US20160057717A1

US20160057717A1 - Network node and method for indicating to wireless device that system information (si) has changed for purposes of a system access procedure

Info

Publication number: US20160057717A1
Application number: US14/829,561
Authority: US
Inventors: Olof Liberg; Mårten Sundberg; John Walter Diachina; Paul Schliwa-Bertling
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2014-08-21
Filing date: 2015-08-18
Publication date: 2016-02-25
Also published as: WO2016027238A1; EP3183912B1; US20160057646A1; BR112017003484A2; EP3183914A1; EP3183912A1; MY179423A; RU2017109124A; CN106576283B; US10142876B2; RU2017109124A3; CN106576283A; ES2667848T3; WO2016027239A1; MX2017001575A; CN106576284A; US20190053090A1

Abstract

A network node (e.g., base station, eNodeB) is described herein which indicates that System Information (SI) has changed in at least one of a frequency correction channel (FCCH) block or a synchronization channel (SCH) block, and transmits the at least one of the FCCH block or the SCH block to at least one wireless device. In addition, a wireless device is described herein which receives the at least one of a FCCH block or the SCH block, and determines if the received at least one of the FCCH block or the SCH block indicates that SI has changed and uses this information for purposes of a system access procedure.

Description

CLAIM OF PRIORITY

This application claims the benefit of priority to U.S. Provisional Application No. 62/040,154, filed on Aug. 21, 2014, the entire contents of which are hereby incorporated by reference for all purposes.

TECHNICAL FIELD

The present disclosure relates to a network node (e.g., base station, eNodeB) which indicates that System Information (SI) has changed in at least one of a frequency correction channel (FCCH) block or a synchronization channel (SCH) block, and transmits the at least one of the FCCH block or the SCH block to at least one wireless device. In addition, the present disclosure relates to a wireless device which receives the at least one of a FCCH block or the SCH block, and determines if the received at least one of the FCCH block or the SCH block indicates that SI has changed and uses this information for purposes of a system access procedure.

BACKGROUND

The following abbreviations and terms are herewith defined, at least some of which are referred to within the following description of the present disclosure.

- 3GPP 3rd-Generation Partnership Project
- ASIC Application Specific Integrated Circuit
- BCCH Broadcast Control Channel
- DSP Digital Signal Processor
- EDGE Enhanced Data rates for GSM Evolution
- EGPRS Enhanced General Packet Radio Service
- FCCH Frequency Correction Channel
- GMSK Gaussian Minimum Shift Keying
- GSM Global System for Mobile Communications
- HARQ Hybrid Automatic Repeat Request
- IoT Internet of Things
- LTE Long-Term Evolution
- M2M Machine-to-Machine
- MCS Modulation and Coding Scheme
- MS Mobile Station
- MTC Machine-Type Communications
- SCH Synchronization Channel
- SI System Information
- UE User Equipment
- UL Uplink
- WCDMA Wideband Code Division Multiple Access
- WiMAX Worldwide Interoperability for Microwave Access

Extended Coverage: The general principle of extended coverage is that of using blind repetitions for the control channels and for the data channels. In addition, for the data channels the use of blind repetitions assuming MCS-1 (i.e., the lowest MCS supported in EGPRS today) is combined with HARQ retransmissions to realize the needed level of data transmission performance. Support for extended coverage is realized by defining different coverage classes. A different number of blind repetitions are associated with each of the coverage classes wherein extended coverage is associated with coverage classes for which multiple blind repetitions are needed (i.e., a single blind repetition is considered as the reference coverage). The number of total blind transmissions for a given coverage class can differ between different logical channels.
System Access Procedure: The steps performed by a wireless device to verify if System Information needs to be reacquired, reacquire System Information if necessary, notify a network node that the network node needs to transmit information (e.g., application layer payload) and receive from the network node an assignment of radio resources to be used by the wireless device to transmit that information.
System Information: The set of parameters sent by a network node on a broadcast control channel (BCCH) used by a wireless device to determine radio related parameters to be applied when attempting system access to the network node on the random access channel (RACH) of the common control channel (CCCH) and to determine the availability of neighbor cells.
System Information (SI) is information broadcasted by a network node (e.g., base station, eNodeB) in a cell to all wireless devices monitoring the specific cell. The reading of the SI by a wireless device, especially when in extended coverage, consumes energy and hence has a negative impact on a battery life of the wireless device. It is therefore of interest for the wireless device to read the SI as infrequently as possible. At the same time changes to the SI could be vital and should be communicated to the wireless device before the wireless device performs a system access procedure, by providing for example information on how the wireless device should access the system. Hence, it is also of interest to, as early as possible, indicate to a wireless device that is in the process of initiating a system access procedure that the SI has recently changed and therefore needs to be reacquired before performing the system access procedure. The aforementioned interests and other interests are addressed by the present disclosure.

