signaling messages. It should be understood be that this information by electronic representations of this data and signaling messages have been generated, the via the use of electric currents, voltage potentials, generates electromagnetic energy or a combination of these has been. additionally contains the following description references to various systems for the answers on, as well as manipulating and generating such information. In the preferred embodiment, the invention, these systems are implemented via the use of digital and analog integrated semiconductor circuits coupled to one another via various conductive connections or via the use of electromagnetic signals, or both. As well the invention can be incorporated in satellite-based wireless telecommunications systems be. Elsewhere everywhere in the application are various known systems in block form described. This was done in order to avoid the disclosure the present invention unnecessarily darkening or blurring.

<figref idrefs="S24">2</figref> is a block diagram of part of a set of cellular telephone systems configured in accordance with a embodiment the invention. Base station controllers (BSCs)<figref>24A</figref> and <figref>24B</figref> coupled with base stations <figref>22</figref> and mobile switching centers (MSC) <figref>16</figref> the <figref idrefs="S23">1</figref> (MSC is not shown in <figref idrefs="S24">2</figref>). subscriber unit<figref>20</figref> is connected to the base station <figref>22A</figref> via RF signals according to the IS-95 standard modulated, and therefore using CDMA modulation techniques. subscriber unit <figref>20</figref> is in a similar distance from base stations <figref>22A</figref> and <figref>22B</figref> shown and in the coverage area of ​​the base station occurs so <figref>22B</figref> on. As in <figref idrefs="S23">1</figref> is shown, the base station <figref>22A</figref> coupled with BSC <figref>24A</figref> and base station <figref>22B</figref> coupled with BSC <figref>24B</figref>,

BSC <figref>24A</figref> is with additional shown detail to a preferred configuration according to a embodiment the invention clarify. CDMA interconnect subsystem (CES = CDMA interconncect subsystem) <figref>30</figref> is coupled to the base stations <figref>22A</figref> and <figref>22D</figref>, selector subsystem <figref>40</figref>. Call control processor (CCP = call control processor) <figref>42</figref>. Access control subsystem <figref>44</figref> and interconnection <figref>46</figref> about the Base station communication network ports <figref>32a</figref>-<figref>32f</figref> (BCN = Base station communication network). BCN-Ports<figref>32a</figref>-<figref>32f</figref> see Frame buffer before by incoming and outgoing frame queuing in the queue. selector<figref>40</figref> coupled with MSC <figref>16</figref> the <figref idrefs="S23">1</figref>And interconnection <figref>46</figref> coupled with BSC <figref>24B</figref>, intercommunication<figref>46</figref> is typically a T1 or E1 connection, their use in the art is known.

During the Operation Changing the various systems, the BSC <figref>24A</figref> make up, as well as the base stations <figref>22A</figref> and <figref>22D</figref>, signaling and information from, using network packets from CIS <figref>30</figref> are passed. Each network packet containing the address of the sub-system to which it is executed passes. selector subsystem<figref>40</figref> leads the Rahmenselektions- and Setting distribution functions for soft handoff described from above. CCP<figref>42</figref> allocates resources and releases them for the processing of the call, including the signal processing resources in the base stations <figref>22</figref> and Selektorressourcen in the selector subsystem <figref>40</figref>,

As in the above-described related thereto Patent 5,267,261 with entitled "Mobile Station Assisted Soft Handoff in a CDMA Cellular Communications System "examines the subscriber unit <figref>20</figref> generated by repeated pilot channels from base stations <figref>22</figref>And when a pilot channel with sufficient strength and for a sufficient time has been detected, a pilot strength measurement report (PSMR = pilot strength measurement report) from the subscriber unit <figref>20</figref> generated and selector subsystem <figref>40</figref> via the base station <figref>22A</figref> and CIS <figref>30</figref> Posted. The PSMR indicates the group of pilot channels, straight from the subscriber unit <figref>20</figref> have been detected, and has its signal strengths and pilot phases out.

