HK1124463B - Access probe randomization for wireless communication system - Google Patents

Description

Access probe randomization for wireless communication systems

Technical Field

The present invention relates to randomization of access probes from co-located (co-located) mobile terminals for collision reduction.

Background

In the field of cellular telecommunications, those skilled in the art will commonly use the terms 1G, 2G and 3G. These terms refer to the generation of the cellular technology used. 1G refers to the first generation, 2G refers to the second generation, and 3G refers to the third generation.

1G refers to an analog telephone system, commonly known as the AMPS (advanced Mobile Phone service) telephone system. 2G is commonly used to refer to digital cellular systems that are prevalent throughout the world, including cdma one, global system for mobile communications (GSM), and Time Division Multiple Access (TDMA). The 2G system can support a larger number of users in a dense area than the 1G system.

3G generally refers to the digital cellular system currently being deployed. These 3G communication systems are conceptually similar to each other and differ somewhat significantly.

Referring to fig. 1, the figure illustrates a wireless communication network architecture 1. The user utilizes a Mobile Station (MS)2 to access network services. The MS2 may be a portable communication unit such as a hand-held cellular telephone, a vehicle-mounted communication unit, or a fixed location communication unit.

The electromagnetic waves for the MS2 are transmitted by a Base Transceiver System (BTS)3, also known as a node B. The BTS 3 includes a radio device such as an antenna and equipment for transceiving radio waves. A BS6 controller (BSC)4 receives transmitted signals from one or more BTSs. The BSC 4 provides control and management of the radio transmission signals from each BTS 3 by exchanging messages with the BTS and the Mobile Switching Center (MSC)5 or internal IP network. BTS 3 and BSC 4 are part of BS6(BS) 6.

The BS6 exchanges messages with a Circuit Switched Core Network (CSCN)7 and a Packet Switched Core Network (PSCN)8, and transmits data to the CSCN 7 and the PSCN 8. CSCN 7 provides traditional voice communications, while PSCN 8 provides internet applications and multimedia services.

The Mobile Switching Center (MSC)5 portion of the CSCN 7 provides switching for conventional voice communications to and from the MS2 and may store information that supports these capabilities. The MSC 2 may be connected to one of the BSs 6, as well as other public networks, such as a Public Switched Telephone Network (PSTN) (not shown) or an Integrated Services Digital Network (ISDN) (not shown). A Visitor Location Register (VLR)9 is used to obtain information for handling voice communications with visiting subscribers. The VLR 9 may be located within the MSC 5 and may serve more than one MSC.

The Home Location Register (HLR)10 of the CSCN 7 is assigned a subscriber identity, such as an Electronic Serial Number (ESN), a mobile directory number (MDR), profile information, a current location, and an authentication period, for the purpose of recording information such as a subscriber. The Authentication Center (AC)11 manages authentication information related to the MS 2. The AC 11 may be located within the HLR 10 and may serve more than one HLR. The interface between the MSC 5 and the HLR/AC 10 IS the IS-41 standard interface 18.

The Packet Data Serving Node (PDSN)12 portion of the PSCN 8 provides routing for packet data services to and from the MS 2. The PDSN 12 establishes, maintains, and terminates link layer sessions with the MS2 and may interface with one of the BSs 6 and one of the PSCNs 8.

An authentication, authorization, and accounting (AAA)13 server provides internet protocol authentication, authorization, and accounting functions related to packet data services. The Home Agent (HA)14 provides authentication of the MS2 IP registration, redirects packet data to and from the Foreign Agent (FA)15 portion of the PDSN 8, and receives provisioning information for the user from the AAA 13. The HA 14 may also establish, maintain and terminate secure communications with the PDSN 12 and assign dynamic IP addresses. The PDSN 12 communicates with the AAA 13, the HA 14, and the internet 16 through an internal IP network.

Several multiple access schemes exist, specifically Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and Code Division Multiple Access (CDMA). In FDMA, user communications are separated by frequency (e.g., using a 30KHz channel). In TDMA, user communications are separated by frequency and time (e.g., using a 30KHz channel with 6 time slots). In CDMA, user communications are separated by digital codes.

In CDMA, all users are on the same frequency spectrum, e.g., 1.25 MHz. Each user has a unique numerical code identifier that separates the users to prevent interference.

CDMA signals utilize multiple chips (chips) to convey a single bit of information. Each user has a unique chip pattern (chip pattern), which is essentially a code channel (code channel). To recover one bit, a large number of chips are combined according to the user's known chip pattern. The code patterns of the other users are random and combined in a self-canceling (sel-canceling) manner, and therefore do not disturb the bit decoding decisions made according to the correct code pattern of the user.

The input data is combined with a fast spreading sequence and transmitted as a spread data stream. The receiver extracts the original data using the same spreading sequence. Fig. 2A illustrates the spreading and despreading process. As shown in fig. 2B, multiple spreading sequences may be combined to create a unique robust channel (robustchannel).

Walsh codes are a class of spreading sequences. Each walsh code is 64 chips long and is exactly orthogonal to all other walsh codes. Such codes are easy to generate and small enough to be stored in Read Only Memory (ROM).

Short PN codes are another type of spreading sequence. The short PN code comprises two PN sequences (I and Q), each 32,768 chips long, and is generated in a similar 15-bit shift register but with different taps. The two sequences scramble the information on the I and Q phase channels.

Long PN codes are another type of spreading sequence. The long PN code is generated in a 42-bit register and is longer than 40 days, or about 4 x 10¹³The chip is long. The long PN code cannot be stored in the ROM of the terminal due to its length, so it is generated chip by chip.

Each MS2 encodes its signal with a PN long code and a unique offset (offset) or a public long code mask calculated using a 32-bit long PN code ESN and 10 bits set by the system. The public long code mask produces a unique offset. A dedicated long code mask may be used to improve privacy. When combined over such a short period of 64 chips, MSs 2 with different long PN code offsets will appear to be effectively orthogonal.

CDMA communications utilize a forward channel and a reverse channel. The forward channel is used for signals from BTS 3 to MS2, and the reverse channel is used for signals from MS to BTS.

The forward channel utilizes its specific assigned walsh code and the sector's specific PN offset to enable one user to have multiple channel types at the same time. The forward channel is identified by its CDMA RF carrier frequency, the sector's unique short code PN offset, and the user's unique walsh code. The CDMA forward channel includes a pilot channel, a synchronization channel, a paging channel, and a traffic channel.