SUMMARY

A network node, a wireless device and various methods are described in the independent claims. Advantageous embodiments of the network node, the wireless device, and the various methods are further described in the dependent claims.
In one aspect, the present disclosure provides a network node in a wireless communication system. The network node comprises a processing module configured to indicate that SI has changed in at least one of a FCCH block or a SCH block. Plus, the network node comprises a transceiver module configured to transmit the at least one of the FCCH block or the SCH block to at least one wireless device. The network node has an advantage in that the network node indicates to a wireless device that is in the process of initiating a system access procedure that the SI has recently changed and therefore needs to be reacquired before performing the system access procedure.
In another aspect, the present disclosure provides a method in a network node of a wireless communication system. The method comprises an indicating step and a transmitting step. In the indicating step, the network node indicates that SI has changed in at least one of a FCCH block or a SCH block. In the transmitting step, the network node transmits the at least one of the FCCH block or the SCH block to at least one wireless device. The method has an advantage in that it enables the network node to indicate to a wireless device that is in the process of initiating a system access procedure that the SI has recently changed and therefore needs to be reacquired before performing the system access procedure.
In yet another aspect, the present disclosure provides a wireless device configured to interface with a wireless communication system. The wireless device comprises a transceiver module configured to receive at least one of a FCCH block or a SCH block. Plus, the wireless device comprises a processing module configured to determine if the received at least one of the FCCH block or the SCH block indicates that SI has changed. The wireless device has an advantage in that while the wireless device is in the process of initiating a system access procedure, it can determine that the SI has recently changed and therefore needs to be reacquired before performing the system access procedure.
In still yet another aspect, the present disclosure provides a method in a wireless device configured to interface with a wireless communication system. The method comprises a receiving step and a determining step. In the receiving step, the wireless device receives at least one of a FCCH block or a SCH block. In the determining step, the wireless device determines if the received at least one of the FCCH block or the SCH block indicates that SI has changed. The method has an advantage in that while the wireless device is in the process of initiating a system access procedure, the wireless device can determine that the SI has recently changed and therefore needs to be reacquired before performing the system access procedure.
Additional aspects of the invention will be set forth, in part, in the detailed description, figures and any claims which follow, and in part will be derived from the detailed description, or can be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be obtained by reference to the following detailed description when taken in conjunction with the accompanying drawings:

FIG. 1 is a diagram of an exemplary wireless communication network which includes a network node (e.g., base station, eNodeB) and a wireless device, each of which are configured in accordance with an embodiment of the present disclosure;

FIG. 2 is a flowchart of a method implemented in the network node (e.g., base station, eNodeB) in accordance with an embodiment of the present disclosure;

FIG. 3 is a block diagram illustrating structures of an exemplary network node (e.g., base station, eNodeB) configured in accordance with an embodiment of the present disclosure;

FIG. 4 is a flowchart of a method implemented in a wireless device in accordance with an embodiment of the present disclosure;

FIG. 5 is a block diagram illustrating structures of an exemplary wireless device configured in accordance with an embodiment of the present disclosure;

FIG. 6 is a flowchart of a method which is implemented by the wireless device in accordance with an embodiment of the present disclosure; and,

FIG. 7 is a flowchart of a method which is implemented by the wireless device in accordance with another embodiment of the present disclosure.