At the Receiving the PSMR is the selector subsystem <figref>40</figref> determine, that the pilot channel from the base station <figref>22B</figref> from the subscriber unit <figref>20</figref> recognized has been. Using a pilot database (PDB = pilot database) located in the selector subsystem <figref>40</figref> (not shown) is determined the selector subsystem that the pilot channel from a base station to the BSC <figref>24B</figref> is coupled, rather as from a base station to the BSC <figref>24A</figref>And therefore not directly accessible by the selector subsystem <figref>40</figref>, in response to this provision transfers the selector subsystem an inter-system soft handoff request the access control subsystem <figref>44</figref>To the BSC <figref>24</figref> to specify, by which the inter-system soft handoff &lt;?page 6?&gt;be performed should.

In addition to the inter-system soft handoff requests receives the access control subsystem <figref>44</figref> also Traffic Report News from BCN-Port <figref>32f</figref>, And also by all other BCN ports <figref>32</figref>, To other BSC's <figref>24</figref> coupled are. (Typically, the BSC<figref>24A</figref> to several other BSCs <figref>24</figref> coupled, although only one in <figref idrefs="S24">2</figref> for ease of understanding for the The invention is shown.) Using the traffic reports accepted the access control subsystem <figref>44</figref> either or denies the inter-system soft handoff request and has the selector subsystem <figref>40</figref> through a signaling message out. If the inter-system soft handoff request is denied, the transition can the subscriber unit <figref>20</figref> the coverage area of ​​the base station <figref>22B</figref> among Use of a hard handoffs over run the MSC will.

If that is accepted inter-system soft handoff request, sends the selector subsystem <figref>40</figref> an inter-system soft handoff initiation message for BSC <figref>24B</figref> and starts forward link frames to the subscriber unit <figref>20</figref> are directed to copy, and to the BSC <figref>24B</figref> about intercommunication <figref>46</figref> to send. BSC<figref>24B</figref> responds it by instructing the base station <figref>22B</figref> Signal processing resources for the implementation the call to allocate, and by forwarding the received forward link frame to the base station <figref>22B</figref>Which the frame to the subscriber unit <figref>20</figref> via CDMA modulated Sends RF signals. additionally conducts BSC <figref>24B</figref> of the base station <figref>22B</figref> received Reverse link frames of subscriber unit <figref>20</figref> to BSC <figref>24A</figref> further where they selector subsystem <figref>40</figref> directed to frame selection will. At this time, a stationary inter-system soft handoff constructed with a minimum of signal exchange and processing by BSC <figref>24B</figref>, Thus, the ability of an inter-system soft handoff BSC <figref>24A</figref> establish, with a minimal amount of coordination and cooperation provided.

Around the access control subsystem <figref>44</figref> allow to the traffic, of over BCN-Port <figref>32f</figref> transfer is to properly monitor, sends the BCN-Port <figref>32f</figref> Link load messages the access control subsystem <figref>44</figref>, In the preferred embodiment, the invention, the connection load messages periodically in a period T_{Sample Load} sent and have to R_ave, The average frame reception rate the BCN-Ports and Q_peak, The peak transmission queue length, in Bytes of BCN-Port <figref>32f</figref> over the last period T_{Sample Load} out. In the preferred embodiment, the invention is R_ave the total number good frame, the BCN-Port <figref>32f</figref> BSC <figref>24B</figref> receive were, while the previous period T_{Sample Load} divided by the duration of the period T_{Sample Load}, additionally is Q_peak the peak queue length, in Bytes of BCN-Port <figref>32f</figref> over the last period T_{Sample Load},

In an alternative embodiment, the invention sends BCN-Port <figref>32f</figref> the link load messages the access control subsystem <figref>44</figref> only when a change in the load conditions in more than a predetermined threshold occurs, as opposed to each period T_{Sample Load}, This reduces the number of transferred Signaling message and increases therefore, the call processing capacity of the BSC <figref>24A</figref>,