The pilot channel is a "structural beacon" that does not contain a stream of characters, but is a timing sequence used for system acquisition and used as a measurement device during handoff. The pilot channel occupies walsh code 0.

The synchronization channel carries data streams that are identified by the system and parameter information used by the MS2 during system acquisition. The synchronization channel occupies walsh code 32.

There may be one to seven paging channels depending on the capacity requirements. The paging channel carries paging, system parameter information and call setup sequence. The paging channel occupies Walsh codes 1-7.

Traffic channels are assigned to individual users to carry call services. The service channel occupies all remaining walsh codes as determined by the total capacity limited by noise.

The reverse channel is used for signals from the MS2 to the BTS 3, and enables one user to simultaneously transmit a plurality of types of channels using a walsh code and an offset of a long PN sequence specific to the MS. The reverse channel is identified by its CDMA RF carrier frequency and the unique long code PN offset for each MS 2. The reverse channel includes a service channel and an access channel.

Each user transmits a service to the BTS 3 using a service channel during an actual call. The reverse service channel is basically a public or private long code mask unique to the user and there are as many reverse service channels as there are CDMA terminals.

The MS2, which is not yet involved in the call, uses the access channel to send registration requests, call setup requests, page responses, order (order) responses and other signaling information. The access channel is essentially a common long code offset unique to the BTS 3 sector. The access channels are paired with paging channels such that there are up to 32 access channels per paging channel.

CDMA communications provide many advantages. Some of these advantages are variable rate vocoding (vocoding) and multiplexing, power control, use of RAKE receivers, and soft handoff.

CDMA allows the use of variable rate vocoders to compress speech, reduce bit rate, and significantly increase capacity. Variable rate vocoding provides full bit rate during a call, low data rate during call pauses, and increased capacity and natural sound. Multiplexing allows voice, signaling, and user secondary data to be mixed in CDMA frames.

By using forward power control, the BTS 3 continuously reduces the strength of the forward baseband chip stream for each user. When a particular MS2 encounters an error on the forward link, more energy is requested and a fast ramp up of energy is provided after the energy is again reduced.

Using a RAKE receiver enables the MS2 to use the combined output of three service correlators or "RAKE fingers" per frame. Each RAKE finger is able to independently recover a particular PN offset and walsh code. These fingers can resolve the delayed multipath reflections of different BTSs 3 by successively examining the pilot signal by the searcher.

MS2 drives soft handoff. The MS2 continuously checks for available pilot signals and reports to the BTS 3 the pilot signals it currently sees. BTS 3 allocates 6 sectors at maximum and MS2 allocates its fingers accordingly. All messages are sent over dim-and-burst without noise suppression. Each end of the communication link selects the best configuration on a frame-by-frame basis with a handoff that is transparent to the user.

The CDMA200 system is a third generation (3G) wideband, spread spectrum wireless interface system that leverages the enhanced service potential of CDMA technology to facilitate data capabilities, such as internet and intranet access, multimedia applications, high-speed commercial transactions, and telemetry. The focus of cdma2000, and also of other third generation systems, has focused on network economy and wireless transmission design to overcome the limitations of the limited available wireless spectrum.

Fig. 3 illustrates the data link protocol architecture layer 20 of a cdma2000 wireless network. The data link protocol architecture layer 20 includes an upper layer 60, a link layer 30 and a physical layer 21.

The upper layer 60 includes three sublayers: a data service sublayer 61, a voice service sublayer 62, and a signaling service sublayer 63. Data services 61 are services that deliver any form of data on behalf of mobile end users and include packet data applications such as IP services, circuit data applications such as asynchronous fax and B-ISDN emulation services, and SMS. Voice services 62 include PSTN access, mobile-to-mobile (mobile-to-mobile) voice services, and internet telephony. The signaling 63 controls all aspects of the mobile station operation.

The signalling service sublayer 63 processes all messages exchanged between the MS2 and the BS 6. These messages control call setup and teardown, handover, feature activation, system configuration, registration, and authorization functions.

In the MS2, the signalling service sublayer 63 is also responsible for maintaining the call procedure state, specifically the MS2 initialization state, the MS2 idle state, the system access state and the MS2 service channel control state.

The link layer 30 is divided into a Link Access Control (LAC) sublayer 32 and a Medium Access Control (MAC) sublayer 31. The link layer 30 provides protocol support and control mechanisms for data transport services and performs the functions necessary to map the data transport requirements of the upper layer 60 to the specific capabilities and features of the physical layer 21. The link layer 30 can be seen as an interface between the upper layer 60 and the physical layer 21.

The separation of the MAC 31 and LAC 32 sublayers is facilitated by the need to support a wide range of upper layer 60 services and the need to provide efficient and low latency data services over a wide performance range, particularly from 1.2Kbps to over 2 Mbps. Other contributing factors are the need to support high quality of service (QoS) delivery of circuit and packet data services, such as limitations on acceptable delay and/or data BER (bit error rate), and the growing demand for advanced multimedia services each with different QoS requirements.

The LAC sublayer 32 is required to provide reliable in-turn delivery transmission control functions over the point-to-point wireless transmission link 42. The LAC sublayer 32 manages point-to-point communication channels between upper layer 60 entities and provides a framework to support a wide range of different end-to-end reliable link layer 30 protocols.

The LAC sublayer 32 provides for the correct delivery of signaling messages. The functions include deterministic delivery when acknowledgement is required, non-deterministic delivery when acknowledgement is not required, duplicate message detection, address control for delivery of messages to each MS2, fragmentation of messages into segments of appropriate size for transmission over a physical medium, reassembly and verification of received messages, and global challenge authentication.

The MAC sublayer 31 facilitates sophisticated multimedia, multi-service capabilities for 3G wireless systems with QoS management capabilities for each current service. The MAC sublayer 31 provides procedures to control access to packet data and circuit data of the physical layer 21, including contention control between multiple services from a single user and between competing users in a wireless system. The MAC sublayer 31 also performs mapping between logical and physical channels, multiplexes data from multiple sources onto a single physical channel, and provides reasonably reliable transmission at the radio link layer using a Radio Link Protocol (RLP)33 to achieve a best effort level of reliability. The Signaling Radio Burst Protocol (SRBP)35 is an entity that provides a connectionless protocol for signaling messages. The multiplexing and QoS control 34 is responsible for enhancing the negotiated QoS level by arbitrating conflicting requests from competing services and appropriate prioritization of access requests.