DETAILED DESCRIPTION

As discussed in the Background section, it is of interest for a wireless device to read the SI as infrequently as possible. In addition, it is of interest to indicate as early as possible to a wireless device that is in the process of initiating a system access procedure that the SI has recently changed and therefore needs to be reacquired before performing the system access procedure. The present disclosure as discussed below addresses these interests and in particular the interest related to indicating as early as possible to a wireless device that is in the process of initiating a system access procedure that the SI has recently changed and therefore needs to be reacquired before performing the system access procedure.
Referring to FIG. 1, there is illustrated an exemplary wireless communication network 101 which includes a network node 100 (e.g., base station 100, eNodeB 100) and a wireless device 110, each of which are configured in accordance with an embodiment of the present disclosure. As shown, the network node 100 (e.g., base station, eNodeB) includes (1) a processing module 102 configured to indicate that SI has changed in at least one of a FCCH block 104 or a SCH block 106, and (2) a transceiver module 108 configured to transmit the at least one of the FCCH block 104 or the SCH block 106 to at least one wireless device 110 (only one shown) (as illustrated in FIGS. 2-3). The wireless device 110 includes (1) a transceiver module 114 configured to receive the at least one of the FCCH block 104 or the SCH block 106, and (2) a processing module 112 configured to (i) determine if the received at least one of the FCCH block 104 or the SCH block 106 indicates that SI has changed, (ii) when the SI has changed then read SI as part of a system access procedure, (iii) when the SI has not changed then determine if a last reading of SI is still valid, and when it is determined that the last reading of SI is still valid then continue a system access procedure without reading SI, and when it is determined that the last reading of SI is not still valid then read SI as part of a system access procedure (as illustrated in FIGS. 4-5).
Referring to FIG. 2, there is a flowchart of a method 200 implemented in the network node 100 (e.g., base station 100, eNodeB 100) in accordance with an embodiment of the present disclosure. At step 202, the network node 100 indicates that the SI has changed in the at least one of the FCCH block 104 or the SCH block 106. In one example, the network node 100 at step 202 a indicates that the SI has changed in the FCCH block 104 by shifting a frequency offset relative to a carrier center frequency to a level (amount) detectable by the at least one wireless device 110. For instance, the network node 100 can shift the frequency offset relative to the carrier center frequency to the level (amount) detectable by the at least one wireless device 110 to indicate that the SI has changed by one of the following: (i) using a negative modulation index for GMSK modulation, (ii) using an alternative (i.e., alternating) fixed bit pattern (it is to be noted that the conventional network node feeds its modulator with a stream of bits having form “0000000 . . . ” to create a tone at +67 kHz offset, while in the present disclosure the network node 100 can feed its modulator with a stream of bits having form of “0101010101 . . . ” to create a tone at −67 kHz offset), or (iii) using some other measure. In another example, the network node 100 at step 202 b uses a flag in the SCH block 106 to indicate that the SI has changed. At step 204, the network node 100 transmits the at least one of the FCCH block 104 or the SCH block 106 to the at least one wireless device 110. A more detailed explanation of this method 200 along with various alternative exemplary methods 600 and 700 associated with the present disclosure are discussed hereinafter.
Referring to FIG. 3, there is a block diagram illustrating structures of an exemplary network node 100 (e.g., base station 100, eNodeB 100) configured in accordance with an embodiment of the present disclosure. In one embodiment, the network node 100 may comprise an indication module 302 and a transmit module 304. The indication module 302 is configured to indicate that the SI has changed in the at least one of the FCCH block 104 or the SCH block 106. In one example, the indication module 302 indicates that the SI has changed in the FCCH block 104 by shifting a frequency offset relative to a carrier center frequency to a level (amount) detectable by the at least one wireless device 110. For instance, the indication module 302 can shift the frequency offset relative to the carrier center frequency to the level (amount) detectable by the at least one