<figref idrefs="S25">3</figref> is a flow diagram illustrating the steps of the access control subsystem <figref>44</figref> be executed to determine whether an inter-system soft handoff request approved or is refused, represents. The processing begins at step<figref>50</figref> and at step <figref>52</figref> received the inter-system soft handoff request. At step <figref>54</figref> it is determined whether the average Frame reception rate R_ave is greater than a Rahmenemfangsratenschwelle R_Tand if so, is the inter-system soft handoff request denied in step <figref>56</figref> and the procedure ends in step <figref>70</figref>,

If it was determined that the average frame reception rate R_ave is not greater than a frame reception rate threshold R_T is, then in step <figref>60</figref> certainly, if the peak transmission queue length Q_peak is greater as a queue length threshold Q_T, And if so, is the inter-system soft handoff request denied in step <figref>56</figref> and the procedure ends in step <figref>70</figref>,

If it was determined that the peak queue length Q_peak no larger than a peak queue length threshold Q_T is the inter-system soft handoff is granted in step <figref>62</figref> and the procedure ends in step <figref>70</figref>,

According to a preferred embodiment, the invention, the thresholds Q_T and R_T based on the data capacity of the interconnection <figref>46</figref> and the sample period T_{Sample Load} adjusted with the preferred sample period T_{Sample Load} equal two (2) seconds.

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In a preferred embodiment, the invention is the peak queue length threshold Q_T based on the number of T-1 or E-1 connections set that interconnect the <figref>46</figref> account. If the intermediate compound <figref>46</figref> from a group of M_T T-1 lines there, then it is determined as follows: <st32:df xmlns:st32="http://lighthouseip.com/">Q<st32:sub>T</st32:sub> = min (3 · 168 · M<st32:sub>T</st32:sub>· 0.9; QUEUE_CAPACITY) (1)</st32:df>in which the QUEUE_CAPACITY the depth of the FIFO queue in the BCN-Port <figref>32f</figref> is. When the intermediate compound <figref>46</figref> from a group of M_e E-1 lines is, the peak queue length threshold Q is_T set as follows: <st32:df xmlns:st32="http://lighthouseip.com/">Q<st32:sub>T</st32:sub> = min (3 · 240 · M<st32:sub>e</st32:sub>· 0.9; QUEUE_CAPACITY) (2)</st32:df>

the threshold for the peak transmission queue length is the number of bytes that can be queued while still allowed all to transmit queued data with a delay of 3 ms. Keeping the queuing delay less than 3 ms keeps the delay, by transferring the traffic frames over BCN-Port <figref>32f</figref>, Interconnection <figref>46</figref> and BSC <figref>24B</figref> was introduced, enough small that the quality communication for the end user remains acceptable. As known in the art is a delay, significantly greater than 100 ms is recognized for the user. With the necessary delay for all the other processing, the run Need to become, is an additional delay for the Buffering preferably not more than 3 ms. Of course, the queue length must also be kept less than the queue to data loss avoid. In a preferred embodiment of the invention is the QUEUE_CAPACITY the BCN-Ports <figref>32f</figref> three kilobytes in size (3 K).

the Frame reception rate threshold R_T is set as follows: <st32:df xmlns:st32="http://lighthouseip.com/">R<st32:sub>T</st32:sub> = (50 * N * 0.9) / 1.05 (3)</st32:df>where N is the maximum number of network packets is that of intermediate compound <figref>46</figref> per 20 milliseconds (ms) time interval can be sent. N is described in more detail further down.

the Reduction to 90% (0.9) is there to error and change in the frame rate due to the 2 second sample period T_{Sample Load} to allow. Further reduction to 1/105% (1.05) is there the signaling messages take. By Grant of requests for Inter-system soft handoff as described above, the present invention allows inter-system soft handoff reliable implementation with a minimal amount of coordination between BSCs <figref>24A</figref> and <figref>24B</figref> or with an MSC.

the maximum number of network packets, N, of the intermediate compound <figref>46</figref> Posted can be, depends of the capacity of the intermediate compound <figref>46</figref> and the nature of the data transmitted be off. Specifically, the IS-95 standard provides two quality levels telephone service before, each level of service an associated group traffic rate or "rate groups" has. The use allows groups of rates generating speech data at variable rates in response on the change in the voice activity, as natural Part of the language occurs. The frame sizes of high quality levels of the service, or "rate group Two "is the service provided in Table I, along with the probability of Occurrence at any rate during a typical conversation.