The physical layer 21 is responsible for coding and modulating data transmitted over the air. The physical layer 20 conditions the digital data from the higher layers so that it can be reliably transmitted over the mobile radio channel.

The physical layer 21 maps user data and signaling delivered by the MAC sublayer 31 on multiple transport channels to physical channels and sends the information over the radio interface. In the transmit direction, the functions performed by the physical layer 21 include channel coding, interleaving, scrambling, spreading, and modulation. In the receive direction, these functions are reversed in order to recover the transmitted data at the receiver.

Fig. 4 illustrates an overview of call processing. Processing the call includes pilot and synchronization channel processing, paging channel processing, access channel processing, and traffic channel processing.

Pilot and sync channel processing refers to the MS2 processing the pilot and sync channels in the MS2 initialization state to acquire and synchronize with the CDMA system. The paging channel process refers to the MS2 monitoring a paging channel or a forward common control channel (F-CCCH) to receive overhead and mobile-directed messages from the BS6 in an idle state. Access channel handling refers to the MS2 sending messages to the BS6 on an access channel or enhanced access channel in the system access state so that the BS6 always listens to these channels and responds to the MS on the paging channel or F-CCCH. Traffic channel processing refers to the BS6 and MS2 communicating using dedicated forward and reverse traffic channels in the MS2 traffic channel control state so that the dedicated forward and reverse traffic channels carry user information such as voice and data.

Fig. 5 illustrates an initialization state of the MS 2. The initialization states include a system determination substate, a pilot channel acquisition, a synchronization channel acquisition, a timing change substate, and a mobile station idle state.

The system determination is a process by which the MS2 determines from which system to acquire a service. The processing may include determinations of analog and digital, cellular and PCS, and a-carrier and B-carrier. The customer selection process may control system determination. The service provider using the redirection process may also control the system determination. After the MS2 selects a system, it must determine on which channel within the system to search for service. Typically the MS2 uses the prioritized channel list to select the channel.

Pilot channel acquisition is the process by which the MS2 first obtains information about system timing by searching for available pilot signals. The pilot channel does not contain any information, but the MS2 is able to align its own timing by associating with the pilot channel. Once this association is complete, the MS2 synchronizes to the synchronization channel and can read out the synchronization channel message to further refine its timing. The MS2 is allowed to search for up to 15 seconds on a single pilot channel before it declares a failure and returns to system determination to select another channel or another system. The search process is not standardized and the time to acquire the system depends on the implementation.

In cdma2000, there may be many pilot channels, such as OTD pilots, STS pilots, and auxiliary pilots, on a single channel. During system acquisition, MS2 will not find any of these pilot channels because they use different walsh codes, while MS searches only for walsh code 0.

The sync channel message is continuously sent on the sync channel and provides the MS2 with information to fine tune the timing and read the paging channel. A mobile station (mobile) receives a message from BS6 in a synchronization channel that allows it to determine whether it can communicate with the BS.

In the idle state, the MS2 receives one of the paging channels and processes messages on that channel. The overhead or configuration message is compared to the stored sequence number to ensure that the MS2 has the latest parameters. Messages addressed to the MS2 are examined to determine the intended user.

BS6 may support multiple paging channels and/or multiple CDMA channels (frequencies). The MS2 uses a hash function based on its IMSI to determine which channel or frequency to monitor in the idle state. The BS6 uses the same hash function to determine which channel and frequency to use when paging the MS 2.

Slotted paging (slotted paging) is supported using a Slot Cycle Index (SCI) on the paging channel and the F-CCCH. The main purpose of slotted paging is to conserve power in the MS 2. Both MS2 and BS6 agree in which time slot the MS will be called. The MS2 may power down certain processing circuits during the unallocated timeslot. Either a regular paging message or a general paging message may be used to page the mobile station on the F-CCCH. A quick paging channel is also supported that allows the MS2 to power up for a shorter period of time than would otherwise be possible with slotted paging on the F-PCH or F-CCCH only.

Fig. 6 illustrates a system access state. The first step in the system access process is to update the overhead information to ensure that the MS2 is utilizing the correct access channel parameters, such as initial power level and power step increments (power step entries). The MS2 randomly selects an access channel and transmits without coordination with the BS6 or other MSs. Such a random access procedure may result in collisions. Several steps may be taken to reduce the probability of collisions, such as utilizing a slot structure, using multiple access channels, transmitting at random start times, and employing congestion control, such as overload classification (classes).

The MS2 may send a request or response message on the access channel. The request is an automatically sent message, such as an origination message (origin message). The response is a message sent in response to a message received from the BS 6. For example, the page response message is a response to a regular page message or a general message.

An access attempt refers to the entire process of sending a layer 2 encapsulated PDU and receiving an acknowledgement for the PDU, which includes one or more access sub-attempts, as shown in fig. 7. The access sub-attempt comprises a set of access probe sequences, as shown in fig. 8. The sequences within an access sub-attempt are separated by a random backoff (backoff) interval (RS) and a Persistence Delay (PD). The PD is only applicable to access channel requests and not to responses.

Fig. 9 illustrates a system access state in which collision is avoided by using a slot offset of 0 to 511 slots.

The multiplexing and QoS control sublayer 34 has both a transmitting function and a receiving function. The transmit function combines information from various sources, such as data services 61, signaling services 63, or voice services 62, and forms physical layer SDUs and PDCHCF SDUs for transmission. The receive function separates the information contained in the physical layer 21 and PDCHCF SDUs and directs the information to the correct entity, such as data service 61, upper layer signaling 63, or voice service 62.

The multiplexing and QoS control sublayer 34 operates in time synchronization with the physical layer 21. If the physical layer 21 transmits with a non-zero frame offset, the multiplexing and QoS control sublayer 34 delivers physical layer SDUs to be transmitted by the physical layer with an appropriate frame offset with respect to system time.

The multiplexing and QoS control sublayer 34 delivers the physical layer 21SDU to the physical layer using the physical channel-specific service interface set of primitives. The physical layer 21 delivers the physical layer SDU to the multiplexing and QoS control sublayer 34 using a physical channel dedicated reception indication service interface operation.

The SRBP sublayer 35 includes synchronization channel, forward common control channel, broadcast control channel, paging channel, and access channel procedures.

The LAC sublayer 32 provides services to the layer (3) 60. SDUs are passed between the layer 360 and the LAC sublayer 32. The LAC sublayer 32 provides proper encapsulation of SDUs into LAC PDUs that are segmented and reassembled and delivered to the MAC sublayer 31 as encapsulated PDU segments.