wireless device 110 to indicate that the SI has changed by one of the following: (i) using a negative modulation index for GMSK modulation, (ii) using an alternative (i.e., alternating) fixed bit pattern (it is to be noted that the conventional network node feeds its modulator with a stream of bits having form “0000000 . . . ” to create a tone at +67 kHz offset, while in the present disclosure the network node 100 can feed its modulator with a stream of bits having form of “0101010101 . . . ” to create a tone at −67 kHz offset), or (iii) using some other measure. In another example, the indication module 302 uses a flag in the SCH block 106 to indicate that the SI has changed. The transmit module 304 is configured to transmit the at least one of the FCCH block 104 or the SCH block 106 to the at least one wireless device 110.
As those skilled in the art will appreciate, the above-described modules 302 and 304 of the network node 100 may be implemented separately as suitable dedicated circuits. Further, the modules 302 and 304 can also be implemented using any number of dedicated circuits through functional combination or separation. In some embodiments, the modules 302 and 304 may be even combined in a single application specific integrated circuit (ASIC). As an alternative software-based implementation, the network node 100 may comprise the processing module 102 which includes a memory, and a processor (including but not limited to a microprocessor, a microcontroller or a Digital Signal Processor (DSP), etc.), and the transceiver module 108. The memory stores machine-readable program code executable by the processor to cause the network node 100 to perform the steps of the above-described method 200. It should be appreciated that the network node 100 also includes many other well-known components, but for clarity, only the components needed to describe the features of the present disclosure are described herein.
Referring to FIG. 4, there is a flowchart of a method 400 implemented in the wireless device 110 in accordance with an embodiment of the present disclosure. At step 402, the wireless device 110 receives the at least one of the FCCH block 104 or the SCH block 106. At step 404, the wireless device 110 determines if the received at least one of the FCCH block 104 or the SCH block 106 indicates that SI has changed. In one example, the wireless device 110 at step 404 a determines if the received FCCH block 104 indicates that the SI has changed by detecting a shift of a frequency offset relative to a carrier center frequency in the received FCCH block 104. In another example, the wireless device 110 at step 404 b determines if the received SCH block 106 indicates that the SI has changed by reading a flag in the SCH block 106. If the result of step 404 is a determination of yes, the wireless device 110 at step 406 reads SI as part of a system access procedure. If the result of step 404 is a determination of no, the wireless device 110 at step 408 determines if a last reading of SI is still valid. If the result of step 408 is a determination of yes, the wireless device 110 at step 410 continues a system access procedure without reading SI. If the result of step 408 is a determination of no, the wireless device 110 at step 412 reads SI as part of a system access procedure. A more detailed explanation of this method 400 along with various alternative exemplary methods 600 and 700 associated with the present disclosure are discussed hereinafter.
Referring to FIG. 5, there is a block diagram illustrating structures of an exemplary wireless device 110 configured in accordance with an embodiment of the present disclosure. In one embodiment, the wireless device 110 may comprise a receive module 502, a first determine module 504, a first read module 506, a second determine module 508, a continue module 510, and a second read module 512. The receive module 502 is configured to receive the at least one of the FCCH block 104 or the SCH block 106. The first determine module 504 is configured to determine if the received at least one of the FCCH block 104 or the SCH block 106 indicates that SI has changed. In one example, the first determine module 504 is configured to determine if the received FCCH block 104 indicates that the SI has changed by detecting a shift of a frequency offset relative to a carrier center frequency in the received FCCH block 104. In another example, the first determine module 504 is configured to determine if the received SCH block 106 indicates that the SI has changed by reading a flag in the SCH block 106. The first read module 506 is configured to read SI as part of a system access procedure if the received at least one of the FCCH block 104 or the SCH block 106 indicates that SI has changed. The second determine module 508 is configured to determine if a last reading of SI is still valid if the received at least one of the FCCH block 104 or the SCH block 106 indicates that the SI has not changed. The continue module 510 is configured to continue a system access procedure without reading SI if the last reading of SI is determined to still be valid. The second read module 512 is configured to read SI as part of a system access procedure if the last reading of SI is determined to not be still valid.