<img img-content="tb" img-format="tif" he="30" wi="125" file="00140001.tif" />

<img img-content="tb" img-format="tif" he="7" wi="125" file="00150001.tif" /> table I. 14.4 Kbps rate group box

&lt;?page 8?&gt;

table II lists N (the maximum number of network packets from the intermediate compound <figref>46</figref> transfer may be) when the interconnect <figref>46</figref> from different Numbers of T-1 and E-1 compounds.

<img img-content="tb" img-format="tif" he="67" wi="156" file="00150002.tif" /> table II.

Still once <figref idrefs="S24">2</figref> received if the subscriber unit <figref>20</figref> fully in the coverage area of ​​the base station <figref>22B</figref> is moved the RF Interface with base station <figref>22A</figref> ended and the call continues in full, base station <figref>22B</figref>, If the subscriber unit <figref>20</figref> continues in the coverage area the base station <figref>22C</figref> move is a "remote" system of internal soft handoff between base stations <figref>22B</figref> and <figref>22C</figref> initiated. As mentioned above, is a system of internal soft handoff between two base stations <figref>22</figref> coupled with the same BSC <figref>24B</figref> or within the same cellular System performed, and an inter-system soft handoff is between two base stations <figref>22</figref>. the different BSCs <figref>24</figref> are coupled and therefore Part of different cellular systems are. A remote system of internal Soft handoff is a handoff performed between two base stations <figref>22</figref>. which are part of the same cellular telephone system, but where the frame selection and the frame distribution from a remote BSC <figref>24A</figref> be executed.

In a preferred embodiment, the invention is the remote system's internal soft handoff in a similar running way as execution of the inter-system soft handoffs during initiation. Particularly, after receiving a pilot strength measurement report (PSMR) from the subscriber unit <figref>20</figref>That indicates, that the pilot channel from the base station <figref>22C</figref> has been detected, sends the selector subsystem <figref>40</figref> an inter-system soft handoff request the access control subsystem <figref>44</figref>But where the frame selection and the frame distribution in a remote BSC <figref>24A</figref> is performed.

Access control subsystem <figref>44</figref> responds by execution the steps in <figref idrefs="S25">3</figref>Either to grant the request or to refuse.

The perform the remote system's internal soft handoffs, as described above, elevated the likelihood of correct and reliable call processing, because in order to perform soft handoff must the selector subsystem <figref>40</figref> Frames to both base stations <figref>22B</figref> and <figref>22C</figref> on interconnection <figref>46</figref> send. additionally must selector subsystem <figref>40</figref> frames from both base stations <figref>22B</figref> and <figref>22C</figref> receive, to perform frame selection. The mission of this additional Setting Increments transmitted to the traffic on the interconnection <figref>46</figref>. and therefore allows execution the remote system's internal soft handoffs, as described above, the fuse that adequate capacity exists to such additional to carry traffic.

Thus was a method and apparatus for operating a cellular Telephone system that allows inter-system soft handoff is described. The exemplary embodiment, as provided above, is there any expert to make, prepare the present invention or use. Various Modifications consistent with the use of the invention, are be the person skilled readily apparent and the original Principles defined herein may in other embodiments without the use of the inventive faculty applied to whoever. Thus it is not beab&lt;?page 9?&gt;into account that the present invention to the described herein embodiments limited is, but that you the widest possible scope granted is as defined in the claims has been defined.