The processing within the LAC sublayer 32 is done sequentially, and the processing entities pass the partially formed LAC PDUs to each other in an established order. SDUs and PDUs are processed and transported along a functional path without the upper layers knowing the radio characteristics of the physical channel. However, the upper layer may know the characteristics of the physical channel and may direct layer (2)30 to transmit a specific PDU using a specific physical channel.

The 1xEV-DO system is preferred for packet data services, characterized by being used only for data or a single 1.25MHz carrier ("1 x") or data optimized ("DO"). In addition, there is a peak data rate of 4.9152Mbps on the forward link and 1.8432Mbps on the reverse link. Furthermore, the 1xEV-DO system provides separate frequency bands and internetworking with the 1x system. Fig. 10 illustrates a comparison of cdma2000 and 1xEV-DO systems for a 1x system.

concurrent services exist in a cdma2000 system such that voice and data are actually transmitted together at maximum data rates 614.4kbps and 307.2 kbps. The MS2 communicates with the MSC 5 for voice calls and with the PDSN 12 for data calls. cdma2000 systems are characterized by a fixed rate of variable power for the forward traffic channel using walsh code separation.

In the 1xEV-DO system, the maximum data rate is 2.4Mbps or 3.072Mbps, and no communication is made with the circuit-switched core network 7. The 1xEV-DO system is characterized by a fixed power and variable rate for a single forward channel using time division multiplexing.

FIG. 11 illustrates a 1xEV-DO system architecture. In a 1xEV-DO system, a frame consists of 16 slots, 600 slots per second, and has a duration of 26.67ms or 32,768 chips. A single slot is 1.6667ms in length and has 2048 chips. The control/traffic channel has 1600 chips in a slot, the pilot channel has 192 chips in a slot, and the MAC channel has 256 chips in a slot. The 1xEV-DO system facilitates simpler and faster channel estimation and time synchronization.

FIG. 12 illustrates a 1xEV-DO system default protocol architecture. FIG. 13 illustrates a 1xEV-DO system non-default protocol architecture.

Information related to a session in a 1xEV-DO system includes a set of protocols used by the MS2 (or Access Terminal (AT)) and the BS6 (or Access Network (AN)) over a wireless link, a Unicast Access Terminal Identifier (UATI), a configuration of the protocols used by the AT and the AN over the wireless link, and AN estimate of the current AT location.

The application layer provides best effort service (best effort) whereby messages are sent once and provides reliable delivery whereby messages can be retransmitted one or more times. The stream layer provides the ability for one AT2 to multiplex up to 4 (default) or 255 (non-default) application streams.

The session layer ensures that the session is still active and manages the end session, specifies procedures for initial UATI assignment, maintains AT addresses and negotiates/provisions the protocols used during the session and configuration parameters for these protocols.

FIG. 14 illustrates establishment of a 1xEV-DO session. As shown in fig. 14, establishing a session includes address configuration, connection establishment, session configuration, and exchanging keys.

Address configuration refers to an address management protocol that assigns a UATI and a subnet mask. Connection establishment refers to the connection layer protocol that establishes the radio link. Session configuration refers to a conference configuration protocol that configures all protocols. Exchanging keys refers to establishing a key exchange protocol in the security layer for authentication.

"session" refers to a logical communication link between the AT2 and the RNC that remains open for hours, with a default of 54 hours. The session continues until the PPP session is also active. The session information is controlled and maintained by the RNC in the AN 6.

When the connection is open, AT2 may be assigned a forward traffic channel and assigned a reverse channel and a reverse power control channel. Multiple connections may occur during a single session.

The connectivity layer manages the initial acquisition of the network and communication. In addition, the connectivity layer maintains AN approximate location of AT2 and manages the wireless link between AT2 and AN 6. And, the connection layer manages, optimizes and encapsulates the transmitted data received from the session layer, forwards the optimized data to the security layer, decapsulates the data received from the security layer and forwards it to the session layer.

Fig. 15 illustrates a connection layer protocol. As shown in fig. 15, the protocol includes an initialization state, an idle state, and a connection state.

In the initialization state, the AT2 acquires the AN 6 and activates the initialization state protocol. In the idle state, a closed (closed) connection is initiated and the idle state protocol is activated. In connected state, an open (open) connection is initiated and the connection state protocol is activated.

The associated connection refers to a state in which the AT2 is not allocated any dedicated radio link resources and communication between the AT and the AN 6 is performed on AN access channel and a control channel. Open connection refers to a state where AT2 may be assigned a forward traffic channel, assigned a reverse power control channel and a reverse traffic channel, and communication between AT2 and AN 6 is on these assigned channels as well as on the control channel.

The initialization state protocol performs actions related to acquiring the AN 6. The idle state protocol performs actions related to the AT2 that has acquired the AN 6 but has not opened the connection, such as tracking the AT location using a route update protocol. The connection state protocol performs actions related to the AT2 having AN open connection, such as managing the wireless link between the AT and the AN 6 and managing procedures that result in a closed connection. The route update protocol performs actions related to tracking the AT2 location and maintaining the wireless link between the AT and the AN 6. The overhead message protocol broadcasts basic parameters such as QuickConfig, SectorParameters, and AccessParameters messages on the control channel. The packet integrity protocol integrates and optimizes packets for transmission as a function of their assigned priority and target channel and provides packet demultiplexing at the receiver.

The security layer includes a key exchange function, an authentication function, and an encryption function. The key exchange function provides procedures that AN 2 and AT 6 follow for authenticating traffic. The authentication function provides the procedures that AN 2 and AT 6 follow to exchange security keys for authentication and encryption. The encryption function provides procedures that AN 2 and AT 6 follow for encrypting traffic.

The 1xEV-DO forward link is characterized by no support for power control and soft handoff. The AN 6 transmits AT a constant power and the AT2 requests a variable rate on the forward link. Since different users may transmit at different times in TDM fashion, it is difficult to achieve diversity of transmissions from different BSs 6 intended for a single user.

In the MAC layer, two types of messages originating from an upper layer (specifically, user data messages and signaling messages) are transmitted across the physical layer. Two protocols are used to process these two types of messages, specifically, the forward traffic channel MAC protocol for user data messages and the control channel MAC protocol for signaling messages.

The physical layer 21 is characterized by a spreading rate of 1.2288Mcps, and a frame includes 16 slots and 26.67ms, a slot being 1.67ms and 2048 chips. The forward link channel includes a pilot channel, a forward traffic channel or control information, and a MAC channel.