As those skilled in the art will appreciate, the above-described modules 502, 504, 506, 508, 510 and 512 of the wireless device 110 may be implemented separately as suitable dedicated circuits. Further, the modules 502, 504, 506, 508, 510 and 512 can also be implemented using any number of dedicated circuits through functional combination or separation. In some embodiments, the modules 502, 504, 506, 508, 510 and 512 may be even combined in a single application specific integrated circuit (ASIC). As an alternative software-based implementation, the wireless device 110 may comprise the processing module 112 which includes a memory, and a processor (including but not limited to a microprocessor, a microcontroller or a Digital Signal Processor (DSP), etc.), and the transceiver module 114. The memory stores machine-readable program code executable by the processor to cause the wireless device 110 to perform the steps of the above-described method 400. It should be appreciated that the wireless device 110 also includes many other well-known components, but for clarity, only the components needed to describe the features of the present disclosure are described herein.
Further, it should be appreciated that the wireless device 110 may refer generally to an end terminal (user) that attaches to the wireless communication network, and may refer to either an M2M device or MTC device (e.g., smart meter) or a non-M2M/MTC device. Thus, the term may be synonymous with the term mobile device, mobile station (MS), “User Equipment” or UE, as that term is used by the 3rd-Generation Partnership Project (3GPP), and includes standalone wireless devices, such as terminals, IoT devices, cell phones, tablets, smart phones, and wireless-equipped personal digital assistants, as well as wireless cards or modules that are designed for attachment to or insertion into another electronic device, such as a personal computer, electrical meter, etc.
The following is a detailed explanation of various technical features and various alternative exemplary methods 600 and 700 associated with the present disclosure. As discussed above, a flag is included in the SCH block 106 indicating that the SI has recently changed, which implies to the wireless device 110 that the wireless device's system access procedure is to also include the reading of SI. If the flag in the SCH block 106 is not set, and the previous reading of SI is still valid (according to some minimum allowed periodicity of reacquiring SI), the reading of SI need not be part of the system access procedure of the wireless device 110. It should be appreciated that the SCH block 106 is also used by wireless devices 110 to synchronize to the cell in both time and frequency. Plus, the SCH block 106 also includes information relating to the frame number and base station identity. Further, the indication where the SI has changed could also be provided in the FCCH block 104 rather than or in addition to the SCH block 106. The FCCH block 104 can be used to indicate that the SI has changed by using, for example, a negative modulation index for the GMSK modulation, an alternative (i.e., alternating) fixed bit pattern or other measures that shift the offset to a level (amount) detectable by the device, e.g., −67.7 kHz. It should also be appreciated that the FCCH block 104 is also used by wireless devices 110 to synchronize in frequency to a cell, and hence if an alternative frequency is used by the FCCH, the wireless device 110 will use the alternative frequency to synchronize to a cell. The current FCCH block 104 includes a single burst block consisting of 142 fixed bits modulated with GMSK which is equivalent to an unmodulated carrier, shifted in frequency by a 67.7 kHz frequency offset when compared to the GSM/EDGE channel center frequency.
Further, considering that different wireless devices 110 will access the system (i.e., network node 110) in different ways (some periodic, some more random, some with different inter-access time intervals), a set of predetermined rules could be used by the network node 100 and wireless device 110 to allow for a clear interpretation of the intention of the flag indicating the modification of SI. Such predetermined rules could include, but are not limited to:

- a. The network node 100 is only allowed to modify the System Information content no more often than once every X seconds and therefore needs to keep the value of the flag (and System Information content) unchanged for X seconds following any given instance of changing the flag value (and content of System Information).
- b. If a wireless device 100 wakes up and determines that the System Information has changed (e.g., the value of the flag has toggled since SI was last read or the amount of time since the wireless device's last system access attempt exceeds Y seconds), then the wireless device shall reacquire System Information.

Referring to FIG. 6, there is a flowchart of a method 600 which is implemented by the wireless device 110 in accordance with an embodiment of the present disclosure (it is to be noted that this method 600 can be referred to as “Simple Boolean flag on SCH indicating a modification of SI content”). At step 602, the wireless device 110 determines that a signal strength is high enough to synchronize to a cell. At step 604, the wireless device 110 reads the FCCH block 104 to provide a rough frequency and time synchronization in the cell. At step 606, the wireless device 110 reads the SCH block 106 to provide a fine frequency and time synchronization in the cell. At step 608, the wireless device 110 reads the flag in the SCH block 106 indicating if the SI has changed. At step 610, the wireless device 110 determines if the SI has changed by determining if the flag is set. If the result of step 610 is a determination of yes, then the wireless device 110 at step 612 reads the SI as part of the system access procedure. If the result of step 610 is a determination of no, then the wireless device 110 at step 614 determines if a last reading of SI is still valid. If the result of step 614 is a determination of yes, the wireless device 110 at step 616 continues a system access procedure without reading SI. If the result of step 614 is a determination of no, the wireless device 110 at step 618 reads SI as part of a system access procedure.
Referring to FIG. 7, there is a flowchart of a method 700 implemented by the wireless device 110 in accordance with an embodiment of the present disclosure (it is to be noted that this method can be referred to as “Simple Boolean flag on FCCH indicating a modification of SI content”). At step 702, the wireless device 110 determines that a signal strength is high enough to synchronize to a cell. At step 704, the wireless device 110 reads the FCCH block 104. At step 706, the wireless device 110 determines if the FCCH block 104 is rotated with −π/2 (90 degrees) (equivalent as placed +67.7 kHz or −67.7 kHz relative to carrier center frequency). If the result of step 706 is a determination of yes, then the wireless device 110 knows that the SI has changed and at step 708 reads the SI as part of the system access procedure. If the result of step 706 is a determination of no, then the wireless device 110 knows that the SI has not changed and at step 710 determines if a last reading of SI is still valid. If the result of step 710 is a determination of yes, the wireless device 110 at step 712 continues a system access procedure without reading SI. If the result of step 710 is a determination of no, the wireless device 110 at step 714 reads SI as part of a system access procedure.
In the foregoing description, numerous specific details are set forth. However, it is understood that embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the understanding of this description. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation. Plus, it should be appreciated that although the features in the present disclosure are exemplified in GSM/EDGE, other types of wireless communication systems may be able to similarly employ the functionality described herein including, for example, UTRAN, WCDMA, LTE, and WiMAX systems.
Further it should be noted that references in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to implement such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
Those skilled in the art will appreciate that the use of the term “exemplary” is used herein to mean “illustrative,” or “serving as an example,” and is not intended to imply that a particular embodiment is preferred over another or that a particular feature is essential. Likewise, the terms “first” and “second,” and similar terms, are used simply to distinguish one particular instance of an item or feature from another, and do not indicate a particular order or arrangement, unless the context clearly indicates otherwise. Further, the term “step,” as used herein, is meant to be synonymous with “operation” or “action.” Any description herein of a sequence of steps does not imply that these operations must be carried out in a particular order, or even that these operations are carried out in any order at all, unless the context or the details of the described operation clearly indicates otherwise.
Of course, the present disclosure may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. One or more of the specific processes discussed above may be carried out in a cellular phone or other communications transceiver comprising one or more appropriately configured processing circuits, which may in some embodiments be embodied in one or more application-specific integrated circuits (ASICs). In some embodiments, these processing circuits may comprise one or more microprocessors, microcontrollers, and/or digital signal processors programmed with appropriate software and/or firmware to carry out one or more of the operations described above, or variants thereof. In some embodiments, these processing circuits may comprise customized hardware to carry out one or more of the functions described above. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.
Although multiple embodiments of the present disclosure have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it should be understood that the invention is not limited to the disclosed embodiments, but instead is also capable of numerous rearrangements, modifications and substitutions without departing from the present disclosure that as has been set forth and defined within the following claims.