The pilot channel is similar to the cdma2000 pilot channel in that it includes all "0" information bits and walsh spreading for W0 in 192 chips.

The forward traffic channel is characterized by data rates that vary from 38.4kbps to 2.4576Mbps or from 4.8kbps to 4.9152 Mbps. The physical layer packet of data may be transmitted in 1 to 16 slots, and the transmission slots employ 4-slot interleaving when more than one slot is allocated. If an ACK is received on the reverse link ACK channel before all of the assigned slots are transmitted, the remaining slots are not transmitted.

The control channels are similar to the synchronization channel and paging channel in cdma 2000. The control channel is characterized by a period of 256 time slots or 426.67ms, physical layer packet lengths of 1024 bits or 128, 256, 512 and 1024 bits, and data rates of 38.4kbps or 76.8kbps or 19.2kbps, 38.4kbps or 76.8 kbps.

The 1xEV-DO reverse link is characterized by AN 6 that is capable of power controlling the reverse link with directional power control and more than one AN that is capable of receiving AT 2's transmissions with soft handoff. In addition, there is no TDM on the reverse link, which is channelized with a long PN code by a walsh code.

The AT2 uses the access channel to initiate communication with the AN 6 or to respond to AT-directed messages. The access channel includes a pilot channel and a data channel.

The AT2 sends a series of access probes on the access channel until a response is received from the AN 6 or a timer expires. The access probe includes a preamble and one or more access channel physical layer packets. The basic data rate for the access channel is 9.6kbps, and higher data rates of 19.2kbps and 38.4kbps are also available.

When more than one AT2 is paged with the same control channel packet, access probes may be sent simultaneously, and thus packet collisions may occur. The problem is exacerbated when AT2 is co-located and is engaged in a group call or has similar transmission delays.

One reason that there may be a conflict is the inefficiency of the current persistence test in the conventional method. Because AT2 may require a short connection setup time, the paged AT may have sent an access probe AT the same time as another paged AT when using the persistence test.

The conventional approach of using persistence tests is not sufficient because each AT2 that requires a short connection setup time and/or is part of a group call may have the same persistence value (typically set to 0). If the AT2 is co-located, e.g., in a group call, access probes arrive AT the AN 6 AT the same time, thereby resulting in access collisions and increased connection setup time.

Therefore, there is a need for a more efficient method to access probe transmissions from co-located mobile terminals requiring short connection setup times. The present invention addresses this and other needs.

Disclosure of Invention

Features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the written description and claims hereof as well as the appended drawings.

The present invention aims to provide an apparatus and method for reducing collisions of access probes from co-located mobile terminals. By randomizing the time at which the access probe is sent, collisions can be avoided.

An aspect of the present invention provides a method of providing a connection to a mobile terminal in a mobile communication system. The method comprises the following steps: sending one or more access probes, each access probe requesting a connection to the network; and acknowledging access probes sent prior to the network connection, wherein each of the access probes is sent according to a random delay calculated as a value between a predetermined minimum value and a predetermined maximum value prior to sending each access probe.

It is contemplated that the method comprises the steps of: transmitting each of the access probes in accordance with the random delay and a mobile terminal time reference. It is further contemplated that the predetermined minimum value and the predetermined maximum value are set in dependence of a quality of service, QoS, requirement of the mobile terminal, a location of the mobile terminal, a relationship between the mobile terminal and other mobile terminals, and/or a service level of the mobile terminal.

The predetermined minimum and maximum values are expected to be the same as the predetermined minimum and maximum values for at least one other mobile terminal having the same QoS as the mobile terminal or being co-located with the mobile terminal. It is also contemplated that the random delay comprises a plurality of chips.

The random delay range between the predetermined minimum value and the predetermined maximum value is expected to be the same as the random delay range of at least one other mobile terminal and does not overlap the random delay range of at least one other mobile terminal. It is also contemplated that the predetermined minimum value or the predetermined maximum value is the same as a respective one of the predetermined minimum value and the predetermined maximum value of the at least one other mobile terminal.

It is contemplated that the method comprises the steps of: unilaterally (unilaterally) predetermined minimum and maximum values are received from the network. It is also contemplated that the method further comprises the steps of: negotiating the predetermined minimum value and the predetermined maximum value with the network.

It is contemplated that the method comprises the steps of: updating the predetermined minimum value and the predetermined maximum value when the QoS requirement of the mobile terminal changes, the position of the mobile terminal changes, the relationship between the mobile terminal and other mobile terminals changes and/or the service level of the mobile terminal changes. It is also contemplated that the method comprises the steps of: transmitting each of the access probes according to a delay comprising the random delay and an access offset, the access offset being fixed until a network connection is acknowledged.

It is contemplated that the method comprises the steps of: one of a plurality of access offsets assigned to the mobile terminal is randomly selected. It is further contemplated that each of the access probes is assigned an access probe number, and the method further comprises the steps of: the random delay is calculated from a user ID and/or the access probe number.

It is contemplated that the method comprises the steps of: the random delay is calculated using a hash function. It is also contemplated that the method comprises the steps of: the normal time schedule (normal time) of the traffic channel is utilized after the connection is provided. Preferably, the method comprises the steps of: not sending a first one of the access probes according to the random delay.

It is contemplated that the method further comprises the steps of: a paging message is received from a network. It is also contemplated that the service level is platinum, gold or silver.

Another aspect of the present invention provides a method of providing a connection to a mobile terminal in a mobile communication system, the method comprising the steps of: receiving a paging message from a network; transmitting a first sequence comprising a predetermined number of access probes, each of said access probes requesting a connection to said network, and transmitting in sequence until a network connection is confirmed or all access probes of said first sequence have been transmitted, wherein each of said access probes in said first sequence is transmitted according to a random delay calculated as a value between a predetermined minimum value and a predetermined maximum value before each access probe is transmitted; and if a network connection is not acknowledged after sending said first sequence, sending at least a second sequence comprising said predetermined number of access probes, wherein each of said access probes of said at least a second sequence is sent according to a random delay comprising a value between said predetermined minimum value and said predetermined maximum value.

It is contemplated that the method comprises steps according to: transmitting each of said access probes of said at least second sequence according to the calculated random delay before transmitting each access probe. It is also contemplated that the method comprises the steps of: transmitting each of the access probes of the at least second sequence according to the same random delay previously calculated for the respective access probe in the first sequence.

It is contemplated that each of the access probes of the first sequence and each of the access probes of the at least a second sequence are assigned an access probe number, that the first sequence and the at least a second sequence are assigned an access probe sequence number, and that the method further comprises the steps of: calculating the random delay from a user ID, the access probe number and/or the access probe sequence number. It is also contemplated that the method comprises the steps of: the random delay is calculated using a hash function.

It is contemplated that the method comprises the steps of: after the connection is provided, a standard schedule of traffic channels is utilized. It is also contemplated that the method comprises the steps of: not sending a first probe of the access probes of the first and second sequences according to the random delay.

Another aspect of the present invention provides a mobile terminal. The mobile terminal includes: a transmitting/receiving unit adapted to transmit one or more access probes to a network; a display unit adapted to display user interface information; an input unit adapted to input user data; and a processing unit adapted to process paging messages, generate said access probes and control said sending/receiving unit to send said access probes until a network connection is confirmed, each of said access probes requesting a connection to said network and being sent according to a random delay calculated as a value between a predetermined minimum value and a predetermined maximum value before sending said access probe.

It is contemplated that the processing unit is further adapted to transmit each of the access probes in accordance with the random delay and a mobile terminal time reference. It is also contemplated that the predetermined minimum value and the predetermined maximum value are set according to quality of service (QoS) requirements of the mobile terminal, a location of the mobile terminal, a relationship between the mobile terminal and other mobile terminals, and/or a service level of the mobile terminal.

The predetermined minimum and maximum values are expected to be the same as the predetermined minimum and maximum values for at least one other mobile terminal having the same QoS as the mobile terminal or being co-located with the mobile terminal. It is also contemplated that the random delay is a plurality of chips.

The random delay range between the predetermined minimum value and the predetermined maximum value is expected to be the same as, and not to overlap with, the random delay range of at least one other mobile terminal. It is also contemplated that the predetermined minimum value or the predetermined maximum value is the same as a respective one of the predetermined minimum value and the predetermined maximum value of the at least one other mobile terminal.

It is contemplated that the processing unit is further adapted to receive unilaterally predetermined minimum and maximum values from the network. It is further contemplated that the processing unit is further adapted to negotiate the predetermined minimum value and the predetermined maximum value with the network.

It is contemplated that the processing unit is further adapted to update the predetermined minimum value and the predetermined maximum value when a quality of service (QoS) requirement of the mobile terminal changes, a location of the mobile terminal changes, a relationship between the mobile terminal and other mobile terminals changes, and/or a service level of the mobile terminal changes. It is further contemplated that the processing unit is further adapted to send each of the access probes according to a delay comprising the random delay and an access offset, the access offset being fixed until a network connection is acknowledged.

It is contemplated that the processing unit is further adapted to randomly select one of a plurality of access offsets assigned to the mobile terminal. It is further contemplated that each of the access probes is assigned an access probe number, and that the processing unit is further adapted to calculate the random delay from a user ID and/or the access probe number.

It is contemplated that the processing unit is further adapted to calculate the random delay using a hash function. It is further contemplated that the processing unit is further adapted to utilize a standard schedule of traffic channels after providing a connection to the network.

It is contemplated that the processing unit is further adapted to not send a first one of the access probes according to the random delay. It is further contemplated that the processing unit is further adapted to: generating a first sequence comprising a predetermined number of access probes and controlling said transmitting/receiving unit to transmit said first sequence in a sequence until a network connection is confirmed or all access probes of said first sequence have been transmitted, each of said access probes requesting a connection to said network and being transmitted according to a random delay calculated as a value between a predetermined minimum value and a predetermined maximum value before transmitting each access probe; and generating at least a second sequence comprising said predetermined number of access probes, and controlling said transmitting/receiving unit to transmit said second sequence if a network connection is not acknowledged after transmitting said first sequence, each of said access probes of said at least second sequence being transmitted according to a random delay comprising a value between said predetermined minimum value and said predetermined maximum value.

It is contemplated that the processing unit is further adapted to transmit the at least a second sequence of the access probes according to a random delay calculated before transmitting each access probe. It is further contemplated that the processing unit is further adapted to send each of the access probes of the at least second sequence according to the same random delay previously calculated for the respective access probe in the first sequence.

It is contemplated that each of the access probes in the first sequence and each of the access probes in the at least second sequence is assigned an access probe number, that the first sequence and the at least second sequence are assigned access probe sequence numbers, and that the processing unit is further adapted to calculate the random delay based on a user ID, the access probe number and/or the access probe sequence number. It is further contemplated that the processing unit is further adapted to calculate the random delay using a hash function.

It is contemplated that the processing unit is further adapted to utilize a standard schedule of traffic channels after the connection is provided. It is further contemplated that the processing unit is further adapted to not send a first one of the access probes in the first and second sequences according to the random delay.

It is contemplated that the transmit/receive unit is further adapted to receive a paging message from a network. It is also contemplated that the service level is platinum, gold or silver.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of the embodiments having reference to the attached figures, the invention not being limited to any particular embodiments disclosed.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. Features, elements, and aspects of the invention that are referenced by the same numerals in different figures represent the same, equivalent, or similar features, elements, or aspects in accordance with one or more embodiments.

Fig. 1 illustrates a wireless communication network architecture.

Fig. 2A illustrates CDMA spreading and despreading processing.

Fig. 2B illustrates CDMA spreading and despreading processing with multiple spreading sequences.

Fig. 3 illustrates data link protocol architecture layers for a cdma2000 wireless network.

Fig. 4 illustrates cdma2000 call processing.

Fig. 5 illustrates the cdma2000 initialization state.

Fig. 6 illustrates a cdma2000 system access state.

Fig. 7 illustrates a conventional cdma2000 access attempt.

Fig. 8 illustrates a conventional cdma2000 access sub-attempt.

Fig. 9 illustrates a conventional cdma2000 system access attempt with a slot offset.

FIG. 10 illustrates a comparison of cdma2000 and 1xEV-DO for 1 x.

FIG. 11 illustrates network architecture layers for a 1xEV-DO wireless network.

FIG. 12 illustrates a 1xEV-DO default protocol architecture.

FIG. 13 illustrates a 1xEV-DO non-default protocol architecture.

FIG. 14 illustrates a 1xEV-DO session establishment.

FIG. 15 illustrates a 1xEV-DO connection layer protocol.

Fig. 16 illustrates an access probe sequence according to one embodiment of the invention.