Claims

1. A network node in a wireless communication system, the network node comprising:

a processing module configured to indicate that System Information (SI) has changed in at least one of a frequency correction channel (FCCH) block or a synchronization channel (SCH) block; and

a transceiver module configured to transmit the at least one of the FCCH block or the SCH block to at least one wireless device.

2. The network node of claim 1, wherein the processing module is configured to indicate that the SI has changed in the FCCH block by shifting a frequency offset relative to a carrier center frequency by an amount detectable by the at least one wireless device.

3. The network node of claim 2, wherein the processing module is configured to shift the frequency offset relative to the carrier center frequency by the amount detectable by the at least one wireless device by one of the following:

using a negative modulation index for Gaussian Minimum Shift Keying (GMSK) modulation; or

using an alternating fixed bit pattern in the FCCH block.

4. The network node of claim 1, wherein the processing module is configured to indicate that the SI has changed by using a flag in the SCH block.

5. The network node of claim 4, wherein the processing module is configured to modify SI content no more often than once per a predetermined amount of time and maintain a value of the flag unchanged for the predetermined amount of time following a modification of the SI content.

6. A method in a network node of a wireless communication system, the method comprising:

indicating that System Information (SI) has changed in at least one of a frequency correction channel (FCCH) block or a synchronization channel (SCH) block; and

transmitting the at least one of the FCCH block or the SCH block to at least one wireless device.

7. The method of claim 6, wherein the step of indicating that the SI has changed in the FCCH block further comprises shifting a frequency offset relative to a carrier center frequency to an amount detectable by the at least one wireless device.

8. The method of claim 7, wherein the shifting step further comprises one of the following:

using an alternating fixed bit pattern in the FCCH block.

9. The method of claim 6, wherein the step of indicating that the SI has changed further comprises using a flag in the SCH block.

10. The method of claim 9, further comprising a step of modifying SI content no more often than once per a predetermined amount of time and a step of maintaining a value of the flag unchanged for the predetermined amount of time following a modification of the SI content.

11. A wireless device in a wireless communication system, the wireless device comprising:

a transceiver module configured to receive at least one of a frequency correction channel (FCCH) block or a synchronization channel (SCH) block; and

a processing module configured to determine if the received at least one of the FCCH block or the SCH block indicates that System Information (SI) has changed.

12. The wireless device of claim 11, wherein the processing module is configured to determine if the received FCCH block indicates that the SI has changed by detecting a shift of a frequency offset relative to a carrier center frequency in the received FCCH block.

13. The wireless device of claim 11, wherein the processing module is configured to determine if the received SCH block indicates that the SI has changed by reading a flag in the SCH block.

14. The wireless device of claim 11, wherein when the SI has changed, the processing module is further configured to read SI as part of a system access procedure.

15. The wireless device of claim 11, wherein when the SI has not changed, the processing module is further configured to determine if a last reading of SI is still valid, and when it is determined that the last reading of SI is still valid, the processing module is further configured to continue a system access procedure without reading SI, and when it is determined that the last reading of SI is not still valid, the processing module is further configured to read SI as part of a system access procedure.

16. A method in a wireless device in a wireless communication system, the method comprising:

receiving at least one of a frequency correction channel (FCCH) block or a synchronization channel (SCH) block; and

determining if the received at least one of the FCCH block or the SCH block indicates that System Information (SI) has changed.

17. The method of claim 16, wherein the step of determining if the received FCCH block indicates that the SI has changed comprises detecting a shift of a frequency offset relative to a carrier center frequency in the received FCCH block.

18. The method of claim 16, wherein the step of determining if the received SCH block indicates that the SI has changed comprises reading a flag in the SCH block.

19. The method of claim 16, further comprising when the SI has changed, reading SI as part of a system access procedure.

20. The method of claim 16, further comprising:

when the SI has not changed, determining if a last reading of SI is still valid, and

when it is determined that the last reading of SI is still valid, continuing a system access procedure without reading SI, and

when it is determined that the last reading of SI is not still valid, reading SI as part of a system access procedure.