Fig. 17 illustrates an access probe structure according to one embodiment of the invention.

Fig. 18 illustrates a block diagram of a mobile station or access terminal in accordance with one embodiment of the present invention.

Detailed Description

The present invention relates to an apparatus and method for reducing collisions of access probes from co-located mobile terminals by randomizing the times at which the access probes are sent. Although the present invention is described with respect to a mobile terminal, it is contemplated that the present invention may reduce collision of signals transmitted from co-located communication devices whenever desired.

The present invention is directed to random access, and more particularly to random access based on QoS or other factors such as service level and location of the mobile terminal. When mobile terminals, which receive messages through the same paging channel and are located close to each other in the conventional system, access the system, the terminal groups perform random access based on the same persistence (persistence) value to shorten the connection time. However, this persistence value approach leads to access probe collisions.

Due to the fast connection requirements of mobile terminals, a more efficient method is needed for access probe transmission. The present invention not only reduces access probe collisions between mobile terminals in the same group, but also reduces collisions between other groups.

In addition to location-based methods to classify mobile terminals into different groups, QoS and GoS (class of service) classification is also provided. Several methods of reducing access probe collisions are presented accordingly. Access probes arriving at the network several chips apart in time from co-located mobile terminals minimize access probe collisions, enabling fast connection establishment without access persistence.

According to the present invention, the mobile terminal denoted as AT _ k calculates the random delay access _ k between the minimum delay value MinAccessDelay _ k and the maximum delay value maxcessdelay _ k in chip units. The start time of the access probe from AT k is then delayed with a random delay, AccessDelay _ k. The minimum delay value MinAccess delay _ k may be selected to be "0" or another value less than the maximum delay value.

Determining the maximum delay value maxcessedelay _ k for each AT2 may take into account the QoS requirements, location and relationship with other mobile terminals of the mobile terminal, or the service level (e.g., platinum, gold or silver) of the mobile terminal. In addition, mobile terminals requiring the same QoS or co-location (e.g., in a group call) may be assigned the same maxcessedelay _ k, such that the index "k" represents the index of a group of mobile terminals. Thus, each mobile terminal or group may have its own random delay range randomized between a minimum delay MinAccess delay _ k and a maximum delay MaxAccessDelay _ k.

The range of possible random delay values between the minimum delay MinAccessDelay _ k and the maximum delay maxcessdelay _ k for a group "k" or for an AT k may not overlap with the range of possible delay values between the minimum delay MinAccessDelay _ i and the maximum delay maxcessdelay _ i for a group i or for an AT i, where k ≠ i,k，i。

the maximum delay maxcessdelay _ k may be determined by the network and provided to the mobile terminal or negotiated between the network and the mobile terminal. The maximum delay maxcessdelay _ k may be adaptively updated by the network or the mobile terminal as the status or requirements of the network or the mobile terminal change.

Fig. 16 illustrates a sequence of access probes generated in accordance with the present invention. Fig. 17 illustrates an access probe structure according to the present invention. Each mobile terminal may be assigned one or more accessoffsets. When the mobile terminal decides to send an access probe, it may randomly select one of the accessoffsets.

The total access delay TotalAccessDelay _ K of AT _ K is the sum of the AccessOffset _ K shown in fig. 17 and the random delay AccessDelay _ K of each probe. The random delay, AccessDelay _ k (τ ρ), should be randomized for each access probe to minimize the likelihood of access collisions. Otherwise, the random delay, AccessDelay _ k, is fixed until the probe sequence is completed or the access is successful.

Each group or mobile terminal may be assigned a certain randomization parameter, and the randomization parameters assigned to each group or mobile terminal are sufficiently separated so that collisions may be avoided or minimized. The randomization parameters of each access probe for each mobile terminal may be the same or different and may be configured by the network or by negotiation between the mobile terminal and the network.

Before sending an access probe, the mobile terminal may sense the access channel it is interested in. If there is an existing access probe, the mobile terminal will temporarily suspend its access probe and wait for another access time.

The random delay, AccessDelay _ k, may be calculated using a hash function based on the mobile terminal identifier and/or the probe number. The possible values of the hash function may be based on 8 chip increments to minimize access collisions and allow a wider search window.

For example, the maximum latency maxcessedelay may be any other multiple of 0, 8, 16, 24, or 8. Further, a default value of 0 may be used. The mobile terminal switches back to the standard schedule for the traffic channel.

The initial access attempt may not use a randomization process. The network may set the access search window according to the cell radius or maximum delay maxcessdelay _ k. Furthermore, the traffic search window may be set according to the randomization used by a particular mobile terminal.

Fig. 18 illustrates a block diagram of a Mobile Station (MS) or access terminal 100 in accordance with one embodiment of the present invention. The AT 100 includes a processor (or digital signal processor) 110, an RF module 135, a power management module 105, an antenna 140, a battery 155, a display 115, a keypad 120, a memory 130, a SIM card 125 (optional), a speaker 145, and a microphone 150.

The user inputs the indication information, such as a telephone number, by pressing a button of the keypad 120 or by voice activation using the microphone 150. The microprocessor 110 receives and processes the indicating information to perform the appropriate function, such as dialing the telephone number. Operational data may be retrieved from the Subscriber Identity Module (SIM) card 125 or the memory module 130 to perform this function. In addition, the processor 110 may display indication information or operation information on the display 115 in order to provide reference and convenience to the user.

The processor 110 issues an indication to the RF module 135 to initiate communication, such as transmitting a wireless signal including voice communication data. The RF module 135 includes a receiver and a transmitter for receiving and transmitting wireless signals. The antenna 140 facilitates the transmission and reception of wireless signals. Upon receiving the wireless signal, the FR module 135 may forward and convert the signal to baseband for processing by the processor 110. The processed signals will be converted into audible or readable information, for example, output through speaker 145. The processor 110 also includes the protocols and functions necessary to perform the various processes described herein for cdma2000 or 1xEV-DO systems.

The processor 110 is adapted to perform the methods disclosed herein to randomize the times at which access probes are transmitted. The processor controls the RF module 135 to transmit an access probe sequence having the structure shown in fig. 18 as shown in fig. 17.

Although the present invention is described with respect to cdma2000, 1xEV-DO, and cdma2000NxEV-DO, it is also applicable to other communication systems that may be employed.

There are at least two typical application scenarios in which conventional persistence tests do not work, whereas the method of the present invention works well. The first case is to use the same control channel packet to call multiple terminals and require a short connection setup time so that they send access probes simultaneously with the same persistence value (typically set to 0). The second case is where multiple terminals in a group call are co-located and a fast connection setup is desired, so that the propagation delay of the mobile terminals is the same. In addition to their geographical location, the mobile terminals should be divided into different groups based on QoS, GoS or other possible criteria, so that different access delay limits can be set for different groups.

The access probe randomization method for minimizing access probe collisions according to the present invention is further enhanced by taking into account QoS or/and GoS (grade of service) requirements of the mobile terminal. With the present invention, in addition to a sector-based approach by which all mobile terminals in a sector share the same value of the maximum delay value maxcessedelay, access probe randomization can be implemented for a single mobile terminal and a group of mobile terminals. Thus, more flexible operation can be achieved.

The present invention improves connection setup time for co-located mobile terminals within a group call that is simultaneously paged. Without the randomization method of the present invention, all co-located mobile terminals within a group call will access the network within a few chips, thus resulting in access probe collisions and longer connection setup times. Furthermore, a reduction of access probe collisions can be achieved even if only a part of the co-located mobile terminals support the method of the present invention.

As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.

Industrial applicability

The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The teachings herein can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures.

Claims (28)

1. A method of providing a connection to a mobile terminal in mobile communication, the method comprising the steps of:

receiving a predetermined maximum delay value from the network; and

transmitting a plurality of access probe sequences, each of the plurality of access probe sequences comprising a plurality of access probes, each of the plurality of access probes requesting a connection to a network and transmitting the access probe until a network connection is confirmed,

wherein each of the plurality of access probes is transmitted according to a random delay between access probes within each sequence of access probes, wherein each of the plurality of access probes is assigned an access probe number, an

Wherein the random delay is calculated based on at least the predetermined maximum delay value and the access probe number before each of the plurality of access probes is transmitted, and the random delay is a value between 0 and the predetermined maximum delay value.

2. The method of claim 1, further comprising the steps of: transmitting each of the plurality of access probes in accordance with the random delay and a mobile terminal time reference.

3. The method according to claim 1, wherein the predetermined maximum delay value is set according to at least one of a quality of service, QoS, requirement of the mobile terminal, a location of the mobile terminal, a relationship between the mobile terminal and other mobile terminals, and a service class of the mobile terminal.

4. A method according to claim 3, wherein the predetermined maximum delay value is the same as a predetermined maximum delay value for at least one other mobile terminal having the same QoS as the mobile terminal or being co-located with the mobile terminal.

5. The method of claim 3, wherein the random delay comprises a plurality of chips.

6. The method of claim 1, further comprising the steps of: updating the predetermined maximum delay value when at least one of a quality of service, QoS, requirement of the mobile terminal, a location of the mobile terminal, a relationship between the mobile terminal and other mobile terminals, and a service class of the mobile terminal changes.

7. The method of claim 1, further comprising the steps of: transmitting each of the plurality of access probes according to a delay comprising the random delay and an access offset, the access offset being fixed until a network connection is acknowledged.

8. The method of claim 7, further comprising the steps of: one of a plurality of access offsets assigned to the mobile terminal is randomly selected.

9. The method of claim 1, wherein the random delay is further calculated as a function of a user ID.

10. The method of claim 1, further comprising the steps of: the random delay is calculated using a hash function.

11. The method of claim 1, further comprising the steps of: a standard schedule of traffic channels is utilized after the connection is provided.

12. The method of claim 1, further comprising the steps of: not transmitting a first one of the plurality of access probes according to the random delay.

13. The method of claim 1, further comprising the steps of: a paging message is received from a network.

14. The method of claim 3, wherein the service class comprises one of a platinum class, a gold class, and a silver class.

15. A mobile terminal, the mobile terminal comprising:

a transmitting/receiving unit adapted to receive a predetermined maximum delay value from the network and to transmit a plurality of access probe sequences to the network, each of the plurality of access probe sequences comprising a plurality of access probes;

a display unit adapted to display user interface information;

an input unit adapted to input user data; and

a processing unit adapted to process paging messages, generate the plurality of access probes and control the sending/receiving unit to send the plurality of access probes until a network connection is acknowledged, each of the plurality of access probes requesting a connection to the network and being sent according to a random delay between access probes within each sequence of access probes,

wherein each of the plurality of access probes is assigned an access probe number, an

Wherein the random delay is calculated based on at least the predetermined maximum delay value and the access probe number before each access probe is transmitted, and the random delay is a value between 0 and the predetermined maximum delay value.

16. The terminal of claim 15, wherein the processing unit is further adapted to transmit each of the plurality of access probes according to the random delay and a mobile terminal time reference.

17. The method of claim 15, wherein the predetermined maximum delay value is set according to at least one of a quality of service (QoS) requirement of the mobile terminal, a location of the mobile terminal, a relationship between the mobile terminal and other mobile terminals, and a service class of the mobile terminal.

18. A terminal according to claim 17, wherein the predetermined maximum delay value is the same as a predetermined maximum delay value for at least one other mobile terminal having the same QoS as the mobile terminal or being co-located with the mobile terminal.

19. The terminal of claim 17, wherein the random delay comprises a plurality of chips.

20. A terminal according to claim 15, wherein the processing unit is further adapted to update the predetermined maximum delay value when at least one of a quality of service, QoS, requirement of the mobile terminal, a location of the mobile terminal, a relationship between the mobile terminal and other mobile terminals, and a service class of the mobile terminal changes.

21. The terminal of claim 15, wherein the processing unit is further adapted to transmit each of the plurality of access probes according to a delay comprising the random delay and an access offset, the access offset being fixed until a network connection is acknowledged.

22. The terminal of claim 21, wherein the processing unit is further adapted to randomly select one of a plurality of access offsets assigned to the mobile terminal.

23. The terminal of claim 15, wherein the random delay is further calculated as a function of a user ID.

24. The terminal of claim 15, wherein the processing unit is further adapted to calculate the random delay using a hash function.

25. A terminal according to claim 15, wherein the processing unit is further adapted to utilize a standard schedule of traffic channels after providing a connection to the network.

26. The terminal of claim 15, wherein the processing unit is further adapted to not transmit the first one of the plurality of access probes according to the random delay.

27. The terminal of claim 15, wherein the transmitting/receiving unit is further adapted to receive a paging message from a network.

28. The terminal of claim 17, wherein the service class comprises one of a platinum class, a gold class, and a silver class.